Originally Posted by Dragracer_Art (Post 4847345)

In latest news... I just dropped $2k on a closed cooling system. It's only a half system and doesn't touch the manifolds... but at least the engine wont have scummy water running through it and it wont freeze over the winter.

https://www.hardin-marine.com/p-1003...lf-system.aspx


Next will be a better set of manifolds with dry joints. Still shopping for the right system. Looking at Stainless Marine and Dana. Cannot swing $8k+ on CMI stuff. $3500 dry joint manifolds will suffice.
I never liked the VP and Mercruiser wet joints. Almost lost my last (merc) motor because of previous owners maintenance neglect. Had water in several cylinders one day after running on muffs in the driveway. Figured it out the next day when the motor was hydrolocked. Pulled all plugs, spun it over to push water out and fogged all cylinders. Resurfaced manifolds/risers and replaced gaskets and it was good as new. Motor wasnt hurt and still ran strong.

Originally Posted by Brad Christy (Post 4847348)

Dragracer,

To my knowledge, that's how all closed cooling systems work. The coolant runs through the engine while lake water runs through the heat exchanger and out through the manifolds/headers, cooling them in the process. Somebody correct me if I'm wrong....

Thanks. Brad.
(937)545-8991

Originally Posted by techman (Post 4847259)

I always thought side exhaust was a weird design. Is it done for packaging reasons? It certainly can't be for sound since you are hearing 4 out of sync cylinders on each side. It makes that V8 rumble sound like a UPS truck.

Originally Posted by Brad Christy (Post 4847346)

Dragracer,

I also wonder about the 90DEG bends in the exhaust routing that is usually implemented with side exhaust. I would think they would induce backpressure that would be unwanted for a higher performance engine. We had them in our Rinker, and I often wondered if they weren't holding the engine back some.

Thanks. Brad.
(937)545-8991

Originally Posted by Knot 4 Me (Post 4847351)

On the Chaparrals talked about here it is due to the hull/transom design. It was easier for them to route it out the side. I had a 266 Crownline that you could have it either way. I choose thru the transom on that boat. Sounds so much better.

Originally Posted by mcollinstn (Post 4847445)

Stay away from huge cubic inches and monster torque, or you'll mangle your outdrive.
A 502/509 is a great combo because the large bore doesnt shroud the valves.
550 hp at 5600 is an easy target.
This is likely the upper limit for yoyr outdrive.

A 572 or 632 will make another 100+ ft*lbs of torque which will be tough for your outdrive to absorb. If you go that route, you will likely have real-world experience on exactly what the breaking point is for a DPX

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Originally Posted by Cap'm Kurt (Post 4846744)

Techman and Icdedppl got it right.

Only thing is, is to check that your WOT rpm is near the top end of your recommended rpm for that motor. Otherwise it will feel more sluggish than it should. Very simple idea, but so many dont understand that concept, or have never even checked it. But chances are what you have is correct.