Thanks guys first of all as far as dale being first a old school small block and new ls based small block are worlds apart dale so sterling wasn't do ls based small blocks 2 different animals and raylar my motors are 450 cubic inch close to a 454 and as far as torque. How is 530 at 3000 rpm and 620 at peak torque and what what the big block guys are missing is the fuel economy is what I was going after with fuel prices going the way they are having bang for the fuel buck you can't beat it it's just like fuel injection the old school guys didn't want it and are getting passed by with it sorry if I ruffled some feathers but I also have I drive that were no t proven and took a chance on them and have had no issues they are good for 1400 hp so I went over kill there did not want any issues they work awesome but I am giving up some speed cause of the beefy drive it is basically a number 6 lower and the upper gears are twice the size of the stock bravo but that's why they will support the horsepower I could have went with blown ls motors and went a lot faster was not my goal we want a fuel miser that could run well over a 100 and 120 or so to me is fine I had big blocks you can't beat torque but are goal was surpassed and am excited about the future with ls based motors so for some to say it was a failure just touched a nerve and I wanted the facts out there thanks guys will keep you up dated and raylar you should know better we can make torque we actually have to much cam shaft in mine we would have made more torque down low I will be home on Saturday will post my Dino sheets for you guys thanks and dale for the record I will race the other big block boat any day any time bring it on

Makes perfect sense to me, seems like a good balance of hauling ass and not giving quite so much coin over to OPEC. I have 6.2Ls in my boat, really pleased with the performance in my Sunny and pleased with the fuel consumption. I'd jump at the chance to have twin LSX blocks.

So which "other" big block boat are you referring to? Mine, or Gail D'Anniballe's 30 Skater that has a pair of 588s just like mine, but with IMCO drives? You really are making yourself look the fool now Jim. Why don't you put your money where your mouth is and offer up some money for this race? I don't even have to bring another big block Skater to beat you Jim, I can bring a couple of different OUTBOARD powered 28 Skaters and beat your boat. And as for your great fuel economy, I seriously doubt you get any better mpg than my boat does at the same speed. I average right around 1.5 mpg at 110mph cruise. At this same speed, you are close to WOT, whereas I am about 1/2 throttle. If you don't lie about your fuel consumption, I'd bet you are doing no better on fuel burn at these speeds. It takes fuel to make horsepower, and my boat takes less horsepower than yours to travel the same speed (obviously, I am nearly 40 mph faster with only 75hp aside more). So to travel at equal speeds, my boat will require less fuel, regardless of wether or not you have slightly more efficient motors. I really don't know what your expertise is Jim, but building efficient, fast catamarans is not it. You should have realized that to build a boat using smaller displacement motors, you should have kept it as light as possible with the most efficient drives possible to see the benefits of the smaller motors. But you did not, and that is why your boat performs so poorly...........

Boy! was just trying to cool the fires and testosterone here not throw gasoline on them!
Jim, I very much respect your build and engines and I was not aware they were nearly 454 size in cubic inch. That being said, I will keep an open mind but from my experience and builds I have not seen a normally aspirated LS engine that will develop, from a lets say 10.0 to 1 compression 450 cubic inch LS engine platform 530 lb/ft. of torque at 3000rpms and 620lb/ft.@peak torque but I sure would like to see and know this was done as you are an LS magician if you achieved those numbers with your engines. I have my student eyes and ears on and I am here to listen and learn.

As for fuel efficiency the BSFC's should show that and I would think Sterlings dyno sheets on Skater30's engines will show that as well as your dyno sheets so it should be a good compariosn to develop the theory that equivalent NA small block LS engines in horsepower and torque may have a better power to fuel economy delivered than equivalent power and torque big blocks im marine applications.

As for the big block/small block argument being brandished here those kind of torque numbers would be I think pretty close to the torque numbers Skater 30's Sterling built big blocks would be making and with the greatly decreased weight of your engines in an equivalent 30 foot Skater hull the speeds should be pretty close on both. Hard to get my head around how 120mph = 150 mph though so there appears to be some discrepencies here that will have to be explained or determined. Again I am all ears and eyes to both boaters here. I need and love to learn from performance projects and situations.

I don't know everything, never will and will I will never stop trying to learn more. Come on boy's - TEACH ME & SHOW ME!

Best Regards,
Ray @ Raylar

So where have the marine LS smallblocks you developed and build end up? How do they run in-hull?

For insurance reasons, JIMKID won't admit numbers...but surely you can tell us what kind of boats your engines were installed in and what kind of results you've seen?

During your R&D, did you take a hull and rig it with one of your HO525s...or even a stock 496HO and run it back to back against the same boat rigged with one of your LSM550s? Just hard data and facts...not assumptions and conjecture.

The performance boating masses want to know! Like you said, "TEACH US AND SHOW US!"

First of all, we were not discussing the LSM550 engine we developed and have subsequently stop producing. We learned a lot about the LS platform and the potential for use in the performance marine engine market. We released the engine in late 2007 and when the marine market collapsed in 2008 we had only built and sold 4 engines, 3 that made nice results for customers in smaller 22 - 24 foot boats but no where near the power and torque levels of JIM's LS 450 inch engines. they were 434 cubic inch, moderately cammed with variable cam timing and produced about 530 lb/ft. of torque peak and were set rev-limit of 5800 rpms. We never had the opportunity to put them in a direct same boat, big block versus LS small block comparison, so I cannot speak to or claim that comparison.
I will dig out and post a smaple dyno sheet from our old LSM550 engine so everyone can see the factual results.

I think its obvious from this thread that Ilmor has done a similar job very nicely and now markets a very nice example of marine 500HP+ LS engine based platform also with similar HP numbers from a slightly bigger cubic inch marine engine.

I am not attacking JIM's results or builds, I am impressed and had just asked to learn more from his results. If he acheived those results he's a better LS engine developer than me and I salute him for that. He has agreed here to post his dyno sheets so I take him at his word on that.

Best Regards,
Ray @ Raylar

Thank you for the response, Ray. I was digging around on your website, but until you mentioned it again, I forgot that you no longer produce the LSM550. I am very interested in what kind of hulls your LSMs landed in, and what were the results you speak of? No doubt those are 3 very pleased customers....I know I would be.

I did not mean to call you out, but you are active on the forums and have both BBC and LS marine experience, so I and many other look to you as a subject matter expert regarding how they compare. I do think it would be a great marketing move for ILMOR to do the back to back comparison between their MV8 570 against a Merc 525 or 565 (or both!?) in the same hull, in similar weather, etc to lay the speculation to rest.

I don't think anyone, myself included, thought that you were attacking JIMKID. There are just lots of us out here who are very interested in this largely uncharted realm of LS smallblocks for performance marine use...and we look to those of you who have experience (Raylar, Haxby, JIMKID, ILMOR) to set the record straight. Thanks.

Woah ! I m almost ready to put my LS in ,but when I read this I might be looking for another engine !

OK, I'm going to stick a foot in my mouth again and am sure I will get slammed for it but first I want to clarify a few things. I fully admit to not being a professional engine builder by any means, however, I was an automotive machinist/engine builder for about 15 years. Granted 90% of the work we did was stock rebuild stuff for cars and trucks but we also built some custom and high performance stuff as well (granted no 15,000-30,000 motors or else I would still be doing it, I am sure my 50% commision checks would have been much better if we did). Also I admit I have never dyno'd or witnessed a dyno using wet exhaust so if one of the professionals can show me that you lose 20% on the dyno with wet versus dry exhaust I will gladly retract my claims. I would also like to state that when I state I am not impressed with a manufacturers results I am by no means insinuating that for some reasons there motors are junk, or that they do not know what they are doing. Having said that I will once again state that I am very pleased Ilmor is coming to market with an LS based marine motor. It is something I have always said I would do if I had the resources. That said I am still not impressed with their results. Don't get me wrong (Ray), the motor may be bad ***, it may be able to idle around the docks at 600 rpms all day and go 1000 hours before a rebuild. The parts and quality may be second to none. I am just not impressed with the final numbers. I feel they are still leaving a lot on the table. I wish we knew a little more about their build. There use of GM head castings has me scratching my head a bit. Did they use the new LS3 heads or the old style cathedral heads, were they CNC ported or out of the box? I would just expect with their vast resources and engineering knowledge that their 454 LSX would make better numbers. Before bashing me consider the latest article in GM High Tech, They took a budget 408 (cast iron 6.0 truck block bored .030, 4.0 inch stroke, 10.0 compression, etc.) and made several dyno comparisons using a pair of aftermarket cathedral heads and a pair of aftermarket square port heads along with 2 off the shelf Comp cams and every combo made over 630 HP and over 575 ft/lbs tq. It just seems to me that a company with the resources and knowledge base that Ilmor has would be able to trump these results. That is unless their goal was just a super docile long lasting big inch small block which I am sure this will far exceed those expectations.

Jim, hats off to you on building a totally unique package that NOBODY else has. Great job on building your own engines also. I dont have a Skater and most likely never will but if i did, i would build it the way I wanted to. People can always recommend this or that but its what YOU choose in the end that makes it YOUR boat. Both your boat and Skater30's are great boats that are completely different animals. I'd love to have a 30 Skater with our new ILMOR MV8 570's.