LS1 with 862 heads

I may have found an LS1 shortblock I can drop in my truck but I want to know if I can use the 862 heads from my 4.8 on the LS1. Also, what will the CR be if I use the 862's on the LS1. Thanks in advance

It will bump your CR up a hair, 4.8/5.3 heads and LS1 heads flow the same, the only difference is the combustion chamber.

So about what is my CR with 862's on a 4.8L and what will my CR be with 862's on an LS1 ?

it's a pretty common mod with ls1 guys to raise compression. I'm not sure the exact numbers, but you may want to lower the boost a psi or 2.

Looks like 66cc combustion chamber volume. Should put ya around 10.5:1 I think.

Not the best choice for a boosted application I wouldnt think. Too much static compression. I would think you would be better off with some heads off of a 6.0 umm 317s i think, they are supposed to slow as well as 243 heads and are cheaper? You could probably sell your 862s and break even. You will have a hell of a time avoiding pre ignition with pump gas with those heads and any kind of boost at all.

Ok there are 3 sets of 317s on performance trucks classifieds right now. One set is less then $200! If your gonna run boost go get em!

Quote:

---

Originally Posted by aj06bolt12r

Not the best choice for a boosted application I wouldnt think. Too much static compression. I would think you would be better off with some heads off of a 6.0 umm 317s i think, they are supposed to slow as well as 243 heads and are cheaper? You could probably sell your 862s and break even. You will have a hell of a time avoiding pre ignition with pump gas with those heads and any kind of boost at all.

---

+1 truck heads would boost your compression too much

http://ls1tech.com/forums/ls1-domest.../t-111207.html

the truck heads are 63 cc and the 317 heads are 72cc

Unless you slapped some dished forged pistons in it. That way you gain some strength and you can keep your heads.

So an LS1 with 317's would put my CR around 10:1 ? If so, then I think that would be optimum for about 12 psi of boost.

I don't see why you guys are stuck on PSI numbers, you dont build for how much PSI you want to run, you build for how much power you want it to make. On a street motor I'd take a higher compression and lower boost number anyday. It will come into power sooner and be easier on equipment. What's the big deal if ya gotta drop the pressure a little if it makes the same power.

Well did u buy it?!?!?

Quote:

---

Originally Posted by Frenchy

I don't see why you guys are stuck on PSI numbers, you dont build for how much PSI you want to run, you build for how much power you want it to make. On a street motor I'd take a higher compression and lower boost number anyday. It will come into power sooner and be easier on equipment. What's the big deal if ya gotta drop the pressure a little if it makes the same power.

---

+1
10.5:1 with 10-12psi > 8.8:1 with 20psi

Quote:

---

Originally Posted by Frenchy

I don't see why you guys are stuck on PSI numbers, you dont build for how much PSI you want to run, you build for how much power you want it to make. On a street motor I'd take a higher compression and lower boost number anyday. It will come into power sooner and be easier on equipment. What's the big deal if ya gotta drop the pressure a little if it makes the same power.

---

I started this thread to find out what heads will yield what compression ratio when installed on an LS1 - wasn't concerned too much with the boost. Thanks for your opinions tho

Bonsoir, un ami m’a parlé d’un site qui propose de bons bonus pour les joueurs en France et j’y suis allé sans trop d’attentes. Au début j’enchaînais les petites pertes, puis au moment où j’ai décidé de tenter un pari plus risqué je suis tombé sur https://win-auras.fr et j’ai lancé une partie de Book of Dead. Deux tours plus tard, un gain bien plus grand que prévu m’a vraiment remis dans le jeu. Depuis j’y retourne de temps en temps, c’est devenu une option fiable quand je veux décompresser après le travail.