I dont want to hijack 69kona's thread so i figured i would ask in my own thread

As most of us know, i have an LS powered jet boat. Its a 5.3 with a bit of a cam and an IRON block.

I have both, a water temp and an oil temp gauge on board.

It seems no matter what the hell i do or how hard i run it or how long i run it, i can not build any oil or engine temp.

Im running a single line from the jet into the water pump ports (with a gate valve) and a single dump overboard.

My "coolant" temp i have never seen past 150* it usually hovers around the 120 mark, if it moves at all.

My "oil" temp i've only seen north of 140-150 once or twice. Maybe 180 on a real long hard run.

Both gauges are new Autometer gauges with brand new sending units.

My engine holds 8.9 quarts with a regular stock location oil filter. I have a gate valve that is open about 1-1.25 turns.

I have never seen a hint of water in my oil it always comes out pretty clean just maybe a little dark but thats from use.

Currently I run 20w50 VR1 or Castrol GTX. I tend to stick with the  Castrol i have not seemed to have a problem.

Since my engine seems to run so cool and the oil temps seem to stay so cool would it be a smart move for me to change the oil weight? Maybe to a 5-30 (stock for these engines) My main clearances were about .0030.0035 and i dont remember the rods but they were on the upper end of spec as well.

I would be inclined to run straight 40wt.

How large is the dump fitting? Headers dry?

Plugs read good? Fat?

There are a few ideas ruining around in my head, but need to do some research on the LS to be sure to not spew BS all over you.

Dump is a single 5/8" dump

Headers are Dry, i do have a Tee on a ball valve at the seat to inject water. But since the wideband gauge i do not inject water anymore

Plugs look pretty good. Maybe a tad on the fat side but not to bad. Air/Fuels are good at the 12.5-12.8 range. Any leaner and the thing breaks up at WOT. Any Richer and it just isnt happy.

Aluminum heads, dont know if that helps

For the most part, the hose size on the dump is virtually irrelevant. You need to know the inside diameter of the dump overboard fitting. 5/8 sounds large, but will be fine. The dump fitting should be no larger than about 7/16? Just a guess.

yeah either 7/16 or maybe 1/2

Actually now that i think about it. It was probably a 1/2" dump fitting with an ID of probably 3/8

its this one

http://eddiemarine.com/shop/plumbing-and-fittings/water-dumps/water-dump-1-2-slip-hose-dump

Steve-

Where do you want your water temp to run? Anything over 160*F precipitates the minerals out. Its more about temp GAIN in an open cooling system. At 120*F, and lake Elsinore water temp at 58*F (and Havasu at 63*), you are adding 60+* to the water.

Why does this matter? In a car, a 'good' radiator will efficiently cool 40-50*F, so 210* water enters at 160-170 range and gains again. On your setup, even at 120* is MORE (water heat) gain than an LS powered truck.

As far as oil temp, I have no clue on boats, however in the truck, the oil temp and trans temp rarely exceed the water temps pulling steep grades in the summer. (F350, 7.3 psd @195* water temp, oil @190* and trans @180* or so)

Hope this helps

Dan'l

I dont really have a preference. I know the boat seems to run a tad bit better after its built a little bit of heat

im kinda worried about condensation

I think your water temp isn't a huge concern. I do agree with your concern with burning the condensation out of the oil though. Going from 50 to 40wt could help bring the temp up a little, but your bearing clearance do seem a tad on the loose side so I I'd be a little concerned there. Something else to consider is to lower the oil level a quart and see if that helps.

Years ago I did some dyno testing with a 10qt Dooley oil pan on a BBC. We ran the engine with a full 10 qts and noticed that the oil psi really started to flutter at high RPM, 6500+. We started lowering the oil level about a quart a pull and each time the psi became steadier, oil temp came up, and the HP number got bigger. We went all the way down to 5qts in the pan just to see if we could keep making more power and it leveled off there. I ran that motor with 6qts in the pan for 6 years and never had issues. I know this isn't a great comparison, but we did see about 20deg more oil temp when we ran 5qts vs the full pan at 10.

thats all good info, thanks!

im wondering if maybe ill start to make some more heat as summer gets closer and ambient temp is higher