I recently had my engine rebuilt and while it was down I took the opportunity to have the heads flowed. These are older (1998 - I bought them used last year) GTP Stage 2 heads. My numbers pretty much agree with what others were saying. Here they are for everyone's enjoyment (gotta spread hard data when you can)

Lift Intake Exhaust
.100 71.08 49.19
.200 136.34 106.82
.300 185.07 151.10
.400 219.03 185.07
.500 242.96 206.15
.600 247.65 215.52
.650 253.80

In perusing other heads' flow numbers from Jody Shapiro's site, these seem to be pretty strong on the exhaust side. The car also made really good power with these heads and my relatively small cam (or at least I think it did).

 

thats pretty wierd! they only flowed 24x at 500-600lift and you made 380rwhp with that cam... something doesnt add up!! but hey whatever works

 

Yeah, I was pleasantly surprised. I made 15 more rwhp with by leaning out the AFR. Timing is stock - I never got a chance to play with it. I also think some of the power gain might be attributed to my mixed rockers. I read in a Vizard book how 1.6's on the exhaust on a dual pattern cam actually hurt power....

I also wanted to mention the flow numbers are at 28".

 

so you mixed? 1.5's and 1'6s? interesting.. never herd of that before. i guess all it changes is your lift #'s

 

Yep, I actually have less lift on my exhaust - works out to be .528/.510. Again, quoting Vizard - exhaust lift isn't as important as duration on an NA motor..... I figured I'd give it a try.... I split the rockers with a fellow f-bud, but his car is not tuned (370 rw with a 224/236-112) yet.

 

Were those exhaust numbers generated with a pipe on the exhaust? Frequently, it seems numbers over 200 cfm peak on the exhaust side of an LT1 are due to the use of a pipe, which tends to improve the numbers a lot.

BRAD

 

I don't know. I'll try to find out.

 

Thats about what mine flowed. I was told 275/220 by Craig...