Cylinder head testing - Part 1 - 823 whp base line on HTA88
Evolved Member
Joined: Oct 2002
Posts: 2,788
Likes: 1
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.
And it's totally friggen... inefficient?? lol
Last edited by crcain; Apr 3, 2009 at 02:22 AM.
Newbie
Joined: Jul 2007
Posts: 6
Likes: 0
From: NY
Head work on the 4g63 is for those who need curbside appeal when they build their engine. Finding HP is more about a finding a combination of parts that work well together. You DONT need to change flow of head. You just re-proved that with your headgames head test.
There are 6 things off the top of my head that dictate flow for HP. compression, cams, intake manifold, ex manifold, A/R of housing. head port size. There is no ultimate best for any one of those. trying to find "best head flow" is only gonna be good for the current combo of parts you are testing them with. changing only one parameter is only good for that current combo of parts.
This fact was learned about 6 years ago in the DSM community. All the 4g63 head needs is good valve job and 15 minute bowl cleanup. Spending anything beyond that on the head is a waste of money. Changing the rest of the parts to get the HP you want is far easier and far cheaper.
one year at the shootout there were two top racers (one was magnus, other dont know) that damaged their high HP heads and had to bolt on bone stock heads in order to finish competing. one team set new ET record for his car at the time. the other went faster MPH than he previously had. then there were threads that started on the subject. and dozens admitted spending thousands on head work and not seeing any gain, many reported actual losses.
There are 6 things off the top of my head that dictate flow for HP. compression, cams, intake manifold, ex manifold, A/R of housing. head port size. There is no ultimate best for any one of those. trying to find "best head flow" is only gonna be good for the current combo of parts you are testing them with. changing only one parameter is only good for that current combo of parts.
This fact was learned about 6 years ago in the DSM community. All the 4g63 head needs is good valve job and 15 minute bowl cleanup. Spending anything beyond that on the head is a waste of money. Changing the rest of the parts to get the HP you want is far easier and far cheaper.
one year at the shootout there were two top racers (one was magnus, other dont know) that damaged their high HP heads and had to bolt on bone stock heads in order to finish competing. one team set new ET record for his car at the time. the other went faster MPH than he previously had. then there were threads that started on the subject. and dozens admitted spending thousands on head work and not seeing any gain, many reported actual losses.
When you have a head like Al's which increases the exhaust 35% compared to stock and 30% on the intake, it has to make power because of the simple fact it's getting more air into the cylinder. There is no guessing to that, it's an absolute fact. If you have an engine that makes 821 horsepower at 45 PSI with a dynamic efficiency of 85% and increase the efficiency to 100%, it will make 966 horsepower. That's without changing compression, it's just with cylinder head development.
Since you mentioned that port size is one of the factors that dictates flow in HP, can you tell me what the proper cross sectional area of the port for an engine that is 2 liters and running at over 8000rpm? I need an actual number, not just a list of words...
Jimib, I understand what he is trying to do. I clearly stated making HP is about finding a good combination of parts that work well together. As did Al, in his first post. What I was trying to convey is for 99.9% of people reading spending money on cylinder head is not wise. Al was making a solid 808whp on the bone stock head, he bolts in a 3500+ cylinder head and the combination looses 35hp. This is exactly what happened at the shootout when two racers went faster with bone stock heads. Al was not around for the early DSM shootout days. This was before his time with the 4g63.
You can take a bone stock engine and port the head and get 25whp. Or you can take the same bone stock engine and bolt in cams and get 25whp. Which is easier and which is smarter?
making a head flow better is easy. making a combination of parts around that better flowing head is not so easy. bolting heads in and out to see what works and what doesnt is about as time consuming as it gets.
I admire anyone like Al, that takes the time to do back to back testing and shares it with the boards. I would have been excited to see you dont need to spend 3500 on a cylinder head to make a potent 800whp. What this means is if you dont need it for 800 then you dont need it for 600 and you dont need it for 400. This is something I learned when the shootout accidentally proved it years ago. Since that time I always steer people away from spending money on cylinder head flow.
I am the type of person who does a lot of parts testing to get a combination of parts that work well together. I know what its all about. My own car has had a long list of parts installed on it to find what works and what doesnt.
Take it as you will. Not trying to start problems. Just stating what I feel is good knowledge to be gained.
Magnus head at shootout was quite an exotic head with titanium valves with smaller stems to improve flow. STOCK head proved better......
You can take a bone stock engine and port the head and get 25whp. Or you can take the same bone stock engine and bolt in cams and get 25whp. Which is easier and which is smarter?
making a head flow better is easy. making a combination of parts around that better flowing head is not so easy. bolting heads in and out to see what works and what doesnt is about as time consuming as it gets.
I admire anyone like Al, that takes the time to do back to back testing and shares it with the boards. I would have been excited to see you dont need to spend 3500 on a cylinder head to make a potent 800whp. What this means is if you dont need it for 800 then you dont need it for 600 and you dont need it for 400. This is something I learned when the shootout accidentally proved it years ago. Since that time I always steer people away from spending money on cylinder head flow.
I am the type of person who does a lot of parts testing to get a combination of parts that work well together. I know what its all about. My own car has had a long list of parts installed on it to find what works and what doesnt.
Take it as you will. Not trying to start problems. Just stating what I feel is good knowledge to be gained.
Magnus head at shootout was quite an exotic head with titanium valves with smaller stems to improve flow. STOCK head proved better......
Back pressure is a restriction in an engine when you enhance the intake by adding more air and fuel, without the ability to evacuate the exhaust pressure. The pressure in the turbine housing will then rise. What do you think happens when the piston is at TDC? The pressure from the exhaust will re enter the cylinder, leaving little to no space for the new incoming fresh charge of air.
Once the back pressure issue is solved, the cylinder head will make power. This has been tested before and the gains have been proven.
Value of airflow is proven, but when dealing with a maxed out turbo, are you going to get more air? In this situation all the air that goes in to the engine comes from the turbo. Making ports larger is essentially the same as adding length to intercooler piping. You have to spin the turbo harder to create the same psi. Maybe its more does this take that particular turbo out of its efficiency range that is the question to be asked?
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?
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.
As an example when I was building Justin Humphries' cylinder heads, we did several tests with different turbos. We ran two GT40s with 1.01 A/R exhaust housings, which equals 91.5 cubic inches per turbo. Al's motor is only 122 cubic inches and he's running a 0.81 A/R exhaust housing. By my calculations, the exhaust housing in Al's application is too small.
Another example is the Formula 1 engines in 1985 which ran 75 PSI thru a 91.5 cubic inch motor with a 1.32 A/R exhaust housing. They saw less than a 1:1 ratio of boost to back pressure.
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.
I see a lot of opinions but no facts. Ted B makes many solid points and people tend to overlook what he is saying.
-Ramon (Using Dave's account since I haven't set one up)
Ramon, I dont have time to post 2000 word essays. You make some good points but none of them disproves anything I said. All the small port engines I mentioned above make tremendous HP per cube, more than 4g63. Problem with head porting and quoting flow bench numbers is you are only quoting one parameter. Flow through port at static valve opening. There is far more happening in an engine and I dont have time to discuss them all. But bringing up back pressure would be a good discussion. F1 engines better a 1.1 ratio and that is far from what we are doing with the 4g63. back pressure numbers are always way higher than ideal so back pressure should be number one subject when finding HP. It is not . 99% of tuners dont log BP. You can flow 30 cfm through 1.0 port and 30 CFM through 1.5 port. When back pressure is high the 1.0 port will resist back flow with its higher velocity.(numbers irrelavent, only size reference important) and thus make more power. This is most likely why Al stock head made more power than free flowing ported head. having to swap lower pressure back housing to get numbers back up clearly shows that from where I am sitting. posting BP logs of everything done so far would have proved what is actually going on.
Evolving Member
Joined: Jan 2004
Posts: 210
Likes: 2
From: Cincinnati Ohio
Ramon, TedB others with similar thoughts. I respect your insight. If we were speaking about naturally aspirated engines here, I would agree totally. And I'm not totally disagreeing. That's why I worded the post that Ramon quoted as a question. I'm on board with the fact that, porting, will make the same power at a lower boost. However, like Al said, what if you are dealing with a turbo setup that is maxed out? If a turbo supports a specific amount of hp, and you are there with your current setup, where do you go from there?
Again i'm not saying there are no gains in porting the head. Also Ramon, I stated that I would not discount your head just yet. I am just more interested in to what extent the work needs to be done for varying turbo sizes. I see nothing but benefit from chamber work, valve job, and bowl/short turn work. Other than ex dividers and guide area, there is not much to do. At least in the intake. The exhaust runners are the only other place where there could be any significant amount or material to be removed. Not much to work with on the port size of the intakes. At least with out cutting, welding, using different gaskets and manifolds that would not match a stock head. So really after all these pages, I'm not even sure what the debate is about. At least for me. I guess that you do not need to spend thousands on a head? Ill second that. But that does not mean that porting is worthless. Cnc ported heads? They are awesome. I would say they are only as good as the hand ported model that was digitized, but you can clean some areas up with the software. And of course the consistency of them. I have been blessed in the fact that I have been able to be involved with the entire process of cnc porting. From making models, to digitizing, creating the model, and cutting the head... And got paid to do it. I guess we just have to wait and see what works for Al, and how economical it is for your average end user.
Again i'm not saying there are no gains in porting the head. Also Ramon, I stated that I would not discount your head just yet. I am just more interested in to what extent the work needs to be done for varying turbo sizes. I see nothing but benefit from chamber work, valve job, and bowl/short turn work. Other than ex dividers and guide area, there is not much to do. At least in the intake. The exhaust runners are the only other place where there could be any significant amount or material to be removed. Not much to work with on the port size of the intakes. At least with out cutting, welding, using different gaskets and manifolds that would not match a stock head. So really after all these pages, I'm not even sure what the debate is about. At least for me. I guess that you do not need to spend thousands on a head? Ill second that. But that does not mean that porting is worthless. Cnc ported heads? They are awesome. I would say they are only as good as the hand ported model that was digitized, but you can clean some areas up with the software. And of course the consistency of them. I have been blessed in the fact that I have been able to be involved with the entire process of cnc porting. From making models, to digitizing, creating the model, and cutting the head... And got paid to do it. I guess we just have to wait and see what works for Al, and how economical it is for your average end user.
Last edited by jimib; Apr 3, 2009 at 02:15 PM.
Again, to test the benefits of a head, the turbo has to be able to keep up. If the turbo is wound out with a stock head, a better flowing head probably won't make much difference.
Then we wouldn't have turbos to muddy the waters.
Evolved Member
Joined: Jan 2008
Posts: 874
Likes: 0
From: Australia
BTW - one thing to note
With the non ported stock head I could not spool the .81 T4 back housing and it did not work well
With the ported head now the .81 is spooling the same as the .63 a/r housing. Now I am considering a bigger housing.
I am starting to lean on the very real possibility that the HTA88 is just out of steam
Maybe some of you guys can help me with this - who is making the most power without nos on a T67 or HTA88 turbo
Al
With the non ported stock head I could not spool the .81 T4 back housing and it did not work well
With the ported head now the .81 is spooling the same as the .63 a/r housing. Now I am considering a bigger housing.
I am starting to lean on the very real possibility that the HTA88 is just out of steam
Maybe some of you guys can help me with this - who is making the most power without nos on a T67 or HTA88 turbo
Al
Newbie
Joined: Jul 2007
Posts: 6
Likes: 0
From: NY
Ramon, I dont have time to post 2000 word essays. You make some good points but none of them disproves anything I said. All the small port engines I mentioned above make tremendous HP per cube, more than 4g63. Problem with head porting and quoting flow bench numbers is you are only quoting one parameter. Flow through port at static valve opening. There is far more happening in an engine and I dont have time to discuss them all. But bringing up back pressure would be a good discussion. F1 engines better a 1.1 ratio and that is far from what we are doing with the 4g63. back pressure numbers are always way higher than ideal so back pressure should be number one subject when finding HP. It is not . 99% of tuners dont log BP. You can flow 30 cfm through 1.0 port and 30 CFM through 1.5 port. When back pressure is high the 1.0 port will resist back flow with its higher velocity.(numbers irrelavent, only size reference important) and thus make more power. This is most likely why Al stock head made more power than free flowing ported head. having to swap lower pressure back housing to get numbers back up clearly shows that from where I am sitting. posting BP logs of everything done so far would have proved what is actually going on.
I'm not sure if you know but the EVO 5/6 has an even larger port than my ported head. So even Mitsubishi follows the same theory...
Ramon, TedB others with similar thoughts. I respect your insight. If we were speaking about naturally aspirated engines here, I would agree totally. And I'm not totally disagreeing. That's why I worded the post that Ramon quoted as a question. I'm on board with the fact that, porting, will make the same power at a lower boost. However, like Al said, what if you are dealing with a turbo setup that is maxed out? If a turbo supports a specific amount of hp, and you are there with your current setup, where do you go from there?
Again i'm not saying there are no gains in porting the head. Also Ramon, I stated that I would not discount your head just yet. I am just more interested in to what extent the work needs to be done for varying turbo sizes. I see nothing but benefit from chamber work, valve job, and bowl/short turn work. Other than ex dividers and guide area, there is not much to do. At least in the intake. The exhaust runners are the only other place where there could be any significant amount or material to be removed. Not much to work with on the port size of the intakes. At least with out cutting, welding, using different gaskets and manifolds that would not match a stock head. So really after all these pages, I'm not even sure what the debate is about. At least for me. I guess that you do not need to spend thousands on a head? Ill second that. But that does not mean that porting is worthless. Cnc ported heads? They are awesome. I would say they are only as good as the hand ported model that was digitized, but you can clean some areas up with the software. And of course the consistency of them. I have been blessed in the fact that I have been able to be involved with the entire process of cnc porting. From making models, to digitizing, creating the model, and cutting the head... And got paid to do it. I guess we just have to wait and see what works for Al, and how economical it is for your average end user.
Again i'm not saying there are no gains in porting the head. Also Ramon, I stated that I would not discount your head just yet. I am just more interested in to what extent the work needs to be done for varying turbo sizes. I see nothing but benefit from chamber work, valve job, and bowl/short turn work. Other than ex dividers and guide area, there is not much to do. At least in the intake. The exhaust runners are the only other place where there could be any significant amount or material to be removed. Not much to work with on the port size of the intakes. At least with out cutting, welding, using different gaskets and manifolds that would not match a stock head. So really after all these pages, I'm not even sure what the debate is about. At least for me. I guess that you do not need to spend thousands on a head? Ill second that. But that does not mean that porting is worthless. Cnc ported heads? They are awesome. I would say they are only as good as the hand ported model that was digitized, but you can clean some areas up with the software. And of course the consistency of them. I have been blessed in the fact that I have been able to be involved with the entire process of cnc porting. From making models, to digitizing, creating the model, and cutting the head... And got paid to do it. I guess we just have to wait and see what works for Al, and how economical it is for your average end user.
Let's suppose that Al's turbo moves 89 pounds of air at 45 PSI at it's peak, the VE would be 89. If you increase your VE to 100 by increases flow in the head, that will generate about 150-170 more horsepower with the same amount of air. Always look at boost like a restriction, it's a measure of how much air the engine can not digest. The idea is to not run as much boost as you can but to allow the engine to consume as much volume as possible to produce horsepower.
Evolved Member
Joined: Oct 2002
Posts: 2,788
Likes: 1
Let's suppose that Al's turbo moves 89 pounds of air at 45 PSI at it's peak, the VE would be 89. If you increase your VE to 100 by increases flow in the head, that will generate about 150-170 more horsepower with the same amount of air. Always look at boost like a restriction, it's a measure of how much air the engine can not digest. The idea is to not run as much boost as you can but to allow the engine to consume as much volume as possible to produce horsepower.
And how can you make more horsepower given the same amount of air (provided charge temp is constant)?
One point in this discussion that I haven't seen is the potential that Al's turbo is being driven harder to maintain the same boost with the ported head since it isn't restricting flow like the stock head. This likely is putting the turbo into its choke limit where it physically can't flow anymore air. This also is putting it into an extremely inefficient region of the compressor map driving intake air temps up and ultimately driving the horsepower loss Al is experiencing. A reduction in boost should bring the turbo back to the same flow point that it was running with the stock head at 40lbs boost. This should then make more power with the improved VE. Over speeding the turbo to maintain 40lbs with the modified head is not doing a thing to show its potential.
Evolving Member
Joined: Jan 2004
Posts: 210
Likes: 2
From: Cincinnati Ohio
One point in this discussion that I haven't seen is the potential that Al's turbo is being driven harder to maintain the same boost with the ported head since it isn't restricting flow like the stock head. This likely is putting the turbo into its choke limit where it physically can't flow anymore air. This also is putting it into an extremely inefficient region of the compressor map driving intake air temps up and ultimately driving the horsepower loss Al is experiencing. A reduction in boost should bring the turbo back to the same flow point that it was running with the stock head at 40lbs boost. This should then make more power with the improved VE. Over speeding the turbo to maintain 40lbs with the modified head is not doing a thing to show its potential.
Evolved Member
Joined: Oct 2002
Posts: 2,788
Likes: 1
Now maybe, just maybe, Al could have reduced the boost with the ported head, and made more power. But I'm inclined to think Al would not overlook the fact he could simply turn down the boost and make more power in this test.
Thread Starter
Account Disabled
iTrader: (91)
Joined: Sep 2003
Posts: 16,850
Likes: 0
From: 2003 Evo VIII - Silver
Then a ported head probably won't help. I'm of the opinion that Al's turbo, pushed as hard as he is used to doing, has approached its limit on both sides. Even if he relieves the exhaust side, how much more power does anyone think that compressor can generate?
Again, to test the benefits of a head, the turbo has to be able to keep up. If the turbo is wound out with a stock head, a better flowing head probably won't make much difference.
Then we wouldn't have turbos to muddy the waters.
Again, to test the benefits of a head, the turbo has to be able to keep up. If the turbo is wound out with a stock head, a better flowing head probably won't make much difference.
Then we wouldn't have turbos to muddy the waters.
I think 800 whp is about all the turbo can do
This is why I plan to put the GT42 back on and resume testing with that turbo at 900 whp
This way the turbo is well within its limitations and we can see what effect the head has
Here is my game plan
1 - Remove manifolds and check for source of leak in cyl # 1
2 - Repair leak
3 - Install Gt42 turbo and dyno with Headway Head - tune to 900 whp even
4 - Re-install stock head and retest
This should give us an accurate A - B test
AL
Thread Starter
Account Disabled
iTrader: (91)
Joined: Sep 2003
Posts: 16,850
Likes: 0
From: 2003 Evo VIII - Silver
But if the ported head reduced a restriction you would see more flow and therefore more power.
Now maybe, just maybe, Al could have reduced the boost with the ported head, and made more power. But I'm inclined to think Al would not overlook the fact he could simply turn down the boost and make more power in this test.
Now maybe, just maybe, Al could have reduced the boost with the ported head, and made more power. But I'm inclined to think Al would not overlook the fact he could simply turn down the boost and make more power in this test.
Having previously made 1060 whp - I don't want to go backwards into the 600 and 700 whp club - heck we have many customers with stock heads and pump gas and meth daily driving at 700 whp.
The only solution is to take off the skirt and go back to the Gt42
On thing I note with great promise is how well the new head spooled the bigger back housing which previously on the stock head was problematic enough that I went to a smalled back housing
Al