I thinking of building a LS3/L92 stroker motor to 415 CID to go into a 1995 Caprice. The car is a Daily Driver and want to produce 500 RWHP/500 RWTQ with good street manners.

I was thinking that since the engine will be apart during the rebuilding process. Is it worth porting (either hand or CNC) the LS3/L92 heads or just do a valve and clean up job???

I ask this in light of the fact that Vengeance Racing is able to produce 520 RWHP/500 RWTQ on a 415 CID L92 on Pontiac GTO through a M6 with unported L92 heads and an unported L76 intake through careful cam selection and tuning.

I am particularly interested if porting the exhaust side will enable me to run a single pattern cam so I can get the most area under the curve and great low and midrange power??

 

A home port probably do more harm than good. As far as having them professionally done? The intake needs very little work, focus on the exhaust side and a good valvejob. The jury is still out on what cam timing works best with these heads, but it's safe to say that a single pattern is about the worst thing you could put in it, even on a heavily worked head. Lingenfelter seems to have them figured out. Their offerings make just as much power as some of the more aggressive grinds out there, but they do it with FAR SUPERIOR drivability characteristics.

 

Thanx Marc for the reply,

If there is anything I've heard about these heads once and thousand times it is that these things breath way differently than cathedral port heads. Also that a single pattern cam is not the way to go. But a dual pattern cam with a slight split with a few degrees favoring the exhaust side is okay.

Funny thing I emailed this question to one of the country's legendary head porting gurus and he told me that considering the my car is a DD and even taking into account my performance goals he said to leave the heads alone.

Wow!! Are these heads that good stock???!!

 

Seems to be a lot of good things about the L92 if you are on a tight budget. I mean 320 cfm peak for 1000 bucks brand new assembled? Slap it on a LQ9 with a LS3 intake....your good to go for cheap (relatively speaking)

I have read total opposites about going with a wide split duration cam or not. Some think a relatively close duration and not too much lift is the better wy to go on stock L92 heads.