Lt1turboTA

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???

Tech

iTrader: (1)

Comp 918s have been run on many much higher lift camshafts. How high are you spinning it?

Bo White

iTrader: (59)

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.

PREDATOR-Z

It depends on the amount of boost.
5>6 psi should be max. Any more and I would go 921's.
But do you have a graph showing float??

Lt1turboTA

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.

PREDATOR-Z

I'm no genius at FI but I'm a heavy juicer and I run XE-R lobes with 918's with no issues.
IMO you might want to look at ring blowby too.

Paul F

iTrader: (2)

How are the springs setup? What kind of seat pressure are you running? This means much more then the kind of spring you are running.


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PREDATOR-Z

Hmm, that does make sense.