[Lyle]

Renaisance Man,

There are several views on this issue:

1. Some say that running without a thermostat does not necessarily make a car run cooler. For regular cruising, the engine probably will run cooler, but the cooling system was designed such that the water needs to stay in the radiator for awhile to have a chance to cool down. Even when wide open, a thermostat is somewhat restrictive and slows the flow of water through the radiator. Supposedly, at some level of thermal load, removing the thermostat can make the car run hotter. (I've never worked an engine hard and long enough to verify that.)

2. Engines, especially ones with EFI, are supposedly more efficient at "normal" operating temperatures. Some of that has to do with clearances being set for "normal" temperatures, and some optimum combustion chamber temperature. Some of it also has to do with emissions - hotter charges burn more fully, so fewer emissions. (Luckily for cobras in Arizona, we don't have to worry about that.) In any event, performance is most consistent when water temperature is constant.

3. The correlation of temperature and power has many parts. A cooler engine has a cooler intake track so should ingest a cooler charge. A cooler charge is denser, has more oxygen, so more power. Another change by lowering temperature on an EFI engine is that the computer responds to lower water temperatures with a somewhat richer mixture. It may have to be alot cooler to make much difference, but if the engine is cool enough that the computer thinks it is in the warm-up phase, the computer will fatten the mixture noticably. Did you ever notice that your EFI car seems strongest during the first two minutes of running?

So, you can take out the thermostat, and it will probably lower your operating temperature under normal operating conditions, but you may end up with other problems. I've tried it on different engines over the years, and always ended up putting the thermostat back in.

Your temperatures do not sound all that bad. If your 180 degree thermostat gives you 190 degrees on cruise, your gauge may be off. You can confirm that the thermostat is calibrated right by putting it in a pan of water with a cooking thermometer, and heat it up until it opens. It should crack open at 180.

If you want to improve things, you might do better by working on airflow over the radiator, or making sure that your water pump is giving you adequate flow.

For what it's worth.

Lyle