What power difference between these two heads with my combo?
1995 Z28
383 LT1(Lunati Sledgehammer Crank, Oliver Billett rods, custom Diamond pistons)
8.8:1 CR
Custom Camshaft 244/254 @ .050, .578/.578 lift, 114* LSA
Super Vic EFI intake
Kooks long tube headers
Custom Y-Pipe
Borla Cat-Back
ASM 58mm mono blade TB
60# Injectors
M6 w/Moser 12 bolt and 3.73's
FMIC
Meth injection
D1SC with 15#'s of boost
24x conversion
My question is, that given that setup, what would be the difference power wise between AFR 227 race ready heads, and AFR 227 competition heads? Given the lift of my cam (.578) the CFM difference between the two is 15 CFM according to AFR's website (at .550 lift).
I am trying to decide between the two and want to know if you guys think I'll see greater than a 15 RWHP difference between the two or not.
IMO its better to get the base 227 castings for now, and have a porter with AFR experience like Tony Mamo or Craig Gallant get his hands on them later on if you want to make things a bit more nasty with a cam swap/port job. Craig did Sakura's AFRs and we all know how strong his car ran.
You already have the supporting mods and computer to get it done. AFR's have very strong exhaust ports and make ridiculous power boosted
IMO its better to get the base 227 castings for now, and have a porter with AFR experience like Tony Mamo or Craig Gallant get his hands on them later on if you want to make things a bit more nasty with a cam swap/port job. Craig did Sakura's AFRs and we all know how strong his car ran.
You already have the supporting mods and computer to get it done. AFR's have very strong exhaust ports and make ridiculous power boosted
I know it won't make a huge difference in power. Volume is the biggest thing that will make a difference in the boosted world, but I am just curious for those that would have an educated estimate, what the actual RWHP difference would be.
15 HP to the flywheel has been guessed. Anyone else have an educated guess?
If its going to be 15 fly wheel HP or less, it is pretty hard to reason the extra $600. Now if we are talking 15-30+ RWHP, then it may be in my best interest to save up for the better competitions.
The big reason I am asking this is that I have a good deal on a set of race ready heads, and I just want to see what the difference between the competitions and the race readys will be on my car.
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I wasn't aware boosted cars where running over .600 lift regularly. Most seem to run lower (or so I thought at least).
I am not really looking for suggestions on my setup here. Just looking for the difference you guys think I will see between the two heads.
If you are coming from 180s then either set of heads will be a big increase in power, but it looks like most agree that spending extra for the additional porting between the two will not be worth it.
While their factory porting is nice, hand parting is still the way to go so I wouldn't spend the extra money on the Comp package. If you are not happy with the standard 227s, save the extra 600 and put it towards a proper port job that will be worth more then the Comps would be.
Why don't you shoot a PM to Tony Mamo? He would be the best person to ask and I'm sure can give you an accurate guess. He has helped me quite a bit over PM, and I didn't even get my AFRs from him.
I would NOT let Tony Mamo touch them. I have a buddy who had a very bad experience with his work. I won't go into details as it was not my car, so I'll just leave it at that.
Last edited by CALL911; May 27, 2013 at 07:40 AM.
The cars pulley combo is already the most aggressive that could be had (and that's where it will stay). Most people who max out the D1SC only see about 15#'s of boost. I have seen a couple make 17#s, and have seen where people have "claimed" to get 18, but most max out at 13-15#s. D1's can make more boost than D1SC's. Your combo besides the pulleys make up quite a bit at what boost level you'll actually see. Honestly, I wouldn't be surprised if after I do upgrade to the larger heads that I would notice a one to two pound drop in boost as boost is a measure of restriction.



I think the poor stock computer is what turned a lot of LT1 owners off from bigger cams, and the mind frame just stuck.
Most SBC guys won't bat an eye at a 260int cam on a 383, but a lot of lt1 guys go way smaller even on strip cars that barely see the street.
I'm all for baby cams and power under the curve on a street car, and loved my 227 in my 350 daily driver, but if its not a daily driver and you have the computer and mods for it then spin it high and let that thing eat!



