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building a 4G63T

pat 92 laser

Probationary Member
2
0
Aug 28, 2008
kingsville, Ontario_Canada
ok i bought a set of je pistons, 1mm over stainless valves set, now im building the engine myself im a car mechanic and i was just wondering what to do with my compression. now i have done the math and it will be around 11.1:1, is that too high? let me what u guys think, and some things i could do to make it lower, thanks
 

BoredDSM

Proven Member
389
7
Apr 11, 2008
Old Bridge, New_Jersey
For an N/A car it sounds ok but for a turbo your going to have some time tuning it let alone getting it to run. You calculated compression ratio after you bought the pistons? What about rods and all the other necessary components for the motor?
 

kahl23

Proven Member
1,093
11
May 10, 2004
Wellesley, Massachusetts
+1 11:1 is a very high compression ratio for a turbo car unless you only plan on running 116 octane or pure meth or the like. Usually you know what compression ratio your pistons will give you, it should say it on the JE box or the documentation that came with the pistons. To give it some perspective, the motor in our car now has 8.3:1 compression, most other people on this site use from between 7.8:1(stock 1g) to 9:1 compression ratio pistons.
 

dsmfa9nutter

Proven Member
1,024
4
May 9, 2005
Nowhere, Wisconsin
You'll want to drop that compression ratio about 2.5-3 points if you want to be able to use pump gas.
 

pat 92 laser

Probationary Member
2
0
Aug 28, 2008
kingsville, Ontario_Canada
well my calculation was wrong, sry about that, never use a online formula i guess, i did al the measurements, and i should be running very close to about 9:1, which sounds better than the 11:1, thanks for all ## help i really appreaciate it
 
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