Posts Tagged ‘water injection’

I’ve recently updated the power calculator to include a turbo calculator. This calculator, performs similar calculations to the supercharger calculator in terms of flow and boost requirements to reach your power goals. It then goes out and chooses 10 compatible turbochargers that match your target application.

I’ve also added the calculations for the minimum size for a single or dual wastegate to properly regulate boost on this application.

After completing this update I sat and thought: “You know what, it wouldn’t take much more work to turn this into a twincharger calculator !” and that’s what I ended up doing.

The video below talks about my preferred twincharged setup which is a sequencial arrangement with a higher rated turbocharger feeding compressed air to a smaller , lower rated supercharger, feeding twicely compressed air into the engine.

In the video we cover the following topics:

1. Preferred twincharged arrangement
2. Air metering and the blow through system
3. Using bypass valves to improve response
4. Alternative arrangement for superchargers that are part of the intake manifold (and therefore can’t have an intercooler placed after them).
5. A hands on example using the power calculator to twincharger the Toyota 5sfe engine to 320 horsepower (which is the same example I did the calculations for manually in my previous twincharged articles).

(Viewing time 27:00 minutes)

The Turbo Calculator calculates:

• The required boost pressure and flow level to reach your power goal
• Cold-side (Before the turbo) and hot-side (after the turbo) optimal intake piping dimensions
• Optimal air to air intercooler volume and cross sectional area for your power, boost and flow levels
• A selection of turbochargers that match your boost and flow requirements
• The recommended turbocharger aspect ratio based on approximate spool rpm and calculated pressure ratio
• Exhaust manifold dimensions (runner diameter, collector diameter)
• Exhaust system dimensions (downpipe and cat-back system diameter)
• Minimum wastegate bore diameter to maintain a stable boost curve
• Fuel flow calculations: fuel pump rating, fuel injector size, fuel feed and return line sizes, and approximate water injection spray levels (optional)
• Total ignition timing calculations based on peak boost, cylinder bore size, rpm, and spark plug arrangement
• Optimal camshaft duration, and lift for your power goals, boost level and target redline rpm.
• Optimal cylinder head flow and valve sizing for your engine’s flow demands
• … and more

Click here to go to the turbo calculator page

Technorati Tags: Intercooler, The Power Calculator, Turbo Calculator, Twincharged, water injection

Here’s an interesting supercharger setup from MM&FF magazine, with a great 305 performance build up:

The 180hp 305 engine has been upgraded by:

Supercharged 347 ci mustang

• An Eagle / DSS / K1 stroker buildup brining engine displacement up to 347 cubic inches (5.7 liters).
• Holley Systemax high performance aluminum cylinder heads
• Holley systemax single plane intake manifold
• Kennedy’s Dynotune custom supercharger camshafts
• vortech J-Trim supercharger geared for a peak of 20psi of boost pressure
• A cog-tooth supercharger drive system to prevent belt slip and maintain peak boost at high rpms
• A custom methanol injection system to cool the intake charge

The final result of this setup is a boost from 180 crank hp up to 660 rear wheel hp and a track-proven 9.70 @ 140 mph quarter mile time.

Find the complete article and more pictures here:

James Noto’s supercharged 93 mustang

Technorati Tags: holley, mustang, pulley upgrade, stroker, Vortech, water injection

Supercharger performance is proud to present the newly updated power calculator. The only calculator built for enthusiasts by enthusiasts…

Get your copy today !

Technorati Tags: boost, CFM, compressor map, header, Intercooler, N2O, Power Calculator, RPM, water injection

 

Illustration shows crank diameter (A) to supercharger pulley diameter (B), it also shows a well designed system where the belt wraps around most of the crank and supercharger pulleys with great placement of the idler pulley for maximum belt traction.

For example, if the crank pulley is 4″ in diameter, then for every rotation of the motor the belt moves 2*pi*r which is about ~25 inches. If the supercharger had a snout pulley that were 2″ in diameter, and there was NO BELT SLIP, then 25 inches of belt rotation will cause the supercharger to spin by 25/(2*pi*r) = 2 complete rotations. To simplify things, the supercharger drive ratio is exactly the ration between the diameter of the crank pulley to the supercharger pulley or in our example 4:2 which is 2:1. 

Quick change supercharger pulleys.

This technology did not transfer directly into cars, however we have something similar. Sometimes supercharged cars at high boost can be a handful on the street due to the increased torque at lower RPMs. This becomes very evident for those of us whole live in areas with unpredictable climates that see lots of rain or snow fall. In a street/strip compromise some companies have come up with two piece supercharger pulleys. The inner piece of the pulley is an inner sleeve that is pressed onto the supercharger snot (as you would press on a one piece solid pulley). The outer piece of the pulley is an outer ring that bolts onto the inner sleeve using some high grade bolts. This design allows a ‘quick change’ of supercharger snout pulleys between your low boost street pulley and your high boost ‘race’ pulley in a matter of minutes. You just release your belt tensioner, remove 4 bolts, swap pulleys, tighten 4 bolts, and then re-tension your drive belt and viola a 15 minute quick change. This is a very nice option for large displacement motors running positive displacement roots or twin-screw type superchargers that have more than enough torque to overwhelm their street tiers. This also works well with an assortment of other street/strip products such as drag radials, water injection, exhaust cutouts where you can -- on a prepared track -- swap pulleys, swap tires, open an exhaust cutout and run open header, and switch on your water injection system for added cooling and fueling. Mr. Jackal and Mr. Hyde mentallity.

Technorati Tags: crank pulley, cutout, pulley upgrade, snout pulley, Supercharger, water injection

If you’re a car geek like myself, then some cars (although modestly powered) will still interest you because of the sheer amount of theory and technology jammed into them. One such car is the mid 90s to early 20s Mazda 929S (AKA the millennia, the Sentia).

The car is powered by a small but very efficient Miller Cycle 2.3 liter 60* V6. The engine utilizes the miller combustion cycle in which the horsepower losses associated with the first half of the compression stroke (when the piston is much closer to bottom dead center), by keeping the intake valve open. Obviously on a typical 4 stroke motor the open valve would allow the air from the previous stroke (the intake stroke) to escape causing a loss in power, but in the miller cycle the air stays trapped in the cylinder and is rather compressed to 2.0 atmospheres due to a roots type supercharger boosting the engine to 14.0 psi. Once the piston rises up in the cylinder bore to a more efficient location, the valve is closed and the piston completes the compression stroke on its own. The short duration of the compression stroke means that the use of high boost and higher compression ratios are possible and the final configuration with 10:1 compression ratio and 14.0 PSI of boost produces a peak of 210hp @ 5300 RPMs and 210 ft-lbs at 3500 RPMs.

The car was quite impressive for its time with a supercharged V6 capable of a 0-60 time of 8.4 seconds, a top speed of 142mph in a luxury sedan, all the while still maintaining a minimum of 20mpg in the city and as much as 28 mpg on the highway; quite impressive to say the least.

Introduction of the Lysholm/IHI supercharger

A cutout view of the Millenia Lysholm/IHI charger, notice the inlet restriction and the tiny throttle body.

Because of the space and packaging limitations on the front wheel drive V6 Mazda motor, Mazda outsourced the development of its supercharger on this car to well know Japanese turbocharger manufacturer IHI, who worked in conjunction with Lysholm Technologies – the twin screw supercharger manufacturer from Sweden to produce the unit used on the Millennia.

According to contact between enthusiasts and Lysholm engineers, the unit on the millennia is closest in specification to the Lysholm 1200AX which moves 1.2 liters of air per revolution and has a maximum operating pressure ratio of 2.2 or 17.5psi and a peak flow of 635 CFM or in other words 423 horsepower @ 17.5psi!

The main difference between the Lysholm 1200AX and the Lysholm/IHI on the Mazda is the design and compactness of the new housing, the design of the housing inlet on the Mazda looks like a significant restriction point (especially since the air passing through it is not yet compressed) and there is potentially a significant power gain to be found by upgrading the supercharger inlet to with a larger throttle body!

intercooler System

As we mentioned previously in our post on intercoolers, typical intercoolers have two main modes of operation:

1- Heat sinking, by maintaining themselves at a much lower temperature than the inlet air charge, and thus being able to extract a significant amount of heat out of the inlet air charger in a very short period of time.

2- Radiation, of the absorbed heat either by being placed in the direct path of the air stream or in a circulating coolant bath for air to water intercoolers.

An engine shot of the KJ-ZEM engine showing the small front intercooler and well as the ram air guide for the rear intercooler.

 The Mazda uses two very small intercooler cores located on top of the engine inside the engine bay, and uses plastic air ducts to try and guide some air into the intercooler to radiate excess heat. However, knowing that their intercooler cores are not that large (for the power of the engine) and knowing that the supercharger produces more heat as its revolutions increase, then Mazda rather than fitting larger intercoolers or a front mount or fender mount intercooler with access to plenty of fresh air, have fitted their car with an intercooler bypass valve. The bypass valve, bypasses the intercoolers below 4000 RPMs and at low throttle openings to try and keep the coolers from being utilized and keep them as cool as possible, to allow them to work effectively (primarily as heat sinks because of where they are located) when they are needed above 4000 RPMs. I guess this kind of design works, but it’s definitely not optimum for peak power production, and for sure, when performing long repeated full throttle pulls back to back, the bypass valve will have no opportunity to operate and the intercoolers will have no opportunity to cool down. Eventually the intercoolers will heat soak and the power figures will drop from the advertised 203 hp dramatically.

Autospeed's dyno of the motor showing the sharp torque drop off at higher rpms...

If you think this is just internet theory, check out this article by autospeed where they have dynode the KJ-ZEM and the intercoolers heat soaked after a short 10 second run.

Based on the most conservative estimates based on the torque peak on that power run, if the torque peak is held to 5300 RPMs, the car stands to make at least 235hp @ 5300 RPMs which means we have at least an easy 35hp to gain on this car with some modifications.

In autospeed’s dyno run they made 196 horsepower with an outlet temperature rise of 75*C, the car also stands to make at least an additional 7 horsepower from better intake cooling.

Exhaust system:

As mentioned in our previous post about basic supercharger performance upgrades: One of the most important parts to inspect when looking to upgrade your supercharged car is the exhaust system. For the duration of time that the engine is in overlap (where both the intake and exhaust valves are open) then any exhaust pressure will work against your supercharger on a 1:1 basis.

How so? If you are in overlap and you have say 5psi of exhaust back pressure and 15psi of supercharger boost pressure, then the resultant pressure differential between your supercharger and your cylinder is only 10psi, and so your power boost from using a supercharger at that point is reduced from 100% down to only 68%. We can see this effect clearly on the falling torque readings on the dyno graph for this engine performed by autospeed. The loss of 35  potential horsepower translates on this setup to about 6psi of losses between the intake and exhaust system …

The 2-1 exhaust mid-pipe with the 180* bendand.

The exhaust system on this car combines short runner manifolds with no use of merge collectors, feeding close coupled catalytic converters, into a two into one mid-pipe with a power robbing 180* bend incorporated and no use of a nice y transition, into a single 2” exhaust all the way back.

Recommendations and power estimates:

I think it is possible to increase the power of this car to over the 250 horsepower mark with a few simple modifications:

1-      Since I intend to add over 50 horsepower to the car, it is advisable to use 1 step colder iridium spark plugs for better heat management, and to assure proper ignition even with the denser mixture.

2-      Replacing the tiny supercharger inlet and throttle body with a larger throttle body matched to the size of the charger housing, and redoing the complete intake system in that size. For a single inlet 250hp system an ideal supercharger inlet size would be a 78mm throttle body (or three square inch inlet) with a supercharger outlet of 58mm or 2.28 square inches. (Read more about supercharger porting here)

3-      Because of packaging restrictions on this engine and how hard it would be to completely redo the intercoolers for a single front mounted intercooler with a single inlet and dual outlets (one for each of the 3 cylinder banks). I would use a proper water / methanol injection system activated at around 4000 RPMs and above 10PSI using two 1.69 gallon per hour nozzles, one for each 3 cylinder bank.

4-      I don’t think anybody makes aftermarket headers for the millennia engine and it is a tight package of an engine. I would replace the closely coupled cats with straight down-tubes (again for 250hp the ideal collector size would be 1.87”) down either into a 1.87” to a 2.92” single exhaust with appropriate smooth transitioning y-pipe) or using a 1.87” x-pipe (for even better exhaust extraction and reduced back pressure) to a true dual 1.87” exhaust.

The cats would be a single (or dual for a true dual exhaust) cat placed after the y-pipe (or the x-pipe if a true dual is possible) and then feeding back into a high flow 2.92” muffler (or dual 1.87” inlet mufflers).

Using a better transition such as a y-pipe or x-pipe has the added benefit in that the different cylinder banks on a V style engine fire 180* out of sync to balance the engine out. The advantage of smoothly merging the exhaust gasses from the two banks together is that when using a smooth merge, the high velocity exhaust gases caused by a combustion in one bank, leaves behind it a temporary vacuum (or low pressure reflection wave) of as much as negative 2 PSI at the exhaust valve of the opposing bank. As soon as the other bank fires and the exhaust valve opens, the exhaust finds vacuum (rather than back pressure) in the exhaust runner which helps evacuate the cylinder faster leaving more room for fresh air in the next cycle and improving scavenging during overlap.

The total potential gain of a properly designed exhaust, with a ported supercharger inlet, and better charger air cooling would be about 47 total horsepower gained and boost may drop from 14psi to as low as 10psi possibly.

How is that for supercharger performance? 47 more horsepower at 4 less psi!

For more information and references:

Lysholm 1200AX supercharger

IHI Corporation

The miller cycle engine explained

Autospeed article on Japanese engines

YouTube Video of intercooler bypass valve actuator

1996 Mazda Millenia S statistics at the auto channel

Technorati Tags: IHI, Intercooler, Lysholm, Mazda, water injection

One of the things that have changed over the last 10 years is the availability (and proliferation of knowledge) about available alternative fuels or octane boosters. Two such options are:

1-      E85 fuel which is comprised of 85% Ethanol which has an octane rating of about 100 to 105 octane vs the typical 87 to 93 octane pump gasoline.

2-      Water / methanol injection systems that can be used either as supplemental fueling system (based on the methanol content which carries an octane rating of 110 octane or higher) or can be used for in cylinder cooling when the water vapor injected with the methanol transforms into steam inside the combustion chamber, thus extracting lots heat out of the combustion chamber, and thus slowing down the speed of travel of the combustion flame front simulating the effects similar to those of a higher octane gasoline.

With the availability of these octane increasing or octane simulating concoctions, it has become more accessible of recent for the performance enthusiast to build more powerful supercharger systems, especially when space limitations dictate the inability to use an intercooler.

The use of a higher octane fuel by definition means that the air fuel mixture is more resilient to auto-ignition and detonation. Furthermore, in the event of a pre-mature ignition, the higher octane fuel creates a slower traveling flame front which gives the piston more time to travel upwards in the cylinder bore (Closer to top dead center) before meeting the flame front and this reduces the time that the piston surface is improperly pressurized and overheated reducing the possibility of catastrophic failure.

Last but not least, the use a water / methanol injection mix includes two phase-change events:

1-      The injected methanol changes from a liquid state to a vapor state at its boiling point of 65*C, i.e. as soon as it hits the compressed air mixture coming from the supercharger outlet. This phase change absorbs a lot of the heat out of the air and methanol mixture reducing inlet air temperatures even before the mixture reaches the combustion chamber and starts to get compressed. This temperature reduction goes a long way towards eliminating or highly reducing the possibility of detonation.

2-      The injected water, changes from a liquid state to a vapor state at its boiling point of 100*C which depending on the availability of an intercooler in the system, my occur in the intake plumbing before reaching the combustion chamber, or may not occur until the mixture is ignited. Either way, when the temperature is high enough, the water mist injected in the air stream will flash vaporize into steam also absorbing a generous amount of the heat created in the combustion.

Why is this important for cooling ?

“The first-order phase transitions are those that involve a latent heat. During such a transition, a system either absorbs or releases a fixed (and typically large) amount of energy. During this process, the temperature of the system will stay constant as heat is added.” … read more

Which means that the water or methanol will try to keep the air / fuel mixture at a fixed temperature of 65*C for the methanol phase change, and 100*C for the water phase change, for a long time (until the entire fuel has changed state) while absorbing a very large amount of heat energy out of the compressed air.

Since the air entering into the water/methanol spray’s path (especially with a lack of an intercooler) can be as high as 100*C above ambient (so with an ambient temperature of about 40*C for under hood temps we’re talking about an air inlet temperature of around 140*C in the intake piping).

Once this 140*C air meets the water & methanol mixture both the water and methanol will attempt to bring down the air / fuel mixture down to 100*C (the boiling point of water) and if all the water has vaporized into steam, then further down to 65*C the boiling point of methanol. If both operations are successful then the final temperature of our mixture is 65*C or 25*C above ambient which is great for any intercooler, and even more impressive for a higher octane non-intercooled system like ours relying on water methanol injection.

Now there are two possible applications for water / methanol injection:

1-      The typical added cooling application:

a.       In this setup, the water / methanol mix is usually mixed in a 50/50 mix of water and methanol.

b.      The jetting is usually about 10-15% the total fuel flow of the system:

For example a 300hp four cylinder car needs four 450cc/min fuel injectors to produce that power figure. Our total fuel flow at peak power is 450cc/min 4 = 1800cc/min or 1.8 liters per minute of fuel.

1 gallon is four liters and 1 hour is sixty minutes so our total fuel consumption is equivalent to 27 gallons per hour of fuel (if you were able to stay at peak hp and rpm for a whole hour).

The reason we’re doing this math is that water / methanol jets are rated in gallons per hour.

So 10 to 15% of 27 gallons per hour = 2.7 to 4.05 GPH injection nozzle.

Now remember that 50% of our mixture is methanol, which is a high octane gasoline. So when injection 15% water methanol mixture with 50% of that being methanol, then our final air fuel ration will be richer by 7% or about 1 AFR point. This means that to reach optimum power again and our optimum air fuel ration we need to either increase boost pressure or retune our car to optimize it for the added high octane fuel.

2-      Using methanol as a fuel

In light of what we just mentioned about methanol being a fuel, you could possibly use water /methanol injection as a supplementary stand alone high octane fuel system. The trick here is to keep in mind that the amount of water you spray in the system must be controlled to prevent the engine from hydro lock.

So in using water / methanol as a supplemental fuel as well as a cooling agent, limit the water content to 5 to 7% of your fuel injector flow, and compensate for your added fuel demands with methanol.

Here’s an example:

We have a car that produces 300 hp and has 450cc/min injectors installed.

At this power level the fuel injectors are already maxed out.

We want to raise the boost pressure on this car to reach a target of 360hp for example using methanol (rather than 93 octane fuel) as our fuel, and using some water injection for cooling as well.

Water content:

450 (cc/min) * 4 (injectors) / 1000 (cc per liter) * 60 (minutes per hour) / 4 (liters per gallon) * 7% = 1.89 gallons per hour of water.

Methanol content:

We want to spray enough methanol to cover our added 60hp worth of fuel.

60 hp requires four 90cc/min injectors

So our total gasoline requirement = 90*4/1000*60/4 =5.4 gallons per hour of gasoline.

One thing to note about gasoline is that you need double the volume of methanol as you would gasoline to reach a target lambda of 1 (ideal combustion) or what in gasoline would be an air fuel ratio of 14.7 parts air to 1 part gasoline.

So our total methanol requirement = total gasoline requirement * 2

Our total methanol requirement = 10.8 gallons per hour of methanol.

Now here are the final numbers:

Water / Methanol nozzle size = 10.8 (methanol) + 1.89 (water) = 12.69 Gallons per hour

Water / Methanol mixture = 1.89 / (12.69)  : 10.8 / 12.69 = 15% water to 85% methanol

So how can I pull this off?

Obviously if you go ahead and get a single stage water methanol injection system spraying 60hp worth of fuel, and you activate it at 3000 RPM’s your car will bog down horribly and you may even cause catastrophic damage by washing the oil right off your cylinder walls with that much unneeded fuel.

To pull this system off successfully you need to use a progressive injection system with an appropriate injection duty cycle controller, tuned to ramp up the delivery of your water/methanol injection as the engine demand increases (based on RPM, MAS voltage, Boost pressure or a combination of these factors).

There are now several 1 dimensional and 2 dimensional water/methanol injection controllers, here are some examples:

Painless Striker Cold Shot	Painless performance integrated 1 dimensional progressive water injection kit: Integrated low level warning light Integrated Boost gauge 0-5 volt based sensor input for 1 dimensional control, this can be wired to use a manifold pressure sensor, a mass air sensor, or a pulse to voltage converted RPM signal for duty cycle control.
FJO 2 dimensional injection system	FJO racing has a two dimensional computer controlled progressive injection kit: Precisely metered based on MAP psi, TPS, RPM, and Fuel injector duty-cycle!  Software programmable 16 X 16 injection matrix with real time monitoring and diagnostics
Aquamist 2d system	Aquamist provides a simplified multidimentional system that tracks and follows your fuel injector duty cycle controlled by your factory ECU. The factory ECU adjust for throttle, boost pressure, airflow readings, temperature corrections, gear selection…etc and the acquamist simply takes the output of all that complex processing and follows it.

Technorati Tags: Ethanol, FJO, Intercooler, methanol, Octane, Painless, water injection

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

The first time I ever heard of twin charging (using both a turbocharger and a supercharger on the same motor) was probably back in year 2000. At that time I was very interested in performance for the Toyota Celica and naturally I also read a lot about its sister cars (that shared some of the engines) such as the Camry and the MR2.

One of the most interesting aftermarket parts I ran across at the time was the HKS turbo kit for the 4AGZE powered 1^st generation mr2. The 4agze (for those that are not familiar with Toyota engines) is a peppy 170 horsepower 1.6 liter engine powered by the Toyota SC-12 roots type supercharger. On this car Toyota used an electromagnetically clutched supercharger that could be disabled during low power requirements such as cruising, and engaged when the user demands it.

One of the most important parts of the HKS kit is the bypass valve. This valve was used to direct air from the supercharger to the engine at lower rpm/flow points. Once the rpm’s rise, and the engine starts to demand more air, and the turbocharger is fully spooled, the valve switches over gradually till the turbocharger alone is feeding the engine while the supercharger is completely bypassed.

The theory behind this kind of system is to use a small positive displacement (roots style) supercharger. Supercharger performance efficiency is typically its highest at lower engine and supercharger rpms (for example from idle to 4000 rpms). Above 4000 rpms the supercharger’s performance and efficiency starts to drop, the horsepower required to drive it starts to rise exponentially, and the air temperature coming out of the supercharger starts to rise dramatically limiting performance.

On the other hand, using a generously sized turbocharger will allow us to feed the engine efficiently with cooler air (than that from an overworked supercharger) and maintain high rpm performance. The problem with using a larger turbocharger is that a generously sized turbocharger typically doesn’t spool before 3000 to 4000 rpms giving us a limited power band and thus providing no performance boost at lower rpms.

The idea of twin charging is to use both a supercharger and a turbocharger to have each one do what it does best, have the supercharger boost the motor for low end torque, and as it runs out of steam, the turbocharger comes online to carry us through to redline.

There are three aspects to these types of systems that make them prohibitive to most tuners:

1. Cost and complexity: Having a complete supercharger system as well as a complete turbocharger system on the same time is a lot of money to spend and a lot of parts to deal with and diagnose in case something goes wrong.
2. The bypass valve used to bypass the supercharger (and yet hold in all the air pressure coming from the turbocharger) as well as being able to control this valve electrically or mechanically requires a custom made one off valve that isn’t quite available off the shelf.
3. Since we are using two different types of chargers with two different efficiency maps, it can get very complicated to figure out how to tune the motor (especially with much simpler fuel injection systems that were used at the time) because the air density can vary dramatically at the same rpm point and pressure level depending on which charger is feeding air to the motor and at what proportion. This is also where the HKS turbo kit for the 4agze was at its weakest, namely at smoothing the transition point fueling between the supercharger to turbocharger switchover.

However, what is interesting to me, is that even with the advent of more efficient superchargers (such as the 4^th generation eaton chargers with coated rotors, higher tolerances, and lower friction drives capable of extending their working rpm range from 12000 rpms up to 16000 rpms), and with the availability of faster spooling turbochargers such as dual ball bearing turbochargers, or VTN (variable turbine nozzle) turbochargers that some people still attempt to turn twin-charger theory into practice.

Here are three examples:

Alta’s Turbo System for the 2002 to 2006 Mini Cooper S

“The Alta Mini Performance Twin-Charged Turbo kit for the Mini Cooper S features a Garrett GT3071R turbo capable of producing up to 400 horsepower! “

“Alta includes a 5% larger supercharger pulley in the kit to reduce the supercharger boost output. By pushing more boost through the turbo and less through the supercharger, the kit increases in efficiency and produces more power reliably.”

As I mentioned earlier, one the main things to understand about these systems is how the different chargers have different efficiency ranges, and based on that, require precise tuning especially at higher boost levels. But unlike 10 years ago, the technology is now available where you could very easily purchase install and tune from scratch a standalone engine management system within a week.

“A fuel computer such as the Turbo XS D-Tec or the Apexi SAFC are both simple options for fine-tuning your fueling. For those looking to take things further, Hydra EMS and Alta have developed a Standalone Engine Management system designed for use with this kit.”

The Twincharged 350z

“An ORC supercharger takes care of the low rpm boosting while a large Blitz/KKK K5 turbine comes into play at higher revolutions. The result? Power all the time with an impressively immediate throttle control. The engine remains completely standard, but even the low boost setting that is currently being used now is enough to develop an impressive 550 PS and a very full torque curve that peaks at 60 kgm.”

With these kinds of systems, the driving feel and engagement from the noise of the engine by is something that can’t be explained or debated over the internet like the ongoing debates of ‘fast spooling turbocharger vs twin-charger vs highflow ported superchagers’:

“The immediate acceleration and lack of lag are what first surprises; there is no trail off of low-down torque or high-end power, and the boosted V6 seems to pull all the time in any gear. It’s almost electric in character. There are all sort of noises being made: supercharger whine, large turbo spool up, an exquisite exhaust note and external wastegate chatter when you lift off the throttle.”

ford Mustang Turbo Kit – The Hell Raiser !

Like I stated earlier, one of the complexities of twin-charging is sourcing a reliable bypass valve and controlling it for a smooth transition between supercharged and turbocharged power delivery.

One solution to this problem is sequential-charging where the supercharger outlet feeds the inlet of the turbocharger or vice versa. The advantage of this type of system is that low boost settings (for example a boost setting of 7psi for the supercharger which is a pressure ratio of 1.5) and a boost setting of 7psi for the turbocharger waste gate which again is a pressure ratio of 1.5) results in more than 14psi as the resultant pressure ratio is 1.5*1.5 = 2.25 which is around 18psi so that neither the supercharger nor the turbocharger has to carry the full load of boosting the engine up to a pressure ratio of 2.25. For the mustang for example, combining a factory set 6.5psi of superchager boost with turbochargers set for 13psi we get a combined 24.4psi of boost.

“The secret is compound boost and water/methanol injection. The Hellraiser kit uses two 61mm Turbonetics turbos that blow into the stock Cobra supercharger. The turbos send 13 psi of boost through an air-to-air intercooler and then to the blower, which compounds the boost to 24.4 psi and pushes it through the stock intercooler (which is mounted directly under the blower) and into the engine.”

The disadvantage of a this kind of a system is that if the turbocharger has outlet temperatures 60 degrees above ambient, and the supercharger has outlet temperatures 80 degrees above ambient, then the combination of two chargers in series (rather than having them in parallel with a switchover bypass valve) results in that the air entering the engine can be as high as 140* above ambient temperatures which is horrible for performance unless you have extremely high octane gasoline or a really low compression ratio boost friendly motor.

In addition to using TWO intercoolers to cool the charge down, the hell raiser kit also uses water injection to further reduce the air temperatures and increase the effective octane rating of the motor’s fueling:

“To allow that kind of boost and power safely on pump gas requires a Snow Performance water/methanol injection system, which Hellion set up with six nozzles firing into the induction tube just before the blower, and they are fed by three pumps and an 8-gallon fuel cell mounted in the trunk. Without the methanol injection, the system can still make nearly 1,000 hp, but the engine is on the ragged edge of destruction.”

This may seem like a lot of work and complexity, but if you think about what it takes to buy a 1000hp car then you’re looking at one of either a Bughatti Veyron, or a Hennessey Venom-1000 SRT-10 Viper, or an extremely modified car (such as a Toyota Supra, Skyline GT-R, Turbocharged M5, or Turbocharged corvette). To be able to buy this kind of power in Kit form is truly a feat of engineering and goes to show the time and effort that Hellion Power Systems has put into developing this kit.

Find the complete articles here:

Alta Turbocharger Kit for the Mini Cooper (discontinued)

Twincharged 350z – Turbo Magazine

Hellraiser by Hellion Power Systems

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