Toyota MR2 Message Board - View Single Post - How to modify the 3vz-fe cylinder head (and others).

4v6 · 07-06-2009, 05:39 AM

How to modify the 3vzfe Cylinder head, a guide by 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 still a rather condensed account of how to proceed 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!
The information contained herein is based on extensive testing I have carried out myself therefore any quoted figures may or may not compare directly with others experiences due to differences in either testing regime or flowbench differences.

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 inhibitor 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.

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.

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.

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.

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.
The pressure is raised in that place and diverts 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.

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.

07-06-2009, 05:39 AM	#1 (permalink)
4v6 http://www.Typ-85.co.uk Join Date: Jun 2007 Posts: 184 Thanks: 2 Thanked 24 Times in 14 Posts iTrader Rating: (0/0% )	How to modify the 3vz-fe cylinder head (and others). How to modify the 3vzfe Cylinder head, a guide by 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 still a rather condensed account of how to proceed 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! The information contained herein is based on extensive testing I have carried out myself therefore any quoted figures may or may not compare directly with others experiences due to differences in either testing regime or flowbench differences. 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 inhibitor 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. 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. 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. 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. 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. The pressure is raised in that place and diverts 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. 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.