Brad Christy

This....

To boil it down even further, I've always been of the impression that HP was all about fuel burned. The more fuel burned, the more HP is created. Following that logic, if higher pressure in a smaller volume is still less F/A than a lower pressure in a greater volume, you're generating lass HP, period. I've heard/read these arguments before from the BMEP trolls, trying to crap on big blocks as inferior to, say, a Subaru boxer engine, because they are generating more HP/ci, and it's utter BS. More HP is more HP. I'm not gonna knock the LS platform, but, at the end of the day, it's all about getting HP to the water for long periods of time. As much R&D as they put in to making turbos work, as opposed to superchargers, if Merc thought they could make a transition to LS and make it work, I'd think they would. But I am curious...

If there is some voodoo to the LS, why not build an LS BB? Is that a bridge too far? Or is the interest in a SB, specifically, and the LS is just the magic bean?

Thanks. Brad.

Wildman_grafix

Mercury has moved most of their engineering to Outboards, period. Except for the turbo motors which are not based on the BBC.

But there are more efficient ways to burn fuel, it's why most car motors are no longer using platforms of old. For me when you are in the 1000HP range in a single speed boat at this point a boosted BBC is hard to beat, not because its the best design, its because its the best design we have in the displacements needed.

Except for the Ford 7.3 gas motor is there any car motor over 5 liter in mass production right now? And even a 7.3 is small compared to most BBC's at this point.

Brad Christy

Wildman,

Agreed. I guess I should have worded it "would have", in regards to their development efforts.

What are they based on? I always though they just started having their blocks made "in-house", rather than buying them from GM or whoever, but were essentially the same block, with small tweaks to accommodate marinization.

So, what I heard/read there is that it's all about the displacement. Again, I guess I should have worded it a bit better. What would be wrong with an LS, with all its improvements over older platforms, in the 550ci range? I think most of us have abandoned the idea of efficiency in lieu of HP through the propshaft. I'd guess if most of us had the option of 1350HP running at maximum efficiency or 1600HP spitting unburnt fuel through the exhaust, we'd opt for the latter. Not to mention that, given that efficiency is nothing more than HP/unit of fuel consumed, if we are getting 1600HP while spitting raw fuel out the exhaust, we are looking at, say, 1700HP if we can burn that fuel, meaning more efficiency, which would require nothing more than packing the intake with more air and/or more positive ignition. Right?

Thanks. Brad.

87MirageIntruder

Someday someone is gonna build up one the of big block LS engines and put it in a boat. That will be cool to see.

Brad Christy

Pistons go up and down. Crank goes 'round. Rods swing and swirl in between. Cam goes 'round. Valves open and close. Air in. Fuel in. Exhaust out. So, what, exactly, makes an LS an LS? Serious question. I see nothing more than a couple of some random MFR's BB heads in those pics. If they are "LS" heads, I certainly don't know the difference.

I'm a blank page. Really.

Thanks. Brad.

boostbros

Well as unusual combos go does any one know how that 2500 hp sonnys billet big block with billet hemi heads worked out? i think it was being installed in a jet ski it looks to be pretty heavy duty. its the first time i have seen hemi heads on a big block kinda curious are they a better flowing head?

hogie roll

Sonny’s chemi’s have been in cars. He advertises a boat model, never seen one in a boat though.

730+ cfm heads I’ve heard. Yes hemis flow more, great high rpm motors. A nightmare on valvetrain though.

offshorexcursion

Another downside to LS is less torque. Especially with most boats only having 1 speed transmissions its very hard to prop a boat high enough and actually turn the prop to get there. Similar struggle with N/A engines. There's a ton of claims of big HP N/A but rarely do they actually push a boat to the same speed as forced induction that makes the same HP, since the forced induction usually makes much more torque. You can make all the calculated HP you want on the dyno and all the rpm but if you can't actually put that to use in the water with the correct prop none of it really matters.

Knot 4 Me

Mike Finnegan has a 711 cu. in. twin turbo Sonny Leonard chemi in his jet boat (first Game Over, now Side Chick). I doubt that is his boat model, though.

plavutka

8.2 HO vs Volvo Penta 430 hp?
https://www.volvopenta.com/about-us/...soline-engine/