Let's talk about cams, high compression, and turbo's.....
06-22-2003, 12:09 PM
#1
Honda-Tech Member
Thread Starter
Let's talk about cams, high compression, and turbo's.....
I've heard of the hypertune guys making good power with os giken flat top pistons in a b16a2, with toda spec c cams.....
I always thought the spec a's were the only ones you could use - because the b's and c's had too much duration to be able to dial out the overlap.....
Thoughts?
I always thought the spec a's were the only ones you could use - because the b's and c's had too much duration to be able to dial out the overlap.....
Thoughts?
06-22-2003, 08:47 PM
#2
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Thread Starter
Re: Let's talk about cams, high compression, and turbo's..... (Black R)
Oh yeah, I forgot to mention high compression.....
Local guys at the dyno shop were telling me that with a higher compression ~9.5:1 they were making more power with the same amount of boost. Likewise, they were able to make more power with higher lift cams and the same amount of boost.....
And I seem to remember some crazy race car in a mag a couple years ago that had 16:1 compression, toda (spec a?) cams, and double digit boost.....
Anyone care to contribute here?
Local guys at the dyno shop were telling me that with a higher compression ~9.5:1 they were making more power with the same amount of boost. Likewise, they were able to make more power with higher lift cams and the same amount of boost.....
And I seem to remember some crazy race car in a mag a couple years ago that had 16:1 compression, toda (spec a?) cams, and double digit boost.....
Anyone care to contribute here?
06-22-2003, 08:54 PM
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Re: Let's talk about cams, high compression, and turbo's..... (Black R)
16:1 compression + Double digit compression = BOOOOOM!!!!! You have to be a miracle tuner to pull off something like that. Also with high lift cams? I believe turbo cars need small lifting cams. Toda/JUN and other High lift cams would be hard to tune and run like crap on a boosted car.
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Black R »</TD></TR><TR><TD CLASS="quote">Likewise, they were able to make more power with higher lift cams and the same amount of boost..... </TD></TR></TABLE>
Maybe they were saying higher lift than the ones they had. Makes some sense. But i am not an expert in this area yet
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Black R »</TD></TR><TR><TD CLASS="quote">Likewise, they were able to make more power with higher lift cams and the same amount of boost..... </TD></TR></TABLE>
Maybe they were saying higher lift than the ones they had. Makes some sense. But i am not an expert in this area yet
06-22-2003, 09:09 PM
#5
Re: Let's talk about cams, high compression, and turbo's..... (Black R)
With long duration, high lift cams you'll have an exhaust scavenge effect which is what essentially make the power in all motor cars. The high compression of an all motor engine aids the exhaust scavenging in that it places the mixture under higher pressure forcing it to escape quicker when the duration of the cam is applied to the valves. This is key since the residual of the mixture (air, fuel and burnt by products from previous exhaust cycle) are left inside of the combustion chamber, and in order to clean the incoming mixture out the vacuum condition of the exhaust system at overlap is enhanced by the pushing through of the burnt mixture, and drawing in of the fresh air/fuel mixture.
With a forced induction engine this aspect is essential for operation, and peak power but duration is a by product of all motor cams not suited for such an application. The duration allows for blow-by to occur when the intake and exhaust cam are opened, so the peak cylinder pressure is reduced since the density of air is reduced. Since peak cylinder pressure is reduced overall power output is reduced.
As far as compression is concerned, higher compression will make a bit more power at the same psi level. The key difference lies in the difference between the cylinder pressure and temperature with a low and high compression engine at the same psi level. The universal gas law PV=nRT states that temperature, pressure and density are all related. A change to one, will make changes in the others. Take this scenario:
9:1 compression. 10psi. The cylinder pressure would be 1500psi (hypothetical), cylinder temperature would be 700 celsius (4th gear loading) and the density would be called 5.
11:1 compression. 10psi. The cylinder pressure would be 1800psi, cylinder temperature would be 800 celsius and density would be 2.
The higher compression set-up would yield more power since the cylinder pressure and tempature would be higher, but the air density in the cylinder would drop since the incoming air would not be cooled in the same manner as the lower compression set-up. The intercooled intake charge of the lower compression set-up will yield less power at the expensive of reduced cylinder pressure and temperature. This inturn reduces pre-ignition/detonation.
Higher lift cams with stock, or lower duration will yield the best gains. You are dialing out the blow-by effect. You can only dial out so much overlap between the intake and exhaust cams by cam gears, but only directly altering the duration will make a dramatical difference. Once the blow-by is reduced, the more air density that can be crammed into the engine thus increasing cylinder pressure to apply more work on the piston. More work=more torque=more horsepower.
With a forced induction engine this aspect is essential for operation, and peak power but duration is a by product of all motor cams not suited for such an application. The duration allows for blow-by to occur when the intake and exhaust cam are opened, so the peak cylinder pressure is reduced since the density of air is reduced. Since peak cylinder pressure is reduced overall power output is reduced.
As far as compression is concerned, higher compression will make a bit more power at the same psi level. The key difference lies in the difference between the cylinder pressure and temperature with a low and high compression engine at the same psi level. The universal gas law PV=nRT states that temperature, pressure and density are all related. A change to one, will make changes in the others. Take this scenario:
9:1 compression. 10psi. The cylinder pressure would be 1500psi (hypothetical), cylinder temperature would be 700 celsius (4th gear loading) and the density would be called 5.
11:1 compression. 10psi. The cylinder pressure would be 1800psi, cylinder temperature would be 800 celsius and density would be 2.
The higher compression set-up would yield more power since the cylinder pressure and tempature would be higher, but the air density in the cylinder would drop since the incoming air would not be cooled in the same manner as the lower compression set-up. The intercooled intake charge of the lower compression set-up will yield less power at the expensive of reduced cylinder pressure and temperature. This inturn reduces pre-ignition/detonation.
Higher lift cams with stock, or lower duration will yield the best gains. You are dialing out the blow-by effect. You can only dial out so much overlap between the intake and exhaust cams by cam gears, but only directly altering the duration will make a dramatical difference. Once the blow-by is reduced, the more air density that can be crammed into the engine thus increasing cylinder pressure to apply more work on the piston. More work=more torque=more horsepower.
07-01-2003, 07:01 PM
#6
Honda-Tech Member
Thread Starter
Re: Let's talk about cams, high compression, and turbo's..... (boosted hybrid)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by boosted hybrid »</TD></TR><TR><TD CLASS="quote">Higher compression will make a bit more power at the same psi level. The key difference lies in the difference between the cylinder pressure and temperature with a low and high compression engine at the same psi level. The universal gas law PV=nRT states that temperature, pressure and density are all related. A change to one, will make changes in the others. Take this scenario:
9:1 compression. 10psi. The cylinder pressure would be 1500psi (hypothetical), cylinder temperature would be 700 celsius (4th gear loading) and the density would be called 5.
11:1 compression. 10psi. The cylinder pressure would be 1800psi, cylinder temperature would be 800 celsius and density would be 2.
The higher compression set-up would yield more power since the cylinder pressure and tempature would be higher, but the air density in the cylinder would drop since the incoming air would not be cooled in the same manner as the lower compression set-up. The intercooled intake charge of the lower compression set-up will yield less power at the expensive of reduced cylinder pressure and temperature. This inturn reduces pre-ignition/detonation.
Higher lift cams with stock, or lower duration will yield the best gains. You are dialing out the blow-by effect. You can only dial out so much overlap between the intake and exhaust cams by cam gears, but only directly altering the duration will make a dramatical difference. Once the blow-by is reduced, the more air density that can be crammed into the engine thus increasing cylinder pressure to apply more work on the piston. More work=more torque=more horsepower.</TD></TR></TABLE>
Ok, so I'm off to look at cam specs..... I wonder why hypertune Mark's setup works so well.....
As for the compression and laws of gasses: couldn't I run higher compression with say a hondata IM gasket, and more efficient intercooler? Say 11:1?
9:1 compression. 10psi. The cylinder pressure would be 1500psi (hypothetical), cylinder temperature would be 700 celsius (4th gear loading) and the density would be called 5.
11:1 compression. 10psi. The cylinder pressure would be 1800psi, cylinder temperature would be 800 celsius and density would be 2.
The higher compression set-up would yield more power since the cylinder pressure and tempature would be higher, but the air density in the cylinder would drop since the incoming air would not be cooled in the same manner as the lower compression set-up. The intercooled intake charge of the lower compression set-up will yield less power at the expensive of reduced cylinder pressure and temperature. This inturn reduces pre-ignition/detonation.
Higher lift cams with stock, or lower duration will yield the best gains. You are dialing out the blow-by effect. You can only dial out so much overlap between the intake and exhaust cams by cam gears, but only directly altering the duration will make a dramatical difference. Once the blow-by is reduced, the more air density that can be crammed into the engine thus increasing cylinder pressure to apply more work on the piston. More work=more torque=more horsepower.</TD></TR></TABLE>
Ok, so I'm off to look at cam specs..... I wonder why hypertune Mark's setup works so well.....
As for the compression and laws of gasses: couldn't I run higher compression with say a hondata IM gasket, and more efficient intercooler? Say 11:1?
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