I was talking to one of my Chevy friends today. He said he knows a guy that bought a set of big block Chevy heads that flowed over 500 CFM out of the box. He had a guy port them and now they flow over 700 cfm. I dont know how big the motor is but he said it made over 1100 hp with one carb. I have never heard of any heads that flow that much. Did somebody BS him or is that possible.

Well I can tell you that 1100 HP does not require anywhere near 700 cfm. I cannot know what head he has but 700 cfm would require a MASSIVE intake port and valve. There are some of the Big chevy stuff that are huge but generally only things like the Pro Mod and Mountain motor Pro Stock type stuff. Even the big hemi stuff would be hard pressed to get near that number.
Todd

I think some of Sonny Leonard's stuff flows in the 700 area...... But those go on motors that are about 1000 cubes.

I saw a pair of Big Chiefs on the flow bench after porting. IIRC, they flowed about 535 and made about 1200 on a 632.

That is what I was thinking. I know the guy he was saying has the heads and I don't think he can afford anything like that. His last car ran in the mid to low 5's in the 1/8. It was one of those old pro cars, I think it is a Oldsmobile Calais or something like that.

I always cry when I see the big Ford stuff flow numbers, I mean c styles are alike 550 out the box😢

Mmmmmmmm..........not exactly.

The 700cfm heads from Sonny's start at about $15,000.

My 5.0 bs Sonny's hemi heads flowed over 600. The ports were small compared to Sonny's 5.3 bs hemi heads. The cost of the heads is cheap compared to the motor they go on. My 762 made over 1500 hp with one 4 bbl. To answer your question, yes there are heads that flow that much, but normally they would be on a larger engine and make a lot more than 1100 hp.

I was making a general statement Dwayne, u know the head game far better then I ever will and that's why u the man! I had just seen a fellow puller post his pro filer c heads and they where 520+ out the box

I was referring to Ford Motorsport C heads...... Nowhere near 500 ootb.
I tested a set of hand ported FM C heads...... That the owner was expecting to be around 500cfm. Lets just say he wasn't that happy after he got the flow numbers.

I'm certainly not any kind of authority on Ford stuff...... I didn't realize Profiler had Ford heads.

However, best flowing head I've ever had on my bench was a CNC ported "Thor" head for a BBF, it was like 535cfm.

Second best was an Indy Legend head CNC ported by Jeff at MCH...... It was 499.

I don't see much of that "big stuff".

We've got a set of SR20's here that goes over 500 at .900 on an SF-1020 with a 4.625 fixture. That's about as much as I've seen a conventional BBC head go. There's reasonable demand for conventional stuff for some of the x275 radial racers where they get a significant weight break. It's all about the rules, if you could get a Predator head under the same ruleset, it'd be very strong. I suspect that's where this 600-13x head will play best.

I'm far from a professional on this stuff, but I'm always surprised how significant an effect various valve/seat angles have on flow performance. It really makes one of the Newen/Serdi single point CNC valve machines look good for a "serious" top end engine program. S/F.....Ken M

This is completely hearsay but I remember one of the top cylinder head guys in the USA say a Pro-Stock or Top Fuel V-twin head goes over 700 cfm. FW that's W. J.Rob

Awww man... now I'm developing flowbench envy.