Justin Adams

I have an 02 lq4 that I'm essentially turning into an lq9. Doing 30 over flat tops, 224/230 .553/.547 111+2 cam, heads, valves springs, the whole works. I have a set of untouched 241s and 317s that are on it now. I see the forums that say to go with the 317s but then some of them say to use the 241s. My original plan was to have 15 thousands or so taken off the 241s to be around 64cc and then just gasket match them for now. I want to be around 11.0:1 compression and make around 500hp. So I guess my question is, what heads should I use, and if I use the 317s, how much can they be milled before PTV is a problem?

hrlyhnx

iTrader: (3)

from what i was told the 317 are the heads of choice for turbo. I dont think it matters 234 or 799 or 317 for nat asp application.
others with more experience than me i am sure will chime in.
GLW build

zzracer

iTrader: (33)

The 317s flow better than the 241s. I wouldn't shave them more than .030 and you should check the valve clearance.

KCS

iTrader: (20)

They both have pros and cons.

The 241 heads have a smaller chamber so you will get more compression out of them, but the ports aren't as good as the 317 heads. The 317 heads have essentially the same port as the 243/799 heads, but again, the chambers are about 5cc larger than the 241 heads.

I would probably recommend going with the 317 heads and milling about .030" off. With the flat top pistons, assuming no valve releifs, you can still get up to 11:1 compression ratio.

nobreaks254

iTrader: (50)

use the 317's. Measure piston to valve clearance and mill accordly