Hotter Thermostat
 

A few questions:

What benefit does a hotter thermostat have on fuel economy, and has anyone tried it successfully?

-RH77

Raises engine temp, engine
 

Raises engine temp, engine performs more efficiently at higher temps (but not too high, don't make thermostats for too high anyway). Better mpg, variable by engine, I'm going to try it. You might see a lot since you saw so much from the WAI. 6 bucks for a new thermostat for me, wish I had it...:-(

Next Mod?
 

I always noticed with the Integra that it takes forever to warm up when it gets into the teens or below (and parked outside). I'm thinking of making this the next mod, and it cant be too hard to install. Stock is 180, and they make a 192 degree model that replaces the OEM unit. It's like $15 with the gasket, so it makes sense...

-RH77

Yeah, same deal for my car,
 

Yeah, same deal for my car, it'll heat up quicker, hit closed loop, good stuff, in my opinion.

In know this is an old thread, but does going to 190+ thermostat help? How about a 200 degree thermostat? I can't seem to find anything above 180 degrees for my '94 acura. Any suggestions for a place to get hotter thermostats? Thanks!

This is the curse of all Honda D15 engines (maybe the whole D series). We have our thermostats located in the lower radiator hose so convection normally carries the hottest coolant from the top of the head on up into the top tank of the radiator and cooler coolant there sinks down into the head. This happens even before the thermostat opens. I have been considering adding a second thermostat in the upper radiator hose of my D15 (right up against the head outlet tube, with a small hole drilled in it for safety) to counteract this effect. My other idea was to add an extra top rad hose and make an S shaped loop that would stop any convection currents.

You know that the temperature of the water system varies a great deal, from the head to the radiator to the expansion tank and back to the water pump.

As soon as the thermostat opens the temperature drops as it mixes with the cold water in the rad, almost 4 litres in must cars, then as it cools and flows around the tank and pump it drops off some 30 degrees Celsius instantly, I know this as I have a temperature probe in my over flow tank which always reads a constant 25 to 30 degrees Celsius lower than my engines water jacket probe.

The grille block must help reduce the thermal transfer of heat from the water in the radiator so the water going back into the engine will be say 10 degrees C lower, but I am not sure what the perfect temperatures of the water being pumped into the engine should be? its not 80 or 90 degrees is it?

Would this make a closed loop that would over heat to quickly?

What is the safety margin here?

...but where can I buy a 195 degree thermostat? Anyone? Thanks.

As others have said, a higher thermostat will raise the engine temp. And up to a point, higher engine temps improve FE (but at the risk of less "safety margin" for overheating issues). And as an added bonus, running your radiator fan less (due to the higher temps) will also save on fuel, as radiator fans use a fair amount of power (and the electricity for the radiator fan ultimately comes from engine drag, as the alternator will put more drag on the engine to make the additional electricity).

OTOH going higher temp is not without its costs and dangers. If you go too high, you can actually weld your engine together (ruining it). Short of that, higher temps can cause additional engine wear (although other factors, such as better engine maintenance, higher quality lubrication, etc, can help to lesson/mitigate such wear issues). And some lubricants and coolants have limits as to how high of a temp they can handle (so if you are going to "run hot", you really should use quality coolants/lubricants that can handle the extra heat). Finally, some ECUs (engine computers) will sense a "too high temp" as a danger signal, and do all sort of FE wasting "limp home" changes to try to compensate (so you never really gain in FE if/when you exceed what your ECU thinks is a "safe temp").

And yes, some of us are going with higher temps with success. In my case, I took the approach of buying/installing an adjustable thermostat for my radiator fan (although that's only one approach that works). I then ran some experiments to figure out what the highest temp setting (on the adjustment knob for this thermostat) I could get away with, without showing troubling signs of "overheating". As a result, my engine runs a little hot (improving FE), but I do monitor heat issues (and also use good synthetic oil that can handle the above normal heat). And as an added bonus, the fan runs less (although I do have a partial grill block helping aerodynamics, so it still runs more than it would without the grill block), so I use less electrical power (which also helps FE).

I look on rockauto and they seem to have nothing. My suggestion is to measure the thermostat and find one close. Thermostats don't have to be exact make and model. They all work the same. If you mic the thermostat or bring it in to a parts store they should be more than willing to help you since thermostats are just boxed up and sold and not packaged in plastic. good luck.

If the temp goes too high on my car. I've noticed that the ignition system retards spark. This was at 205-210f when I was testing aero mods blocking off part of the grill openings. Needless to say, fuel economy and performance went to hell in a handbasket when it retarded spark. I was getting MPG readings in the 30's instead of 50+ when I hit that problem.

As for closed loop, I noticed my car goes into closed loop within a block or so of home after no warmup. I guess different cars would be different in that regard.

All in all, I wish I hadn't spent the $15 on a new hotter thermostat.

Cheapy, what kind of car was it? Different car manufacturers will program that "safe mode" differently. It would be good to compile a list of cars where the hotter thermostat helps, and one where it doesn't.

One idea, modify the coolant temperature sensor so it thinks the coolant is 10-20 degrees cooler than it really is....the only problem with that is the it might effect the time it takes to shift to closed loop.....defeating part of the purpose of a hotter thermostat.

before getting a hotter thermostat check and see when your cooling fan turns on. im using the stock 180 degree thermostat on my 98 civic hx and with it the car runs around 193-198 degrees according to scan gauge. the cooling fan turns on around 202 degrees. to my understanding the thermostat will start to open at the specified temp, in my case 180 degrees.

with the 180 degrees thermostat the engine runs around 15 degrees hotter and by my guess with the 195 thermostat the engine should run around 210 which means the cooling fan will be on constantly which is a waste of power.

having a hotter thermostat will not let your engine warm up faster since the radiator is still trying to cool the already cool water or warm water.
if you want a faster warm up i'd suggest a grill block mod.

Good points. I'll have to check that out. Still haven't done the grill block or WAI...those are the next mods I'll do anyways.

Also might want to look at a slightly higher pressure rad cap. Some systems run a 14psi cap and if you even go to a 12 it'll boil over so running the extra heat you will want more pressure.

I've got electric fans on the CRX - I will have to check out the thermostat on those as well, as I am ready to upgrade from a 180 to a 195 thermostat for the water line.