rag engine questions. 383 sbc

[Ezarge]

hi,

my buddy is finishing his 383 sbc. he is replacing the double humps that came with it with AFR and wants to know how much power to expect, and what size heads to buy

it is 12.5:1 compression
solid flat tappet , 550 lift, 250s@ 50 duration
edelbrock single plane intake running e85 with an hp 950 carb

car is a first gen firebird, about 3400lbs race weight
g force 101a 4 speed transmission
29.5 tire

questions
1. how much honest power would a combo like this typically make with AFR heads?
2. what size heads. He leaning towards the AFR 195s
3. should he upgrade the headers from 1 5/8 to something bigger?

thanks for the replies

[mag2555]

What rear gear will the car have as that's a detail that plays into port volume.

Figure on needing 3.8 Intake cfm @28" per cylinder to make 1 hp, and also figure that with running that amount of valve lift that those AFR heads will be flowing some 260 Intake cfm@28".

Header wise for that vid motor you want the tube to be 1/16" bigger in ID then the OD of the Exh port.

[jed]

I'm just wondering if the 3.8 CFM per cylinder for 1 hp applies to just OHV engines or can it be used for OHC and
side valve engines??
John

[mag2555]

It depends on the efficiency of the overall flow thru the head and the motors compression , some motors need 4.2 cfm@ 28" to make 1 hp .
Take the middle of the road of 4 Intake cfm and you will likley not be dissapointed in the results with a non full race motor.

[jed]

Thank you Sir.
John

[CGT]

I would expect that engine to make around 520ish on the dyno I use. But that depends on some things for sure. That flat tappet cam will definitely hurt it compared to a good roller cam.

[DSRE388]

There is some other killer heads out there for 23* sbc, check Speir Racings V Factor heads as well, but if you go with AFR i wouldn't go any smaller than a 210 head, especially using E85 and 12.5:1 compression with an intake like a super victor 2 intake or Holley Strip Dominator, 950 carb even with A Flat Tappet Solid cam I'd expect at least 540-550hp if built correctly and if you can step up to a solid roller you will see a good size jump in power.
You definitely will want a 1-3/4" × 3" header minimum imo
You need to match all of the components in order to maximize your combination and every detail counts