L-20 crank and rods Z-20 pistons t4 garrett and a 750cfm holley 25psi boost at nearly 500hp through a gm power glide to a ford 9inch
11 sec 1/4 miles with this setup in Ron Folck's 1200 I'd say go with what others have proven on the track.

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STD gasket is only 1.2mm when compressed. With those parts you got about 11:1 comp, just right for naturally aspirated engine. (min volume = chamber + piston dish + gasket - deck height as pistons come over deck height) is about 36cc + 12cc + 5 - 2 = 51cc

Comp ratio is (500+51)/51 = 10.8

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How much advance is retarted when on boost? With those comp and boost there should be very little advance in boost, probably under 10 degrees as mixture burns very rapidly at high pressure.

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Change that SSS-head to standard A87 closed-chamber which has about 43cc chamber. That itself lowers comp ratio under 10: and chamber should be ported for better flow which also increases volume by few cc. And remember that with high comp ratio and high boost needed ignition advance under boost is minimal, with 24 degree advance engine probably won't detonate but as mixture burns too early pistons can't handle heat.

thanks again for the replies more info
cam shaft is set at zero deg witch is no ! mark on aftermarket gear the timming of dist is 24 at full boost is that to much?do you think the carb is enoughfor such a motor?just tell me what pistons, head gasket combo and carb (year make & mode) and we'll go that way. we dont want to go back to carb only we want H.P.!but dependable H.P.what timming? all answers are appr.I know everybody has their own opinion but i will take what looks the most correct to my knowledge help we want to go off roading soon

So there's no chance of getting the vehicle on a dyno, so appropriate A/F ratios can be checked throughout the rev range?

Tuning by ear/eye is not the best way. Especially when you want to go out and thrash the engine to within an inch of it's life.

Chris

are you blowing thru the carb or drawing thru, if you are drawing thru, your intercooler has all of your fuel in it and that is your problem. one sneeze and you would blow thew front off of your car.

its a draw thru and i have heard of sneazining sould we get rid of intercooler and just go to a holley or posible injection as in pro injection?also water/alky injection would that help as well?I personally have a 2300 cc air cooled vw with t-4, gm injection with 52 lbs injectors with intercooler water/alky inject 8-1 comp with no problems with 20 psi boost

no chance of a dyno but could install once running a o/2 sensor and meter ratio as well but was wanting to get running first with aleast the right parts and yes these engines get get beat up severely they are thru the rpm range probably more than any other driving that why i'm asking for help with this matter

The problem with draw through and the intercooler, is that while driving fast, the fuel would drop out of the mist and condense on the cool intercooler surface, and never make the engine, that would be a nightmare to tune. This is why EFI engines position injectors so that they squirt onto the intake valves. This stops the metered fuel mixture from forming large droplets and settling in the intake. That would be a fire hazard waiting to happen, imagine the fuel laying in the base of the intercooler after a run...I'd almost bet this caused a lean condition, which would cause the pistons to meltdown.

I'd definitely get rid of the intercooler on a draw through turbo setup. These are for blow through or EFI only I'd think.

Chris

ok chris we get rid of the intercooler no problem. now what piston head combo now?

on a suck through set up, you do not run an intercooler as a rule so once you get rid of it, lower the boost, tune the car and you should increase the boost gradually. You should be right, as mentioned earlier, the lean condition would melt your pistons.
have you checked out the suckthrough turbo group on yahoo.com?

draw thru turbo club

there is also the blowtrough group.

blowthrough