N2spd

Let me start by saying my motor is not a marine engine. It's a 496 stroker. I am running a crossover but my thermostat housing does not have a bypass and I'm not running a thermostat. My water temp won't get above 130. At idle or wot. The oil temp never rises. I bought some restrictors. 1" 3/4 and 5/8. The 5/8 is the only one that brings my water temp up. I am getting 150 degrees. But now my exhaust is running hot. Or should I say hotter. I'm running emi thunder exhaust. I am happy with the engine temp but don't know how hot is too hot for the exhaust. You can still touch it but can't hold your hand to it anymore. I have only run it on the hose with the restrictor at idle. So don't know how hot or cold it runs on water yet. I was going to buy the Hardin marine thermostat housing with the bypass and run a 160 thermostat but the bypass hole is only 5/8 in it so seems like my exhaust will still be running the same temp. Guess after all that I just need to know if it hurts to run the exhaust hot. Doesn't look like there is any less water coming out but it's definitely hot water now. Thanks for any help.

N2spd

Headed to the lake. If anyone feels I should not run it please post otherwise I guess ill update you after a weekend of wot.

Young Performance

Depending on the type of exhaust you have, you can certainly damage them by running them too hot. If possible, you can preheat the water by cooling the exhaust first and then running it into the engine. You would need to have manifolds with a dry joint b/w the manifold and riser in order to do this. The other option is to just run the engine cold. We run pretty much all of our engines that way. However, we run an oil thermostat so that we always build oil temp. You need to make oil temp. Not sure about your engine, but we build ours to run cold. You need to have the engine set up to run cold. For example, you must have a little more piston to cylinder clearance since the block isn't heating up and expanding as much as it would if it were 180*. If there isn't enough clearance, you will start to hang the piston in the bore when the piston gets some heat in it.

If you decide to run a thermostat, then you will need a housing with the provision for a bypass. I think there are ones with larger than a 5/8" bypass. If not, you can drill (3) 3/16" holes in the outer rim of the thermostat. This will help bypass more water to the exhaust and help to give the thermostat a more consistent temp reading to stop it from opening and closing rapidly and frequently. This will also stop the wild fluctuations in the temp gauge.

Hope this helps.
Eddie

Full Force

I run bypasses with no stat, water temps normally 110, oil WOT 180-200 on average going back into engine...