Hi flow thermostat vs stock type ???

[Green Machine]

Do the high flow "robert shaw" type stats hold the temp any closer to the set point than the stock type does ??? Assuming adequate radiator capacity of course else it wouldn't matter much.

I want to tune for max mpg and that likey involves running the mech and vac advance close to but just below pinging. Pinging ususally occurs on very hot days as the engine temp tends to climb. I just want to assure an even of temp as possible.

Also does anyone have an opinion on running a 180 degree stat vs a 195 for mpg ??? I know hotter is supposed to be better, but depending on what the engine wants, could it be more effiecient to run more advance on a 180 stat vs a 195? Any comments welcome, thanks.

[4x4Poet]

RS claims that their thermostats open more accurately at the rated temp. Also, you can just look at them and see that they must flow better since the water passages are much larger than stock thermostats. And RS therms are more hydrodynamic.

Flowcooler recommends using a RS thermostat with their high flow water pumps since adding water pump pressure/flow quickly taxes the stock thermostat's flow capacity- at least at higher rpms. Upgrading coolant flow would also help keep water in the coolant from *lingering* too long around the head compression chambers where it can suffer steam pockets from nucleate boiling- a major cause of detonation in an otherwise well tuned engine.

As for which rated thermostats are better with regards to mileage, 180º or 195º, I would think that a 195º thermostat would help provide better mileage during warm up periods since it would retain block-only coolant circulation longer thus retaining heat in the block longer which would enable the pistons & rings to expand sooner and thereby more quickly reduce excess clearances between them and the cylinder walls which would reduce blowby and add burn efficiency. But that's just conjecture on my part.

[Karl Hoh]

Even my old diesel gets the best milage if I can get the temp up around 200F and maintain it there.

[Green Machine]

After looking I seen that Stant makes a "super stat", supposed to be better than stock ones, any opinions on those vs robert shaw type ???

[4x4Poet]

Flowkooler has info and diagrams of RS therms.

I didn't know Stant has a high perf therm. Summit Racing sells rebadged RS therms under Mr. Gasket brand. You can really see the large openings for high flow. Also BeCool thru Jegs looks like a RS design.