Cylinder head testing - Part 1 - 823 whp base line on HTA88
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From: 2003 Evo VIII - Silver
94awdcoupe,
I too agree with just about every single thing you have said, especially about combination of parts, as everyone knows, I do a hell of a lot of testing myself.
I do not agree about the cylinder head though. I am not aware of the head swapping that went on at the shootout.
I do know for a fact that there are some heads that are screwed up by a lot of people and I've seen many that I am sure a stock head would outperform.
There are areas of the head that are important for flow and then there are areas of the head that are important for keeping detonation to a minimum. The bowl area is one of the bigger increases in flow we have found but the combustion chamber work has proven to provide the most room for more power through tuning.
I see a lot of guys who port their exhaust manifolds to match the steel exhaust gasket and I see people porting the heads to match that, I do not agree with that process and have found it to not work well.
A 25 whp cam change is easier than swapping a head but once you've done the cams and other parts the head is the other 25 whp you were looking for and many times the head work is required to run a cam that gives you 75+whp instead of 25 whp.
Also, as for Al's engine being down. I'd venture to guess with that one hole down, unless it is some serious damage, fixing it will make NO difference on the dyno. Some of the fastest times I have ever run and some of the highest numbers I have ever produced on the dyno were with engines so worn out and down on compression they were hard to even start. Once, we had to hit my RS with starting fluid to even get it to fire, then it made the highest HP ever following that. Rebuilt the engine, put it back in the car, NO gains, NONE.
We had the same thing happen in Colorado with the old tube car. Some knuckle head (me) put the pistons in backwards. So of course the small valve reliefs weren't enough for the intake valves and it bent the valves. After turning the pistons around in the bore (had no ring compressor at the track) we put the head back on and knew the valves were bent. The car would not start, filled it with starting fluid and got it to fire then held it on the rev limiter to get it as hot as we could and hopefully slam the valves around enough to straighten them out. Well it worked, compression in the highest cylinder was 90 psi. The car ran 8.1 at 5,000+ feet, the best it had ever run was 7.9 at the time.
I too agree with just about every single thing you have said, especially about combination of parts, as everyone knows, I do a hell of a lot of testing myself.
I do not agree about the cylinder head though. I am not aware of the head swapping that went on at the shootout.
I do know for a fact that there are some heads that are screwed up by a lot of people and I've seen many that I am sure a stock head would outperform.
There are areas of the head that are important for flow and then there are areas of the head that are important for keeping detonation to a minimum. The bowl area is one of the bigger increases in flow we have found but the combustion chamber work has proven to provide the most room for more power through tuning.
I see a lot of guys who port their exhaust manifolds to match the steel exhaust gasket and I see people porting the heads to match that, I do not agree with that process and have found it to not work well.
A 25 whp cam change is easier than swapping a head but once you've done the cams and other parts the head is the other 25 whp you were looking for and many times the head work is required to run a cam that gives you 75+whp instead of 25 whp.
Also, as for Al's engine being down. I'd venture to guess with that one hole down, unless it is some serious damage, fixing it will make NO difference on the dyno. Some of the fastest times I have ever run and some of the highest numbers I have ever produced on the dyno were with engines so worn out and down on compression they were hard to even start. Once, we had to hit my RS with starting fluid to even get it to fire, then it made the highest HP ever following that. Rebuilt the engine, put it back in the car, NO gains, NONE.
We had the same thing happen in Colorado with the old tube car. Some knuckle head (me) put the pistons in backwards. So of course the small valve reliefs weren't enough for the intake valves and it bent the valves. After turning the pistons around in the bore (had no ring compressor at the track) we put the head back on and knew the valves were bent. The car would not start, filled it with starting fluid and got it to fire then held it on the rev limiter to get it as hot as we could and hopefully slam the valves around enough to straighten them out. Well it worked, compression in the highest cylinder was 90 psi. The car ran 8.1 at 5,000+ feet, the best it had ever run was 7.9 at the time.
My ear is twlling me that the leak is actually comming from the head - we'll see tomorrow or the next day when I pull the intake and exhuast manifolds and see where the air is going
With all that said - also - it is obvious to me that with the kind of power I am making on this set up the car is running exceptionally well
I am thinking that after I fix the lean down issue I will put the Gt42 back on and test both heads at the 900 whp level with moderate boost this way the turbo is no longer a limiting factor
Al
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From: 2003 Evo VIII - Silver
I am one determined and persistant guy so I will hunt down the power.
Al
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From: 2003 Evo VIII - Silver
While it may not be the optimal drag racing turbo for a heavy Evo, it is a turbo which certainly will not be a limiting factor
My goal here is to try and determine what gains or losses can be obtained from the CnC ported cylinder head
With the Gt42 turbo I will remove the issue of the turbo being a limiting factor from the testing
Al
My goal here is to try and determine what gains or losses can be obtained from the CnC ported cylinder head
With the Gt42 turbo I will remove the issue of the turbo being a limiting factor from the testing
Al
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While it may not be the optimal drag racing turbo for a heavy Evo, it is a turbo which certainly will not be a limiting factor
My goal here is to try and determine what gains or losses can be obtained from the CnC ported cylinder head
With the Gt42 turbo I will remove the issue of the turbo being a limiting factor from the testing
Al
My goal here is to try and determine what gains or losses can be obtained from the CnC ported cylinder head
With the Gt42 turbo I will remove the issue of the turbo being a limiting factor from the testing
Al
I think the theory that backpressure is too high on your setup and is the limiting factor still is the top contender on the list of why the headway head lost power.
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Here is my simpleton notion of what is happening.. as hp rises, back pressure rises... as HP rises, the backpressure begins to work negatively on the system, whereby more boost = more HP but not as much HP as previous boost pressure increases. The stock head in a no backpressure environment can flow X and the ported head can flow Y. The stock head has more velocity though. But in the 800 hp range, there is so much backpressure, that the flow through the head is beneath X and Y. Therefore the ported head was useless and actually lost power because of the loss in velocity.
I'm probably way off in that theory but just throwing things out there.
Also Al, did you measure the Headway head versus the stock head to see if they had the same height? ie same CR and cam timing would be the same?
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From: 2003 Evo VIII - Silver
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But would that remove the back pressure issue from the equation?
Here is my simpleton notion of what is happening.. as hp rises, back pressure rises... as HP rises, the backpressure begins to work negatively on the system, whereby more boost = more HP but not as much HP as previous boost pressure increases. The stock head in a no backpressure environment can flow X and the ported head can flow Y. The stock head has more velocity though. But in the 800 hp range, there is so much backpressure, that the flow through the head is beneath X and Y. Therefore the ported head was useless and actually lost power because of the loss in velocity.
I'm probably way off in that theory but just throwing things out there.
Also Al, did you measure the Headway head versus the stock head to see if they had the same height? ie same CR and cam timing would be the same?
Here is my simpleton notion of what is happening.. as hp rises, back pressure rises... as HP rises, the backpressure begins to work negatively on the system, whereby more boost = more HP but not as much HP as previous boost pressure increases. The stock head in a no backpressure environment can flow X and the ported head can flow Y. The stock head has more velocity though. But in the 800 hp range, there is so much backpressure, that the flow through the head is beneath X and Y. Therefore the ported head was useless and actually lost power because of the loss in velocity.
I'm probably way off in that theory but just throwing things out there.
Also Al, did you measure the Headway head versus the stock head to see if they had the same height? ie same CR and cam timing would be the same?
Good points
I agree with your theory
I doid not measure compression ratio
If the new head hs a leaking valve then we need to fix it and goi back to scratch on the testing
Today I had an onslought of mail in tunes which took most of the day and a Subaru Hydra tune to finish - I may not get to the tear down till the weekend
At least I have business which I quess is a good thing !
A turbo is a big fudge factor that covers up a multitude of inefficiencies and sins. If something isn't optimized, we can make up for it by increasing air density (boost pressure) so long as our octane allows, right up to the limit of the turbo. At that point, a better head won't make the turbo flow more air.
You'll probably need to either pretend you're one of the masses that mostly cares about what is practical with pump fuel (e.g. 93 octane), which means reducing the boost pressure, or, install a large turbo that you cannot push to the limit.
30 psi shouldn't make you feel like a girlie man Al, my RS ran a 9.77 at 145 mph at 30 psi on 93 octane.
I do all my testing at 30 psi of boost. What I have found works at 30 psi of boost has almost always also worked at 40 psi of boost. I have only found one part that did not work as well at 40 psi as it did at 30 psi. Refer to my intake manifold testing that is still going on to find those results.
Robert from FP was here a few years ago when the HTA35r was initially released. I believe at the time I was running a .63 T3 turbine housing. We did back pressure logs at various boost levels and I was very suprised at the fact the back pressure wasn't nearly as high as I'd have guessed it was. I no longer have those logs but Robert might.
I can not see the T4 housing on your car being a limiting factor at 40 psi of boost. Just my opinion.
I do all my testing at 30 psi of boost. What I have found works at 30 psi of boost has almost always also worked at 40 psi of boost. I have only found one part that did not work as well at 40 psi as it did at 30 psi. Refer to my intake manifold testing that is still going on to find those results.
Robert from FP was here a few years ago when the HTA35r was initially released. I believe at the time I was running a .63 T3 turbine housing. We did back pressure logs at various boost levels and I was very suprised at the fact the back pressure wasn't nearly as high as I'd have guessed it was. I no longer have those logs but Robert might.
I can not see the T4 housing on your car being a limiting factor at 40 psi of boost. Just my opinion.
David, thanks for your post. I will agree to disagree with you on the head flow. In short velocity is king. I would say the only reason your stage three head makes more power is its increased detonation resistance from the smoothed chambers. And secondly you built the combination around the stage 3 head so it appears to work great. You really havent done enough testing in the cylinder head area to prove your point. There is sooo much evidence that smaller faster moving ports are better.
ports on hondas= way smaller than 4g63
look how much smaller valves/ports are on 4b11
motorcycle guy who makes ports smaller to make more HP, now manufacturers are doing it too. I could go on and on. The best was years ago in gainsville. abut (8-10 years ago) I was in the pits looking at the spare head being prepped on the worlds fastest 4 cylinder ford focus (at the time 8.50s at 165mph). I stood in udder shock looking at the ports on the head. they were nearly half the size as 4g63 heads. comical really. wish I had photos to show you. no attempt at making them bigger. and the intake manifold runners were big. very big. no port matching whatsoever. its like the intake ports were the size of a quarter and the runners were size of small cell phone. the engine design was 30 years old (40 today) and they were the fastest 4 cylinders out at the time. I asked the guy a few questions about the head design without being too intrusive. I learned the importance of air velocity that day.
This argument is no different than the discovery that a smaller plenum on intake manifold is king. Text books can be wrong, theories can be wrong. assumptions can be wrong.
Als test here with stock head versus CNC ported head flat proves my point. you guys just dont see it yet.
Guy in my area here running 5.16, 5.17, 5.16 passes told me he hurt his motor on last pass. 60% leakdown on one cylinder. next pass was a 5.17. If piston is round at top you will make power.
ports on hondas= way smaller than 4g63
look how much smaller valves/ports are on 4b11
motorcycle guy who makes ports smaller to make more HP, now manufacturers are doing it too. I could go on and on. The best was years ago in gainsville. abut (8-10 years ago) I was in the pits looking at the spare head being prepped on the worlds fastest 4 cylinder ford focus (at the time 8.50s at 165mph). I stood in udder shock looking at the ports on the head. they were nearly half the size as 4g63 heads. comical really. wish I had photos to show you. no attempt at making them bigger. and the intake manifold runners were big. very big. no port matching whatsoever. its like the intake ports were the size of a quarter and the runners were size of small cell phone. the engine design was 30 years old (40 today) and they were the fastest 4 cylinders out at the time. I asked the guy a few questions about the head design without being too intrusive. I learned the importance of air velocity that day.
This argument is no different than the discovery that a smaller plenum on intake manifold is king. Text books can be wrong, theories can be wrong. assumptions can be wrong.
Als test here with stock head versus CNC ported head flat proves my point. you guys just dont see it yet.
Guy in my area here running 5.16, 5.17, 5.16 passes told me he hurt his motor on last pass. 60% leakdown on one cylinder. next pass was a 5.17. If piston is round at top you will make power.
Last edited by 94AWDcoupe; Apr 2, 2009 at 05:52 PM.
The picture is a bit more complicated than that. Port velocity is just one factor in overall airflow efficiency, which is how much air the port flows with respect to velocity. We can't just eyeball a port and gauge it by the way it looks.
Velocity is a good thing, until a point. When velocity through the port reaches a certain speed (e.g. 0.6 mach), you won't flow any more air through the port. Velocity is a bit like spool characterstics - it's more important at less than all-out situations.
A Honda head may appear to have small ports, but they don't give small flow figures. I've seen Honda heads put up some very impressive flow data - much better than an EVO head. Better airflow means more power per unit of boost pressure, and it does not necessarily equate to velocity issues.
As for the turbo Focus, I know the car, know the owner. The head used to make those 8.X second runs is an Esslinger ARCA head, fits the Lima series turbo Ford engine, and despite what the ports looked like to one's eye, they are inefficient. They give pretty good flow figures at very high lift and with huge valves, but have poor velocity. I know, I own one.
Velocity is a good thing, until a point. When velocity through the port reaches a certain speed (e.g. 0.6 mach), you won't flow any more air through the port. Velocity is a bit like spool characterstics - it's more important at less than all-out situations.
A Honda head may appear to have small ports, but they don't give small flow figures. I've seen Honda heads put up some very impressive flow data - much better than an EVO head. Better airflow means more power per unit of boost pressure, and it does not necessarily equate to velocity issues.
As for the turbo Focus, I know the car, know the owner. The head used to make those 8.X second runs is an Esslinger ARCA head, fits the Lima series turbo Ford engine, and despite what the ports looked like to one's eye, they are inefficient. They give pretty good flow figures at very high lift and with huge valves, but have poor velocity. I know, I own one.
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Ok, but a better head will deliver more power with less boost. If you make it such that the turbo is the limiting factor in the equation, a better head won't help that.
A turbo is a big fudge factor that covers up a multitude of inefficiencies and sins. If something isn't optimized, we can make up for it by increasing air density (boost pressure) so long as our octane allows, right up to the limit of the turbo. At that point, a better head won't make the turbo flow more air.
You'll probably need to either pretend you're one of the masses that mostly cares about what is practical with pump fuel (e.g. 93 octane), which means reducing the boost pressure, or, install a large turbo that you cannot push to the limit.
A turbo is a big fudge factor that covers up a multitude of inefficiencies and sins. If something isn't optimized, we can make up for it by increasing air density (boost pressure) so long as our octane allows, right up to the limit of the turbo. At that point, a better head won't make the turbo flow more air.
You'll probably need to either pretend you're one of the masses that mostly cares about what is practical with pump fuel (e.g. 93 octane), which means reducing the boost pressure, or, install a large turbo that you cannot push to the limit.