racer442olds

iTrader: (2)

Any ideas what size carb is needed? All out drag race 408 12:1 Compression LS3 heads. heavy car with a TH400

TTur1996

4150 950cfm. We have a 14:1 408 with 245 AFR heads. Cathedral though. We run the Holley Ultra HP. Supposedly flows 1025cfm. We are very happy with it. Even pretty good on the street. When we ran E85 it was a 850 QuickFuel though.

Bowtiedford

iTrader: (9)

same 4150 950 E85 by pro systems. flows about 1000 cfm also. but I'm 428 LS3 heads, LLSR, Holley intake , about 10.25 comp. it was great right out of the box

Doug G

Something in the 900-1000 cfm range should do OK

But use caution.... Holley's are dry flow rated Vs. Demon's wet flow rating.
A "750 Holley" flows a lot less than a "750 Demon" Or so I was told by a BG Tech when we talked about how people have issues tuning a Demon over a Holley.
Claimed a 750 Mighty Demon on a Holley flow bench would be in the 925-950cfm range.

speedtigger

iTrader: (16)

I changed from a Holley 950 HP(bs flow rating) with 1.375" venturis to a Holley 1000 CFM(true flow rating) with 1.55" venturis. The car picked up a full tenth and 1 mph in the 1/8th. This was done back to back at the track.