Gt-40X's shaved .25 what effect will this cause
01-30-2007, 10:51 PM
#1
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Gt-40X's shaved .25 what effect will this cause
I have a pair of gt-40X aluminum heads that have been shaved .25. What effect will this have on my motor. I know it changes my compression but will that be good or bad. Also i'm pretty sure i can't supercharge my engine. my engine is a 93.
01-30-2007, 10:53 PM
#2
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RE: Gt-40X's shaved .25 what effect will this cause
yea it will up the compression and that is a good thing it increases hp. but u could supercharge ur motor, but i would just say be safe and not run too much boost. the pistons are decent pistons, good enough to handle like 4-6 lbs of boost safely. im not too sure hope somone could help me on this one.
02-01-2007, 12:28 AM
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RE: Gt-40X's shaved .25 what effect will this cause
Were they 58cc combustion chamber originally. Compressions going to be pretty high now if they were.Well over 10:1. I wouldn't go suppercharging you, uping the compression that much is going to put added stress on stock pistons rings which are probably already worn a little bit.
02-01-2007, 06:12 AM
#5
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RE: Gt-40X's shaved .25 what effect will this cause
I believe the gt-40x heads have 64 cc combustion chambers so trimming them .025" should put you somewhere around 9.4 to 9.8 to 1, not exactly sure. In your case though, the compression ratio would be less of a concern to me than piston to valve clearance. If in fact the engine your putting these heads on is an 1986 5.0 and it has stock pistons without valve reliefs (only year they did that) I'd be extra careful installing any performance cam. No valve reliefs and milled heads could equal piston to valve contact. Evenwith amuch small lift and duration cam then theother year 5.0's are using you shouldbe concerned. Just food for thought.
02-01-2007, 07:33 PM
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RE: Gt-40X's shaved .25 what effect will this cause
ORIGINAL: Chitown racer
I believe the gt-40x heads have 64 cc combustion chambers so trimming them .025" should put you somewhere around 9.4 to 9.8 to 1, not exactly sure. In your case though, the compression ratio would be less of a concern to me than piston to valve clearance. If in fact the engine your putting these heads on is an 1986 5.0 and it has stock pistons without valve reliefs (only year they did that) I'd be extra careful installing any performance cam. No valve reliefs and milled heads could equal piston to valve contact. Evenwith amuch small lift and duration cam then theother year 5.0's are using you shouldbe concerned. Just food for thought.
I believe the gt-40x heads have 64 cc combustion chambers so trimming them .025" should put you somewhere around 9.4 to 9.8 to 1, not exactly sure. In your case though, the compression ratio would be less of a concern to me than piston to valve clearance. If in fact the engine your putting these heads on is an 1986 5.0 and it has stock pistons without valve reliefs (only year they did that) I'd be extra careful installing any performance cam. No valve reliefs and milled heads could equal piston to valve contact. Evenwith amuch small lift and duration cam then theother year 5.0's are using you shouldbe concerned. Just food for thought.
The most important thing, especially if you are wanting to run boost at some point, is to find out if they were the 58 or 64cc heads. IIRC, you can get them either way. If they were the 58cc heads, your best bet would be bump your timing and run N/A w/ 91-93 octane. You wouldn't be able to run much (if any) boost.
02-01-2007, 07:50 PM
#8
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RE: Gt-40X's shaved .25 what effect will this cause
I have the Gt-40X heads with the 64cc chanbers and the motor is a 93. I'm not going to supercharge anyway because of my block and the heads being milled, I figured if i if do get a supercharger I will rebuild the block and get some AFR's but anyway will I need a different size push rod or will stock work. I am running 1.6 roller rockers with an E cam. thanks for everyones help.
02-01-2007, 08:36 PM
#9
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RE: Gt-40X's shaved .25 what effect will this cause
which is it they came with either 64/58 cc 6049-x302/x303 have a 64 6049-x304/x305 have a 58cc///regardless what ya have millin a head.025 in the 64 or 58 chamberd heads, .025 isnt gonna raise ya hardly anything///i have milled mine b4 at .020 and i didnt get any rise in compression on my gauge.. they say ideal comp on a SC is around 8-9.1 comp//ya can on a10.1 but ya better knowwhat ya are doin and build itto last..
02-01-2007, 09:02 PM
#10
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RE: Gt-40X's shaved .25 what effect will this cause
i have a stock 93 with a 6psi setup on it. shaving the heads will up ur compression so id be careful about supercharging it. the 93's have hyperutectic pistons which are not as strong as teh forged ones. it will probably hold but i wouldn't go more then liek 300 hp with those internals