I would tend to think you could run the Vortech A-Trim which runs about 5-6 psi. You are one the verge of having too much compresion, so even the A-trim might be a little sketchy. However, if you are running a stock bottom end, there is no better reason to get a new block if it blows.

 

5-6 # would be about as far as I'd want to go w/ that compression and "hyper-you-cracked-it" pistons. You'll want to change your fuel pump to a Walbro GS340 (255lph high pressure) and maybe step up to bigger injectors depending on whether or not you plan to run an FMU. With the same heads and cam (assuming stage 1?), 9:1 compression, and 8# of boost, my car makes 414HP and 409TQ at the wheels.

Make sure you have the fuel demands covered, and run fairly conservative timing, and you should be OK. Just don't let it get anywhere near detonation, or you'll crack a piston.

 

Any blower should work, at lower boost levels. Figure about 7% horsepower increase per PSI boost, probably 5-6 PSI would be the max you'd want to run. The hard part is resisting the urge to increase boost beyond the point where reliability becomes a problem. In Calif, 91 octane gas holds us back, but if you want more boost, an intercooler system or alcohol injection will help. I think that with your engine, you'd have plenty of hp at 5 PSI.

Lots of people are running 9.5:1 with blowers--see the Corral for info:
http://www.corral.net/forums/forumdisplay.php?s=&forumid=311

Forrest

 

The fuel they sell over here are 92/95/100 octane. Up to what compression could I run on premium? Any advantage hp-wise?

I am thinking about a rebuilding kit which has 10:1 compression and I will not run a supercharger.

Thanks,
Lukas

 

Wade Can you tell me what pistons you are using,with which cyl, heads and the difference bewteen the stock size comb. chamber,and the size of the comb. chambers on your cyl.heads.I am tring to figure out which forged pistons to run n/a for now but want to supercharge later.My concren is ending up with a motor that will not run very well naturelly aspirated.Thanks Greg

 

I ran my 9.7:1 compression motor @ 12psi for quite awhile with no problems. I had forged pistions O-ringed heads and studs. Turbos rock! Be careful if you have don't have forged pistions! Them hypertectic pistions don't like boost or the squeeze.......

 

Lukas,
You can easily run 10:1 compression with 100 octane gas. Probably even 11:1. More compression = more power. We used to do that here in America years ago, but today it is difficult to find high-octane gas, especially in California. (There is high-octane race gas, but it is VERY expensive.)

This is one reason that European cars run so well in Europe, but suffer when they are in the American version.

Forrest

 

Whatever you do you are going to have to replace the T-5. It's just a matter of time before it blows, especially after the blower install.

 

Originally posted by Antony:
Whatever you do you are going to have to replace the T-5. It's just a matter of time before it blows, especially after the blower install.

If you're poppin' T5's with just a 302 and a blower you need to learn to row the gears a little better. Now if you're talking a T45 that's a different story...

 

Forrest,

Over here the price difference between 92 (lowest) and 100 octane is only 10percent or so. Doesnt matter much, I can use my company card to pay for it ! I will get asked why my fuel consumption would double from one day to the other!

 

Lukas,
I ran a 14.5:1 engine with 108 at one race. It was a touch lean, but ok for drag use. As Forrest suggests, 10:1 should be no problem with 100 octane. If I could get 100 for just 10% more I would go 11:1. You can always back out the timing a little if you see some detonation.

Remember that the static compression ratio is effected greatly by cam choice. Long duration cams reduce CR significantly.

 

Originally posted by scultr:
Wade Can you tell me what pistons you are using,with which cyl, heads and the difference bewteen the stock size comb. chamber,and the size of the comb. chambers on your cyl.heads.I am tring to figure out which forged pistons to run n/a for now but want to supercharge later.My concren is ending up with a motor that will not run very well naturelly aspirated.Thanks Greg

pistons are TRW/Speedpro 2482F. Heads are stock TFS Twisted Wedge...advertised chamber volume = 61cc. I'm using the Ford Racing B51 graphite head gaskets.

 

Wade and others, thanks for the info. Wade, I have looked at your build page and am impressed, you even painted your own car. By the way, I used to live in Burke, VA when I worked at the Pentagon (84-87). You live in a beautiful area in Warrenton.