Supercharger Performance and Engine Performance Parts

Posts Tagged ‘engine performance parts’

The LS1 powered Camaro Z28 is a great car, with plenty of power and great modification potential. One of the typical upgrade paths for Z28 owners is high flow heads, high lift moderate duration cams, and healthy doses of nitrous oxide. In unleashing this nitrous driven frenzy on the LS1 engine, the LS1 has proven to be a fairly robust contender in the face of a 200 horsepower shot of nitrous unleashed on the motor at 2500 RPMs, some people have even gone as far as spraying 300 shots on their stock LS1 with great success.

One of the great things about nitrous is it gives us some insight on the power of our engine. Since nitrous is typically delivered all at once in a single shot, then it usually produces huge torque figures at lower rpm ranges, and as the RPM’s rise, the torque increase from the nitrous shot drops down, as horsepower stays maintained.

The reason for this is the basic relationship between torque and horsepower.

Horsepower (hp) = Torque (ft.lbs) * RPM / 5252

By applying this math we find that a 200 horsepower shot sprayed at 2500 RPMs add about 420 ft.lbs of torque to the motor. And if we look at a dyno for a stock LS1 engine such as this one I found for a 2002 6speed SS, we find that the motor alone is making about 290 ft.lbs of torque at 2500 RPMs.

The motor on nitrous will be expected to make: 290 (motor) + 420 (nitrous) = 710 ft.lbs of torque. Quite impressive for our 5.7 L V8.

Now if you’re using 200 and 250 and 300 horsepower shots of nitrous, you will get bored fairly quickly of the amount of money and time that you waste refilling the nitrous bottle, and you may be willing to pay one time lump sum to have that power avaialbe to you ‘on tap’ rather than in the bottle.

Using our same formula and taking our 710 ft.lbs of torque up to the LS1’s redline of 6200 RPMs I find that I can fairly safely set my peak horsepower goal to be:

710 * 6200 / 5252 = 838 horsepower.

So let’s think about this for a minute, I can make 515 horsepower using a 200 shot worth of nitrous, or I can make 838 horsepower using a centrifugal supercharger setup all the while not exceeding my bottom ends’ well known, tried and true, withstand of 710 ft.lbs of torque. I think this is a very safe adventure into supercharger performance.

Looking at the stock LS1 dyno we can see that peak power is delivered early at 5200 RPMs through the use of conservative 202*/210* duration camshafts (intake/exhaust) in stock format. According to my calculator, that duration cam would typically put peak power around 4500 to 5000 RPMs which corresponds to our dyno shoot.

Before we find out how much boost we should expect to need to reach 838 horsepower we should factor in the fact that we plan on making 838hp at 6200 RPMs rather than 5200 RPMs through the use of a proper supercharger camshaft. Again using my power calculator I come up with an ideal cam configuration of 210*/244* (intake/exhaust) with a target LSA of 112 to 115 degrees. And based on our new peak power RPM we find that we will probably need 18psi of boost to make 838 hp @ 6200 RPMs (on the other hand we could make 838 hp @ 5200 on the stock camshaft at a much higher 24 psi… I personally would rather make the power with RPM at lower boost than use much 20+ PSI figures on a restricted motor).

Based on my calculator, the following falls into place for our 838 horsepower stock block LS1 build up:

Quite an impressive build we are about to take on. Now these are calculated figures. Not all of them will end up being exact as we need to source available parts that work for our target build.

Supercharger:

Procharger offers a supercharger kit for the LS1 based off of its P1SC2 supercharger (or the even larger D-1SC) which

P-1SC1 impeller...

are at least capable of delivering 1200 CFM @ up-to 32psi of boost if needed. Perfect for our requirements of 1200 CFM and 18psi.

Camshafts:

Looking around for a bit I found thunder racing’s cheater camshaft which is perfect for our application: 214* intake duration, 230* Exhaust duration, and 117* LSA. Notice in the description they say ‘responds very well to nitrous’, well high boost supercharger applications have similar cam requirements to nitrous oxide in that you neither want excessive overlap (to waste your nitrous or boost into the exhaust manifold, and at the same time your duration requirement on the intake cam is reduced (to reduce overlap and because of the compression of the air via nitrous or a supercharger means that you can ingest more air volume in a shorter duration of time). A great find.

 Thunder Racing Custom Camshaft
“CheaTR” - 214/230 .601/.575 117 LSA. Off Idle-6800 RPM Power Band. Broad power range. Works well with stock exhaust manifolds and catalytic converters. Stock like idle. Minor tuning required on automatic transmission cars.  Responds very well to nitrous.  Due to the fast ramp rate of this camshaft, the use of 1.8 rockers is not recommended.  Double valve springs and titanium retainers required for this cam.

The ideal figures we got for cold side and hot side piping are 190mm and 170mm respectively. These figures are calculated based on less than 1 horsepower loss in the intake system and less than 0.01 psi pressure drop. Now air is a compressible fluid. If it needs to go through a 90mm intake system rather than a 170mm intake system it can do so. However, there is a certain pressure required to force the air to flow through this bottle neck of a restriction and that shows up as a pressure drop.

As we said earlier we’re going to need 18psi of boost to reach our target hp goal on the motor giving the parameters given in the calculation. But if we use a 92mm throttle body costing us 18hp and 0.25psi, a 125mm intake hose (as we have calculated later on for our MAF housing), costing us another 6hp and 0.1 psi, as well as an undersized header with another 3 or 3 psi in back pressure from using 2” primaries rather than 2.4” primaries, then the overall pressure losses in the system can add up to about 4psi. What this means is that in the end, when all is said and done, we will probably make our target 838 horsepower somewhere between 18psi and 22psi because some of our parts were undersized.

For the supercharger cold-side piping, the supercharger has a 3.75” inlet which we will expand out to 125mm or a 5” intake using our new 125mm MAF housing and a 5” air filter.

For the supercharger hot-side piping, the supercharger has a 3” outlet which will take out to 3.5” using 3.5” piping into our procharger air to air intercooler and all the way into a 92mm (3.62”) throttle body.

This 92mm throttle body is the largest I could find for a bolt on LS1 throttle body and comes as part of a package with the Fuel Air Spark Technologies (F.A.S.T) LSX style intake manifold for the LS1.

This throttle body will cost us 18hp at our target power level, but we should more than make that up elsewhere. Why so? Because all these calculations are done based on a stock motor (stock intake, header, exhaust) figures. The only modification I have factored in here is Cams and boost pressure. If I were to factor in the fact that the factory motor is restricted by the factory intake, header, exhaust systems, and that it could potentially gain 3 or more psi of pressure losses by upgrading those items, and if you factor in that we in the process of installing our supercharger package are in fact upgrading those same items, then it’s safe to say that my 838 is a somewhat conservative estimate of what a Cammed LS1 can put down at 18psi of boost. However, I like to do my math conservatively and be pleasantly surprised by the results later on J.

Intercooler

The kit also comes with procharger’s twin high flow intercoolers which are each sized at 11 x 9 x 4.5 or a core volume of 445.5 cubic inches. In total we have 891 ci of intercooler cooling volume (between both intercoolers) compared to our original calculations of 1470 cubic inches. Instead I would call up procharger and try to get a larger core (to try to stay away from needing water injection for this application) … and choose something like their Air to Air core at 27.5” X 12” X 4.5” which they rate to 1300hp and should do very nicely on our 838 (or more) horsepower build. Furthermore this intercooler has 3.5” inlets and outlets which match our chosen throttle body for a good matched package.

Headers

Kooker race header with 2" primary and 3.5" collector.

This was actually pretty tough to find. There are probably many supercharged LS1 powered Camaro’s out there, but yet the only header that I could find that comes close to our requirement (2” primary, short 12” (or longer) runner length into a 3.5” collector) seems to be the Kooks race header with venture collectors. The kooks header comes with 2” primaries and 3.5” collector.

Exhaust

For the exhaust there are two options:

1-      To do a custom dual 3.5” exhaust with 3.5” X-Pipe and under car turn downs releasing the exhaust gases before the rear differential (see picture), or even using some custom 3.5” side pipes if you like.

True dual x-piped exhaust with under car exit before the bell housing.

2-      To make a custom 3.5” exhaust cutout section right after the 3.5” collector exit on our cook headers, and then from then on reduce the exhaust back down to a typical 3” exhaust and get an aftermarket single or dual 3” exhaust that will be used for normal street use. When full power is demanded, the 3.5” exhaust can be unleashed right at the headers at the flick of the switch by opening the e-cutouts and dumping the exhaust before the cat-back.

Fuel System:

According to our calculations, we need to be able to supply 350 liters per hour (lph) of fuel at a constant fuel rail pressure of about 40psi. Most typical single fuel pump upgrades use a Walbro 255 lph pump instead of the stock pump. Although this pump alone is good with the proper hotwire kit to 610 crank horsepower, it will not be enough for our target power figure. One option is to install a kenne-bell boost a pump which can increase the pump voltage from 14volts (stock with a hotwire kit) to 17 volts or 20 volts. Increasing the voltage from 14volts to 20 volts potentially gives us a 42% increase in flow making our pump capable of delivering 362lph of fuel which can meet our requirements.

Lonnie's performance fuel kit

I think for our application, I would rather cut it safe than cut it close. Who’s to say that we end up geared with our pulley system for exactly 18 psi? Who’s to say that we don’t end up making 850 horsepower with our setup when all is said and done? Who’s to say that the motor won’t want to run a one point richer air fuel ratio at that power level and so our fuel delivery requirements will actually be higher by about 8 to 10% to cover that extra point of air fuel ratio.

Instead a better approach for this application would be to use a complete fuel supply kit, including dual in-tank pumps, a hotwire kit to deliver full 14volts to the pumps, complete with new fuel feed and return lines (matched for 800hp) and some high flow fuel rails to make sure that every injector (weather it is right at the fuel feed or at the end of the fuel rail closer to the return) sees the same amount of fuel pressure, because the fuel rail is large enough that there is no significant pressure drop between injector #1 and injector #4.

One such kit is provided by lonniesperformance in conjunction with racetronix.

The kit includes

Double Pumper Kit & Complete Custom Fuel System
Camaro/Firebird ‘99up LS1 Double Pumper -- Twin High Output Fuel Pump Kit,  Wiring Harness & Hobbs Switch -- Fully Assembled & Tested - Requires your sending unit for modification

Includes -8 Supply & -6 Return lines, fuel rails, regulator, filter, & all fittings needed to connect to double pumper sending unit.
LS2 fuel rails optional.
LS7 fuel rails optional.

Fuel Injectors

Delphi 75 lbs/hour injectors

Again we can pick these up from lonnies performance. By our calculations we need 630cc/min injectors (or 63 lbs/hr injectors). It’s a good rule of thumb to have injectors that will deliver your fuel needs at around 85% duty cycle. Which means to deliver 63 lbs/hr of fuel per injector we need a fuel injector that can deliver 74 lbs/hr.

Driving larger injectors to 85% of their maximum capacity is ultimately safer than trying to extract 100% of the capacity out of a smaller injector. The reason is that an injector that is running at 100% duty cycle is more likely to fail, and any variation in power level or boost level means that you have no room to increase your fuel delivery because your injectors are maxed out.

A set of 75# (or 75 lbs/hour) Delphi injectors will do the trick for our build.

Tuning

One simple route for tuning is typically to use a matched pair of an upgraded MAF sensor and upgraded injectors. For example using a 100% larger MAF sensor or MAF housing recalibrates the performance of the factory computer around the use of injectors that are also 100% larger than stock.

This approach works well for low boost packages or normally aspirated buildups of the healthy 5.7L V8.

The largest MAF housing I could find was a 100mm MAF which is maxed out at a reading of 511 grams per second of air. If we do some calculations we find that 511 grams per second comes out to about 545 hp worth of air which is shy of our eight three eight horsepower goal. If we were to use this kind of setup on our car, the ECU would not know the difference between 600 hp and 800 hp because at both situations it would be reading full MAF voltage and giving the command to the injectors to go Full on at 100% duty cycle.

There are two reliable ways we can go about solving this problem:

1-      Upgraded MAF / Injector combo

850 horsepower / 545 hp = a mass ratio of 1.56 (or an increase in area of 56%).

TSP 100 mm MAF

To make our stock MAF sensor capable of reading 850 horsepower it is possible to transplant the sensor into a housing that has an area that is 56% larger. Doing the math we find that transplanting the sensor into a 125 mm housing can do the trick. The problem with continuing to transplant the stock sensor into a larger housing is two-fold:

As the housing gets larger, then at very low flows (such as at idle) the small amount of air flowing through the larger 4.7” pipe can get turbulent, and as it gets turbulent, then the sensor reading oscillate as the air spinning inside this 4.7” pipe hits the sensor in waves (rather than in nice laminar flow). What this does is it gives inconsistent readings to the ECU about the amount of air flowing, and results in a wandering air fuel ratio because the fuel supply itself can be oscillating based on the reading.

One of the things talked about in mechanical engineering is the flow profile of a fluid in a pipe. Obviously the walls of the pipe have some resistance to the air flow, and this wall resistance means that the air travelling in the center of our 4.7” pipe is at a higher velocity than the air travelling on the surface walls of our pipe (because this air has some frictional forces reducing its velocity). As our flow pipe gets larger then our sensor gets moved farther and farther away from center of the pipe, and thus our sensor’s reading is less accurate because it’s measuring the slower air closer to the pipe walls.

If you find that you have either of the two problems (a poor idle and wandering air fuel ratio, verified with a wandering OBD-Log of your MAF reading, or a sensor that seems to be under-reading the amount of air as you get into boost verified with comparing your required injector duty cycle to sustain your target air fuel ratios compared with the amount of air that your sensor is reporting) then one typical solution is to use some fine wire mesh to create your own MAF screen. The screen that we see common on factory sensors helps reduce this velocity profile for the air as it enters the sensor for metering and makes the air closer to laminar at that point, such that any sample of that air being metered is very similar to the velocity, density, and temperature of the rest of the air being unmetered by the sensor.

Matching our 125mm MAF, with our 75lph injectors we can then do the rest of our tuning using the factory ECU and a flash tuner.

2-      Speed density setup:

A speed density setup eliminates the MAF sensor altogether replacing it with a manifold pressure sensor, air temperature sensor, and uses both RPM and throttle position readings as well to approximate the car’s air flow requirements based on those inputs.

I prefer directly metering air myself rather than extrapolating it from pressure and some assumptions about volumetric efficiency. When you directly meter air, if you for example open your exhaust cutouts (as stated earlier in our exhaust section) and those cutouts allow your engine to breathe in more air, then that air will get metered and your ECU will know about it adding more fuel. If you use a speed density setup then when you get into situations where your motor is breathing in more air at the same (or even lower) boost pressures because of a change in volumetric efficiency then your ECU will be completely oblivious to the change.

Water Injection

Since we got cams for our setup (to reduce our peak boost requirements for our target horsepower) and since we were able to source a good sized intercooler for our power goals, we may not need water injection at all on this build. This is not by accident, but rather by design. In our calculations we came up with 12 gallons per hour of water injection (typically this figure comes in as 10 to 15% of the fuel delivery of our car).

If you have a 12 gph water/methanol injection setup and a healthy 2 gallon tank in your trunk, then you will run out of water/methanol mix in 10 minutes of full throttle time.

It quickly becomes clear that you would rather invest in some power upgrades (to lower your peak boost level and thus your peak inlet air temperatures) as well as invest in a healthy sized intercooler (again to lower your peak inlet temperatures) so that you can steer away from having to drag behind you a water/methanol tanker to keep up with your supplemental injection needs.

Spark plugs

Typically 1 step colder spark plugs are needed for every added 100hp as well as a 2-3* ignition timing retard for the same, at least that is a good starting point, and then hotter plugs or more ignition advance can be added when tuning.

The stock NGK spark plugs for the LS1 is a TR5 which is a 14mm 3/8” hex plug with 18mm reach and a projected tip, a tapered seat and is resistive for reduced EMI.

After looking NGK’s part code I think the best start would be BR10ECMIX iridium plug (or a similar BR10ECS copper plug which is cheaper). The spark plug has 1mm more reach, but is a non projected tip which we need for a high power application and is 5 heat ranges colder than stock as required by our additional 500hp. Furthermore the ‘CM’ designation means that this is a compact plug with a low profile or even side discharge ground strap so both the spark plug gap is reduced (for high boost) and the ground electrode is moved farther away from the center of the combustion chamber and reduced in size to prevent it from becoming a hot spot and an instigator for detonation.

Expected dyno:

Based on an expected boost curve and a stock LS1 dyno, I’ve created the following expected dyno for our car.

-          Blue lines are stock hp and torque.

-          Green Lines are Stock + 200 shot of n2o (peak torque at 700 ft.lbs and peak hp at 500hp).

-          Red Lines is our custom supercharged setup. If you look closely you see that I have not crossed the 700 ft.lbs line on this setup yet we are able to reach our peak power goals over 800 horsepower. Reliable, progressive power delivery from zero to redline.

LS1 stock, vs 200 shot vs 18psi + supporting mods centrifugal

 Some Procharged LS1’s on youtube …

Links to parts:

Thunder Racing (Split patter camshaft for 6800 rpm supercharger application)

Procharger (P-1SC2 supercharger kit and race intercooler)

Lonnie’s Performance (Complete fuel system solution up to 1000 hp)

Kooks headers (2” primary headers into 3.5” collector)

DMH (electric exhaust cutouts)

Burns Stainless (X-pipes and custom exhaust)

FAST (intake manifold and 92mm throttle body)

Texas Speed and Performance 100mm MAF

Clubplug (NGK spark plugs)

Technorati Tags: boost, Camara, camshaft, CFM, engine performance parts, Intercooler, kooks header, LS1, MAF, Procharger, supercharger performance, twin-pump fuel system

Positive displacement superchargers do not usually compress air inside the supercharger but rather better described as air pumps. Positive displacement superchargers are usually rated in liters or cubic inches (or a similar measure of displacement). The reason behind that is that a 1.5L rated positive displacement supercharger moves 1.5 liters of air per revolution and so to produce 15psi of boost (or a pressure ratio of 2.0) on a 1.5 liter engine, the supercharger would have to be geared to double the rotating speed of the engine. Thus for every round of the engine, the engine would normally ingest 1.5 liters of air, at the same time for every round of the engine, the supercharger completes two full rotations because of the gearing between the engine crank and the supercharger, and thus the supercharger puts out 3.0 liters of air for every 1 revolution of the engine.

The result is that the supercharger pumping and feeding 3.0 liters of air to a 1.5 liter engine, which results in the air being compressed inside the intake manifold between the cylinder and the supercharger, and effectively forcing the engine to breathe twice as much air, simulating a motor that is twice as large, and producing double the horsepower.

Based on this theory, the easiest way to raise the boost and thus increase the power of a supercharged car is to increase the gearing between the engine and the supercharger, making the charger spin faster and force more liters of air into the engine for each revolution.

However, superchargers are limited due to the size and weight of their rotating assembly, the tolerances between the tips of the rotating rotors, and the adiabatic efficiency of the supercharger to a certain maximum operating rpm. Exceeding the maximum rpm causes the supercharger to become inefficient, producing extremely hot output air which isn’t good for performance, possibly over-vibrating and overheating its internals and permanently damaging the rotors or having them contact the housing, and increasing the supercharger drive requirement excessively (the horsepower required to spin the supercharger to that rpm).

One of the solutions to increasing the performance of your vehicle is to upgrade to a larger supercharger, that can pump more air per revolution and so produce more boost and more power at its maximum operating rpm. However, having most supercharger kits incorporate the supercharger and intake manifold or the supercharger and throttle inlet in one mechanical package it becomes difficult to just swap to a bigger supercharger as you would with a turbocharger.

The next best solution available in such a situation is modifying the existing supercharger to make it more power friendly. Since the primary utilization of positive displacement superchargers is for factory vehicles and OEM manufacturers, there are many provisions built into the manufacturing process of the supercharger geared towards reducing the supercharger’s manufacturing cost as well as improving its NVH (noise, vibration, harmonics) performance such that the factory vehicle can adhere to local or international design standards.

Now if we’re willing to spend some money to improve our supercharger, and we’re willing to put up with (or better yet yearning for) more of that iconic supercharger whine, then supercharger performance porting becomes a viable option.

The goal of supercharger porting is to essentially turn our 1.5 liter supercharger into a 1.8 liter supercharger for example. So in simple terms, modifying the supercharger so that it is capable of pumping more air volume per revolution, and so producing more peak airflow (in CFM) at the same maximum operating rpm.

The modifications typically performed when modifying a supercharger include:

·         Enlarging, blending and smoothing the supercharger inlet port

·         Casting protrusion elimination

·         Raising the roof

·         Enlarging and reshaping the outlet port

·         Rotor coating

·         Plugging the silencer ports

A brief overview of the twin rotor supercharger:

The supercharger typically has two helically twisted three prong rotors encased in a dual chamber housing. Air enters the supercharger from the back of the charger through the inlet port, and is guided to the top part of the rotor housing called the roof. As the rotors turn in opposite directions, they grab the air that is available in the roof of the charge, and trap it in tight tolerance between the rotor blades edges and between the supercharger sidewalls. No compression is performed to the air, it is just trapped against the supercharger wall and pumped downwards with the rotation of the rotors.

As the rotors reach the bottom (the floor) of the supercharger they release the air into the manifold through the supercharger outlet port. The fact that the supercharger is overfeeding the engine causes the air to compress as it exists the outlet port (as explained earlier) through positive displacement of more air than the motor can breathe.

Now in light of that, let’s review our modifications:

·         Enlarging, blending and smoothing the supercharger inlet port

The supercharger inlet port is where our modifications will give us the most improvement result because it reduces restriction in the intake path of the supercharger. With reduced restriction, the supercharger can flow air more easily and that reduces horsepower drive loss and increases flow per revolution. Since this part of the supercharger has no fuel in it, and thus there is no fuel atomization requirement, the internal walls of the inlet port can be polished and smoothed. Any sharp turns or transitions between the throttle body or the supercharger inlet and the supercharger housing should be smoothed, also any rough transitions between the inlet port and the rotor housing should also be smoothed especially on the top half of the charger (opposite the outlet port) as that is where the rotors get their fresh air.

·         Casting protrusion elimination

Due to cost reductions in supercharger production, sometimes there are some materials protruding the inlet port of the supercharger. Any such protrusions should be removed, and then the housing refilled with aluminum putty filler or JB Weld, and then resurfaced smooth.

·         Raising the roof

Slightly raising the roof of the supercharger gives the supercharger more volume of air to grab per revolution.

·         Enlarging and reshaping the outlet port

Depending on the target pressure ratio for the application, there is an obvious relationship between the area of the inlet port and the area of the outlet port. If air enters the supercharger at 0psi (which is 1 atmosphere) and exists the supercharger at 15psi (or 2 atmosphere) then the exiting air although it has the same mass, has half the volume. So it makes sense that if our inlet port is 20 square inches large that at a target pressure ratio of 2.0 our outlet port need only be 10 square inches larger. Thus enlarging the outlet port doesn’t necessarily have much power gain potential because inherently it is less of a restriction.

When porting the supercharger outlet port, there is a limitation to how much we can enlarge the port or reshape it. The supercharger has a helical twisted rotor and for eaton this is a 60 degree twist. If you visualize a twisted rotor spinning, capturing air between the rotor and the housing, and then as the rotor’s blade reaches the floor of the rotor housing the rotors blades create a V shaped contact area.

This is why the outlet port is V shaped or triangle shaped to match the twist of the rotors and to make sure that air stays trapped properly till the rotors reach the floor of the housing to force the air into the manifold.

Enlarging and smoothing the outlet port is possible however, the maximum that we can enlarge this port to can be found by tracing a line around the exact point where the rotor touches the housing floor of the charger housing and porting to that line.

·         Rotor coating

One of the changes between the earlier and later generation Eaton superchargers is that the newer blowers have coated rotors. The rotors are coated with Teflon/Ceramic/Carbide abradeable coating. The coating does two things:

1-      Helps the rotors withstand, distribute, and manage heat better especially when using the supercharger at higher rpms.

2-      The  coating adds thickness to the rotor. When the rotor is heated by its normal operation it expands to a certain extent. If the rotor expands too much within the housing then rather than having a proper seal against the housing wall (to trap air) it may touch the wall causing the whole assembly to catastrophically seize. To prevent this seizure, there is typically a tolerance (a room for error if you will) left between the rotor tip and the housing. This room is bad for performance because it allows the air to escape rather than be trapped by the rotating rotor and thus reduces the superchargers pumping and adiabatic efficiency. To improve efficiency on the later generation superchargers the Eaton engineers have come up with an abrade-able teflon-carbon based coating that makes the rotor slightly thicker. When the rotor expands it now basically touches the housing, but this is now not a metal on metal contact, but rather a metal (housing) to carbon-teflon (rotor coating) contact. What happens here is that the harder material (which is the aluminum housing) wears down the softer material (the carbon-teflon coating) shaping it to the exact shape of the housing and giving a more exact seal between the rotor tip and the housing, better trapping air, improving supercharger flow per rotation, reducing pumping losses, and thus reducing outlet air temperatures. This idea can be used on any twin rotor charger to improve rotor seal and is really a great engineering solution.

·         Plugging the silencer ports

Besides the supercharger outlet port, there are typically two or more smaller ports called the silencer ports. Depending on weather whether the air in the supercharger housing or the air in the intake manifold has a higher pressure, then these ports allow air to flow in and out of the supercharger housing around the rotors to faster equalize the pressure between the two chambers. Reasons for having pressure differences between the supercharger and the manifold attached to it would be like having a throttle body in the system after the supercharger for example. If this throttle plate is rapidly opened (jumping on the throttle –full throttle) or rapidly closed (going from wide open throttle immediately to no throttle) then positive and negative pressure waves will travel back and forth between the throttle body plate up the intake system and reflect off the supercharger outlet back and forth. These pressure pulses and fluctuations caused by the dynamics of the engine are unavoidable. As we all know, sound is created from pressure waves and so these waves reflecting back and forth in the intake system create some unwanted noise in the engine bay, more so if we have a sealed system where the pressure waves are trapped to reflect back and forth multiple times. The supercharger silence ports are small bleed ports between the outlet of the supercharger that bleed air back into the supercharger housing. This is obviously bad for pumping efficiency because some of the air pumped in by the supercharger is not held as boost, but always being bled back (as a designed air leak) back into the supercharger housing. But as we said before, in situations where there are dynamic pressure changes between the supercharger housing and the rest of the intake system, having this air bleed allows the pressure to equalize faster (rather than waiting for it to reflect and die out) which improves noise performance.

Since we are interested in improving the pumping efficiency and are not required to adhere to noise, vibration, and harmonics standards like original equipment manufacturers, these ports are typically plugged with aluminum putty or JB weld and surfaced down to a smooth finish. Now that we’ve done so, 100% of the air pumped by the supercharger is trapped in the engine which increases our boost pressure and our positive displacement of air per revolution.

Results of all of these modifications are typically in the 10 to 15% range, so depending on whether we are talking about a 200hp capable Eaton M45 or a 500hp capable Eaton M120 gains will vary between 20 and 75 hp which are sizable increases. Further performance gains can be found by increasing the supercharger rpm (now that it is able to flow more air at higher RPMs after it has been ported) and so higher gains are possible for race applications. I would be reserved though about exceeding supercharger manufacturer stated peak operating RPMs for road going vehicles that will see extensive use of the supercharger at those RPMs.

Technorati Tags: engine performance parts, Porting, Positive Displacement, Rotor, supercharger performance

This is the triple distilled guide on engine performance parts to help you make the most power with the least effort. There’s an abundance of bolt on and custom application engine performance parts available for any vehicle, and the internet is full of advice, trials, and feedback from enthusiasts, brand promoters, magazine editors, and even racers about which performance parts are best for your car. 

Engine performance hinges on one of THREE general factors:

1-      raw power factors

2-      efficiency factors

3-      Power boosters

3-      Power Boosters:

Typically called forced induction, power boosters include serious modifications to your engine that can result in a 30 to 400% power increase while maintaining the same raw power and efficiency figures (i.e. at the same peak rpm and with the same displacement).

Because of this serious increase in power, power boosters are the great equalizer that allows smaller engines to simulate and exceed the performance of a much larger engine. Originally these technologies were developed for conditions where more power was needed with a limitation on the physical dimensions of the engine. A prime example for this would be requiring more horsepower for a plane that would see most of its usage in high altitude thin air. The engine for this type of aircraft faces the difficulty of having to carry its weight and still maneuver with high performance and accuracy, which places maximum weight and size requirements on the engine and complete aircraft. Furthermore, the engine would have to operate efficiently and produce power in thin air which is less dense and thus less oxygen rich making it have less power potential.

After time these technologies moved into automotive racing and from there into aftermarket modifications and finally into production automobiles.

There are three types of Power boosters I want to mention here:

Engine Compression ratios:

Some may argue that this is an efficiency modification, but since this modification actually ADDS more horsepower rather than freeing up system inefficiencies I have chosen to set it apart here.

The addition of 1 compression point typically results in a 4% power increase and reduced fuel consumption. Bumping up a car’s compression ratio from a typical 9:1 compression ratio to a more performance oriented 15:1 for example is a potential power increase of 24%. I don’t think this kind of power increase can be considered an ‘efficiency’ upgrade but rather a legit power boost.

Let me disclaim here that increasing the motor’s compression ratio , as well as using all the other power booster modifications in this section, significantly increases the final combustion pressure produced inside the motor (especially when using more than one power booster in tandem), and thus there is definitely a need for:

1-      Higher octane fuel requirements to prevent preigntion detonation and reduce the speed of the flame front for normal ignition events.

2-      Heat management, through increased head cooling, using aluminum heads, colder spark plugs, and upgraded cooling system capacity to be able to cope with a significant increase in power (and its co product which is heat).

3-      A more conservative retune to a richer air fuel ratio that helps maintain stable exhaust gas temperatures that indicate a sustainable combustion process rather than an explosion occurring inside the engine

4-      A more conservative retune to for ignition timing and cam overlap that helps maintain stable exhaust gas temperatures that indicate a sustainable combustion process rather than an explosion occurring inside the engine.

Chargers (weather they are turbochargers or superchargers)

Turbochargers and superchargers intercept air in the intake system before it reaches the engine and compress it making it denser leaving more oxygen per volume of air. If the air is compressed to half its size for example then we will be able to fill a 2.0 Liter engine with 4.0 Liters of air per revolution. If we also make available double the fuel injection coupled with proper tuning, then we can successfully produce double the horsepower because there is literally twice as big a combustion occurring inside the engine.

Of course under normal conditions the engine would never breathe 4.0 Liters of air on its own, and thus charger works as a pump that keeps the engine pressurized by overfeeding or force feeding it with more air than it would have ingested under normal conditions.

The term boost or ‘psi’ (pounds per square inch) is a measure of how much pressure is placed on the motor and thus boost is highly related to how much more air is ingested into the motor. Every 1psi of boost is equivalent to a power increase of 7% over what the engine would make without a turbocharger, so increasing the pressure of an engine by just a few psi can show a significant increase in power and torque.

With 93 octane gasoline and proper tuning, boosting an engine to 15 to 18psi is pretty safe and thus increasing an engine’s power by 120% is not uncommon with a ‘street’ friendly turbo system. More power increases can be seen with race setups and higher octane availability.

One of the advantages of turbochargers and superchargers is that since the air is compressed (for example to half its original size at 14psi) then  a conservatively sized 45mm throttle body looks to like a 63mm throttle body from the point of view of the compressed air. In this way, turbochargers and superchargers can overcome inefficiencies in the design of the engine’s intake path because compressing the air makes it occupy a smaller volume (for the same oxygen content) which makes the intake system seem like less of a flow restriction.

This also makes some of the efficiency modifications (namely those between the charger and the intake valve) less in need of being modified as they are less of a power restriction.

Nitrous Oxide Injection

Nitrous oxide injection is similar to turbochargers and superchargers in that it delivers more oxygen to the fire in the same volume of air and thus in the same engine displacement. Nitrous oxide does this in two ways:

1-      Rather than compressing air to a smaller volume to increase oxygen density, nitrous oxide is composed of two nitrogen molecules and 1 oxygen molecule. This composition makes nitrous oxide 33% oxygen rich by volume compared with normal air which is around 16% oxygen by volume. What this means quite literally is that if we had an engine breathing pure nitrous oxide flowing at room temperatures and atmospheric pressure then the horsepower output would simply be doubled.

2-      However nitrous oxide is delivered to the engine in compressed form (as it is compressed to 1000psi when it is packaged into the bottle). Using the same formula for pressure and volume that we used for turbochargers, a 1000 psi pressurized bottle is compressed 70 times or to 1/70^th its original volume. This  means that feeding an engine purely with nitrous oxide at the temperature and pressure at which it comes out of the nitrous bottle, we could potentially produce 140 times more horsepower from that engine than we could having it breathe normal air! How is that for a replacement for displacement?

Practically speaking, nitrous oxide is usually used for a power boost of 50 to 100% depending on how prepared the engine (and the user is) for the power boost, and depending on the style of nitrous delivery (for example progressive direct port nitrous injection is the most reliable type of injection for 100% or more nitrous power boosts).

So in summary of the whole article…. Here’s what I recommend:

1-      Figure out how much horsepower you want to achieve

2-      As stated in part 1, figure out the engine combination with the highest potential that is allowable for you in the rule books.

3-      Look at how much boost you will need if any with that engine combination to reach your power goals

4-      Depending on weather you need a 20% power boost or a 200% power boost, pick your power adder (from a small compression increase, to a small nitrous shot, to a larger supercharger or turbocharger setup, to a combination of power boosters) that will allow you to reach your goals.

5-      Last (and not first), plan out the supporting and efficiency modifications that are required for that engine and power adder combination (from part two of this article). Basically you want to install the efficiency parts that will allow you to flow the amount of exhaust gas that you need at your peak power level, and optimize your entire engine package around your target peak PRM, anything else would be a waste of money.

6-      Understanding that upgrading engine efficiency is limited to a 10-20% power increase over stock as well as performing modifications planning in the sequence that I have just described, may save you TENS of THOUSANDS of dollars from being wasted upgrading a motor that just frankly doesn’t have the raw power potential (in terms of displacement, RPM or stroke) to meet your power requirements, or requires an unrealistic power boost combination (such as a 400% power hike using an exotic turbo setup) to reach the power goal requirements that you have.

I know that most of the advertising and development in performance modifications spent on things like intakes and exhausts (covered in part two of this article), but that is easily explainable:

1-      Those parts although they don’t add much horsepower to your car, are exactly what 80% of the people are willing to install on their cars because they sound cool, are cheap, may require no tuning at all, and are fairly easy to install.

2-      Those parts are also a gateway modification to more power modifications in the future, and so come at a smaller entry price and smaller install complication to get you willing to work on your car and purchase parts (basically a marketing ploy). If everyone were chucking their stock engines for a larger big block grabbed from the junkyard then all the shallow aftermarket performance companies (producing only efficiency parts) would go out of business leaving only the companies that have the depth of experience and science to build crate engines and power adder kits. So for these companies to stay profitable they need to keep you invested in your stock engine which allows them to secure their place in the industry, weather that wins you races or not.

However if you are serious about modifications, you will use my 3 piece guide to start your modifications plan with the end in mind. If you really want 700hp then you are much better off with a 500hp engine running a measly 6psi of boost than you are trying to boost a 150hp 4 cylinder to 54psi or trying to feed it 550 horsepower worth of nitrous.

Technorati Tags: compression ratio, Displacement, engine performance parts, exhaust, intake, N2O, Supercharger, turbocharger

The ferocity of running circles around the competition can be further enhanced in the Cayman S through the use of engine performance parts and supercharger performance:

Cayman n. [From the language of Guiana: cf. Sp. caiman.]

The South America alligator.

The Porsche is Cayman S is a great package of performance, handling, and comfort. Being a Cayman in nature, the car sometimes requires an increase in its element of surprise and in its ability to grasp its prey with an un-escapable grasp followed by the infamous alligator ‘death roll’.

Naturally Aspirated Option:

If you’re an interested in a good increase of your Cayman’s performance, without the added complexity and cost of a supercharger system, then the following engine performance parts are available and proven for your car:

Intake components:

The Evolution Motor Sports V-Flow intake installs “in the factory location and utilize the OEM “ram air” fresh air ducts for lower air intake temperatures and added power. Additionally, [the] systems also incorporate a custom cotton air filter and a 6” injection molded Venturi” to improve airflow.

Dyno proven for 6 to 8 hp

Road Sport Supply (RSS) deliver two complimentary and proven products for the Cayman Intake system: The first is a

RSS IPD intake plenum

 high-flow intake plenum to improve airflow into the engine, this part alone is proven for a power gain of 23 hp @ 6300 RPMs. Additionally RSS has just released a complimentary 82mm ported throttle-body initially taken off a 997GT3. The addition of the throttle body has in some dyno tests shown an improvement of 11hp @ 6200 RPMs!

Dyno proven 23 to 34 hp

Exhaust components:

On the exhaust side of things, FabSpeed offers a complete exhaust solution for your Cayman including:

High flow performance headers featuring:

o   Equal length runners

o   A highflow merge collector

o   A 200 cell spun cell high flow catalytic converter.

o   Shifts peak power from 6200 RPMs up to 7000 RPMs producing higher peak power as well as a wider power band

A cat-back exhaust system featuring:

• Manderel bent tubing for smoother air flow
• Fabspeed Exhaust
• 10 lbs weight reduction over the factory system
• Eliminates the secondary catalytic converters reducing back pressure
• Fully compatible with the stock computer system
• Balance tube between the mufflers to equalize flow between both cylinder banks
• Dyno proven for 9 hp

Camshafts

                Schrick de & Doctor Schrick have been producing performance camshafts for European and especially German power cars since 1969. Schrick makes available for the Porsche 3.6 liter engine two sports cams:

                282 degrees of duration with 12mm of lift (Suitable for an 8000 RPM power peak)

                292 degrees of duration with 11.5mm of lift (Suitable for an 8600 RPM power peak)

Shifting peak power from 7000 RPMs to 8000 RPMs has a potential power increase of 14% or over 28 HP for your Cayman

Tuning & Support

Iridium spark plugs:

NGK offers the BKR6EIX-11 spark plugs for your Cayman, Iridium plugs give better and more consistent performance to your car and also improve idle stability and fuel efficiency.

GIAC Chip-tuning are the GO TO Chip tuner for euro car performance tuning and have tuning options for your car no matter what level of performance and what engine modifications you have performed on it. Their tune for a stock engine with only an added high flow air filter is dyno proven for 13 hp gain @ 6400 RPMs.

The combination of the above mentioned modifications will easily propel your Cayman over the 310 hp mark and extend your power band out over 7000 RPMs.

Supercharger Performance

If this kind of performance is still not satisfactory, then we need to change the plan a bit:

VF Engineering has been supercharging the Porsche 3.6 liter since it was introduced in the Carrera C2 and C4. Their supercharger kit will boost your engine to 6 PSI and provide a 40% increase in power over all other modifications. The kit is comprehensive and includes:

VF-Engineering Supercharger Kits

• Vortech V2 SQ supercharger.
• Vortec Chargecooler.
• Bosch high flow water circulation system.
• Porsche OEM water radiator kit.
• GIAC chip tuned with larger Bosch injectors.
• Top speed governor removed.
• Bosch pressure relief bypass system.
• High temp molded polymer pipework
• K&N induction filter.
• 1 year unlimited mileage warranty on supercharger kit parts.
• Made in California, USA

The kit includes its own intake kit to feed air to the supercharger, as well as its own performance tune from GIAC, so the Evolution Motorsports V-Power intake is no longer needed and neither is the GIAC chip tune recommended earlier. Also, it is advisable when adding more than 50hp to a vehicle to switch to a 1 step colder spark plug such as the NGK BKR7AIX-11 or Denso IK24. So bear this in mind when deciding your ultimate power goals for your Cayman as it is wasteful to spend money on parts only later to replace them when you supercharge the car.

With the following modifications:

RSS Plenum & 83mm Throttle body, the Fabspeed Header and Catback Exhaust, and the GIAC tuned and K&N Fed VF Engineering supercharger kit you can expect to reach over the 420hp with your Cayman S. Serious bite from a serious car!

Technorati Tags: Cayman S, engine performance parts, EVOMS, FabSpeed, GIAC, Road Sport Supply (RSS), Schrick, Tuners, VF Engineering, Vortec, Vortech

Are you interested in supercharging your land rover range rover ?

Range Rover Classic 3.5l to 3.9l V8:

Powerdyne performance and vortech superchargers offer a supercharger kit for your engine. The kits provide three options for power increase depending on the boost pressure:

Stage 1 kit:   7 psi & 212 HP

Stage 2 Kit:   9 psi & 228 HP

Stage 3 Kit: 14 psi & 283 HP

Stages two and three come with a water injection kit for increased cooling.

Further power increases can be attained with additional engine performance parts such as genie high flow exhaust headers and a Borla performance cat-back exhaust system.

Powerdyne supercharged 3.5L Range Rover

Powerdyne Supercharged 3.9 L dynograph

Borla 3.9L Cat-Back Exhaust

Find your parts here:

Range rover 3.5 – 3.9 supercharger kits

Range rover 3.5 – 3.9 Headers

Borla Catback system for 3.5 – 3.9 liter V8

Range Rover 4.4 liter V8:

Arden performance, a German tuning company specializing in luxury performance vehicles have developed a complete performance package for your Range Rover V8.

The package includes:

1-      An engine rebuild kit including:

a.       Stroker crank bringing up the displacement to 4.8 litres

b.      Lower compression 9:1 pistons

2- Complete supercharger package

3- intercooler

4- ECU reprogramming

The kit produces an astounding 500 hp @ 6250rpms and 516 ft.lbs of torque @ 4250 rpms. This is capable of accelerating the vehicle from 0-60mph in a short time of 6.5 seconds.

Performance can further be improved using Arden designed ‘off road only’ performance headers and high flow cats. Furthermore, a high flow exhaust system is available jointly through Arden / Meisterschaft

Arden Supercharged 4.8L

Range Rover Arden/Meistercraft Exhaust

Find your parts here:

Arden Performance

Meisterschaft exhausts

Interested in building your own kit?

Here’s an interesting application performed on a 3.5liter engine (similar to the Range Rover 3.5) found in its sister car the TVR.

The kit built here includes:

                eaton M62 superchager

                Custom pulley plate with extra idler and tensioner pulley

                Custom supercharger outlet plate

                Custom supercharger mounting bracket

                Modified intake manifold (rotated 180* for added clearance for the superchager)

                Relocated pre-supercharger throttle body

                Recirculation and bypass valve connected pre-throttle body and post supercharger

                Custom mounted front mount intercooler

                Vortech SFMU (super fuel management unit)

                Relocated Air flow meter and air filter pod

                A zex nitrous oxide wet kit for additional power delivery

When all is said and done, the completed kit delivers 250 hp without the nitrous oxide injection.

Eaton M62 custom install 3.5L TVR

Pulley setup showing idler and tensioner pulley

Find the full discussion topic here:

Custom supercharged TVR 3.5 liter engine

Technorati Tags: Ardin, Borla, engine performance parts, Genie, Meistercraft, Powerdyne, Vortech, water injection

A brief guide that explains how to pick the least engine performance parts to improve the performance of your supercharged car.

A lot of times we find ourselves seeking a supercharged car, not only because it has good power from the factory, but also because we expect that a car that has forced induction from the factory is:

1-      Better engineered or even over engineered with strengthened blocks, thicker rods, factory cast pistons, upgraded cooling capacity, additional engine oil and transmission oil coolers …etc.

2-      Has factory revised engine performance parts, such as a longer duration higher lift camshaft, a factory ported cylinder head, an extrude honed intake or exhaust manifold, more robust ignition system…etc

3-      More overall power potential, as manufacturers like to deliver cars that are easy to maintain and will last for a very long time, they usually ship the cars with very conservative boost settings, conservative air fuel ratios, and conservative timing figures to make sure that no matter what condition the car is used in (towing, sand duning, extreme heat, extreme cold ..etc) that under no possible extreme condition will the car lean out, over heat, or fail giving you a healthy margin of safety to work with to increase the car’s performance if you don’t live in an EXTREME climate. Which most of us don’t!

If you are interested in upgrading the performance of your supercharged car using engine performance parts, these are the modifications I would recommend:

 1-      Performance pulley:

A supercharger performance pulley is either a smaller supercharger snout pulley, or a larger crank pulley, or a kit that includes both. This may also be known as an ODPS (over drive pulley system) in case you need to google search for engine performance part manufacturers later.

The cheapest, most widely available and very effective upgrade for a supercharged car is the pulley upgrade. The pulley on the snout of your supercharger decides the mechanical gearing between your supercharger and your motor. Changing this gearing increases the maximum rpm that your supercharger will reach (which is a function of maximum engine rpm), and thus will increase the maximum amount of boost pressure that your engine will find available for it to create horsepower.

Typical supercharger systems will ship from the factory at a boost setting of 7 to 10psi, whereas the performance pulley will usually extend your supercharger’s working rpms to the maximum safe rpm bringing boost up between 13 and 15psi (depending on the exact setup of your vehicle).

Each psi of boost (from the same charger) is worth 4.5% of your factory horsepower so a jump from 7psi to 15psi can be an increase of 36% of your factory horsepower!

That is quite a horsepower gain for a part that typically costs 300-500 dollars and can be installed over the weekend with basic tools.

                Depending on the exact vehicle, a performance pulley may require some supporting modifications. In some cases it may be even sold in ‘kit’ form. These kits will typically include some or all of the following:

1-      One stage colder spark plugs, typically copper or iridium.

2-      A flash tune for your ECU, a fuel pressure regulator upgrade, or a different MAS/Injector combination.

Again this depends on your exact car specifications, and are needed when the factory ECU is unable to compensate on its own for the increased airflow and performance. This is not the case with about 75% of the cars out there, but it may be with yours so I’m letting you know right now.

 2-      Performance exhaust system:

Unlike turbochargers, where it is fairly straight forward to find a larger turbocharger in the same family or series of turbochargers that you have on your car, and perform a turbo upgrade; superchargers are typically packaged into the intake manifold of the engine, and have a unique snout and pulley system to connect the supercharger to its drive belt.

What this means is that once you have increased your supercharger gearing using the pulley upgrade system we mentioned earlier that you have run out of ‘boost’ need to find a different way to increase the performance of your motor.

Boost or pressure ratio is a ratio of how much air the supercharger is moving at that rpm divided by the amount of air the engine would breath normally at that rpm

Pressure ratio = Supercharger flow (CFM) / Engine natural aspiration (CFM).

If you look at a supercharger compressor map you will see that at any given supercharger rpm and for every given boost pressure (or pressure ratio) there is a range of flow that the supercharger can positively achieve.

This leads us to a performance opportunity that goes as follows:

“If my supercharger boost is maxed out, and I cannot upgrade to a larger unit like I would a turbocharger, then the only way for me to make more power, is to flow more air (CFM) at the same boost level!”

Here is where upgrading the exhaust system comes in. A typical factory exhaust system with a poorly designed header, a close coupled cat, crush bent small radius piping, a second cat converter, and several mufflers and pre-mufflers can have 5 to 7 psi of back pressure in the exhaust manifold.

In other words, if the exhaust back pressure is 3 psi and the supercharger boost pressure is 15psi, then the total engine boost pressure is only 15-3 = 12psi.

In essence we are making our charger work harder to maintain a psi level, and at that level it is not flowing the maximum amount of CFM that it can flow, because the entire system is choked off at the exhaust side.

Upgrading the complete exhaust system will relieve the engine and supercharger of some 3 to 5 psi of exhaust back pressure which will result in a 14% to 22% power increase. This system would include a well designed header or high flow manifold, a single high flow catalytic converter, a properly chosen pre-muffler resonator, and a single high flow exhaust muffler, all connected using adequate sized mandrel bent piping Having the least number of best producing and high flowing parts in the system will give minimal backpressure allowing the engine to breathe better.

With this, you will make more horse power and at the same time you will see your boost pressure drop somewhat here’s why:

Pressure ratio = Supercharger flow (CFM) / Engine natural aspiration (CFM).

New pressure ratio = Supercharger flow2 / Engine natural aspiration 2.

There is a doubly effect going on here:

1-      As the exhaust system is more free flowing, the engine is able to breathe more air now and produce more horsepower (even if there were no supercharger boosting it).

2-      This increase in natural aspiration (which is our denominator) makes the new pressure ratio lower because the supercharger is having to work less hard to move the same CFM, and it can’t increase the boost because it is mechanically locked to its gearing relative to the engine RPM.

3-      The decrease in boost pressure, moves the supercharger to a higher efficiency point on its compressor map where it can produce even more CFM of flow at the new lower boost pressure, and with less effort, giving us cooler denser air into the engine.

4-      The increase in supercharger flow (our numerator) means that the resultant boost pressure increases a bit, but usually is not as high as it was before.

From this sequence of events you can see how upgrading the exhaust system on a supercharged car (and similarly on a turbocharged car) has a double improvement effect on horsepower so long as the supercharger or turbocharger CFM (not boost pressure) portion of the compressor map has not already been maxed out.

Kamikaze headers are designed with 0.25" larger primaries, shorter primaries, and a 2.5" outlet collector for supercharged hondas.

One thing to keep in mind is that headers for supercharged engines would be different in design from a header for the same engine without a supercharger. So if you own a corvette for example, and install a supercharger package, then headers designed for a normally aspirated corvette will not be optimal for your car. Supercharged cars usually perform better with headers with shorter and larger primary tubes. Furthermore, since the supercharged car produces more horsepower (typically 50 to 100% more) then the collector outlet, and exhaust system should also be upsized to match the engine’s exhaust flow demands.

The combination of the two modifications mentioned here can be installed in a 3 day long weekend and can result in an overall gain of 58% horsepower over your stock power figure.

As I said earlier, there may be some supporting modifications needed depending on the exact setup of your car’s ECU and fuel system, however, if I wanted to invest in 20% of the modifications that would give me 80% of the gains, this is where I would put my money FIRST, then comes everything else. Actually, I am more of a high power / low boost junkie than a high power / high boost junkie, and so in that sense I personally would do these modifications the other way around. First I would upgrade my complete exhaust system, making the engine smoother and more efficient, and extending my power rpm range up higher closer to redline and I’d see if that much power increase was satisfactory for me. If not, then I’d go ahead and increase the boost pressure on an already efficient system.

The reason people go for the pulley upgrade first is that it is cheaper to do, and gives higher power gains so therefore it is a bigger bang for your buck quite literally. But I prefer things the other way around.

Technorati Tags: engine performance parts, header, pulley kit, supercharger performance