Trigger wheels
Turbo Mini Forums

I'm helping a friend with his miglia, at the moment he has a trigger wheel with only 3 teeth on it (4-1). As the miglias are not allow to have any form of load sensor, (MAP, MAF or TPS) it's a tottaly flap map with simply rpm sites only. The ECU is about to be replaced, while we are there would benfit at all from having a 36-1 trigger wheel. I know the theory we would, but in reallity, on the dyno would we see any difference?

Team Racing

I'm guessing as I've only used 36-1, but a couple of possible reasons that a 36-1 would be better:

1. Better resolution. If the ECU is calculating 10 degrees at a time then it will be more accurate than if it was calculating 90 degrees.

2. Better transients. If the engine revs can rise rapidly, by the time it has determined TDC from the missing tooth on a 4-1, the crank will have moved on much further than with a 36-1.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

is it 4 notches cut out, or 4 lumps sticking out?

You could save some weight but doing 36-1!!

it's 3 lumps sticking out, so it would gain weight if we added 32 more teeth

Team Racing

3 teeth sounds very primitive indeed !!!!

Would it be possible to use a hot wire airflow meter instead of a flap ?

With no load parameter at all, how on earth do they get throttle enrichment etc right ?

Or is it ignition only ?

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

Ign only...

the max torque and max bhp advance are mostly quite near and in the powerband (mostly above 4k i reckon) i would not expect the advance needing more than 3-5 degrees change at the most, probably less.

i don't know if more resolution would be better in this case

Edited by Sir Yun on 18th May, 2008.

That sir, is not rust, it is the progressive mass reduction system

http://aseriesmodifications.wordpress.com/