Mega Jolt Race Car Application

[RAT]

Hi

We are interested in using a mega jolt system on our porsche 914 SCCA race car. We have some questions to relate directly to this application;

Firstly would you recomend a MAP or TPS system? our cam has 310 degrees of duration and .5" lift and is intended for race use only, that said this car will not need to idle smoothly for long and normal 'street' drivability is not an issue.

Secondly we do not run an alternator, will the system still work and make power with input voltages as low as 10v?



Thanks,
Tom

[MartinM]

MAP or TPS?

See http://www.autosportlabs.net/Choosing_b ... MAP_or_TPS


Operation at 10v - no problem for the MJLJ....mine works fine at 6.5v. Not sure about the EDIS though....maybe there's some specs that Googling might uncover. I should think it's probably OK as it must have been designed to be able to start engines from very cold when battery voltages gets fairly low

[RAT]

Thanks for the info, ive read through the FAQ but im not sure how 'aggressive' is 'aggressive', if you see what i mean!

It turns out we have run an injection system with a MAP sensor with this cam and it worked fine so i think we'll go that route and see what happens.

[brentp]

Hi Tom,

Welcome! Which region SCCA do you participate in?


For your question- do you already have a stable source of vacuum to run your distributor advance? What's your intake manifold arrangement like- separate carbs on either side of the engine?

We often talk about MAP pressure stability at idle for lumpy cams, but in a race car you're rarely idling, agree.

If you have a convenient way of fitting a throttle position sensor to your linkage TPS might be the way to go. If you have a readily available take-off point for vacuum, then MAP might be an option as well.

As far as voltage- the pure physics indicate that you will loose spark energy with reduced voltage. The MJLJ's internal circuit works at 5V, so it will work with the battery voltage not far above that.

Agree with Martin that the EDIS is a bit of an unknown- but... if Ford designed it for robustness I think they would make it run as low as possible to help those with bad alternators / dying battery conditions limp to their destination (one would hope. )

If I recall correctly there are systems available to boost and regulate battery voltage specifically for your situation. You might want to look into that if only to maintain strong spark.

Regards,

[RAT]

thanks, any idea on what the systems might be called or who they were available from?

Tom