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Quote:

Originally Posted by blownzr1 (Post 4504509)

572s,10.5 compression,1050 quick fuel carb,bill miller intake,357 afr,cant remember cam specs right now without looking.bought these used but got dyno sheets saying they made 740-750 hp.were ran with eddie marine thunders on them in other boat with dry exhaust

Scrap the SM's.

For that I would go with Thunder n Lightning Headers/Manifolds; http://www.diamondperformanceparts.c...cat=282&page=1

A 598" I built with T&L's. https://youtu.be/u-5P0vw1UqQ

Blown the Gen II's are ok with the right pipes but really need Gen III's. NA, the Thunders are the way to go!

Quote:

Originally Posted by blownzr1 (Post 4504509)

On that combo i would guess about 40-50hp difference,the big n/a engines really like headers they really like the big tubes 2 1/8 now if it were a blown 509 making 700 the headers would be good for 20 or so at best

Quote:

Originally Posted by Panther (Post 4520319)

Man those things are Uugly, :helmet: sounds like a swap cam :ernaehrung004:

Quote:

Originally Posted by MDGperformance (Post 4520335)

Good info.

How about a blown 540, making 900-950?

Quote:

Originally Posted by 33outlawsst (Post 4520344)

Man those things are Uugly, :helmet:

And that's when bling can fuk you.

At 600hp+ level NA it's either this or correctly sized tubular headers.

BT: I've seen these in Merc Racing blue and they look pretty good. Obviously my opinion.

im thinking I don't have enough room between the motors for the 2 1/8 headers....side by side boat

My buddys pro charged 509's have stock HP500 Gils, with boat running 107, they gotta be making 825-850 HP, seems that exhaust is fine for him, he researched it years ago, everyone said with the boost it would not matter much at all... I think boost is a totally different animal..

Quote:

Originally Posted by 33outlawsst (Post 4520344)

Man those things are Uugly, :helmet: sounds like a swap cam :ernaehrung004:

All about personal preference I suppose.

Headers look like "money" because they cost you "money" and lots of "money headaches" down the road.

[ATTACH=CONFIG]563854[/ATTACH]

Quote:

Originally Posted by Panther (Post 4520388)

All about personal preference I suppose.

Headers look like "money" because they cost you "money" and lots of "money headaches" down the road.

[ATTACH=CONFIG]563854[/ATTACH]

I personally dont think those thunder n lightning manifolds look bad. I mean sure,stainless tube headers look cooler, but its not like the GIL or SM regular manifolds are pure sex. At least imo.

Quote:

Originally Posted by blownzr1 (Post 4504509)

According to pipemax, a build like that maxing at 6000 rpm, making 750ish hp

For low to mid range power, a 2.06 to 2.131 diameter primary, with 18.8 inch x 3.829 to 4.079 diameter collector.

For mid to upper rpm power, a 2.206 to 2.331 diameter primary, with 18.8 inch x 4.079 to 4.579 diameter collector.

Thats a mile, wait, 10 miles, away from a typical stainless marine standard manifold. In the car world, if you stuffed a 750hp 572ci big block in your car, and ran a 1 7/8" shorty header, with a 3" inch collector, someone would smack you across the cheek. :cartman:

I believe MER Performance recently dynoed a 650ish hp 509 build. Made close to 640 with the 2.25 dyno headers. Bolting the stainless marine manfolds on, it made right about 600hp, and lost a bunch of torque as well. About 30ft lbs I think at peak tq .