Studytime

iTrader: (15)

I've played around with porting heads before, but I've never put a [finished] set on a car. My last set picked up 28.5 CFM at .550". These were 5.3L heads with the factory sized truck valves. I was impressed by the gains for my quite conservative efforts (there was minimal material removed).

I continue to hear how the average home-porter / novice doesn't know what they're doing in terms of how their changes will affect swirl/tumble/turbulence. I've heard that swirl isn' that all important, but tumble is. I didn't touch the short side radii on the last heads I did for that reason, but did spend some time in the bowl area. I just did the basics and cleaned/opened up the bowl area, and they responded well to it.

So the above leads me to thinking that it'll be hit or miss even if I can do another set of heads with good flow numbers. Can anyone shed some light on this? I'm not convinced that I HAVE to run an aftermarket head to make power. If I do that's fine too. I also have a set of Dart 205s, but the porting projects are more fun than just bolting on a set of finished heads.

Any input guys? Please don't suggest to go get some CNC LS6 heads- that's not what I'm looking for here. I guess I'm looking for some reassurance to invest the time on a set of 241s (?), and to discuss the differences in a 280 CFM head at XXXcc's that sucks VS a 280 CFM head at the same runner size but making good power.

Ben T.

Bo White

iTrader: (59)

Your just a gear head, cant blame ya though. I never go over 218cc(27X cfm) on a LS1 head for that reason, I try to keep the port small for the main thing a street car needs- responce down low. But then again Ive seen a few 22Xcc or so heads on a few benches that only went 28x, and with a bigger valve. The seat work is the most important, just remember that and you will do pretty good.

Studytime

iTrader: (15)

Bo, I'm not trying to say that I could replicate your work, but what does a set of your heads do for a LS1 car? If you get into all of the flowbench hype, it's not supposed to be worth your time unless you're bolting on a set of 315 CFM LS6 heads. I don't fully subscribe to that theory for something like my daily driver street car.

Do you see consistant gains with your ~218cc head? Strong midrange, how's power, etc? If you care to, please elaborate on these increases.

Ben T.

Bo White

iTrader: (59)

Yes, Ive seen 420 pretty regularly or better with these heads with a 230 or so cam on a Dynojet through the exhaust. Just take the rocker boss out, swirl ramp out and reshape the guide boss- the rest is just blending into the existing runner shape. That is just a thing I tell beginners to do, I do more but its been by trial and error.

Brian Tooley Racing

iTrader: (13)

The key to making great power is the flow at .300", .400" and .500", above that doesn't mean as much. The only way to get great midlift numbers is chamber deshrouding, valve job technology and valve job technology.....did I mention valve job technology.

We have had 225cc, 241's with stock valves make 450 RWHP at GMMG with an LS6 intake....that was 30 RWHP more then some WAY hogged out CNC ported LS6 heads have made on their dyno.

Bo White

iTrader: (59)

Agreed , another thing that Ill add to Brians post is make sure the shop doin the valve job is up to par

AmericanMuscle313

iTrader: (5)

What do you mean by take the swirl ramp out and what shape do you you recommend for the guide boss? Any pictures showing an example would be very helpful. What do you recommend for lq4 heads (for a street car)?

Bo you are the DIY Home Porting Hero.

Bo White

iTrader: (59)

Shapes to shoot for: