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Eric68 · Joined: 01 Nov 2007 Posts: 331

I'm looking at a SBC 377" with a 4" bore x 3.75" stroke 8.8:1 compression blow through deal. It has a 250/264* solid roller cam and AFR 210 aluminum heads.

The engine currently makes 900 rear wheel HP thanks to 22 psi from a nearly maxed out Procharger F1R. It is currently intercooled, but the intercooler is maxed out (rated at 1050 flywheel HP) and I believe holding this engine back. On the chassis dyno the engine peaks early and stays flat indicating something is a bottleneck.

My question -- do you guys think that if we removed the intercooler and switched from 112 octane race gasoline to E85 the engine would work without detonation? Hoping to pick up significant power by ditching the intercooler and going to E85.

Thanks
_________________
E85 racer and E85 carb builder
www.horsepowerinnovations.com

E85 powered 68 Camaro street car
Best ET on motor 9.96 @ 133 MPH, 5.92 on N2O in the 1/8th

hotrod · Joined: 19 Apr 2005 Posts: 872 Location: Colorado

Before you toss the intercooler you ought to get some data so you know what is going on.

You at least need to measure the pressure drop across the intercooler, and the charge air temp in and out of the intercooler.

E85 would help, but the only way I would consider tossing the intercooler would be with a water injection system.

Your flat performance could be either the intercooler, or the procharger maxing out, or it could be due to a boost leak or blow off valve that will not hold closed at max boost.

It could also be due to an exhaust restriction, (you can't get it in if you can't get it out).

If it has a street exhaust, pull the exhaust and see if it picks up.

Log your boost and see if the boost continues to rise ahead of the intercooler but goes flat past the intercooler due to choked flow in the intercooler. If the pressure drop does not change across the intercooler it could be the procharger that is the limit. Does your intake air temp go up rapidly about the time the power curve goes flat? In turbos the intake air temp goes ballistic when the turbo goes into choke or exceeds max tip speed on the impeller.

Any chance your setup is sucking an intake pipe closed or strangled by high intake air flow restriction infront of the procharger?
Have you measured the pressure drop in the intake piping ahead of the procharger? More than about 0.5 psi would have me looking at flow limits on the air filter and inlet piping. On some of the turbo imports they can suck the intake piping closed at max boost due to the suction of the turbo on some silicone rubber intake tubing. People have also sucked air filters inside out on some setups.

On 8:1 compression 4 valve head engines inthe DSMs they are running peak boost on E85 ranging from 35-42 psi without detonation, from what I have heard. But that is intercooled.

Larry

crispeed · Joined: 24 Dec 2007 Posts: 98

Eric68 · Joined: 01 Nov 2007 Posts: 331

crispeed, it is a dynojet with Winpep 7 software.

All good stuff to test Larry. You're right. We probably should back up and get some data.

We have had some boost leaks in the past, but believe we have them all taken care of now. Part of the reasoning behind ditching the intercooler is to eliminate the complicated (prone to leaking) piping. There is no hose/tubing that could collapse, all thin wall aluminum piping with a few silicone sleeves joining sections together.

We actually split the intercooler on our first outing to the track. It seemed like the engine backfired into the intake tract and it blew the welds out of the ProCharger (inlet) side of the intercooler. We had it repaired and seems to be OK since.

I have some thermocouples I can install before and after the IC. Maybe that is my next test.

I don't have anything I can measure and record pressure DP across the intercooler with at this point. Will think about that one.

Thanks for the ideas.

PS. On the dyno the boost pressure was recorded from under the carburetor. It was linear and increased steadily with RPM; However, we did not measure before the intercooler and have nothing to compare our data to.
_________________
E85 racer and E85 carb builder
www.horsepowerinnovations.com

E85 powered 68 Camaro street car
Best ET on motor 9.96 @ 133 MPH, 5.92 on N2O in the 1/8th

hotrod · Joined: 19 Apr 2005 Posts: 872 Location: Colorado