99C5JA

Well this car has always been a work in progress since I got it in the spring of '01. I originally put in a TR 227/224 (big cam at the time) and bought some Absolute Speed ported 241's. Back then AS was considered one of the better heads you could get. The heads were flowbenched by the porter for about 300cfm @ .600 on the intake and about 215cfm on the exhaust. The combo made 417rwhp and 385rwtq. Last year I swapped up to the larger F13 cam after seeing good results from it. I was hoping to get a nice boost of about 20-30rwhp, but instead got only around 10. The tune was done at FLP and they did a great job on it (it did pick up 15-20 more rwtq/hp below peak). So my question is would swapping out the heads for a set of Trickflows or AFR's be worth it? I'd really like get somewhere in the 450rwhp range. Would the heads get me there?

exSSer

The newer heads should get you there, no problem. Make sure you have them milled for optimal compression.

silverbandit0996

iTrader: (2)

what is optimal compression for a street car on 93?

99C5JA

Thanks for the reply. I am seriously considering the Trickflow 215's with the 64cc chamber. Not sure where this leaves the compression vs. my milled 241's (~.020 iirc).

Studytime

iTrader: (15)

I'd leave those heads in place, and grab a Fast 90/90. I think you'll find the power you're missing. You can only get so much air through that GM intake. I'd remove that restriction first before going further. That 227/224 makes good power, that's another reason hp didn't jump up 30 at the wheels.

My vote is to keep those heads in place and atleast try a better intake before you buy and install a set of heads.

Ben T.

99C5JA

Well I haven't seen anyone get major gains on a 346 with a 90/90 setup (maybe I haven't looked hard enough). Maybe 10rwhp or so. It's always seemed to me that unless you are running big cubes the 90/90 setup is just to squeeze that last bit out of it.

1997bird

iTrader: (2)

I would read this thread before condeming the 90/90 set up. https://ls1tech.com/forums/advanced-engineering-tech/631476-can-you-over-throttlebody-efi-motor.html
On my cousins car with his stock bottom end 93,000 mile 346 with RHS/ETP casting heads w/225cc int runners, FAST 90mm int, Ported LS2 TB, and new cam was able to get 445 RWHP & 406 RWTQ on 7 cylinders (bad brand new MSD coil).

99C5JA

I'm not condemning it. I'm simply saying I have not seen anyone get a large gain on a 346 by switching to a 90/90 setup. Yes there is a gain. No I don't think that this is giving the motor to much air. Those are great #'s your cousin is making, but how much did the 90/90 gain in that combo is the question. To switch to a 90mm setup I would need the intake ($800), TB (~$200), air bridge ($100), MAF (~$100) and new filter (~$300). So is the gain from a 90/90 setup really worth $1500? Going from factory ported castings to AFR/Trickflows seem to net a healthy gain (and should be healthier in my case seeing as how my heads are from the early days of LSx head porting) at a cost of ~$2200. I'm open to the idea of a 90/90 setup. I just haven't seen anyone who has swapped only the intake/tb and made much more than 10rwhp on a run of the mill 346 combo.

1997bird

iTrader: (2)

We changed his 99' Vette engine combo all at once, so I don't have a intake only compairison. Just his stock heads,cam, and intake/TB compairison. You might PM Tony Mamo and see what he has for data for you. This is the closest compairison that I have read here https://ls1tech.com/forums/showthrea...98#post6493898.

99C5JA

Well I'll have to eat a little crow. Looking at the dyno section a bit more it does look like they are getting 10-20rwhp/rwtq out of the ported FAST's. Still, the heads seem to be a better bet as far as hp/$$ at this point.

1997bird

iTrader: (2)

I really am a believer in the ETP heads now! The only other ones that I would consider is the Trick Flows (Unless your looking for a lower budget head).

exSSer

I'd get the heads milled to give you around 59cc, since you have 93. With GM MLS gaskets, you should have close to 11.3-1. If you get the TFS heads, you won't have to worry about PTV clearance, unless we're talking really big cam. I have the TFs, @ 61cc, and with only 92 available here I get no KR.