What type of flow numbers to look for in heads to reach 600ish hp for SBC?

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patrickonb
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What type of flow numbers to look for in heads to reach 600ish hp for SBC?

Post by patrickonb »

Hi folks,

Wanting to build a 580-600hp SBC (Gen 1, not LS) and need to know what kind of flow numbers I should look for in a head?
Not using turbos/nitrous, simply a NA engine.

Thanks for any input/info you can give.
Patrick
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Re: What type of flow numbers to look for in heads to reach 600ish hp for SBC?

Post by mag2555 »

There's a lot more to it then just Intake flow numbers, like compression and VE, overall Intake and Exh ratio, but if you can't make a minimum 600 hp from 300 cfm@ 28" then something is far and away wrong with your combo!
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Re: What type of flow numbers to look for in heads to reach 600ish hp for SBC?

Post by dannobee »

There's a lot more to it than that. "Most" people will agree with cfm to potential power output, i.e., 300 cfm @28"H2O can potentially make 600 hp, or 2hp/cfm, but even that's a stretch. What we can say that with a 150 cfm port and 600hp, well, you ain't gonna get there from here.
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Re: What type of flow numbers to look for in heads to reach 600ish hp for SBC?

Post by patrickonb »

OK great, this gives me something to work from!!

I can tell you what I've been thinking in terms of a build, and then you can tell me what you think from there...

I'm looking at going with a 383 build.

Scat 4340 Crank and 6.000 H-Beam rods
CP Forged 5.1cc Dome Pistons
Compression will be in the 12.5:1 range with 65cc head.
Heads that flow as per above question (AFR 227cc Eliminator Race Heads?)
Intake and carb to match said heads (this is why I need to figure out the head issue) I was thinking Victor Jr./750-830 carb
Solid lifter cam .580-.600 lift, 260/270 @050, 106 LS

So what are your thoughts?
Thanks.
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Re: What type of flow numbers to look for in heads to reach 600ish hp for SBC?

Post by novafornow »

Thoughts and opinions will vary with personal experience. My 2 cents: contact Eric Weingartner and get a set of his Dragonslayers, ditch the vicJr, And get a little more lift in that cam choice.....600hp maybe more.
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Re: What type of flow numbers to look for in heads to reach 600ish hp for SBC?

Post by mag2555 »

You should attain 600 hp easy with that combo, but the headers will need to be right!
The primary tubes need to be .060” larger then the exh port exit, especially on the floor.

A primary tube length average of 31 to 32 inches should be sought.
These should feed into a merge type collector of 3.250” Id with a length of 14”.

I would run the 830 carb.
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Re: What type of flow numbers to look for in heads to reach 600ish hp for SBC?

Post by PRH »

I’ve made 600hp with a SBC 383 combo similar to what’s been laid out by the OP.
I used ported World Sportsman 2’s flowing around 280, 271/279-107 roller cam, cleaned up Super Victor, “bigger” headers, nice oil pan, good carb.
Somewhat handy with a die grinder.
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Re: What type of flow numbers to look for in heads to reach 600ish hp for SBC?

Post by skinny z »

PRH wrote: Fri Jul 02, 2021 4:05 pm I’ve made 600hp with a SBC 383 combo similar to what’s been laid out by the OP.
I used ported World Sportsman 2’s flowing around 280, 271/279-107 roller cam, cleaned up Super Victor, “bigger” headers, nice oil pan, good carb.
What peak HP RPM?
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Re: What type of flow numbers to look for in heads to reach 600ish hp for SBC?

Post by 1980RS »

I know my AFR CNC competition 210's will make 600hp.
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Re: What type of flow numbers to look for in heads to reach 600ish hp for SBC?

Post by patrickonb »

Wow, thanks for all the replies guys, this really helps me out, and gives me more direction. Have built simple 400-425hp small blocks in
years past, running in the 12's, but the wife and I are coming back from a 23 year break after having kids, and we're wanting something
more powerful this time around.

We're planning to build a 4 speed stick car this time around, and try to put 'er in the mid-10's. Looking at a couple of rollers right now,
one is an 88 Camaro and another is an 94 cutlass supreme.

Thanks for all the info and help,
Patrick
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Re: What type of flow numbers to look for in heads to reach 600ish hp for SBC?

Post by mag2555 »

Save some funds for a much more robust rear to handle power shifting a 4 speed 600 hp car then compared to 425 hp car!
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Re: What type of flow numbers to look for in heads to reach 600ish hp for SBC?

Post by PRH »

skinny z wrote: Fri Jul 02, 2021 5:04 pm
PRH wrote: Fri Jul 02, 2021 4:05 pm I’ve made 600hp with a SBC 383 combo similar to what’s been laid out by the OP.
I used ported World Sportsman 2’s flowing around 280, 271/279-107 roller cam, cleaned up Super Victor, “bigger” headers, nice oil pan, good carb.
What peak HP RPM?
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Somewhat handy with a die grinder.
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Re: What type of flow numbers to look for in heads to reach 600ish hp for SBC?

Post by patrickonb »

mag2555 wrote: Sat Jul 03, 2021 9:38 am Save some funds for a much more robust rear to handle power shifting a 4 speed 600 hp car then compared to 425 hp car!
Yep, we've got a Ford 9" rear in the garage right now. Going to use Strange spool and axles as well. :)
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Re: What type of flow numbers to look for in heads to reach 600ish hp for SBC?

Post by patrickonb »

PRH wrote: Sat Jul 03, 2021 1:44 pm
skinny z wrote: Fri Jul 02, 2021 5:04 pm
PRH wrote: Fri Jul 02, 2021 4:05 pm I’ve made 600hp with a SBC 383 combo similar to what’s been laid out by the OP.
I used ported World Sportsman 2’s flowing around 280, 271/279-107 roller cam, cleaned up Super Victor, “bigger” headers, nice oil pan, good carb.
What peak HP RPM?
Nice!! Thanks for sharing that. :)
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Re: What type of flow numbers to look for in heads to reach 600ish hp for SBC?

Post by prairiehotrodder »

the 227 AFR require offset shaft rockers, and offset lifters and grinding where the pushrods rub. I would either use the conventional 220 heads or jump up to the 245's if i was going to commit to the offset exotic parts. I think 600 hp can be reached without the exotic parts personally. I think brodix makes a 233 head that uses standard parts. There is lots of options. I'm working with a friend on a 423 SBC thats using the 227's and we wish we had gone bigger while we were spending the money.
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