I have heard, anecdoticaly, the following information:

1. The Honda S2000 rarely shows above 3 bars. I know of one owner (Barry WY) who has reported his car at 4 bars with a blocked air intake.

2. Three bars covers a fairly wide temperature range.

3. The ECU does something (retard timing?) to reduce power when temperatures rise.

All of this makes me wonder:

A. Is the above accurate?

B. What is the actual temperature range that three bars covers?

C. What actual temperature does the power reduction occur at?

D. Is it worth adding a Mugen/spoon cap & thermostat as well as possibly a real (digital?) temperature gauge to keep the car under full power under track-like conditions?

Any thoughts?

 

Add:
E. Why would you need both cap AND thermostat? Putting a high pressure cap on makes it such that the coolant remains pressurized longer and thus allows it to get up to a higher temp before boiling. If you put in a lower temp thermostat, the temp shouldn't ever get that high. So wouldn't the cap add extra capability that is not needed when the new thermostat is doing its thing?

 

[QUOTE]Originally posted by xviper
[B]Add:
E. Why would you need both cap AND thermostat?

 

It would also be interesting to know whether some of the insulating blanket techniques that are being discussed reduce engine oil/water operating temperature...

 

I am using a high-pressure radiator cap for a different reason. To improve heat transfer from the engine to the coolant to the radiator, I am using 15% antifreeze with WaterWetter and distilled water. The WaterWetter lowers the engine temperature by improving water's heat transfer properties, and the high pressure radiator cap protects me from overheating if anything goes wrong.

Since this solution has a lower boiling temperature, the higher pressure cap raises my boiling point back up to level provided by 50/50 antifreeze/water. I am also running the Spoon thermostat and Spoon radiator fan switch.

I don't have access to OBD information, but my car is definitely running cooler than it was with grill cover and stock cooling system. I haven't come out to the car after work and found it at 3 bars yet; this was an almost daily occurance before I made the changes. The engine compartment also is much cooler after long drives.

I was one of the guys seeing 4 bars and getting poor performance in heat with stop/go driving; this is also gone.

 

[QUOTE]Originally posted by Tanqueray
[B]I am using a high-pressure radiator cap for a different reason.

 

A higher cooling system pressure will also improve heat transfer, although I can't explain exactly why. Many high end race teams run very high cooling system pressures so they can run smaller radiators and reduce aero drag. In our case, since our radiator stays the same size, we should transfer more heat.

UL

 

Anti-freeze raises coolant boiling point.. some numbers here: http://www.babcox.com/editorial/us/us60024.htm

A higher pressure system has a high boiling point and I think the aftermarket thermostats should actually lower system temperature slightly (assuming the radiator is not under sized). On the track airflow is very good, I was thinking that system temperatures tend to go up with stop and go driving at lower speeds.

 

antifreeze changes both freezing and boiling point of the solution.

if you want the real low down, here's a good thermodynamics page:

http://www.taftan.com/thermodynamics/

 

Stop and go, A/C on type driving certainly heats things up...

But on the track, the % of time spent at 7K - 9K rpm is so much higher...

I think I really need a proper temp. gauge and check things out.