so what part of the port is moving the most air?i'll assume the upper part of the runner?

 

You know what's nice.... is that you won't go wrong with either one. You can't make a bad choice if those are your options.

I wish the rest of my car-modding decisions had as many good choices.

 

best reply in this thread




though my money's on Tony

 

Depends on where in the port... at very high velocity the speed over the short side radius is very critical, so is the pushrod pinch (in something like a SBC) Different lifts will have different velocity maps and different effective runner cross section. This is where you can really apply something like a high pressure bench, something in the 100" of hg range.

Bret

 

thanks for replying.now i have a better understanding of why my ported 5.3s kick *** up to .450 and then back up 20cfm at .500.

 

Yeah that's probably most likely a problem with the short side... don't ask me I'm not a head porter, I just talk with a lot of them and if you don't know what you are talking about you can't find the good ones without flowing and dynoing a few heads. That's always a help on top of it, but before you spend the coin you want to hear the right things.

Bret

 

All you guys with head envy, check out the current issue of Super Chevy. They are working on a Bill Mitchel 427" SBC. They put on a set of 195cc Ken Duttweiler Trick Flow heads that flow 258/196 at .600" We are jaded and don't realize how good our heads are.

 

isn't that the truth.how's the car coming?i'm going to Dynotechs open dyno day june 4th.wanna come down and see what your beast puts out?
chuck

 

Great data, thank you for sharing it, Tony

As a base line it would be really nice to see the same heads flowed with an LS6, FAST etc in place because the intakes do make a very real difference. I've seen the data from several sets of LS1/LS6 heads flowed with and without the intakes in place. What looks great without the intake sometime isn't so great with. What looks "OK" without an intake can do very well with an intake in place. It's all part of creating a matched combo and how far you want to take it. I sure can understand Tony's point about how much time that sort of testing can take because that's very true.

Friends in NASCAR say they develop their ports (for whatever head) using flow data with the intake in place (as well as lots of other things) for best results. Part of the evaluation for a head is flowing with and without the intake in place.

Likesome someone else posted learn and verify.

 

99 Black Bird T/A,

The other thing that is interesting is that the intakes on the LS motors all choke off flow at a certain CFM no matter what you do. The funny thing is if you have a cylinder head that goes from 290cfm to 330cfm you will have more power even if the head flows the same with the intake on.

We really want to quantify power directly with CFM @ 28" but it's not that easy. There is way to much flow bench racing now adays. A flow bench is a tool to find improvements in a head port rather than grinding, throwing the heads on a motor and seeing what you made in terms of power, way to many other variables there. You could have a big gain on the intake and none on the exhaust and then the cam is off for the application and you could loose power, it's not a simple task. NASCAR teams do this because they have the ability to get a cam for a new set of flow numbers and try it out. Hell they have done tests where they do nothing but change the volume and cross section of the ports in a motor with the flow numbers changing and they find more power.

The other thing that is interesting is that in NASCAR heads you don't just work them as a matched pair, you actually change them seperately and cause a mismatch in the intake and heads (due to the rules) to find gains from different cross sectional areas in the intake manifold. Looking at them you would think they are way off, but the motor likes it.

Information is power, data is data. Figures never lie, but liars figure.

Bret

 

I can't argue with any of the things you mention....

Also, as I have mentioned previously, other tools and techniques are used here in the actual development of the AFR port designs. The reality is the more commonly accepted figures that get thrown around the Internet and heat up the local bench races are figures simply derived from straight up flow testing without intakes, headers, etc. And while those figures might not mean everything, in a perfect world if everyone's equipment read the same, it would certainly be some good data points to start formulating opinions from, especially having the size of the ports in question as well.

The other problem with flowing and advertising numbers with an intake manifold in place is which intake?? Ported, unported, stock, or aftermarket? Then trying to compare numbers from two different locations becomes a total waste of time....the variables would continue to stack higher and higher. Also, it wouldn't be fair to flow a very large high flowing intake port with a stock LS6 intake in front of it...the gains would be completely erased.

Anyway...I updated the list with another larger LS6 ported casting ("S") I had the opportunity to check out this afternoon. The only thing worth noting with this particular head was the fact it had a 2.02 valve but to be honest, it didn't really show any appreciable gains on the smaller bore which I assume was the object of putting the smaller valve in a larger ported head (231 cc's). It peaked at .650 on the small bore going 303 CFM's, and peaked at .600 lift on the large bore at 304 CFM. Just some additional data to pour over for the number crunchers....

Have a good weekend everyone.

Tony M.

 

thing is though alot of people DO throw there high dollar high flow heads behind a stock ls6 manifold.

 

hell, i threw my heads under a LS1 manifold!!!!

i wonder if any other head porter is willing to put their heads on a completely stock motor like AFR did???

 

The funny thing is if you have a cylinder head that goes from 290cfm to 330cfm you will have more power even if the head flows the same with the intake on.

 

Back from the dead...

Just an FYI that I updated the list to reflect the latest head I head the opportunity to test. This head just made the cut at 227 cc's (trying to keep this thread primarily representative of the larger cylinder heads, 225 cc's and larger) and was actually a ported LS1 casting with aftermarket 2.020/1.570 valves.

I'm guessing it was probably a Stg. 2 or 2.5 and the execution was fairly neat. This head was better suited to a 3.900 bore where it peaked at .600 lift around 303-304 CFM's. If the peak numbers on the exhaust were a little stronger (only 216 CFM @ .600 on a small bore), it would have ranked as one of the better LS1 ported heads I have had the chance to see.

Thanks,
Tony

 

Im on the market for heads now. Im not swaying more or less in any direction. spending $2500 or $2000 for heads isnt an issue for me as long as my motor and car dont break apart. I dont mind if I DONT squeeze every last drop of HP our of my motor. I just want it to stay together for 30 more years. And, feel that the price for the heads as worth the expense.

What I do know is :
I wont be going with patriot heads because of all the problems

I wont be going with TEA. After reading 6 pages of threads, something that Brentb @tea was saying during the 6 pages turned me off to their heads.

Fear not, it took me a year for figure out if I should go with the TR224 on a 114. A rule of thumb on cams that I didnt follow. Find the one thats right for you, and go one larger.

 

Hi Phil...

It's obvious what set of heads I'm convinced best suits your needs and with the continued release of positive results in the Dyno section (all independent results) I'm not sure what you are still waivering on, especially if saving money deosn't seem to be your primary goal. The AFR's are obviously not the cheapest heads but in my opinion they offer some of the strongest "value" for what you actually get for your dollar. Those who have purchased them will all attest to that.

I would prefer to keep this thread more technical in content and related to the topic, so if your still not sure which heads you want and are looking for opinions perhaps starting a different thread would be better. If you have questions related to our product, and specifically related to your application, I would prefer to handle that in PM's or better yet over the phone. You can reach me directly at (818)890-0616 Ext. 109

I know you have been doing lots of research and would love to have the chance to speak with you personally. Give me a call next week at the office if you have some time.

Regards,
Tony

 

Another "player" added to the list (Head "U").

Had the opportunity to test this head a few days ago and updated all averages across the board to take into account the recent additions to the list.

This was a ported 5.3 litre casting of average size (based on the heads featured here) with below average test results, especially on the intake side. It was fitted with aftermarket 2.020/1.600 valves.

 

Greeat thread, just the info I'm looking for. Has anyones heads come close to flowing what they claim?

 

I know tony's not going to release names to go with the letters...and i'm not asking...
but, looking at that chart, think tony could be making some side money....