Thermostat at 180F or 160F ?

Here is what my engineer builder says on this subject…

“It is true that engines make a little more power cold, so going from 195 to 160 is about 10-15 hp depending on the horsepower range of engine, 700 hp engine will be about 15 from what we seen on the Dyno.  

One (1) whole compression point is 20 hp and 20 foot pounds of torque that is a mathematical number that is on engines and is an increase from 1000 RPM to 8000 RPM as it is a linear increase because it’s mechanical, but going from 195 to 160 does not mean you get a jump on extra point on compression ratio, that’s part of the build.

Compression ratio has a relationship with the octane in the fuel and timing.

If you try to run your motor down to 160 two things come to mind:

1. Good luck with that in Arizona

2. if you build a motor to run that cold, you have to run looser piston to cylinder wall clearances because the block doesn’t expand as much so the cylinder doesn’t grow as much.

We have to do that on boats when we run boats at 130-140° water temperature because they’re pulling up lake water and we have to add .002-003 piston clearance on those motors because the cylinders don’t grow as much.”

So basically, just running your engine colder with no other changes MIGHT give you an (unnoticeable) power increase (3.5 HP on a 400 HP motor).  To get benefits from it, you have to pair it with a number of other related modifications… like just about everything else you can do to get more horsepower!

Rocky

I have a Pantera Electronics fan controller in my setup that uses a separate temp sensor to start the fan ramp up.  Don't quote me but I think the first fan step starts around 150F.

In my car the first step is reached within 10 minutes of driving and typically never turns off unless ambient temp is 70-80F and I'm cruising around 80MPH.

Maybe it's an Arizona thing, but I'm not convinced the cooling system runs less than 180F unless you are in low ambient climates and have plenty of air flow.

forgot to add that I should get some accurate coolant temp readings in this summer once the Sniper 2 EFI is installed. 

@jwelch68 posted:

I have a Pantera Electronics fan controller in my setup that uses a separate temp sensor to start the fan ramp up.  Don't quote me but I think the first fan step starts around 150F.

In my car the first step is reached within 10 minutes of driving and typically never turns off unless ambient temp is 70-80F and I'm cruising around 80MPH.

Maybe it's an Arizona thing, but I'm not convinced the cooling system runs less than 180F unless you are in low ambient climates and have plenty of air flow.

On a 100 degree day at 75 mph my engine will run at 180 degrees because that is what the thermostat is rated at. If I put a 160 degree thermostat in, then it would run at 160 degrees. I am actually cheating here because I have an all aluminum Fontana engine with sequential port fuel injection and a redesigned cooling system. The engine in producing about 550 horsepower at the flywheel and it is bored .070 over and stroked to 390 cubic inches. I have seen a couple of Panteras with Cleveland blocks that do run quite cool, but mine never did.

@jwelch68 Quote:

If I put a 160 degree thermostat in, then it would run at 160 degrees.

This might be the case if your cooling system overall is able and capable to achieve 160F under these weather conditions. Maybe it runs at 175F and that’s it.

@FWJ posted:

@jwelch68 Quote:

If I put a 160 degree thermostat in, then it would run at 160 degrees.

This might be the case if your cooling system overall is able and capable to achieve 160F under these weather conditions. Maybe it runs at 175F and that’s it.

When I got my car back from Pantera Performance Center the engine was running at 160 degrees. That was indicating on a good Autometer water temperature gauge and not the factory Veglia gauge. When I called Dennis about this, he told me that he put a 160 degree thermostat in my engine because he thought that all of the Pheonix Pantera owners used them. The problem is that I live 200 miles from Pheonix and at over 4100 feet. The mornings in my area can be very cold and it is a different climate zone than Pheonix. I took the 160 degree one out and installed a 180 to get the temperature up to where it needed to be. If you are using a Cleveland block, there is the potential problem to have thin spots in the cylinder walls due to the thin wall casting method that was used to build them. Some blocks have the problem and some don't. If you bore a Cleveland block that already has thins spots, then you are making your cooling problem worse. Now put in a bigger camshaft and up the compression ratio and the problem gets worse because you are making more power.