Supercharger Performance and Engine Performance Parts

I ran into this great article on DIY head porting on the Toyota 3VZ-fe (V6) engine. The article illustrates a step by step on porting the head complete with flow numbers and port moulds. In the article, the Toyota gains flow from 204CFM to 230CFM on the intake side and from 154 to 170 CFM on the exhaust side at 28″.

Every 1.5 CFM on the intake flow is worth about 1 hp when all is said and done depending on the engine’s effeciency at using this airflow and so a gain of 26 intake CFM is worth an increase of around 17 horsepower as a rough estimate.

This gain is doubly present on a supercharged car as follows:

Take for example the original head flowing 204 CFM and producing roughly 136 horsepower.

If we were to supercharge this engine using something like an eaton M62 supercharger and taking the engine to a maximum safe boost range for pump gas of around 15psi we would endup with a 272 horsepower combination…

272 horsepower for this head is 408 CFM at a pressure ratio of 2.0 (or 15psi of boost).

When we port the head, the head flow increases by 26 CFM as we’ve just illustrated due to a better shaped (and minimally enlraged port).

The new boost pressure at the same supercharger gearing will drop

New pressure ratio = 408 cfm / 230 cfm = 1.77 pressure ratio or 11.3 psi

So porting the head was worth 4psi of boost!

Now that our boost had dropped, we overdrive the supercharger with a 13% overdrive pulley bringing boost back up to a pump gas safe 15psi and the net result is :

306 horsepower (460 CFM) @ 2.0 pressure ratio (15psi of boost).

Thus by porting the head on a naturally aspirated car, you stand to gain 17horsepower because your ‘boost’ is limited to atmospheric pressure. But on a supercharged car, where you can control your boost level, you stand to gain 34 hp (double that of a naturally aspirated car) if you compensate for the observed boost drop by overdriving the supercharger to raise boost pressure up again.

Another thing to notice here is the exhaust to intake flow ratio. On a typical car an intake to exhaust flow ratio of about 80% is optimum for performance. On a turbo, supercharged, or nitrous equipped car (where the intake gasses are compressed and thus require less flow capacity from the intake port) then an 85% exhaust to intake ratio is about ideal.

Of course alot of factors affect flow such as cam lift and duration, intake and exhaust valve sizes, as well as port flow and so those three factors can be used (such as a more aggressive exhaust cam on an undersized exhaust valve) to try and compensate for one of these other factors being undersized.

If we look at the stock port numbers we find that the exhaust to intake flow ratio is 154 / 204 which is around 75% so slightly undersized. Now look at the ported head numbers and we find 170/230 which is alos around 73% so I would consider this a street port for naturally aspirated car and possibly opt for an exhaust cam with longer duration or higher lift to reach better exhaust flow when all is said and done.

The reason you don’t need equal intake to exhaust flow is because intake flows in at 1 atmosphere (or 2.0 atmoshpere if you are running 15psi of boost) whereas exhaust leaves by the force of cylinder pressure due to combustion which can be as high as 26 atmospheres. This higher pressure is better able to force exhaust gasses out of a smaller port and so the ratio of exhaust to intake flow is always less than 1.0.

One last thing to note here is cleaning the combustion chamber inside the head of any puts, burrs, rough edges …etc This is done on supercharged and turbocharged cars because any burrs or rough parts in the combustion chamber (or on the piston surface as well) can create a hot spot inside the chamber.

Hot spots increase the chance of being a source for pre-ignition and detonation which can start a chain reaction of maltimed ignition that will runaway and destroy the engine. Clearing thise hot spots by sanding and cleaning combustion chambers as well as sanding and cleaning possibly sharp edges on piston tops reduces the possibility of pre-ignition and allows you to run more boost for the same octane rating.

Below is the article:

How to gain approx 20bhp (peak) via 3vzfe Cylinderhead modifications, a guide by 4v6.

“Copyright 2009 T.Warren ( 4v6)”

The disclaimer.

You, yes you, are entirely responsible for any work you decide to perform on your engine or vehicle.
The procedures described in this article can be accomplished by most anyone with common sense and a fair degree of patience, skill and time.
It cannot be stressed highly enough that the three components above are ESSENTIAL to producing a quality job that performs as expected.
If you do not posses the necessary qualities, or you doubt your ability to perform the following actions, then do not proceed to attempt them.
In short, if you destroy your engine or hack your own head off with a grinder in the process of making modifications based on procedures described in this article, then its not my responsibility, no one made you do it!
Use common sense and employ safe working methods when making any modifications.
I have tried to ensure as much relevant detail as possible is included but this is a rather condensed account of what to do because the flowtesting part isnt included and errors and omissions can unfortunately creep in, so if in doubt at any point, re-read and if still unsure ask!

Now thats out of the way, lets see what tools are needed.

Youll need either a high speed air or electric die grinder (variable electric is best) although an electric drill can be used and at a pinch a dremel type tool- however theyre generally unsuitable because the tools are smaller and remove less material.
Better to use that for detailing/cleaning up jobs later on.
A supply of 80 and 120 grit abrasive cloth on a roll.
A carbide “Oval” Burr.
Sanding Rolls 80 to 120 grit.
Some wd40.
Engine degreaser.
Paper towels ( lots of them)
A vacuum cleaner would be useful also.
A plastic storage box for washing purposes.
A valve spring compressor to remove the valves.
A piece of ¼ inch rod around 6 inches long with a slot hacksawed into one end.
A dust mask and some eye protection.
At this point ill assume you have enough knowledge to have removed the heads off the
engine,
removed and ordered the valves correctly.
Read the engine manual if youre unsure how to do that and get familiar first!
Clean the head in the plastic box with Jizer or some other engine cleaner that has a corrosion
inhibiter in it otherwise the guides and seats will rust.
Once done with the majority of cleaning, dry the head and blow it off with compressed air if available and use your can of WD40 to coat the guides both inside and out and the seats to further protect them along with the cam cap retaining studs.
Unless you want your hands torn to shreds, its a good idea to deburr all sharp external edges
with a carbide cutter or sanding roll, so do that next and save your fingers.
Ok, if you look down the intake ports youll see all manner of interesting stuff.
Casting marks, valve guides, the bosses and ridges left by machining ops at the factory etc.
The first thing to note is this: Be guided by the fact that youre not going to be making these
ports monstrously bigger so resist vigorously the urge to go bananas with your carbide cutter!
If youve got a pile of chippings as deep as your armpits when youre finished, then you may
have gone a little too far…..
This first photo shows a view down the port as itd normally appear minus the valves of
course.

A look at the stock intake port

Things to note.
Rough surface texture, guide bosses and guides, fairly wide splitter, machining ridges left by
the factory.
Incidentally, the reason theyre not removed ( on newer engines they are very much better
finished) is because the engines built to meet a specific aim in terms of power and cost
which, even in this state it does so, plus its a design thats over 15 years old and was never
really intended to do what we’re asking of it.
The next shot shows the chamber, the seat and bowl areas.
Ive sprayed these with a welding product called flaw finder/developer, it highlights contours
quite well.
You can clearly see the ridges and changes in port cross section thats been left by the factory
machining ops.
At the other side of the port theres a sharp edge

A look at the unported combustion chamber

Ive already taken port moulds of these heads on numerous occasions and you can clearly see
how uneven and poorly finished the surface comes as stock.

Intake port mould showing the valve guides

Intake port mould showing the valve guides and a concerning ridge near the exit

So where to start?
First attach a vacuum cleaner to the port and use it to keep the dust and chippings down.
If you cant use a vacuum cleaner, then wear a dust mask, aluminium dusts not supposedly
good for your health ( alzheimers) so protect yourself just in case.
I usually start at the port mouth and smooth the surface, just removing casting lines, flash etc.
Its important to run the tool fast enough to cut the port material but not press on it as itll clog
up rapidly and end up slowing you right down.
Just let the tool cut steadily and keep it moving.
Youll develop a natural sweeping motion as you progress.
Once youve done all the port floors or roofs, turn over the head and do the opposite sides, just
removing marks and ridges.
By now youll start wondering if youve done the right thing and worrying how long itll take.
Its not a fast job and thats where the patience part comes in.
This is how itll look as you proceed.

Porting the inlet with a rough bit

Results of roughing out the port #1

Results of roughing out the port #2

After a few hours youll have removed the casting marks and generally smoothed the surface.
The valve guide bosses on these can give you a couple of cfm for just a few minutes work, so
its worth spending that time to reduce their size.
Just remove the material at either side and lower the height of the surface blending it in to
meet the guide, making it more aerodynamic.
Try to get both sides of the boss symmetrical and mirroring its neighbours but dont worry too
much about surface condition at this point, minor changes wont make any noticeable
differences and in any case the surface will be addressed lastly after everything else is done.
Use the photos as a guide for what to aim for.
Have a look at the following photo of an unmodified intake port.
Its an experiment I did some time ago using smoke trails to get a visual clue where the air
was going.
Look at the right hand trail. Its got a definite bump to it that proves the pressure is higher as it
travels over the guide boss, its almost a dead copy of the profile in that area.
What happens is the air is deflected up by the high pressure (well higher than elsewhere)
created as the air is flowing.
Its raising the pressure in that place and diverting the air, stopping it from going where it
would like- straight.
You obviously cant eliminate this effect entirely but by making the bosses less pronounced,
that pressure rise isnt as great and Its very easily measured on the test bench.

Smoke tail illustrates how the valve guide protrusion disrupts the airflow

Assuming youve got all the guide bosses reduced in height and nicely shaped and the ports
lead in sections all roughed out, we can turn the head over and start from the other side.
Position the head so the manifold face of the intake port faces upwards.
At the bowl area use the oval burr to remove the edges of the alloy that overlap into the
airstream, blending the material so it ends up level with the valve seat insert.
Youll notice at the sides of the port a deep ridge that alternates on each set of ports, caused
by the factory machining.
Feather these into the seat insert and port as youve done with the rest of the bowl.

Now turn the head over ( prop it up on a length of timber if needs be) so the intake manifold
face is pointing downwards.
The short side radius turn is next up.This is opposite the bowl that youve just blended in.
If you look at it, youll notice an apparent lip, almost an overhang where the factory tooling
has cut into the port to produce the seating area for the insert, its the “arch” shape you can see
on this port.

The ridge (sharp lip) right before the port exit needs to be smoothed out

This sharp lip is detrimental ( very) to getting air into the cylinder because air dosent like to
take sharp turns and when its moving at close to supersonic speeds as in a port it really
dosent like to change direction because even air has mass. Hang your hand out the car
window at 80mph- feel the force.
The air coming off that lip creates vortexes and back eddys that make the stream turbulent
which stops air further back up the intake from going where we want it.
When reshaping this turn we want to be making it aerodynamic, as in an aerofoil section of a
wing, which is what the profile will resemble when we’ve finished on it.
Ive already done the hard work for you here and made a copy of the profile to aim for in 3D
out of silicone rubber.
Compare it with the mould of the stock port on the right for the differences.
You need to try to copy the shape as closely as you can and use it to check the shape of the
turn as you go.
This is one of the hardest parts of the job and itll take quite some time to get it just right but
the payoff is way better flow with the valves in than youd get just by rounding that edge off.

Before and after comparison of the moulds of the ridge (bottom) and the inlet port (top)

Once youve carefully shaped the short side radius, you need to apply some efforts to the sides
of the port walls where the SSR meets the vertical parts.
If you position the head on its end and look back up the intake from the valves, youll notice a
“hump” type shape as the port wall makes the turn.
Its present on both outer and inner walls ( splitter side).
Youll need to be careful how you approach this bit of the job, what youre doing is making
room for the air as it slows and goes around the SSR and blending the sides and SSR
together, but not cutting into the already modified SSR.
In my case I transfer the head back and forth to the bench, test it, modify the area then retest
to check the changes, takes ages.
Youre not going to be able to do that, so just aim to smooth and flatten that hump on both
sides of the port, blending it in to the SSR at the apexes.
A gentle touch with a finger can usually detect what the eye dosent, so use that as a guide and
stop when it feels smooth and flat.
Now youve done all these, turn your attention to the port divider/splitter.
The basic idea here is to slim the bluff nose of it down, reducing its width at the leading edge
and smoothing the surfaces as it proceeds further into the port.
No need to knife edge it, just apply a small radius so its not dead sharp and dont work soley
on one side, itll end up biasing the flow one way or the other which affects overall flow,
again patience and care will see you right.
Use a pair of dividers to keep it central in the port by measuring.
You can see the basic shape to try and reproduce on the following photos of the port moulds.

Mould of the original port exit

Mould of the much smoother ported port exit

Once youve completed all the major works in the ports you can start to apply a surface
finish.
I use 80 grit sanding drums and 80 grit emery wrapped around a rod to further flatten and
smooth the surfaces and impart a nice flow friendly surface.
Its best to run this at a moderate speed as too fast will just make it uncontrollable and the
media wears faster.
You can use wd40 to help but I dont find it always necessary except in the chambers.
Start at the port mouth and work around the periphery, youll feel and see the effects of it
almost immediately, continue that method all the way .
To get that cross hatch effect, stroke the tool back and forth covering the entire port, but be
sure to not dwell in one area, keep it moving until youre satsified with the results and you
have a uniform finish.
This is what youll end up with.

A smooth and uniform finish for the port is the last step in the process.

In the chamber, use the sanding drum to carefully dress the surface and remove the myriad of
pits and marks in the alloy.
Youre just aiming to remove sharp edges and blending surfaces.
Try to form smooth contours where the alloy runs down to the seats.
There are lots of edges in this part of the chamber and I use a homebrewed cutter to remove
them evenly, but its possible to use old valves with the outer diameter reduced and the head
ground with a bevel to protect the seats while youre working in the chamber with a sanding
drum( its what I use).
Aim for a 120 grit finish in the chamber. You can go smoother but it takes a lot of effort and
time and its likely not worth it.
Aim to get the ports and chambers as shown in the photos.

What a finished chamber should look like

What a finished port should look like

Freshly cut valve seats for great valve seal, better compression, and higher effeciency

The exhaust ports are far simpler to work on believe it or not.
They too suffer from all the intakes casting flaws and can be improved quite markedly.
The 3vz fe has a compromised head design especially on the exhaust ports because theyre not
identical across all three of them.
Two are of a “dog leg” design whereby one side of the port is a straight shot out with the
other runner coming in at around 40 ish degrees and merging.
This creates turbulence and a loss.
All we can really do here is improve it so it flows better.
The “odd” port out on the end of the head is more of a siamesed design with almost equal
length runners and this definitely flows better to the tune of around 10cfm over the other
exhaust ports.
That kind of leads to a bit of a quandry.
Improve it or not?
Well yes, but bear in mind itll easily outflow the other exhausts if you apply the same
measures to it as all the others.
I tend to develop the dog legged ports to flow equally and as highly as I can and then do that
“straight shot” port last, balancing the airflow to match the others.
Takes time and effort.
All youll be able to do, is make them resemble each other as closely as possible and leave it
at that.
I have it on great authority that balancing the exhaust flows isnt as critical so im happy to
bow to much greater knowledge on that score.
Heres the 3vzfe’s exhaust ports in silicone rubber, not a pretty sight.

The sorry state of the factory exhaust ports

Ok, proceed with the exhaust ports as per the intakes, removing casting lines and
imperfections at the port exit (at the face and working inwards).
Theyre awkward to do due to their shape, but stick with it and youll get there.
The guide bosses are a fair size on these.
Reduce them as per the intakes, mostly on the widths and the “ramp” at the front of them
leading to the guide, smoothing and blending them in.
Once youre happy with these, turn the head over and examine the bowl area ( under the valve
head).
Youll notice some material just on and below the seat which needs removing and a rather
large overhang.
I try to blend the overhang into the seat insert/ port but its pretty much impossible to remove
it entirely as youd have to burrow into the material far deeper than really is good and its
purely an aesthetic operation to remove it which you wont see when its all together anyway.
In this case, just smooth it as best as possible.
The sides of the ports at the divider have a similar “hump” to the intakes, so again its a case
of basically flattening them and blending in to the rest of the port.
The exhaust also has an SSR which heavily influences how well the port can flow.
This mould shows the kind of condition the factory leaves the heads in.

Between the very tight short side radius (SSR) and the protruding valve guide, this is a very poorly shaped factory port.

A finger prodded into the port will expose a sharp edge which creates major restriction and
turbulence just as on the intakes.
Once youve addressed that and modified it to more closely resemble the next photo, apply a
similar finish to the exhaust port surfaces as the intakes using the methods youll now have
developed.
You can finish these to 120 grit as itll help to reduce carbon buildup than a rougher surface
which can alter the flow of the ports over time.
Modified exhaust port shape.

Reshaped port with a reduced valve guide protrusion and less sharp short side radius

Reshaped port mould #2 with a smoother transition from the runner into the valve exit

Reshaped port mould # 3 showing the smoothened valve guides

A look at what a finished exhaust port should look like

If youve done a good job, you should have ports that are closely matched for both flow and
give a good improvement over stock.
Typical bare port flow for a stock 3vzfe is 204cfm@28″, the result of your efforts if you work diligently should enable an improvement to approx 230cfm.
Typical exhaust flows are 154cfm@28″ on exhausts, yours should rise to at least 165-170 after mods.

At this point in time, ive done limited tests regarding valves and seats, so its far from clear what the ultimate seat angle, width and number of cuts plus optimum valve shape is for these ports, that will come later when I have more time to spend on them.

Power gain to expect will be from 185 ish stock to as high as 215bhp, that figure being the highest seen thus far.

Copyright 2009 T.Warren ( 4v6)

Technorati Tags: 3VZ-FE, Combustion Chamber, Cylinder Head, Head Porting, Short Side Radius, supercharger performance, Valve Guide

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