are 918's crap?
Thread Starter
Teching In
Joined: Jan 2005
Posts: 11
Likes: 0
From: Jacksonville, Tx
are 918's crap? Will Comp 918's float the valves with a .590 cam with boost behind it.
We have a problem car that will not make the boost it should. Been through the turbo system several times and no luck. Have been told several times that the 918's are no where near up the job for this application.
Opinions???
We have a problem car that will not make the boost it should. Been through the turbo system several times and no luck. Have been told several times that the 918's are no where near up the job for this application.
Opinions???
I usually keep the 918s for .595"/232 and less cams, anything more than that I use PRCs or Comp 921s. A boosted application would aggrevate the problem and would require more spring than a N/A application.
Thread Starter
Teching In
Joined: Jan 2005
Posts: 11
Likes: 0
From: Jacksonville, Tx
Thats the issue, the graph doesnt really show float. The engine is a built 383 with a 228/232 .588/.590 on a 115. We are trying to run 12psi, but we cant get it above 8. We have tried 3 different turbos, 2 intercoolers, 2 wastegates, and 3 wastegate springs. Oddly enough, the most power we got was from a 60-1, not the t-76 or t-70. The 60-1 made 560/660 at 8psi. That is way out of turbo, but was just a temp while we got the t-70 which we are sticking with. Now, there may be a 200hp difference between back to back runs. The way I am thinking, NA the 918's are done. Now we try to run 12psi through and I'm just blowing boost through. I'd love to blame the springs, but I'm not sure yet.
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TECH Senior Member
Joined: Mar 2004
Posts: 14,620
Likes: 17
From: BFE
Originally Posted by Unaffiliated Racing
I will agree with Paul. Spring pressure is what is going to make the difference on a turbo motor. Due to back pressure from the turbo, the exhaust springs may not have enough pressure to keep the valve closed.
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