Ls3 head question.
Ls3 head question. Got a stock ls3 bottom end that’s possible getting a set of Trick Flow 255 heads. Question is... is a 67cc too small and will compression be to high or should I be fine? Cars going to be a daily and ran on ca shitty 91 oct gas.
Thanka
Thanka
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What will your compression be?
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The ls3 head has 70cc chambers as standard.
Going down to a 67cc is not much different.
You will be fine.
If you are fitting a camshaft with some positive overlap they will bleed off some of your compression anyway.
Stock compression is 10.7:1 on the LS3. With those heads you are looking at around 10.89:1, if it runs on the gas fine now I don't see any reason there would be an issue with the new heads.
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2. Are you gonna stay with OEM heads gaskets or are you gonna install a set of .040" compressed thickness head gaskets?
3. Why TF-255 heads.....why not TF-260 heads?
4. What vehicle is this engine going in to...and it's weight?
5. What transmission you gonna run?
KW
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Brett Foote 1. What's your cam specs?
2. Are you gonna stay with OEM heads gaskets or are you gonna install a set of .040" compressed thickness head gaskets?
3. Why TF-255 heads.....why not TF-260 heads?
4. What vehicle is this engine going in to...and it's weight?
5. What transmission you gonna run?
KW
2. Are you gonna stay with OEM heads gaskets or are you gonna install a set of .040" compressed thickness head gaskets?
3. Why TF-255 heads.....why not TF-260 heads?
4. What vehicle is this engine going in to...and it's weight?
5. What transmission you gonna run?
KW
2-OEM stock .051 gaskets
3- got good deal an 255s. Saved $$$
4-C5z stock weight
5-Tick built T56
6- my stupid self thought I had an ls3 when I really have a L99 short block. So with that said I have the valve reliefs in my pistons and not flat tops like a “true” LS3. So that’s gonna change it a little as well.
Also, I'd go with .040" head gaskets. This will bump your compression a tiny bit, but it will bring your quench to .035" range which is EXACTLY where you want to be for a compression ratio that's higher than stock.
BTW.....the LS3 in my daily driver '95 Impala is 11.3:1 CR.....in my '14 SS, it's 12.2:1 CR.
If you don't have it yet, don't get your cam until AFTER you have everything else sorted out. THEN....call a reputable cam company with all your specs and tell them EXACTLY what you want out of the car. They should be able to spec you a cam specifically for your setup.
Best of luck!
KW
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The TFS LS3 heads are not worth the money over the factory LS3 heads. Richard Holdener latest LS book showed a 21 hp difference on a stock bottom end LS3.
The GMPP CNC LS3 heads are worth 15 hp over the factory LS3 heads. Just some food for thought.
The GMPP CNC LS3 heads are worth 15 hp over the factory LS3 heads. Just some food for thought.
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If anyone wants to upgrade the LS3 heads, your best best is using small bore LS7 heads.
These will cost less than high end cathedrals,
Produce around the same low and mid range torque as the cathedrals but make more torque an HP above 5000rpm and will rev higher
These will cost less than high end cathedrals,
Produce around the same low and mid range torque as the cathedrals but make more torque an HP above 5000rpm and will rev higher
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i wonder who you learned this from......lmao. You can say a ls3 with a 255 runner is smaller than a factory ls3 head yet a ls7 will generally have a smaller port than either for the same bore size. Port is taller as is no way around it even with a 255cc ls3 head.
Last edited by Smokey B; Apr 26, 2019 at 12:49 AM.
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Regardless, the LS7 head will make more power and torque.
