JAKE

I remember one of the mags ran a long article a couple of years ago on flow bench comparisons of cylinder heads.

No, it isn't the one that ChevyHiPerformance ran at Westech, the ones I'm trying to find were done at a university by university students. I believe the university was in the mid-west.

The article went into detail on how maticulous they were in setting up the flow bench to ensure every head got a fair shake.

I can't recall the mag that ran the tests and I can't seem to find the site.

Does anyone remember which mag did these tests.

I want to do a comparison against what ChevyHiPerformance came up with.

Since AFR is citing CHP's results in their catalog and website, I'm suspicious that there may be some collusion involved.

I'm interested in the most objective comparison available.

Thanks,

Jake


[Modified by JAKE, 8:02 PM 10/29/2003]


[Modified by JAKE, 1:53 PM 10/31/2003]


[Modified by JAKE, 1:54 PM 10/31/2003]

SpedRacr93

The CHP tests were legit I'm sure. AFR just quotes it because its free advertising.

I believe the article you're looking for was tests done by University of Miami. This was a few years ago I remember because the article also had a big write up about their program there in Automotive engineering and I was considering going there for a while, but never applied. It was either in Hot Rod Magazine or in CHP because those were the only ones I was getting at that time.

Hope that helped!

hookedup

If you're looking for LT1/4 data try this link:
http://www.fierolt1.com/lt1_lt4_headflow.htm

Dave :thumbs:

JAKE

Thanks for that link; I checked it out and added it to my Favorite Places for future reference.

Jake

JAKE

Sped, I'm gettin old so my memory is only a shadow of its former self, but I keep thinking it was in GM HIGH-TECH PERFORMANCE mag.

Does that ring a bell?

I went to that site but couldn't find it there.

Jake

Mez

This is my favorite head flow comparison chart. I am not a racing guy, but to me this shows a lot of solid, factual information. Please note that there are variations in the flow test on what seem identical heads tested by the various shops. Please study the column with the calculated flow factor. This takes into consideration the flow rate at various lifts. The valves are at the max lift only a small % of the total cycle. So the ratings of max flow at max valve lift are not necessarily what makes the best power.

You can see why people love the LT4 heads because unported, they flow very well. Just pocket porting my LT4 heads, i was over 250 cfm at .500 lift on the intake side. To get over 300 cfm, you need a high-lift cam and lots of porting. If you plan to only race, that is the way to go. But for a street legal engine, its a whole different set of rules.

It is important to note that getting the highest flowing heads may first appear the way to go if you want a good street engine. The problem these heads get these numebrs at very high valve lifts - in the area of .600 to .700in. of lift. A street legal cam does not have that much lift. More like .525-.575".

Also, a head that flow those big numbers have a huge intake port. Since the valve open and close, the air starts and stop. These are the pulses that the enginers try to time to generate a ram effect into the combustion chamber. You can screw this up by using a big head with a big cam but try to run it on a L98 intake. What happens is by the time the head/cam start to generate power, the intake is too small to deliver the air. A dog of an engine.

Conversly, if you have a big head with a big cam and have a small, constrictive port engine, it will also be a dog.

The goal is to have the smallest port size that generates the highest flow across the whole valve lift range.

COMPVET

When I was in the maket for heads for my 455 inch small block I did alot of research and decided on the AFR 227 CNC race ready units. I fealt they were the best bang for the buck by a big margine. They were so nicely finished that I wanted to put them on my coffee table instead of under my hood. They work real good
Pete

0ski_dwn_it

You ask, you shall receive....
http://www.airflowresearch.com/artic...e11/A11-P1.jpg

http://www.airflowresearch.com/artic...e26/A26-P1.jpg

JAKE

Thanks guys. I should have been a bit more detailed in my question.

I already have the flow data posted on the ChevyHiPerformance website which Air Flow Research cites on it's website and is in AFR's catalog (just got my new one Monday). Those were done at Westech.

The ones I'm looking for were done by university grad students and, the more I think about it the more I'm convinced, the results were printed in GM-HIGH TECH PERFORMANCE magazine.

I did a long search on GMHTP's site but couldn't find them posted. I even put up a similar posting to that GMHTP's message board, but I keep getting responses directing me to the CHP/Westech link.

I remember posting the link on this forum right after I read it in the mag, but even that post has gone now - passage of time I guess.

Jake


[Modified by JAKE, 11:54 AM 10/30/2003]

Darkness

Looks like you're wild goose hunitng!

JAKE

I heard geese meat is greasy, is that right? Never had any.

Don't give up on me, Darkness; I'm gonna find it sooner or later. I'm one of those persistent types.

Jake

Irocan

Yes, it was in GMHTP. I'll dig up the issue after dinner. It compared Trick Flow's, AFR's, Vortec's, L98's, Edelbrock etc
Good article.

Bob

bjankuski

It was GM-High Tech performance and it was the september 2000 issue. The article was on page 27 and it compares 12 different cylinder heads. This is the article that convinced me to buy Trick Flow heads over AFR's. The AFR's slightly outperformed the Trick Flows but dollar for dollar the Trick Flows are very hard to beat.

sothpaw2

Is there some supply/demand issue with LT1/4 heads? It seems a lot more expensive to get an AFR (or other, insert brand name here) LT1 head than when I was looking at Generic small block heads on the Pro Topline site.

Pro Topline wanted $1000 for a new head, not ported but as cast, w/ flows as follows: .300" lift: 200, .400" lift: 250cfm, .500": 260cfm .600": 268 cfm. Says 200cc intake runner, 64cc camber.

I am probably missing something, but this seems like a lot of flow for a little cost.

JAKE

Thanks Brian. I really appreciate you tracking that down for me.

Now I'm going to GMHTP's site armed with the information I need.

Jake

SkarodoM

An easy way to compare approximate area under the curve is to do what Reher Morrison does...

(Lift Point 1 + Lift Point 1 + Lift Point 2 + Lift Point 2 + LP3 + LP3... + Peak Lift) x .05

Of course, you need to use the same lift points & number of lift points to get comparable results, but it's quick, easy to remember & uncomplicated :).

larrybsp

I have saved head flow articles for years. Overall the AFR heads seem to be the winner. I have nothing to do with AFR. In tests they flowed the best numbers under standard test conditions at livable valve lifts, under .600". Check the stall numbers. This is the valve lift where the flow stops increasing. They also have the highest exhaust to intake flow ratio which is probably why they are so good. I bought mine after studying the test data I collected. The dyno proved me right. 500 Ft. lb. of torque out of 355 C.I. Not bad.

JAKE

There are a couple with slightly higher intake/exhaust ratios - TFS Twisted Wedge and Edelbrock Victor Jrs to name two -, but overall, I agree, AFR makes the best flowing heads for the price. The main problem with them is availability.

In every flow shoot-out I've read, they've always come out on top.

Jake