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Originally Posted by MILD THUNDER
(Post 4656501)
what kind of top speeds were you getting with the 650s compared to stock 496's?
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Originally Posted by jadento
(Post 4656505)
Best ever 94.3 on gps. 91-92 everyday. Stock Ho's, 80-81.
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Originally Posted by MILD THUNDER
(Post 4656513)
i noticed in the thread with the guy selling those LS engines, that made 651hp, he only saw 88mph in his 32 sunsation. Seemed kinda slow for 650's in that hull.
MT, Torque? big vs. small block? Maybe he was not propped right? I turned Stock 30 inch bravos to 6K. For another comparison, Bailey had blown 502's in his Dominator similar speed as the NA509's but he turned 32's. Tired his 32's one day and while cruise was up, top speed was down. |
I think like rookie said, sometimes the dyno king number isnt always the fastest setup.
then you have the whole dyno correction factor stuff, plus many dont dyno fully dressed in marine trim. Dyno headers vs manifolds can be significant, as well as sea pump, water pump, alternator, steering pump, etc. That stuff could add up to 50+hp losses |
i didn't think 650hp na was such a unicorn for a bbc lol we've done 800+ pumpgas friendly out of bbc's,,, but obviously that wouldn't work well in a marine application, too much loss in bottomend.
But anyways to my concerns,,,i'm going to just stick to the 454's,,,i think the ls's wouldn't have torque downlow to match the bb's unless i match the same ci, which then my build would be costly. I think i have to stop listening to my guys here that want to swap the world with LS lol |
Originally Posted by XtremeCFM
(Post 4656530)
i didn't think 650hp na was such a unicorn for a bbc lol we've done 800+ pumpgas friendly out of bbc's,,, but obviously that wouldn't work well in a marine application, too much loss in bottomend.
But anyways to my concerns,,,i'm going to just stick to the 454's,,,i think the ls's wouldn't have torque downlow to match the bb's unless i match the same ci, which then my build would be costly. I think i have to stop listening to my guys here that want to swap the world with LS lol John |
Originally Posted by XtremeCFM
(Post 4656530)
i didn't think 650hp na was such a unicorn for a bbc lol we've done 800+ pumpgas friendly out of bbc's,,, but obviously that wouldn't work well in a marine application, too much loss in bottomend.
But anyways to my concerns,,,i'm going to just stick to the 454's,,,i think the ls's wouldn't have torque downlow to match the bb's unless i match the same ci, which then my build would be costly. I think i have to stop listening to my guys here that want to swap the world with LS lol |
Originally Posted by XtremeCFM
(Post 4656530)
i didn't think 650hp na was such a unicorn for a bbc lol we've done 800+ pumpgas friendly out of bbc's,,, but obviously that wouldn't work well in a marine application, too much loss in bottomend.
But anyways to my concerns,,,i'm going to just stick to the 454's,,,i think the ls's wouldn't have torque downlow to match the bb's unless i match the same ci, which then my build would be costly. I think i have to stop listening to my guys here that want to swap the world with LS lol the issue isnt isn’t the ability to build it. The issue is making it live in a boat. Plenty of high horsepower apps out there for cars but making them last in a boat is a different animal. Water in exhaust, docking where you’re in and out of gear at low speeds, always at 3500-4500 rpm. Very different than an automotive setup. |
well aware of the constant abuse of a marine app...done many of them.
I actually think that a NA setup holds up far better then a boosted one...that constant wot for 5 to 10 min straight under boost is pure torture,,,god forbid you have a slight fuel distribution, its going to eat a piston real fast. i plan on running a dry exhaust setup in the boat also |
Boosted is by far the more reliable and safer setup once you get into the 600+hp range. Nobody sells more hi performance marine engines than mercury, and they know this.
biggest weaklink in a marine engine is the valvetrain. Boosted engines dont need radical valvetrains to make big power. |
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