16v turbo dyno testing
11-11-2010, 10:37 AM
#32
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Well there are a few hurdles to jump over to do the 16V correctly. That's the reason why most don't commit to it. Yes it has many advantages to the **** poor (that's me being nice) 8V head. However, going 16V requires new pistons, custom intake and exhaust, etc. And when you can get 500whp from a large displacement 8v, it's hard to not go the 'easier' route.
11-11-2010, 10:39 AM
#33
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11-11-2010, 10:54 AM
#34
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11-11-2010, 11:13 AM
#35
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Does this mean Rolex's engine is done?
11-11-2010, 12:13 PM
#36
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When I flow tested a bone stock 8v head he suddenly got interested in it, it was flowing air better than the castings he was using (at least up to our .5” lift). When I put a 16v head on the bench I think he started drooling, he could not get those kind of numbers with any mods (again – up to .5”, over .5” lift he was making a lot more flow!)
4V chamber heads usually have inferior flow coefficient numbers to 2V chambers. But, the 2V intake valve is only 45mm, versus 39mm for the 968 head (37 for both the S and S2). That is a single valve equivalent of 55mm (52.3mm). So the overall flow is always better.
And overall horsepower is a function of three things - volumetric efficiency, thermal efficiency, and mechanical efficiency:
VE - F(airflow), and a 55mm equivalent valve flows a lot more than a 45mm one, making the 968 head the best starting point.
TE - F(CR). The centally located plug an increase in compression by about 0.7-0.8 points, sometimes as high as 1.0. Again, the 4V chamber is better
ME - F(friction). The only one of three that hurt the 4V chamber, due to added friction of hte second cam. But it is minor compared to the cranktrain and pistons.
SO there are the Cliff's NOtes versions of why the 16V head is gaining interest. I could probably write a few chapters on most of this stuff, but I'm an engineer and would probably put everyone reading but Chris to sleep (and Hell, he'd probably have a red pen out correcting me!). Hope what I put out there helps answer some of the questions.
Oh yeah - the GM pushrod engines are a LOT more sophisticated than they get credit for. GM has freakin' great engineers. I'd take them over Porshce engineers any day of the week (yes, I did just say that). It is no longer ancient technology. The advantages of it, as any LSX 944 owner will tell you, is its power to weight ratio, and relative reliability. It is a very compact engine, and very robust for one making its power level. Yes, it costs less than, say, the new Ford 5.0L, but it costs a lot more than the Ford Modular 2V's, which are "technologically superior" due to the OHC design. Had Ford's old 32V Modular been produced in like volumes, it would have been cheaper than the LSX, as well. Still cheaper than a turbo 4 banger with all of the bells and whistles, though!
11-11-2010, 12:32 PM
#38
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Its been assembled for quite a while (a long time…) – we were waiting to get the tuning done on my engine and any info / mods that came out of that will go in to his, Rolex’s engine is very similar except it is using the stock cam drive, vario cam, a custom Vitesse turbo and Ti connecting rods. Rolex’s engine should pick up revs faster that I can imagine!
11-11-2010, 01:17 PM
#39
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Its been assembled for quite a while (a long time…) – we were waiting to get the tuning done on my engine and any info / mods that came out of that will go in to his, Rolex’s engine is very similar except it is using the stock cam drive, vario cam, a custom Vitesse turbo and Ti connecting rods. Rolex’s engine should pick up revs faster that I can imagine!
11-11-2010, 01:53 PM
#40
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11-11-2010, 01:57 PM
#41
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FWIW, the 8V head had the best flow coefficients (which is flow normalized to valve size, allowing you to compare apples to apples) of any head it autdom at least into the early 2000's. The reason is pretty simple, the damn port sits on top of the head - looks more like a Formula 1 port than a normal street port.
4V chamber heads usually have inferior flow coefficient numbers to 2V chambers. But, the 2V intake valve is only 45mm, versus 39mm for the 968 head (37 for both the S and S2). That is a single valve equivalent of 55mm (52.3mm). So the overall flow is always better.
And overall horsepower is a function of three things - volumetric efficiency, thermal efficiency, and mechanical efficiency:
VE - F(airflow), and a 55mm equivalent valve flows a lot more than a 45mm one, making the 968 head the best starting point.
TE - F(CR). The centally located plug an increase in compression by about 0.7-0.8 points, sometimes as high as 1.0. Again, the 4V chamber is better
ME - F(friction). The only one of three that hurt the 4V chamber, due to added friction of hte second cam. But it is minor compared to the cranktrain and pistons.
SO there are the Cliff's NOtes versions of why the 16V head is gaining interest. I could probably write a few chapters on most of this stuff, but I'm an engineer and would probably put everyone reading but Chris to sleep (and Hell, he'd probably have a red pen out correcting me!). Hope what I put out there helps answer some of the questions.
Oh yeah - the GM pushrod engines are a LOT more sophisticated than they get credit for. GM has freakin' great engineers. I'd take them over Porshce engineers any day of the week (yes, I did just say that). It is no longer ancient technology. The advantages of it, as any LSX 944 owner will tell you, is its power to weight ratio, and relative reliability. It is a very compact engine, and very robust for one making its power level. Yes, it costs less than, say, the new Ford 5.0L, but it costs a lot more than the Ford Modular 2V's, which are "technologically superior" due to the OHC design. Had Ford's old 32V Modular been produced in like volumes, it would have been cheaper than the LSX, as well. Still cheaper than a turbo 4 banger with all of the bells and whistles, though!
4V chamber heads usually have inferior flow coefficient numbers to 2V chambers. But, the 2V intake valve is only 45mm, versus 39mm for the 968 head (37 for both the S and S2). That is a single valve equivalent of 55mm (52.3mm). So the overall flow is always better.
And overall horsepower is a function of three things - volumetric efficiency, thermal efficiency, and mechanical efficiency:
VE - F(airflow), and a 55mm equivalent valve flows a lot more than a 45mm one, making the 968 head the best starting point.
TE - F(CR). The centally located plug an increase in compression by about 0.7-0.8 points, sometimes as high as 1.0. Again, the 4V chamber is better
ME - F(friction). The only one of three that hurt the 4V chamber, due to added friction of hte second cam. But it is minor compared to the cranktrain and pistons.
SO there are the Cliff's NOtes versions of why the 16V head is gaining interest. I could probably write a few chapters on most of this stuff, but I'm an engineer and would probably put everyone reading but Chris to sleep (and Hell, he'd probably have a red pen out correcting me!). Hope what I put out there helps answer some of the questions.
Oh yeah - the GM pushrod engines are a LOT more sophisticated than they get credit for. GM has freakin' great engineers. I'd take them over Porshce engineers any day of the week (yes, I did just say that). It is no longer ancient technology. The advantages of it, as any LSX 944 owner will tell you, is its power to weight ratio, and relative reliability. It is a very compact engine, and very robust for one making its power level. Yes, it costs less than, say, the new Ford 5.0L, but it costs a lot more than the Ford Modular 2V's, which are "technologically superior" due to the OHC design. Had Ford's old 32V Modular been produced in like volumes, it would have been cheaper than the LSX, as well. Still cheaper than a turbo 4 banger with all of the bells and whistles, though!
Yeas ago we did a lot of work with the 32v mod engine , bone stock out of the box engine with exhaust system and pulleys was good for 340 whp....
A prepped engine ( show room stock ) well ......
11-11-2010, 02:57 PM
#42
Race Car
Hope I'm not thread jacking, but the head on the 2003 4.6-4V was very good. It outflowed the BMW M5 head. Problem with it was teh interface to the intake. The lash adjusters pushed the port down, making the interface to the intake horrible. We fixed all that with newer, better HLA's (among many other things) on the new 5.0L, which is a phenomenal engine.
11-11-2010, 03:37 PM
#43
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11-11-2010, 03:55 PM
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11-11-2010, 09:12 PM
#45
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Here is the dyno graph – its in excel since the dyno likes to dump the data into excel tables.
There was a slight misfire at 6k (you can see the hick up in the line) and I believe that I can flatten out the torque curve on the top end with the cam timing. If I can get the torque flat to 7k then the hp will be about 675 (at 15 psi!).
Then I can try 18…..maybe a tad more just for fun!
Anyway - the torque curve ‘shape’ is what I was looking for - +/- 5% from 4k to 6.5k. That’s what gets you out of the corners fast!!!
There was a slight misfire at 6k (you can see the hick up in the line) and I believe that I can flatten out the torque curve on the top end with the cam timing. If I can get the torque flat to 7k then the hp will be about 675 (at 15 psi!).
Then I can try 18…..maybe a tad more just for fun!
Anyway - the torque curve ‘shape’ is what I was looking for - +/- 5% from 4k to 6.5k. That’s what gets you out of the corners fast!!!