Turbo talk.

[10secondC]

@KrazyKid

whats worthwhile? 1000HP? if so nope not worth it, should have built it from the ground up with that figure in mind FI. 700Hp, large single, 7-10psi should put him close to that right?

and yeah I agree, compression is just a number, each motor and their designs are completely different so its irrelevant until those design specs come into play.

food for thought:

LM7 5.3L with stock heads and stock HG is 9.5:1
LM7 5.3L with 243 heads and stock HG is 11.0:1
LQ4 6.0L (stock dished pistons) with stock heads and stock HG is 9.5:1
LQ9 6.0L (stock flat top pistons) with stock heads and stock HG is 10:1
LQ9 6.0L (stock flat top pistons) with 243 heads 11.5:1

8-10 psi (76MM) on the lm7 will get you 500hp with a junkyard block.
8-10 psi (76MM) on the lq4 will get you a bit more with a junkyard block.
8-10 psi (76MM) on the lq9 will get you a bit more but you better have good head studs.
8-10 psi (76MM) on the lm7 & 243’s will get you 600hp+ with a junkyard block but dont go nuts with the boost.

yeah you see the trend. and are right. I wouldn’t be pushing it past 11.5:1 compression FI. unless you run like 5psi or something. and most large frame turbos like to spool up to be in their efficiency range.

Well to put these #'s in comparison his N/A motor at 12.5:1 should make around 500hp. Unfortunately on that compression with our current state of tuning I wouldn’t put more than 5-7psi on 12.5:1(thats what I meant by not worth it,IMO less than 10psi on a Gen III is a waste of money). Now if you drop compression to 9:1 these things will take 20 psi pretty comfy and make in the neighborhood of 1200-1300 crank hp on a 426 and 1100 on a 370.