CoreyH

I have a set of 317 heads and a set of 243 heads. Which would be better for boost? I have a 5.3 block with flat top pistons. I understand the 317 heads are 10:1 compression and the 243s are higher. Plan on adding boost, but which head will be better for that set up?

Sales3@Texas-Speed

iTrader: (2)

Not on a flat top 5.3. I feel you got it a little mixed up. 317's would put you at 9.18:1 compression. 243 heads would put you at 10:1. It depends on boost level and intercooler/meth as to which way to go.

Lonnie

CoreyH

I read on a forum on here that the compression on the 317s is 10:1. I should have measured that before I took those off.
I broke a rod and I just got a new one and everything is ready to go back together. The cam I am looking at is a 228/235 .608/.610 114+2LSA. I want to turbo it, but probably won't be able to do that until next summer. I want to do this the best way now, so I have a good set up now that is capable of supporting boost in the future. Is that possible?

sawblade99Z

iTrader: (1)

That's the compression of a stock 317 headed LQ9.

CoreyH

I see that now. I went back to the article and seen the lq9 is the 6.0. So my question now is if I mill the 317s 20thousandths, which heads should I go with? I won't be able to do the turbo setup until probably next summer. I don't have the 243s righr now but I have the chance to swap my 317s for the 243s. So I'm either going to mill the 317s or trade for the 243s. Will the 243s handle turbo with stock bottom end of a 5.3?

Darth_V8r

iTrader: (4)

243 is a great turbo head for a 5.3. It'll lower compression just a bit but flow much better - especially exhaust flow

CoreyH

Perfect. I am going with the 243s. I'm going to look into bigger valves and a good port job.

omc8

iTrader: (7)

If you are going run a lot of boost , Id go with the 317s
or mill the 317s 30k and you be at 67cc

5.3 61cc
243 64.45 cc
853/241 67 cc
317 71 cc