Originally posted by Brett.w
Ok have i been racing today and it has been very hot, i have run my JP and i only seem to get 4 mins, i was going to lean it a bit to get more milage but its runnning hot and i dont want to lean it anymore. I have checked the plug and the bottom is brown to going black and the coils is bright silver but it looks "burnt" were it touches the edge (bottom) of the plug.
Any ideas about what to do would be great!
i have tried another engine and it does the same thing.
I cannot actually pin point why the engine is overheating. Just guessing here but I'm sure you already know that on a hot day, you need to lean the needles to maintain correct AFR because of less oxygen per volume of air. So that would explain the high fuel consumption...
As for the overheating part, I'd like to know what type of track did you run the engine? Technical or high speed? What plug number did you run? High speed would prefer colder plug like 7TF. Shorter technical tracks you could live with a no. 6. Wrong plug would make the engine overheat and make for higher fuel consumption. But my guess is you're using a hot plug on a hot day which would make fuel consumption high as well as overheating the engine.
Was the car overgeared? Did the engine rev at the top end a lot or were you at 0 to 50% of the throttle most of the time? How was the idle? Rich and difficult to start in the beginning or the idle coming in high after a few rounds?
If the engine revved a lot at top end RPM, then your HSN needle would have been too lean which made the car overheat this time and not the last time previous. If the engine was at mostly 0 to 50% throttle on the track, then your low end would have been too lean to overheat your engine. My 2 cents...