Cylinder Head Comparison - Chevelle Tech
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post #1 of 9 (permalink) Old Aug 4th, 05, 8:59 AM Thread Starter
 
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Cylinder Head Comparison

Is there a testing standard for flow? It seems that EACH mfrs testing yields the highest results for THEIR heads. I think Chevy High Performance had a head shoot-out, but was limited in scope. Just like camshafts, everyone has their own specific application. Seems to me, that they would have a standard to test by, dictated by SEMA or SAE.

EVERY CYLINDER HEAD MANUFACTURER SHOULD STATE:

Head thickness (important for the NOS/Turboblower guys)
Access bolt holes
Combustion Chamber CC's
Intake runner CCs
Intake and Exhaust Flow at .100, up to .700 (at box stock, mild port,radical port)
I/E ratio
Ratio of sold/returns (to see whats junk!)

Alot of the times, you can't find this info without researchin your butt off. Seems like there would be a database somewhere.

I would like 180cc runner / 60-62cc SBC aluminum heads to perform from 1500-6000 rpms. Just can't decide WHICH head to use. Any suggestions, and which to stay away from?
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post #2 of 9 (permalink) Old Aug 4th, 05, 3:19 PM
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Re: Cylinder Head Comparison

Go to www.carcraft.com they have a head flow database of all the heads.

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post #3 of 9 (permalink) Old Aug 4th, 05, 6:30 PM
 
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Re: Cylinder Head Comparison

I really like my Canfields. I got them from competition products $1055 delivered to my door. Mine are out of the box 195's. Trick flows are nice too and cheap.
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post #4 of 9 (permalink) Old Aug 4th, 05, 11:16 PM
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Re: Cylinder Head Comparison

Quote:
Originally Posted by Beenaway2long
Is there a testing standard for flow? It seems that EACH mfrs testing yields the highest results for THEIR heads. I think Chevy High Performance had a head shoot-out, but was limited in scope. Just like camshafts, everyone has their own specific application. Seems to me, that they would have a standard to test by, dictated by SEMA or SAE.

EVERY CYLINDER HEAD MANUFACTURER SHOULD STATE:

Head thickness (important for the NOS/Turboblower guys)
Access bolt holes
Combustion Chamber CC's
Intake runner CCs
Intake and Exhaust Flow at .100, up to .700 (at box stock, mild port,radical port)
I/E ratio
Ratio of sold/returns (to see whats junk!)

Alot of the times, you can't find this info without researchin your butt off. Seems like there would be a database somewhere.

I would like 180cc runner / 60-62cc SBC aluminum heads to perform from 1500-6000 rpms. Just can't decide WHICH head to use. Any suggestions, and which to stay away from?
=
Almost everyone uses 28"
The biggest problems come from bore size used & weather a pipe on the exhaust is used.
And just plain bogus tests (polite wording for bull poo-poo )

I don't know of a head out there that doesn't have accessory bolt holes.

Head thickness is a phone call away but the thickest head I know of is the AFR at .750

Who doesn't give you chamber cc's?

Intake cc's are only a valid indicator of the same family of heads.
IE: 23 deg sb, 18 deg SB, BB oval, BB rect etc.
The cross sectional area is a number that should be added as this is limiting factor in what RPM the head will work to on a certain sized engine, not CC,s.

If you have head flow you have I/E ratio.

I think you will find engine size may make a "slight difference" in port volume needed at 6000 RPM

If it's a 350 it should be fine.
If it's a 383 it's probably gonna be a little small
If it's a 400,, see above.

In my opinion the AFR is the best "out of the box" head you can buy.

And,,, if you contact me you might be surprised at how little more it is then the "good deal" canfields listed above
Nothing against the Canfields, I just feel the AFR is a better head & it does not cost much more unless you start adding options.
Another outstanding head in this area is the Brodix RR & the new "IK 200" but the IK 200 is only available in 200cc & 64cc chambers.
For info, the 200cc RR with the CNC chamber will outflow a 210 AFR to almost .500",,,

Mike (Wolfplace)
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post #5 of 9 (permalink) Old Aug 5th, 05, 11:19 AM
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JIM
 
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Re: Cylinder Head Comparison

The more I watch actual tests on heads on flowbenches, the more I am convinced that the flow numbers are only really valid for comparison if you have experience with the performance of THAT bench.

*IF* you were to take a set of heads out of the box, run them and compare them to another set of heads you had run on the motor and flowed on THAT bench the same way, you would have valid comparisons.

Or at least flow heads out of the box, then port them and test on that bench and look for improvements, THEN you have something. Forget the raw numbers, look for the improvement. We don't race flowbenches or dyno's, just use them for tools. Just like any other tool, some work, some don't. Working with bad tools gives bad results.

With all the number of heads out there these days with #'s adv. relatively close, you really need to get some real world experience to help out. It would be awful hard to give fully ported numbers because as we all know there are "hoggers" and there are "porters". Big difference in the results!

I've been watching some flowbench tests of some BBC heads throughout this year. These heads have been tested and developed on a bench I trust with a porter I trust. His bench has been verified against other benches in his area and they are all in line. That's all good and when porting happens on his bench by him, performance as well as flow numbers show good increases. Then that same set of heads were placed in a box and shipped cross country to another guy I trust who has his own Dynojet and does lots of development work with great results. When they were tested on the bench he always uses, they flow somewhat less than expected. Still good, but less raw numbers.

Hmmmnn...strange, because we had suspected his bench was optimistic considering the numbers he had on his Dart 335's. But his performance is great (714 RWHP on a 93 octane 540 through the mufflers), so who knows?

Then we get a set of AFR 357's that flow a LOT less than adv on the normally used bench. Quick cleanup port work on exhaust side picks them up dramtically, And I mean quick. Nothing fancy. Intakes are left alone, while nowhere near adv. they are really good flowing ports. Performance on motor is about what is expected considering the compression and cam. Best part is the AFR's greatly extended the rpm range without falling off.

Then there is a new set of Brodix 3Xtra's. They are flowed on one bench where we also completely trust the bench and operator, then they are put in a box and shipped crosscountry and tested again. This time, they flow a lot less than advertised and a lot less than they did a few days earlier on the other bench. Remember, this bench previously posted higher numbers than another known bench on the west coast that we have had great results from. May be a trend here, but again exhausts were down somewhat even when tested with a pipe. Some more serious work has them flowing like crazy on exhausts. Consensus was that without a LOT of high $$ work the intake weren't going to improve much. They were really good out of the box, just like we have come to expect from Brodix.

Now, after all that, my head ported called the above guy...they are friends and were taught by same folks and stay in touch to compare results. They reached same conclusions after studying things.

My heads were developed on one bench and we had lots of things that were tried to get the final results. Some worked, some didn't. The important part is that all work was done on same bench by same guy. No telling what they would show on another bench, but I do know that they no longer "fell off" at higher rpms like before. Head porting, a new intake and a new cam had it making approx 95 more HP at peak, but what gets the car down the track is that at 7000 rpm it is up over 230 hp!! No longer does it hit the brick wall. I have a much broader power band.

So to me, all this means that you need to find out actual performance results from a particular head and use results from whatever bench you can regularly use to determine "what gets what". This is why a builder can tell you that "this will get you this" when he is porting heads. He knows what THAT number on his bench will produce on the motor, regardless of what it actually is.

We all have to rely on whatever advertisers tell us, but I encourage you to seek out a well known local builder and consult with them on actual results when you are looking at spending a lot of money on heads. CNC stuff is great if you don't have access to a great porter, but you might be surprised what a good porter can produce for you if given a chance. Be careful making choices on advertised numbers alone.


JIM
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post #6 of 9 (permalink) Old Aug 5th, 05, 10:09 PM
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Re: Cylinder Head Comparison

excellent post Jim. alot of people get caught up with the "flowbench" numbers. most just go by what someone told them they flow or what they read about it, when there is just so much more to it than that, like you explained.
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post #7 of 9 (permalink) Old Aug 10th, 05, 12:42 PM Thread Starter
 
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Re: Cylinder Head Comparison

Great post Jim.
Thats why I mentioned a standardized test. I used to be HEAVY into snowmobile racing. The dynos for sleds were NEVER even close to each other. Each builder's dyno would read 10-15 horse more with THEIR motor on it.



Thats why SEMA should step in with a standardized test of some sort.
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post #8 of 9 (permalink) Old Aug 10th, 05, 11:10 PM
 
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Re: Cylinder Head Comparison

I have had an SF600 since 1992. With the calibration plate bolted on it still flows the same as the day I bought it. I have flowed tests radius plates on 2 other sf600 benchs that were within 10 miles of me and all three were within 1%.
I have also flow tested some heads that had been tested on other benches. Its interesting how sometimes my bench seemed lower than the head porters bench. I had one customer who told me the guy flowtested his head right in front of him to prove his numbers were legit. The customer noticed the spark plug was left out and once it was replaced the numbers fell into line.

FWIW I have a set of out of the box 195cc TFS heads on my '71 Nova. They flowed very close out of the box to the specs listed on TFS' website. I run a 355 with 9.6-1, an original Z28 hi rise intake and 780cfm 3310 carb. A set of small tube hooker headers and 2 1/2 inch exhaust to the bumper. The mechanical cam specs are 238/238 @ .050" .520"/.520" net lift and 110 lobe seperation.
It has a 2200 stall speed and 3.31 gears and 27" tires.
I ran a 13.3 @ 108 in 100 degree weather with a pathetic 2.200 60 foot time (tires are too tall). It idles nicely (14" @ 800 rpms)
SInce then i installed a better exhaust system with a crossover pipe and an RPM air gap intake. The engine really woke up over 5500 rpms compared to the old combo. But I havent taken it back to the track yet.
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post #9 of 9 (permalink) Old Aug 11th, 05, 11:00 AM
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Re: Cylinder Head Comparison

Jim, very good reading.

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