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Are aluminum heads worth it? Which ones? Here are some answers.

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Old 01-17-2010, 07:36 PM
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It is this interaction with everyone and his honesty that put me on his door step last winter. I am thrilled with my 572's with aluminum heads from Eddie.
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Old 01-17-2010, 08:48 PM
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Very informative thread, Thx Eddie
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Old 01-17-2010, 10:24 PM
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It is this interaction with everyone and his honesty that put me on his door step last winter. I am thrilled with my 572's with aluminum heads from Eddie.
And all this time I thought it was my striking good looks and being hung like a hummingbird.
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Old 01-18-2010, 12:01 AM
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And all this time I thought it was my striking good looks and being hung like a hummingbird.
Oh God I think I hear banjos.
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Old 01-18-2010, 01:09 PM
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Eddie:

Very nice job of providing numbers from your work and great comparisons of cfm flows at various lifts.

Question? Do you have a velocity probe on your flow bench?

When we worked with Darrin Morgan and developed our Raylar 496 BigPower aluminum heads we found that looking at flow numbers was important , but not the whole story. We found out that port velocity of the air flow was also of major importance.
It also seems to sometimes hold true that some supposedly smaller air flow heads make more power on the dyno or in the boat. I suspicion the reason is air flow balanced with good port velocities as well as some air charge direction into the combustion chamber and tumble, things we had to learn before we could really get an exceptional head and make good marine performance power.

As a good comparison on our standard Stage 1 Raylar head we have only a 318CC intake port and just a 2.20" intake valve and yet at .600 lift we develope 365 cfm.
How did that happen - VELOCITY OF THE AIR! This is also a very important factor as you already know in developing low and midrange power and torque which are very important as we all know in performance boating.

I guess what I am leaning towards here is the fact that bigger flow numbers are not always the real answer or final point for selection of a good marine performance head, especially on normally aspirated engines.

We also with this air velocity measurements at various places in the intake and exhaust port found out amazing things, like on the exit floor of most BBC ports the area about 1/8" to 3/16" up off of the floor had almost NO AIR FLOWING! while the rest of the port was screaming! Good reason for straightened-raised exhaust ports. the bends and negative sections in ports really help destroy flow and velocity.

Just some info here, do not want to hijack your work and post! I really appreciate it when knowledgeable people and shops like yourself share their knowledge and expertise.

Eddie, it would be nice to make these velocity measurements and compare the differences between these heads you are comparing and I think from what we've seen its pretty easy to rig a simple velocity probe on your flow bench. If you have a SuperFlow, I think they can get you setup for that probe. Might show some interesting info that will help in head selection.

Hope Raylar's head development work can help all our fellow OSO'ers in their head changes and modifications.

Best Regards,
Ray @ Raylar

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Old 01-18-2010, 01:17 PM
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It seems I have been asked these questions a lot recently. I will try to help answer these questions with some data. I recently did some flow testing on some stock cast iron heads that were both stock, as cast, and ported, a set of Brodix BB-2Xtra CNC that had also been hand ported and some AFR 357 CNC heads. This is by no means a scientific experiment. However, I did try my hardest to keep all of the variables the same. These test were done on the same flow bench with the same fixture, using the same operator.
The first thing I was trying to see is how much my port work helped. Next, how much better are the aftermarket heads then a set of stock cast iron heads. Finally, were the CNC heads maxed out or was there more to be found with porting.

Disclaimer!!!
This is not a scientific test. These numbers will be on the low side as compared to published numbers. I was looking more for a comparison then all out max flow. Several factors will cause my numbers to be low.....I used a 4.5" bore fixture instead of a 4.600" that most manufaturers use. That larger bore fixture will help flow by unshrouding the valves. Next, I did not use a pipe on the heads. I never have used one in the past, so I wasn't going to start now since I would have no way to compare to previous tests. The pipe will not only increase flow, but it will also represent more realistic conditions since there will be a pipe on the heads on the engine. These two factors alone could account for 30 -40 cfm or more. Again, I am not looking to see what the max flow is as much as I am looking to compare the heads and see if porting will help.
Here are the numbers:

Stock GM cast iron head (188 casting)

Exhaust stock ported

.200 117.3 117.3
.300 149.8 150.6
.400 174.4 180.0
.500 183.9 191.8
.600 187.0 197.0
.650 187.0 197.0

Intake stock ported gain
.200 149.0 150.1 .9
.300 197.0 203.8 6.8
.400 232.6 246.4 13.8
.500 258.1 277.8 19.7
.600 279.6 303.5 23.9
.650 287.0 311.4 24.4

This was not a full port job. I only did the chambers and the bowls, since they were the worst. I did not touch the runners at all. So with a little more work these heads can really be improved. The bowl area was really bad. The seats did not match up with the head at all, so there was a large step left in the head when it was cut for seats. This is where I did most of the work ( along with the area around the valve guides)

Now for the aftermarket heads. First up are the Brodix heads. They are the BB-2Xtra 355 CNC . I flowed one of the heads right out of the box and one that I did some port work to. I didn't really do a bunch of aggressive cutting. I spent more time on polishing and cleaning it up. Now you may say why do you have to do any work to a CNC head. Well, you don't have to but the numbers show that they can certainly be improved upon. It really depends on what you are looking for in terms of hp if it is nesseccary. I haven't done any work to the AFR heads yet. I'm not sure if I will. They really look nice and I was expecting them to really outflow the Brodix heads. They did in the lower lift, but not in the upper lift ranges.

Brodix BB-2Xtra 355CNC:

Intake: stock ported gain
.200 148 148 0
.300 220 224 4
.400 282 292 10
.500 323 335 13
.600 354 370 16
.700 375 394 19
.750 383 403 20

Exhaust: stock ported gain
.200 128 128 0
.300 165 168 3
.400 227 231 4
.500 255 257 2
.600 271 277 6
.700 281 286 5
.750 285 289 4

AFR 357 CNC:
Intake exhaust
.200 159.0 141.1
.300 235.2 190.2
.400 289.2 237.8
.500 326.1 248.8
.600 355.1 252.0
.700 378.6 254.2

Like I said, I haven't done any port work to the AFR's yet. When I do, I will post those flow numbers. Again, these numbers are going to be low compared to the published numbers for the reasons listed above. I hope this may help someone make a decision as to which route to go. Thanks for looking.
Eddie
You really should do some research before acting like you know what your talking about!!

Very impressive!!!!
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Old 01-18-2010, 03:16 PM
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Thanks for the info Ray. At the time, I did not have a velocity probe. I am working on it now and will have it set up the next time. All of these heads were going on SC engines so I wasn't that concerned about losing much velocity. The other thing is that you would be surprised at how little I did. They actually did not require much.
The Brodix heads had a few holidays where the cnc bit did not even cut, especially around the guides. They also did not meet up where they cut from both sides. On both the Brodix and the AFR's there is over 1/16" step where the cutters met in the middle. They both also left a sharp turn on the short side radius of the exhaust port. This is where I did the majority of the work.
I didn't have to do the Brodix heads. I could have used them like they were and made the power that I was after. I sold the customer a complete package, so I essentially did the heads for free. I did not get any extra money for doing it. I just saw an opportunity to try a few things to see if I could improve it.
Eddie
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Old 01-18-2010, 03:55 PM
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Eddie,

What about aftermarket iron heads vs. the aluminum you selected? Such as Grumpy Jenkins and Iron Eagles vs. the others?

Frank
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Old 01-18-2010, 04:29 PM
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Panther,
I rarely use cast iron heads. I'm sure there are several good flowing heads out there. I usually stick to the alum. for the head dissipation qualities.
I would love to flow a set to see what they do. I don't really count on published numbers because they are all trying to make their heads look better than the others. That is why I did this. I wanted a direct comparison without the variables of different flow benches, different operators, with or without a pipe, etc.
I am not trying to sell port work. I absolutely despise porting heads and if I never have to do another set, then that will be fine with me. You can never get enough money for the time it takes. I wanted to see if they could be improved on and how they compare with each other.
I will definitely do more in the future. I will be glad to post the results. Thanks.
Eddie
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Old 01-18-2010, 04:48 PM
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Eddie,

What about aftermarket iron heads vs. the aluminum you selected? Such as Grumpy Jenkins and Iron Eagles vs. the others?

Frank
Panther, I have asked JimV this. He says the Dart Iron Eagles flow the same as the Pro1.
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