Since an ls motor is going to be making it's power higher in the rpm range, would there be a benefit to running a numerically higher geared outdrive for torque multiplication? I know it's not as simple as picking a rear gear and tire size on a car, where the rear gear is the outdrive and tires are the prop. Id assume you could turn a higher pitch prop this way, but props are more complex an animal than tires.

I would have to give an edge to the BBC overall, but not by much. Either built properly and only turning that amount of rpm and HP should be extremely reliable and make for very long lasting combo. If that is your goal, I would talk with your engine builder and get his opinion. If he feels strongly either way that is what I would do.

I think a huge factor most do not consider is WHO is building and tuning a combination. If you had a great local LS shop (Example HKE Vengeance LMR Etc.) then Going LS would make a lot more sense as you have great support there.

I think it is very important to keep them in the loop. Either combination built/tuned improperly will be neither reliable or durable.

Thanks Graham, I went ahead and "liked" your Facebook page. You guys are building some nice stuff over there.

If that is directed at me I honestly have zero idea. I am not a marine guy. We are a glorified machine shop with a drag racing problem.

Lee Warren might know, but he deals with very high horsepower drag boats so I think overall their are lots of guys on here with better information on that than us.

It was an open ended question to anyone reading. You happened to post as I was typing it up.

Yes - you should gear the LS engine so that you can still use a prop with a pitch that is ideal for the boat. In general, if you're running a 1.50 ratio with a 5400 rpm big-block, you should run a 1.65 drive with a 6000 rpm LS. Formula and Ilmor are working through this exact issue with the 353 that was introduced at the Miami show.

Graham@KPE, thanks for chiming in on this forum and offering your honest input, that was a pleasant surprise. I originally posted the story about your 493 LS here because there has been a long running debate over here over an LS motors ability to produce enough torque down low to be a relevant substitute for the BBC. It appears to me from some of the responses on here that some people did not read the link to the story before responding. I have argued on here before that a good cathedral port head on a large inch LS motor would make some awesome numbers and the story of your trophy truck motor seemed to validate that. And while I agree much of that motor was most likely overkill for a marine application much of it could be somewhat replicated for much less expense. I could see building a similar combo with a tall deck LSX and 4.250 stroke with the same basic heads and intake (minus any extra work you guys put into them) and running a similar carb setup with an MSD or some other retro fit ignition conversion and a wet sump for a fairly reasonable price and getting excellent trq numbers and HP numbers. Also I tend to agree with you on the older FAST intakes, in most of the cases where I read about the 20+HP increases with the FAST they were usually running a ported one. Also they were almost always destined for an F-body or Corvette. If I were going to stay EFI in a boat on a budget I would go with the truck manifold and try to figure out how to make it less ugly.

Thanks for spreading the word a little about the TT53 motor and the shop.

Your definitely on the right track. Cubes and cathedral ports make for a very nice curve and one of my favorite parts, they are a very forgiving combination. If you dont have the perfect valve events on the cam or a little intake restriction they still seem to make great power.

Pretty spot on with the how I would properly "downgrade" the trophy truck motor to a much less taxing marine application. All thought I think for most, an ls3 block would be the ticket over the LSX. The LSX block is very heavy and the extra strength and cubes are not really needed for most I think to get into the power range they are looking for.

416ci LS3 with good trickflow or AFR head in a good engine package will make big number and again, a great curve. This is also a great option to put a blower on as well for when it becomes boring again and we need a little positive pressure in out lives.

On the truck manifold, A lot of guys on Performance truck have done cosmetic work to them. If you get around to it search smoothing truck intake on there and you will get a bunch of information.

This works for me. No info on what octane but pretty cool.
http://m.youtube.com/#/watch?v=xMehJ...%3DxMehJ0QruN4

you've gotta admit that Carbon XR intake would be sexy under the hatch of a boat.