1badrocZ

iTrader: (1)

Hey guys ive decided to build a carbed 383 intead of the 406 and i have a few questions concerning heads. First off, i have a scat 4340 forged , scat rods, weisco forged flat top pistons and clevite 77 bearings going in the 383. My engine builder has a NEW set of Alum. fastburn heads (62cc, 210cc)he wants to sell me for $1000. I originally was going to use AFR 195 heads, will i see much of a difference in the 2 sets of heads? Would the $400 and 10 week wait on the AFRs be worth it or should i stick with the fastburns? I plan to run a fairly large cam, what lift are the springs good for? Im really for 500hp n/a on high oct. pump gas, will this be possible with the fastburns? Ive done a little research on how they flow compared to other big name heads and every thread i read was considerably different on flow numbers. They seemed to not flow as well as the others but still manage to put up good hp. numbers. What do you all think?

swerve-driver

Off the Gm Performance Parts site:
"When tested on a 383 ci small block engine with 9.5 to 1 compression ratio and .540" lift roller cam, single plane intake manifold and 750 cfm Holley carburetor, the Fast Burn heads produced 497 hp at an incredibly low 5800 rpm."
Also, right in the GM Performance Parts description, "Raised runner (.240" higher than conventional 23* head) intake ports with 210cc ports and runners provide adequate flow for applications well in excess of 500 hp."

As for your other question, "Would the $400 and 10 week wait on the AFRs be worth it or should i stick with the fastburns?".
Only you can answer that- its your engine, your money and your time.

Me personally, I'd buy the fastburns and put the saved dollars and time where it would be of more benefit. You don't mention your cam lift, but it appears the heads will easily take the a 0.540" lift. If you are going more, put your $400 into improving lift. You can then spend the 10 weeks however you like.
A 10 week lead time on any component for a SBC is pretty sad. It goes back to an old adage that the best way to make yourself look like a great cook is to starve the guests first.
In the end, you are the only one that can make the decision.
I'm sure the engine will work well either way.
Best-
S-D

1badrocZ

iTrader: (1)

How do these fastburns compare to the AFR heads? $1000 for new fastburns is hard to pass up, but i don't want to buy these then wish i had got the AFR heads later on. From what GM says they made 497hp on a 9.5 to 1 with a 540lift hyro roller cam in a 383. To me that seems a bit high, i wonder if they inflat those numbers a bit? Would flat top pistons and the 62cc make my compression too high where i couldnt run pump gas? Im guessing it would be around 11.0 or a little lower.

swerve-driver

I doubt GM would put themselves out on a limb by overstating their research. Likely not worth it to them.

You will need to calculate own your compression ratios- don't guess. Once you have an accurate number in hand, make a decision from there. The aluminum heads disapate heat well, so you might get away with a higher compression ratio, but I would be cautious if you are in the 11:1 neighborhood.

If the CR is too high with the flat top pistons, you may have already answered your own question concerning which heads to use.

As far as a comparison between the two sets of heads, do the research, the numbers are out there. What it will likely come down to are the personal decisions like cost, time to obtain, what you hope to get out of them, etc.. all questions only you can answer.

S-D

FullSendRacing

Just for reference, I've got a zero decked 383 with 74cc AFR 195s and Ross forged flat top pistons that have valve reliefs. The heads had to be milled .020" to get up to around 10.5 compression. I just did a quick calc and it looks like if I had 62cc heads, I'd be running around 11.5 compression. As is I really gotta be dialed in correctly to ward off detonation with 93 octane.

IIRC the zz4 comes with 62cc heads, but they run a dish piston to keep the compression down below 10.

Blackroc86

I was running Fastburn heads on my 406 with flat top pistons, XE294 flat tappet cam, Super Victor vortec intake, Speed Demon 850DP and ran 11.86 at 113.

My friend has a 406 with similar compression. solid roller cam, rpm air gap. 750DP Speed Demon. AFR 195 heads.

He has run an 11.99 so far but has lots of tuning to do and his car weighs 400lbs more than mine. I suspect he could get to an 11.50 when it is tuned properly.

If I was buying heads again I would go with the AFR's for a sbc.

shaggy56

I vote fastburns. Ive seen independent tests of the AFR heads and I wasnt impressed. I think maybe they fib on their flow #s or maybe the ones I seen were defective or something. I know guys that can get 11.99 with ported stock vortecs. I know someone now doing 12.5 with stock unported vortecs and its a 350 not a 406

1badrocZ

iTrader: (1)

Well i went with the fastburns, hard to pass up for $1000. From talking to people ive heard alot of positive about these heads. My engine builder said my compression should be around 10.5 with the 62cc chambers and flat tops. Hope hes right i don't want to run 110 oct. gas or mixed. Gas prices are ridicules as is. Has anybody heard anything about the headers not matching up with the exhaust ports on these heads? Is there a particular set of headers that will work fine with these?

FullSendRacing

I was able to run the SLP shorties with either straight plugs or angle plugs. With the angle plugs though, I had to clearance the primary a bit for #8

eXesiv|83ta

iTrader: (4)

The aluminum should help a little bit with the compression problem and also if you have a large cam it will help decrease detonation.

swerve-driver

I used my SLP headers. I used a carbide to shape them to match the D port on the fastburns. Didn't take much. Unbeknownst to me, this caused a small exhaust leak, which I was certain was a blown head gasket the first time I started the motor. I chased that for a week until I figured out what it was. No clearance problems with the plugs- they work well.
S-D