First, who uses what? Do you use a thermostat, a restrictor, or nothing?

What temp stat if you use one?

I just pulled the thermostat housings off my old engines and they have what looks like an old thermostat that has been taken apart and is just now a stainless ring with a 3/4" hole in the middle. Kind of resembles a restrictor I used to use in drag race motors.

Anyway, just wondering what I should use in the new engines.

Use a high flow thermostat, Stewart makes a marine version with bypass holes in it. Helps the engine warm up faster and I need it it in early spring when the water is just above freezing. I'm pushing 700hp with a crossover setup and I run right at thermostat temp at wide open on a 90 degree day.

I just started using restricktors. Engine had no thermostat and i did not like having very low engine temp 100 at best. Even though the oil stayed at 180. The engine now runs 140 to 150 and the oil is 200 to 210 with good water pressure. I had no water pressure with no thermostat. It has a crossover with a by pass hose to thermostat housing.

Where do you get these?

Any high performance store should have them. Summit , Jegs or make your own. It takes a little experimenting to get the flow and temp you want.

The high flow thermostats use a Robertshaw thermostat with a cup style moving diaphragm with 3 - 3/16 holes in the diaphragm to allow water to flow around the thermal spring, making it react faster. DO NOT use a standard automotive style, the don't flow enough or react quick enough. And yes, you can get them just about anywhere, just make sure it is the marine style. Check CP Performance or Kieth Eckert they will have the style with the holes already in them.

So what temp t-stat are you guys running then? I see they sell a 120, 140, and 160....

I run a 160 with a crossover set up and it stays real close from idle to WOT.

Can a drilled or "relieved" 160 degree thermostat allow enough water to the exhaust manifolds, prior to opening, to prevent overheating of the exhaust? (3) - 3/16" holes?

I'm breaking in a new (replacement) engine for a procharger application (was / will be crossover without bypass and no t-stat). I'd like to get some break-in hours on the engine at normal temp prior to (re)installing the procharger.

the thing with really low block temps (no thermostat) is the bores aren't big enough. the amount they expand is designed into the piston-bore clearance. running cold bores wears them out much faster. if it is a 10 year old salt block with temp problems, you are gonna float-test the block in the forseeable future anyway, so it isn't such a big deal...