Hello, so I'm putting together an engine for my jet boat. Crusing rpm will be between 3000-3700 depending on my impeller selection and rev limit will be around 56-5800.

Im going to put new bearings/rings in it while I can since its apart for the cam change. If I get an overwhelming "dont worry about it" or "too low of mileage" than I probably wont. Its an 88k engine with a compression spread between 195 and 205. Pics of the pistons in the holes and bore can be found in the link in my sig.

I know its not a good idea to reuse rings even if just pulling the slugs out for inspection, but what about bearings? I assume since I have it apart I might as well replace it all so I don't have to worry.

Any suggestions on ring gap and bearing clearances? Clevite H or P? Ive read conflicting reports on the boat forums and none of them were on LS engines, so Im asking the "experts" here...stock rods and crank.

Keep in mind engine water temps will be between 160-200 range (160 deg. thermostat) and running 20w50 Oil. I assume oil temps will be 180-220 range, but I dont have a cooler so I'm just guessing there.

Just doing some research it looks like .002 - .0025 for rods and .0008 - .0020 mains since its an aluminum block for stock type applications.

Also, what about ring gaps? Any type of ring I should look for? I assume stock specs are fine since it won't be boosted. Any ring suggestions for extended higher rpm usage? Its wont be spinning 7000 rpm, but occasional bursts to 5600 ish with most of its time around 3500.

Thanks in advance. Ive done a bunch of research, but there is still tons to learn left. I did buy the "How to build/modify LS engines" book, so that should help with the assembly tricks.

Joe

edit: Stock high volume/pressure oil pump since I'm keeping the VVT

 

http://www.m2omarine.com/resources/I...epairSpecs.pdf

 

Thanks for the link. I found one pretty similar to that for the MarinePower engines. Unfortunately, its all iron block specs, nothing for aluminum.

 

I called AZ speed and marine. They suggested .0020 for the mains and .0025 on the rods. I think from the reading I have done those are pretty much stock specs, just on the looser side.

He also said just a hair bigger than stock specs on the ring gaps.

I assume this sounds OK for my uses.

Does anybody think I should run the P or H bearings? Steel or Moly top ring?

Thanks

 

Looks like either will work on a stock crank, read post 4 below:

https://ls1tech.com/forums/generatio...-bearings.html

 

Those clearances should work great. I would use the H series over the P series. They're a tougher bearing and they're design better for more abusive environments.

Stock type rings should work fine, like mentioned, just open them up a bit and keep the second ring gap larger than the top ring gap.

What are you doing about the aluminum? Is it going to be in salt water or fresh water?

 

I run pretty much fresh water. The engine will be close-cooled so it will have a separate river-water/glycol cooler. The last motor I had (2.2l supercharged ecotec) was aluminum set up for cooling the same way. No real corrosion problems. The few times I have run in the salt, I just find a fresh water source to rinse everything off in on my way home. I spray the engine down with fresh water and haven't had too much of an oxidation issue. I also tried to spray a bit of wd on the engine over the winters. Ive debated painting the block, but maybe Ill just put some clear engine paint on it.

Thanks for the advice so far. I appreciate it.

 

I have run lots of ls engines in jet boats pleasure and racing. What actual engine is it? I am guessing an ls3. If so you definately need an oil cooler and 20w50 is way to thick of oil. These engine are designed for 5w30 and that is what a guy should run. oil type is determined by brg clearences among other things. watch the timing unless it isa fuely because they like to detonate at anything over 28 deg even on AV. 26 for 91 octane. Factory clearences are fine

 

Roger that, thanks for the advice. Its a L76 vortec max with AFM delete and the Mast cam/ecm, and the LS3 intake.

Im headed to drop it off at the machine shop for a cleanup now. Ill be looking for that ~.002 mains and .0025 rods area. Also, a few other shops have recommended those clearances and the 5w30 to 10w30 as well.

Thanks again

Joe

 

Great make sure about the oil cooler. I couldn't run above 4000 rpm for very long and the oil temp would be above 240. In our race boat running at 6000 rpm on an ct525 for 30 min the oil temp sits around 250.

 

Ill keep that in mind. I'm definitely not discounting your experience but both Riddle Marine and Waterthunder both don't run oil coolers and actually recommend against it. They both say the aluminum block will be fine for wicking the heat. I was skeptical, but Marine Power and Kodiak don't run oil coolers and they even have Iron blocks. Mast Motorsports said I will probably be fine, as most of their engines going into the airboats don't use them. I'll probably try it first without, but if I run into issues I can fab up a small exchanger in the remote oil filter hose using fresh water cooling. One guy I talked with tried using a cooler on his 5.3 and had to remove it. From what I saw of that one it was most likely too big.

Do you know what temp thermostat you were using? What about ambient temps where you race?

Thanks again for the advice. Heck, I could always just plumb one inline and hook it up if I needed to.