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Has anybody tried or had any experience with GM perfamance LS6 cnc
ported head P/N 88958622
How do they compare to AFR's 205,s looking for any input

 

I've looked at both of these heads and am wondering the same thing.
I think I can get a good deal on the GMPP heads . . .
I believe the GMPP LS6 heads (ported by lpe) are actually 244cc on the intake runner.
Much bigger than the AFR 205s but some here have had good results with the GMPP heads and small/medium cams so go figure . . .

 

AFR is worth the money as well as TFS and ET. GM heads are a good into head for a smaller cam. just my .02

 

I have some sitting @ the house waiting to go on very soon. I decided on these heads because they are supposed to be the best match for my GMPP ASA cam (226/236 .525 110lsa).
Here are the flow #'s I was given
Lift......Int.....Ex
.200....150....117
.300....225....168
.400....273....202
.450....285....210
.500....291....217
.550....304....221
.600....311....222

 

What length pushrods and rockers are you using?

Keep us posted on the results.

 

I decided to go with the AFRs they were about the same cost as the GMPP, but have smaller cc intake runners. I already have MTI LS1 R2 heads with large intake runners
A Thunder racing cheater cam, LGM long tubes pros. I need more lower midrange power to 6000rpm. more than top end. I use the car for HPDE track days on a road race corse.
Thank you the for input

 

Be sure to check our newly revised LS6 heads too!

https://ls1tech.com/forums/generation-iv-internal-engine/943839-prc-ls6-ls2-heads-get-face-lift-225cc-runners.html

For the difference in cost, you can buy a FAST 92/92 combo and be well ahead in power over the GM CNC'd heads! Let us know if we can help with your combo. We'd be happy to earn your business!

 

I'm going to use stock rockers and plan to measure the for the proper pushrod length when the heads are installed, so I'm not sure yet.
I'll be sure to post the results!