question on theromstats

[Rapid Fire]

A friend of mine told me that if you put a cooler thermostat in that the engine will produce more horsepower. he said it tricks the computer to thinking that the engine is not fully warmed up which changes tuning parameters. anybody know if this is correct?

[KLS]

Now why didn't Toyota's hundreds of expert engineers think of that?


Ken

[Agent WD-40]

Toyota probably put a higher temp thermostat in because it helps the engine warm up faster. By doing that you reduce emissions. The most emissions are produced when the engine is still cool. The cats also need to have exhaust at a certain temp to do their job best. Another thing to consider is that the tranny might also think the engine is not warmed up and use the different shift pattern for when the engine is not warm. It usually keeps it in gear longer and keeps it out of OD. Other than that, I guess you could give it a try and see what happens.

[Rapid Fire]

8-10 degrees or less difference than the stock thermo? Still within the warmed up window, but at the lower end. Would the computer try to tweek for optimum...whatever? or is the computer/sensors not that sensitive. My truck seems to run better between 1/3 to 1/2 on temp guage. Of course that just might be my perception.

Ken, perhaps Toyota's hundreds of expert engineers had to de-tune the tundra to get it to pass emission tests. Cali. lost 4-5 hp.

R.F.

[KLS]

Originally posted by Agent WD-40
Toyota probably put a higher temp thermostat in because it helps the engine warm up faster. By doing that you reduce emissions. The most emissions are produced when the engine is still cool. The cats also need to have exhaust at a certain temp to do their job best. Another thing to consider is that the tranny might also think the engine is not warmed up and use the different shift pattern for when the engine is not warm. It usually keeps it in gear longer and keeps it out of OD. Other than that, I guess you could give it a try and see what happens.

The truck warms up just as fast with any thermostat. The warm up time depends on the outside temperature and the load on the engine. The thermostat only determines the temperature that the engine will maintain. If you put in a 180° stat, the engine will warm up to 180° just as fast as it will with a 192° stat.

With a lower temperature stat there's the risk that the engine's computer will think that the engine is never warmed up fully and keep the engine running rich. That'll just waste fuel.

Ken

[Agent WD-40]

Thanks for the lesson. I always thought that the thermostat stayed partially closed untill the engine reached a certain temp. This would reduce flow and make the engine warm up faster. Then when the temp was reached it would open up fully.

[mzoerner]

Most vehicles I have seen have some means to allow a small amount of coolant flow at all times, this prevents localized hot spots. I think some allow it to flow through the heater core all the time, other have by-pass ports in the thermostat housing, not sure what the Tundra uses.