I built this motor with other intentions than a boat, but I have been really considering putting it in my Power Play (Powerquest) 230 conquest. It has a chevy 350/alpha 1 right now and it needs more power, top speed on GPS on a good day is 47 mph.

Motor Specs:
-Stock bore/stroke Gen 4 5.3 LS with a fresh hone, and all new bearings.
-OEM flat top pistons from a 4.8 (compression ratio ~10.4)
-Stock 706 heads cleaned and assembled with dual springs
-LS9 cam, specs in the pictures
-Summit racing full roller rockers

The motor is fresh, I haven't even fired it yet. But like I said it was not built with intentions of going in a boat. Will this cam choice/compression ratio be acceptable for marine use?

Im curious what the experts will say. I will say at 10.4:1 compression that engine is going to build more heat in the summer. I bumped my Harley from 9.6 to 10.4 and on really hot days stopped at a red light that engine is throwing some heat off of it.

I built a very similar motor, but with a texas speed 224r cam instead of the ls9 cam for my Jeep wrangler. I fought cooling issues for a long time after I got that motor in. Its now got a massive aluminum radiator and like 3500 cfm worth of fan to keep it cool.

Seeing as you will be using it in a marine application cooling should not be a factor assuming it is plumbed and pumped sufficiently. My first concern would be the compression. I think its too high for what you intend.

For cooling I am very open to suggestions, but I was thinking the LS to BBC water pump brackets and use a BBC crossover. Water supplied via the alpha 1.
On your compression comment, was that geared towards marine application in general or my specific application?

corey331 i believe is the member here with great LS swap info threads boat info. Cooling, exhaust, etc. It’s not a very cheap transplant, mostly because of the exhaust.

I will look him up, thank you.
I know its not going to be cheap but I have a lot of tools/parts to still (hopefully) make it budget friendly. For instance I already have HP tuners software so the VATS and tuning is no issue for me. Another thing that I came across that could be a huge cost save is using ford 351W manifolds. I haven't seen it done yet but the spacing between cylinders is the same.

Silly question, why not just build a 383 SBC, it would make more torque, which is great in a boat. And probably a lot less hassle.

1. I enjoy a good challenge and im a lot more familiar with the LS platform than SBC
2. The alpha 1 is going to stay so torque is not my friend
3. I have the LS motor finished, paid for, and sitting in my barn

I say run it. What do you have to lose if thats what your wanting to do. If your scared of compression and want to lower it some you could always pull the heads and go with a fatter head gasket. Im not an expert and would check on that first from a machine shop. All in all I so go for it if your up to the challenge.