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

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Old 01-20-2010, 11:55 AM
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Old 01-20-2010, 12:46 PM
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Seem's to me the point is about the flow produced on the afternmarket iron heads was comperable to the aluminum... I don't see it as a pissing match between setup, just that the heads were made to flow enough to support that amount of power...

Assuming those heads were on a 540" @ 5500 rpm maybe they'd make as much power as another 540 with AFR's????

When detonation becomes an issue I can see the advantage of going to aluminum but if you're just trying to make 50-75 more HP over what you have it might make sense to go with a cam and porting the heads you have?

Let's not be defensive, it's an open forum.
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Old 01-20-2010, 01:19 PM
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Originally Posted by Raylar View Post
Ben:

Thank you for the compliment, my compliments to you on your engine package! The best of continuing success to you!
You are right in that this type of engine is very feasible, just not practical for the average performance boater.
When one uses a race type engine setup like this in the average recrational performance boat it would be a recipe for disaster as far as endurance goes and being user friendly at cruise rpms and idling. As for the standard Bravo drives I know from hundreds of inputs from users that an engine you describe making about 700 ftlbs of torque at those HP numbers and with those rpms around 6000 or so, it's gonna be a short trip for the average Bravo in a heavier performance boat in bigger water than average Texas lake water!
I wana see the Bravo drive that can go 15 years behind this motor, cause I am gonna buy a boat load of em and make some good money!
I realize that a few OSO'ers like to push the envelope of engine and drive performance and its this push that yields some great performance and racing results. The problem is I have yet to see or meet any quantity of these boats that can run 400-600Hrs without serious rework, rebuild and constant garage and dockside tweeking to keep them running season to season. If you've got such an animal, yes then at $30-$40K they should sell like HOTCAKES!

Keep in mind the performance boating market for both boats and engine and drive packages is like a tiered pyramid. At the very tippity top you've got this 5% or so group of buyer-users who can afford almost any package and any amount of upkeep and rework. But under that 5% tip you got the 95% of the market mass who does not have the wallet, knowledge, patience or expertise to own and operate these kinds of boats and mills! I can't stay in business and make a profit selling to that 5% part of the pyramid, I gotta stay down here with the other 95%!
Raylar's got some pretty incredible engine packages like our HO750 and such, we just can't stay in business, especially in Todays Economy selling just these type of engines, We'd starve if we tried and everybody at our Funeral would Say:
"Those Raylar Guys Did some Cool Stuff!"

Best Regards,
Ray @ Raylar
ray how much HP does your 509ci package make?
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Old 01-20-2010, 01:32 PM
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Seem's to me the point is about the flow produced on the afternmarket iron heads was comperable to the aluminum... I don't see it as a pissing match between setup, just that the heads were made to flow enough to support that amount of power...

Assuming those heads were on a 540" @ 5500 rpm maybe they'd make as much power as another 540 with AFR's????

When detonation becomes an issue I can see the advantage of going to aluminum but if you're just trying to make 50-75 more HP over what you have it might make sense to go with a cam and porting the heads you have?

Let's not be defensive, it's an open forum.
I don't doubt for a second that you can get aftermarket iron heads to flow what aftermarket alum. heads will. As you said, the problem is heat dispersion. You just can't run as much compression with the iron heads.
I guess it all depends on what you are trying to do as to what heads are best for your application.
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Old 01-20-2010, 01:38 PM
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I havent been in here for a while and even longer since posting. I have been porting heads for years and have done most of my work matching port volume to RPM engine size and port velosity.
I will attempt to explane the importance of port velosity and how it out performes the bigger is better attitude.
Most unported heads factory and aftermarket design for a air speed of around 200 FPS. Most heads i have done are about 300 FPS.
What happens in the cylinder as a piston moves downward on the intake stroke reaches BDC and starts coming back up. Somewere during the downward cycle air speed rises to 200
FPS. During the upward movement of the piston the air speed begins to decrease as the inertia of the air flow is over come by the upward stroke. Making it worse is over lap allowing the charge to be pushed right out of the cylinder.
Having a higher air speed the piston down stroke fills the cylinder more and on the up stroke the piston will travel up the bore further before the momentum of the incoming air is over come.
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Old 01-20-2010, 01:49 PM
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Originally Posted by Young Performance View Post
I don't doubt for a second that you can get aftermarket iron heads to flow what aftermarket alum. heads will. As you said, the problem is heat dispersion. You just can't run as much compression with the iron heads.
I guess it all depends on what you are trying to do as to what heads are best for your application.
Eddie
I'm totally with you Eddie!!! One day I'd like to get rid of my Merlins and put on some AFR's or Brodix... Out of the box I think the increased compression (less cc chamber), increased flow (possibly needing less boost for same power) and less chance of detonation would be an excellent addition to my blower engines!

Question: Going from a 119cc combustion chamber with a 4.530 bore to a set of AFR's or Brodix, how much of an increase in compression would it be assuming I'm currently at 8.3:1?

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Old 01-23-2010, 12:04 PM
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Default New Marine Heads

Here is whats in the works. A true marine head.
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Are aluminum heads worth it? Which ones? Here are some answers.-new-head-picts.-002.jpg   Are aluminum heads worth it? Which ones? Here are some answers.-new-head-picts.-004.jpg  
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Old 01-23-2010, 01:23 PM
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Cool! When porting around/near the valve guildes, is it important not to make it too thin causing a hot spot?
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Old 01-23-2010, 08:07 PM
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Here is whats in the works. A true marine head.
What's cookin' Jim??? Looks really COOL---How about some details to go with them photos! Keep us posted. Thanks
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Old 01-23-2010, 09:01 PM
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Originally Posted by JimV View Post
Here is whats in the works. A true marine head.
Is this going to be the aluminum Valako marine head? Your port design finally cast into a head. That will bump up the compression so all that is needed is a head, cam and intake swap or mod? 454 - 565? with no need to get into the internals and change pistons to up the compression ratio? Kind of like you choose your compression ratio?

I know you have talked about this.
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