Autosport Labs

Hi Everybody

I'm in the process of gathering parts and knowledge to ditch the dist. on my Spitfire. It seems that I'm going to go the TPS route because of my dual Weber carbs. I can't seem to understand how a TPS can sense engine load just by the throtle position. I would think that at full throtle in first gear grunting away from a stop light the load would be very different than full throtle in top gear on a road course. So how does the unit adjust the advance for these different conditions based on the same throtle position? This seems like a basic tuning question that I should already know.

Thanks

Mike

The engine doesn't actually care that much about what gear you're in. What you are trying to do is get the spark timing right for every combination of RPM and cylinder pressure. The cylinder pressure is related directly to Manifold Absolute Pressure, which is directly related to throttle position (in a non-turbo setup). In a low gear, the engine accelerates quickly, but the ignition controller should easily keep up and set the correct advance all the way through the rpm range.