Engine efficiency improvement through higher temp thermostat?

[diesel_john]

I run pure Seirra antifreeze in a cast iron block with aluminum heads. i did it to help prevent detonation. I boiled the water out of the mixture by turning off the fans and taking off the rad cap and letting ti idle until it got to 250 f and there were no more bubbles coming out. It doesn't even boil at 250 now with the cap off. no steam separation in the heads equals a better resistant to detontion. the solution is a little bit more viscous than 50/50 make sure you have a good enough water pump on cold starts to circulate in the block and the stock thermostat will run hotter because of this. i always take out the thermostat and drill a 1/16th hole thur it if its doesn't have a little air bypass check valve built in.

[elhigh]

Originally Posted by Lazarus

Actually I have done this with no affect on FE. Tested it up to 60 mph with no increase.

Ah, well. Ford did it on some of their old Falcon stock cars and it seemed to work well for them - it looked like a car with four headlights, but two of the "lights" were just big holes ducted back to the carbs.

I guess there just isn't enough dynamic effect at the kind of speeds we mere mortals have to drive.

[NoCO2]

Originally Posted by elhigh

Ah, well. Ford did it on some of their old Falcon stock cars and it seemed to work well for them - it looked like a car with four headlights, but two of the "lights" were just big holes ducted back to the carbs.

I guess there just isn't enough dynamic effect at the kind of speeds we mere mortals have to drive.

It WOULD have somewhat of an effect at the speeds of race cars purely because they are going 150mph+ in most cases. You have to think though, superchargers spin at speeds approaching 15k-20k RPMs, with that kind of rotation, you get a lot more air then just forcing it in with what you're talking about which is essentially a "ram air" system where the air is being forced in because of your speed.

You're right, at normal, "mortal" speeds you will likely not see any improvement, you may see something at 80+ which is still pretty average (around where I live) for most people to be traveling on the freeway, but no one here is "normal" in that respect I don't believe.

[8307c4]

All I know is you want neither the coolest nor the hottest thermostat under the hood, neither of those are meant for any situation except one that specifically calls for it.

On some older cars it has been known the cooler thermostat extends engine life at the cost of some minor mpg loss yes, but the hottest one is as likely to create strains and pressures that may result in premature failure of hoses and pumps and whatever else could go, because as temps increase so does psi.

That having been said I think on most vehicles the second hottest should do well, but I wouldn't push it beyond this.