I've got a good line on a set of vortec heads than have been rebuilt. I've got a solid tbi L05 which is suppose to be from a 1995 1/2 ton pickup (the motor is currently in my Landcruiser). I wondering if I am going to run into problems with compression with slapping the vortec heads on the LO5 bottom end. I believe are 62cc and the LO5 heads which are 76cc? Will I at least be able to run "plus" fuel with proper tuning (ebl when it gets here)? I'm not building a monster motor here just a nice solid semi-budget offroad motor ($1500ish budget).

Thanks...

 

IIRC the LO5 heads are 65 to 68 cc. Truck LO5 use shallow-dish pistons to raise the effective total chamber volume to ~76 cc, and they had 8.5 CR.

Car LO5 use flat top pistons with 5 to 6 cc valve notches, and they had 9.3 static CR.

As a sanity check, the ratio of these effective chamber volumes is (65+6)/76 = 0.934. Scaling the truck L05 CR to the passenger LO5 CR is 0.934*9.3 = 8.7, a number close enough to the truck's advertised CR. So the math works. I don't know if the L31 Vortec head is actually a 62 cc chamber, or 64 to 65 cc..... but you can use the same exercise, as above, to see what the Vortec CR will be if you use 62 cc chamber and dished pistons. I don't think the CR will be a problem because the iron LT1 heads ran 10.0 CR without any probelm and the iron LT1 head is a clone for the L31 chamber you want to use. HTH.

 

thanks, I appreciate the response. I've done some other searching on other forums and it seems like its the consensus that it should work with no issues. I dont really want to run premium but it would be ok as this is not a daily driven rig... If other's have any other comments...I'm all ears. thanks!