Found this page on RHS' site that I thought might help some of those people that aren't too sure on what size runner they should choose for their application.

RHS - Which intake runner volume should I choose?

This page will basically help get some of you pointed in the right direction in building your engines to perform how you want it to. Of course you still have to decide on what cam and intake to run as well as other things. But this is one less headache that you have to rack your brain over.

 

Good find but I call BS on their numbers. I went through their heads and started studying their flow data. Now I'm on full BS alert.

According to them their 180cc head Flows better than AFRs old 190cc head. 263 cfm@ .600" compaired to AFRs 261@ .600"

"Remember that velocity produces low rpm torque, and flow produces high rpm horsepower. So that 170cc cylinder head that you’ve been looking at -with its smaller, higher-velocity runners and valves, is going to accelerate well from a stop, produce lots of low speed torque, and be a great performer below 6000 RPM (which covers about 97% of all street-performance scenarios), but it may not reach the peak RPM you’d want in say, a drag race engine. Conversely, that high–flowing 235cc Small Block Chevy cylinder head that your friends tell you is all the rage at the local track is going to help your engine to rev like crazy and produce a ton of upper rpm horsepower, but it won’t build power below 3500 RPM -making it virtually unusable on the street."

This is all true. So I dug deeper and checked the flow numbers for their 220cc Pro Action head. The one recommended for my 6500rpm street 383. It flow 272 cfm @ .600" lift. Cool race motor territory. BUT AFRs Street Eliminator head with its smaller 195cc runner. Stomps a mud hole in them flowing 280cfm @ .550" lift. Spring for the CNC port job and it gets bumped up to 301cfm @ .550" Thats BB territory and still maintaining the smaller runner for good low end torque. So what AFR has done is given the best of both worlds.


This is a good comparison between heads. Air Flow Research My rule of thumb is 170-195cc up to 350cid. 195-230cc for whatever else. Of couse the low side is street and the high side is race.

Here is a test CHP did a few years ago before AFR even came out with the latest greatest new head. For what its worth I have the Canfields that at in this test. They came in second, ahead of Brodix, Holley and Edelbrock.

I'm not picking on you Ole Blue. I just hate RHS. Definitly not the best bang for your buck in my opinion. Carry on.

 

Ya i was posting it mostly for the intake runner sizes compared to rpm ranges. I know a lot of people are not positive on what size runner they choose. I know when I get around to getting a new set of heads for mine I plan on getting a set of 200cc heads. Double humps are not bad if you get them for a good price (being a couple hundred bucks), but compared to todays port designs they dont stand a chance.

 

Most people buy aftermarket heads with the biggest numbers. Biggest runners, highest flow, largest valves, etc., etc.... But as Damon pointed out, that's just a really poor way to choose heads. You don't want 200cc runners for most street applications on most smallblocks. Now if your smallblock is bored and stroked, and has a huge cam with operating ranges too high for most street use, then you'll want heads to match that.
Most people would be better served by a good set of double humps, Vortecs, or aluminum heads with smaller runners.

 

For what it's worth, I had played with numbers a while ago on my D.D. program, using different AFR specs (I want to get AFR heads). On my stroker, the 195's gave better overall h.p. and torque numbers than any of their larger runner heads did. I know it's only a program, but it's handy for doing comparison tests. Plus these flow facts have been verified by a lot more than just home computer programs. Unfortunately, some people still fall into the "bigger is better" trap. Whenever in doubt, it's always good to talk to a manufacturers' tech rep, especially AFR who really know what they're doing when it comes to making performance heads.

 

ya, well I know how I want my engine to turn out and when I get the money to do the cam and heads they will be done around the same time and I will be running up to 6500 rpms. so a 195cc or 200cc head would be about right.

 

I say, talk to your engine guy. If he's like mine, his first questions will be what car?, what trans?, what's the gear ratio?, and primary use (street or strip). If he has a flowbench, spend the money and have them spec them out. I have a regular old set of 882's that my motor guy built up. They were dynoed on a 383 stroker and made 420 hp, I forget the tq, but, it was good. Bolted on mine it dynoed in at 334 hp and 400 tq. These were set up to maximize the drivetrain set up I will be running. I know this motor could make a little more, but, at 6000 I'm smiling.

 

I am my motor guy. Camro69, the AFR Eliminators are the head to beat in my opinion. The smaller runner makes torque and then has the flow to make top end power. If I were to build another motor from scratch those would be on it. As a matter of fact I want an LS so bad I can't stand it. But those heads are still in my mind. They support 600 N/A horsepower.

 

Ya I was posting this for other people that need help with choosing heads. I do pretty much all my own work on my vehicles. I know what set up I will be running on my car.

 

Again I agree with Camro69. A talk with the tech line. I also build the car around the engine, not the other way around. While I agree you need to be real with yourself. Don't tell the teach line your plans are street/strip if you'll only go to the track once a year. I don't particularly care about gears or tranny until I know what I'm running.

My personal goal is north of 500 STREET hp. My car MUST idle in traffic. It cannot run hot or load the plugs. I also don't need it to idle like a pro stocker. It does sound good though. It has to run like I bought from a dealership.

These are just my tips to choosing heads.