Aluminum cylinder head Q's

[396_WAYS_TO_SPIT]

Way to much head for even a 502. Car guys get to enjoy dumping the clutch at 4000 rpm or running a stall converter that is flashes at 5000. Boats whether jet, VD, or I/O don't get to use such "advantageous RPM providers".
Whether "FREE" or not you going to be out time and some money for parts and when splashed you are not going to be happy. If you were turning the engine 8500 rpm and running a power band of 7000 to 8500 peak then they may work, but with a peak of 6000 to 6500 you way over headed.
A 310cc intake runner is enough volume for a 502 CID engine to turn 7000 to 7200 without being a restriction.
One last thing, with boat engines "power under the curve" is more important then anything. From idle to max rpm you want the greatest amount of power you can make so that curve is flat. This gives you hard accelleration at any point. Two equal engines in power, the one that accellerates the quickest will always with the race. We accomplish this with proper cylinder head cross section to provide port volume and port velocity then add a camshaft with the right valve events to create a valve path to feed and relieve the engine.
When you get the dyno sheet from you buddy the powerband will be very steep, not broad. . . peaky. What takes more energy to do, walking up a hill or on flat ground? Drag cars need peaky power because they have gearing and transmissions to keep them in that narrow powerband. With boats you need that "walk flat" powerband.
Killer info Chris I just want him to read this so he can get an idea on whats going on
I got the numbers Chris. Ill call you hopefuly next week and have some $$ sent out to you. Thanks Michael

[thatguy]

I've got a .040 over 454, 10:1 compression, .575 245@50 cam. Just could not bring myself to pay for new aluminum oval ports. thinking of future use. SO, I bought a new set of Brodix 280cc rectangle. #BRO-2011001 from summit. Here is what they have to say.
"Quality heads from the folks at Brodix.
These Brodix BB-1 heads work well with heavy cars and small engines. The intake ports flow over 280 cfm with only the bowls blended and the intake ports matched to the gaskets. The combustion chambers are properly shaped for use with either methanol or gasoline, preventing detonation. These cylinder heads accept all standard pistons, intake manifolds, and rocker arms, and the valve cover rails are now raised to prevent oil leakage."
Will be running this weekend, so will post how it works out.:idea:
Tommy

[ck7684]

Interesting...280cc rect ports?? The Edelbrock ovals are 290cc...
http://www.edelbrock.com/automotive_...t_bb_rpm.shtml

[thatguy]

Well, thats what they advertise them as. I don't own a burrett any more, so I did not cc them. All my manifolds laying around are rect. So, I figured a small rectangle should do the job. It took almost 3 months to get them delivered, so I guess there isn't a big demand.
tommy

[cfm]

The BB-1's are a decent head out of the box, but they really shine with porting. So if you do build a bigger motor, send them out to be ported. Shouldn't have to sell'm for somethin else unless you go ludicrous with next build.
They are like most Brodix's - set up with extra meat and the right countouring for head porters to go in and do their thing.
Another reason why consumers will pass by the Brodix's - their out of box flow #'s. They are less than most others out of box. Again, the reason is typically because they are made knowing they are going to the porting shop.
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The Edelbrock oval's are nicknamed 'rovals' because they are more rectangular than oval. Take a look at them. Same thing with the GMPP oval port - that's a roval too.
Oval is round - rectangular is rectangular. Do not let the cc's make you think one or the other. It's the shape.
Their are 380cc + ovals out there !!!! But, no, standard oval port doesn't bolt up. Here is a 497cc oval - love it. http://www.brodix.com/heads/pb1200.html
This is major league major rpm/compression/exotic stuff.
Anyway - smaller cross sectional ports take less energy to get the air colum moving and to keep moving. Large csa's take more energy to get moving, thus the bigger the csa the more cid and/or rpm you need to take advantage of them.
Ton more to it - if in doubt talk to the head manufacturers themselves or a head porter or engine builder you absolutely trust !!!! Not just internet heroes like CFM hiding behind a keyboard. LOL.

[ck7684]

Thanks for the info!! 280 or 290 seem like great numbers to me, thats why I chose these heads...(not a edel vs brodix thing at all)