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Old 07-06-2006, 12:14 AM   #72
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Join Date: Feb 2001
Chapter/Region: NWIC
Location: Portland, Oregon
WRX H6-3.0 Turbo


Originally Posted by BadTrip
Some very interesting info in this thread:

Here's a couple key points:

"This is a stock H6 motor except for the addition of Supertec Forged H6 8:1 CR pistons. The stock valve train components are a very limiting factor in pushing the motor, so this initial tune is just to help develop maps."

"Given the valve train limitations (the exhaust valve springs are only 15 lbs), I didnít want to push the boost up above 14psi. I started at about 8psi, which quickly netted about 330whp. Upping to 10psi netteted 370whp, and 12psi over 400whp. At about 13psi, I was able to get ~420whp and about ~400 ft-lbf torque. I was very happy to get 400whp at only 12psi on pump 92 octane without the motor even breaking a sweat. At this low boost level, I could run AFRs anywhere from 11.1 to 12.5:1 without knock. "

"Here you can see the injector duty cycle, boost, and knock levels. With a peak injector duty of about 55%, 100% duty would be in the theoretical 730-750whp range. " <<Now throw in alk injection and you could be getting in the ball park, no?
Hey, that's me!

The topic of 1000whp has been something we have been discussing for some time. Adding something like Alky injection only allows the engine to make the most of the available air, not create horsepower where additional air is not available.

With the H6 at 3.0L, there are two limiting factors that make 1000whp challenging. First, the longer stroke puts some limits on RPM (as does the VERY heavy variable lift buckets). The second is of course the amount of boost you would need.

As a rough calculation, 3.0Ls at 85% eff at 6500rpm at 40psi yeilds about 70 lbs/min of air. Using something around 10-11hp/lb/min of air gets you about 700hp.

If you jump the boost to 50psi, you are talking about 80lb/min, or a bit over 800hp.

You would then need a turbo that can flow that kind of air at those pressure ratios. A 40 couldn't do it, but a 42R could. You would be at the top of the PR map at 50psi, but still workable. If you then added a 200 shot of NOS, you would be in the right ballpark.

If you really wanted 1000hp with no NOS, you would need something on the order of 60psi at 7000 rpm, which would be very very hard to do on any normal turbo. Even looking at a GT60, there is not enough PR height.

If you could rev to 8000rpm at 45psi, you would be at 90+ lb/min, which might be tweakable to 1000hp.

If you could increase VE at high RPM to 92%, 8000 rpm at only 40psi would be close to 1000hp, and right on the GT42 map.

Just some food for thought. Even with a turbo, displacement makes a big difference.

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sponaugle is offline   Reply With Quote