The dizzy on my race engine has no vac advance, and mechanical advance is all in by 3000 rpm.
Since I don't work the engine under 4500rpm what is to be gained through using TPS or MAP?
Can I run MJ without either, with a 2D map?
All I'm looking for is precision through crank-sensed ignition.
MJL on Race Engine
Moderators: JeffC, rdoherty, stieg, brentp
Hello Mike,
Yes, you can downgrade to 2D ignition mapping.
To do this on a TPS optioned MJLJ you would tie the TPS input to ground, and fill in the ignition map with the same values across the RPM range, for every load axis bin.
You may also consider an alternate use of the TPS input- instead of using the Throttle Position Sensor on your throttle, you could install a knob on the dashboard to manually retard or advance ignition from the cockpit, for on-the-fly fine tuning.
Yes, you can downgrade to 2D ignition mapping.
To do this on a TPS optioned MJLJ you would tie the TPS input to ground, and fill in the ignition map with the same values across the RPM range, for every load axis bin.
You may also consider an alternate use of the TPS input- instead of using the Throttle Position Sensor on your throttle, you could install a knob on the dashboard to manually retard or advance ignition from the cockpit, for on-the-fly fine tuning.
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KimolosMike
- Posts: 2
- Joined: Tue Oct 14, 2008 6:45 am
Thanks Brent. I couldn't think of a situation where I needed the engine to perform better at anything less than full throttle, and since that's already been figured out on a rolling road dyno there seemed nothing to be gained through the hassles of fabricating a bracket and adapting a TPS.
Interesting idea about a manual advance knob.
Interesting idea about a manual advance knob.
Mike
Queensland
Queensland
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Alexander_Monday
- Posts: 43
- Joined: Tue Sep 09, 2008 10:28 am
- Location: Springfield, MO
What kind of racing? Full throttle does not necessary mean constant load.
Unless it is at the same load, usually there is some advantage to varying the
advance at different load levels.
Take for instance the trick we used to use in drag racing in the old days.
By running a dual point distributor but wiring the points independently back to
a toggle switch to select between them. One point could be set advanced from
the other, and you flipped the switch in high gear at about 5000 rpm to run the
other point. Dinosaur technology now, but it was effective enough to give 2 to
5 mph through the traps even though the pedal was on the firewall the whole
way.
You can check the HP on the dyno at varying loads under full throttle while
changing the advance, and get a map of the most HP at X load with X advance.
Unless it is at the same load, usually there is some advantage to varying the
advance at different load levels.
Take for instance the trick we used to use in drag racing in the old days.
By running a dual point distributor but wiring the points independently back to
a toggle switch to select between them. One point could be set advanced from
the other, and you flipped the switch in high gear at about 5000 rpm to run the
other point. Dinosaur technology now, but it was effective enough to give 2 to
5 mph through the traps even though the pedal was on the firewall the whole
way.
You can check the HP on the dyno at varying loads under full throttle while
changing the advance, and get a map of the most HP at X load with X advance.
There are 10 types of people.
Those who understand binary, and those who don't.
Those who understand binary, and those who don't.