ECeptor

If one converted a twin stock SBC boat like a Scarab 29 over to LS engines, how much weight could be saved?

engines - 350lbs each
exhaust - 50lbs each
misc brackets/mounts to bolt every thing up +50lbs total
anything else?

So, I'm thinking a net weight reduction of ~750lbs for a twin application. Using an LS364 or LS376 would put the power in the 450-500hp range up from the 350Mag's 300hp.

Did I miss anything?

handfulz28

Converting from twin SBC to twin LS-x? An all aluminum LS maybe weighs 100lbs less than an iron block/AL head LT1. Bore/stroke, additional fuel system pieces, you won't be saving much weight. Not to mention spending as much on a good exhaust as you will for the motors themselves.

Build up the 350MAGs with aluminum heads and other good pieces, add good aftermarket exhaust, you'll be way ahead of things. An LT1 will make 400hp with little more than a cam/rocker/exhaust swap. And you can use already available marine exhausts. Build it out to 383ci, maybe you can even run 87 octane with 9.5:1 cr and still make great torque/good HP.

ECeptor

This is a paper/theoretical exercise only...

Only 100lbs savings? Raylar is claiming 450lbs per engine savings with his LS based 450ci engines vs big blocks. I thought the weight delta between an iron SBC and iron BBC was only 100lbs, no?

handfulz28

I see a 350MAG/Bravo weighs in just under 1,000lbs. A 502MAG/Bravo weighs in just under 1200lbs. If you use Raylar's LS-M 550 with a 450lb delta, that includes exhaust. So I'm coming up with a best case scenario of 250lbs savings from 350SBC to LS-x SBC. Remember, Raylar's exhaust is a stainless header design, and his LSM 550 is over $20g's per.

I enjoy the paper/theoretical exercise, and I'm a huge fan of the LS-x idea in boats. But they're just not cost effective unless you use a "recycled" LS motor. And even then, once you're done marinizing it, you'd be so much further ahead starting with a classic SBC.

If you're stuck on LS-x motors, your best bang for the buck is to find a LQ4 6.0L out of a truck, put a cam in it, find someone to make an exhaust that doesn't break the bank, and see how it fits. Don't forget that the LS-x will need accessories and brackets for marine app that aren't widely available. Things won't just cross over from SBC-classic.

ECeptor

Considering the cost, one could pull the stock 350Mags and sell them outright. Given they would be a very nice upgrade for 1000's of smaller lakeboats/skiboats there shouldn't be a problem selling them.

Then take that cash and get the LS's. As far a marinizing the LS's, I wouldn't be afraid of the stock longblocks any more than I'd be afraid of a 496Mag or HO from Merc. Given a thermostat controlled cooling system the tols should be fine plus the hyper pistons would be fine if no boost was added.

Coming at the weight saving a different way...

Heads -70lbs per engine
Block - 70lbs per engine
Exhaust - +50lbs per engine
Intake - 20lbs per engine
???

As for the brackets for accessorys, I am assuming most would be made by me in my shop. So, the only cost would be my time plus some material.

With gas hitting +$4/gal, it makes sense that upgrades add power AND reduce weight. Since I trailer my boat (and likely always will), the weight saving helps on the water and on the road.

handfulz28

Here's an idea: go out to ebay and shop for these pieces. I'm willing to be you'll get a very good estimate of weights, so you'll have those details. Just another item to consider, since you brought it up, is closed cooling. Yes, I can guess KS means fresh-water boating. But even Raylar uses closed cooling and I'm thinking that's the best way to ensure longevity. Just another item to consider.

FWIW, LS-x motors are in production by marine builders, so pieces are out there. Only you know what your time is worth, and the value of your innovation versus a known, proven quantity.

I'll stand by my best bang for the buck order:
1) build out the 350SBCs
2) go with a known piece, LQ-4 6.0L

Like I said, I'm a fan, so don't take my responses as trying to discourage altogether. For example, there's a guy here in FL who is retrofitting Cessnas with LS-x motors. Redundant ECUs, digital LCD data displays. He's trying to get the package FAA certified. While it's a novel idea, and a perfectly functioning package, it just doesn't have a significant enough cost-benefit to be widely marketable.

Adding power and reducing weight are admirable goals. But again, best bang for buck comes from maximizing efficiency in the power plant. What's the better deal: spend $5k to save $200/yr or spend $20k to save $300/yr?

ECeptor

LS364/440hps look to be selling for $5,300 brand new. If I assume a used but good 350Mag MPI fully loaded could be sold for $3k each, that starts the upgrade cost at $4,600. How much else to finish? $5k? $10k? More? The power would go from 600hp total to 880hp total...a nice jump.

MTRiverrunner

You can get Gen IV 6L motors from Marine Power, Kodiak and now Indmar. They are very popular options in white water jet boats. All the motors that I have seen them offer are based on the iron truck blocks.

I have been looking into building one of these LS based motors myself and the weight savings isnt substantial. An aluminum block, aluminum head Ls-x is 100 lbs lighter than an iron head Gen I/II. The iron blocked Ly6 is 88 lbs heavier than the aluminum block LS2. If you put aluminum heads on a Gen I/II then you are getting close to the weight of the LS2 and are lighter than a LY6.

From what I have seen from other people running the Gen III/IV motors is that they get better fuel economy and respond very well to forced induction. They are a well designed motor IMO. If you are looking at buying a crate motor and marinizing it, they arent too much more expensive than a comparable Gen I/II

pullmytrigger

classic sbc with some real good aluminum heads like AFR's.....pretty hard to beat......and you arnt stuck with a bunch of one off pieces which could be real bad down the road if the company you bought them off goes out of biz or stops producing them and all you get is a "sorry"

Raylar

Thought I would weigh in here on this subject to shed a little factual information and data for those mis-statements on this subject.

First, the only way a LS engine is going to have considerable weight savings over and iron small block is to use an aluminum block LS whcih is what Raylar has utilized, developed and is now selling. Second if you are going to use an aluminum block you must use closed cooling, even in fresh water, most fresh water is high in minerals and galvanic action from high flow water cooling will cause corrsion issues even in fresh water.
Third, when it comes to a price discussion lets talk apples to apples. The Raylar LSM550 is an all blueprinted hand built 434 cubic inch LS all aluminum closed cooled engine with stainless headers, variable electronically controlled valve timing, all forged aftermarket crankshaft, rods, pistons and special oil pump, 9 quart custom oil pan with remote oil filters, oil cooling and special stainless raw water pump, should I continue!! You are not going to be able to buy and build the parts for this level of engine-remember over 550 ft/lbs of torque and 550HP from a 434 cubic inch small block at 5600 rpms that weighs by the scale 527lbs complete with bellhousing flywheel coupler and exhaust fully trimmed ready to drop in and run!

If you were to take a GM LS crate engine 6.0L advertised 440HP which by the way only has 405 ft/lbs of torque and marinize it you will spend a huge amount of money and time just getting it to a state you could run in an offshore type performance boat and when you were done and put it in the boat you would probably have the stock engine grenade on you in 5-10 hours of normal performance boat use. How do I know this, two years of testing and actual evaluation with blown engines and problems have taught Raylar this.

We have spent over two hundred fifty thousand dollars and over two years developing our Raylar LSM550 engine and if someone can come along and do it with a crate engine and get these kinds of results and reliability needed for a 550HP all aluminum small block engine with a one year engine warranty, BE MY GUEST!!

Yes, quality, powerful, reliable marine engines are expensive, and yes performance boating is an expensive hobby and sport, but if all those who sit on the sidelines and quarterback how to build and price marine engines were in charge of engine development and offerings not very many performance boats would ever leave the trailer or the dock!

Remember Mercury, Volvo and others are coming out with all aluminum high performance engines in 2009, most of which will be smaller cubic inch supercharged versions (We feel this is a mistake-discussion later) of the LS engine, it is just we were first at nearly two years ahead of everyone else and with what Raylar considers a better product for boats than what they will be offering.

Enough tooting my own horn! If you want a real marine high perfromance all aluminum 527lb -550HP engine, give us a call, we have them in build as we speak.
Raylar does not spend a lot of time flapping, we spend time delivering!

Best Regards,
Ray & Larry @ Raylar