MSefi.com read only forum (Jan.15,2018)

Is there a rule of thumb scale on the how much to retard the advance based on a certain IAT? The defaults seem to very require a really high IAT before retarding starts. Reason for asking is now that summers starting (in Australia!!) my fibreglass bodied car is getting quite hot .. and IAT are suffering. GAIR helps.. but I am pinking at high IAT.. (over 50 deg C).

I'm looking at getting some defaults to test without too much testing (aka risk to destroying my engine)..then I can fine tune.

I generally start with 1° retard for every 15°F. This, of course, assumes it's all tuned for spark correctly first to Minimum Timing for Best Torque, and is only a guide for equivalent conditions. Humidity, fuel, boost, and a hundred other factors can influence the correct amount. If the engine itself is also getting hotter, that's a whole other issue and relates to CLT retard. Hope that helps.

David

David.. yes that's great thanks. From what IAT would you start retarding?

From wherever it was tuned correctly. This is a good place to see the negative effects of hot underhood air at low speeds, and why cold air induction is important for a number of reasons. Of course, hot air from boost is in the same category.

David