camaroandreas

As long as you have a turbo that can flow well on low boost, larger heads will make more power at lower boost compared to stock heads. It depends on the turbo!

67Firebird455

iTrader: (27)

It's the ol blowing through a straw theory. Think about it! =)

MY99TAWS6

iTrader: (3)

Interesting have also seen a lot of dynos even have book of just ls1 dynos and they stated over and over that a more built engine would be better for FI. Then showed lots of dynos.
I guess I can't really see why I would want to have a turbo that would need to go to 35psi on my big cubic inch v8. If can make say 1000rwhp at 15 or 18 and likely same amount of torque. And properly sized should be getting fulll boost at 3500 or so with some nice sized twins like the upgraded aps turbos mine are only good for maybe 800 rwhp. Actually Darren Ps hit that briefly and 1000ft pounds pretty sure he said.

And as for having 1000ft pounds at 3800 or whatever that sound great on the dyno but how the hell do you hook that up on the track or street?? My good Even running way less than that now can't hook it up on the colder roads. Canada and sweden both get pretty cold. Course I dont' normally try to drive my car this late in the year but no snow, not stupid cold yet and just had to get a few more weeks in since just finished the build a few weeks ago.

Anyway interesting theories and results. But as said I am just going to stick to my combo and current heads. If nothing else the thing is a monster off boost and you don't want to go into boost all the time around town. At least i like staying out of jail!

Would for sure like to see some videos of your car running on the track or street.

ohplz

wow heaps of replys...

want to make at least 700 - 850rwhp if poss ( at 500 atm )

i have my ls1 heads already fitted with 918's manley pushrods and tit retainers... but when i do the bottom end, i was going to change the heads and throw on a bigger turbo... so far i hear 317's are good ( with some cometic head gaskets etc ) and i thought i could use my bits if possible? or would i need to get all new parts for the 6.0 heads?

money isnt an issue, but im not a fan of spending 3k for afr heads if it gets me 10hp more then 317's ported etc...

i like to do my research...

z28adiction

iTrader: (1)

I guess if you upgrade your heads and see a loss of boost, that only means its time for a bigger turbo.

FTW

Losing boost isnt bad if the air flow is still rising.. If you're losing boost at higher rpm, all that means is your motor is outflowing your turbo which isnt as uncommon as you may think.. Just because the pressure ratio in the intake isnt as high as it should be, doesnt mean you're losing airflow..

98Z28MASS

iTrader: (6)

If your staying in those power ranges then a set of ported 317's would def fit the bill. Id say though look into heads studs just to make sure when you push it to 850 rwhp that they stay tight. The AFR's are really nice but when you can get a set of Patriot Performance Stage III 317's for $1300 thats not a bad deal IMO. The heads come with dual valve springs and titanium retainers so they are fully assembled and ready to go, no need to swap anything over.