I had my L98 heads pocket ported, gasket matched to the ZZ4 intake gaskets and had larger Manley Race Flo Valves installed (2.000, 1.560). I have flow numbers for a ported L98 head but not with larger valves or gasket matching. Does anyone have flow numbers of an L98 head with port work and larger valves?

 

do a search fopr rhurac31 ( think that's the name) he took a set of L98's to various stages of porting and flowing as well as installing larger valves.

I have the links saved on a different computer, I'll boot it up tomorrow and post if you don't find them

IIRC he had the intakes in 250/255 range and exhaust in the 190's/200 range.

 

Check the thread and the links.

https://www.thirdgen.org/techbb2/sho...hreadid=183264

 

i posted this a while back about my aluminum vette heads:

https://www.thirdgen.org/techbb2/sho...hreadid=248661

 

I suppose that I should have mentioned that they are the aluminum L98 heads. LOL. It seems like so many people bag on the L98 heads for performance use. I believe that their flow potential to runner velocity ratio is exceptional for a brutal street engine. Especially in the low end torque and throttle response area. Granted you can't create AFR or even Trick Flow numbers without port work and larger valves but if you already have these heads like so many ZZ engine owners, there is little reason not to work them over. I thought long and hard about Fast Burn heads or AFR's but I did not want to mill heads for compression or have to mess with pushrod length checking. Besides in a third gen with a single 3" y-pipe exhaust anything over 325HP gets choked off. Large heads and big cams don't typically see much gain. My 430 HP engine is down about 30 HP even with a cutout in place of the cat. Furthurmore, when running a carb the 3/8" sending unit in the tank limits our vehicles to approx. 425HP. Even if you had long tube headers, using big heads to go over 425HP would necesitate fuel tank modifications. Just some food for thought. Great replies, keep them coming.

 

a properly ported set of aluminum L98s flow almost identical cfm numbers to the AFR 190 except with even better low lift numbers and better velocity due to the narrower runners. also, possibly the best E/I ratio going. i say go for it.

 

That won't be the case UNLESS you can't feed the engine fuel. A 3" Y pipe with similar intermediate pipe is good to flow 400 hp easy.

 

It will flow 400HP and you will be loosing about 25HP. Hell, Traxion went 12's on a 3" y-pipe and then hit 11's with full length headers. All I am saying is efficiency will suffer.

 

Headers are a different subject. LTs always outperform shorties by a bit.