Shtstr

Will try this again without auto correct.
I've searched the net for the flow numbers and on here only to find flow numbers anywhere from 248 to 278cfm @.600 lift for factory as cast. Is there anyone on here that has had these heads on a flow bench with a ls6 bore size 3.9''and tested them with that instead of a 4''bore that will give higher flow number please.I want to see what they really flow on a ls6 bottom end.

Fast355

I have seen high 240s/low 250s from a test on a 3.90" bore. I forget the exact number and if that was a 0.550 or 0.600 lift number. Considering port variances, ~250 cfm should be close.

On a 3.78 bore they only flowed 238/185 @ 0.600.

99 Black Bird T/A

iTrader: (4)

From ~20 years ago, ~246 cfm to 248 cfm was what my set of stock LS6 heads flowed peak in 2003 on a trustworthy flow bench with 3.9 bore @ 28

After one of TEA's choice porting programs, they flowed 308 cfm. There was typically ~8 cfm difference in TEA's bench (320 cfm) and the one used to flow my stuff locally back in the day. Well within typical flow bench variance.

Same LS6's ported were roughly ~318 to 330 cfm on 4 inch bore in my experiences depending on the bench IIRC.

slowride

iTrader: (3)

I would be curious at what point a 243/799 flows much better when going from 3.780" 5.3 bore to a 3.898" ls1/6 bore. I doubt it's linear, but after taking some pictures of a stock bore 5.3 head 706/862 it's clear why they do so well on the stock bore as anything over the 1.9: intake valve is shrouded pretty good.