Launch control and rev limit

[zetecmike]

I've just downloaded the new s19 file and loaded it onto my chip, have run the engine up but havent yet driven it. To test the soft rev limit I set it to 2500rpm and hooked up a timing light, as the revs got up to 2400 the timing backed off and it sounds promissing. I Know someone was developing a cicuit to give the hard cut using thyristors, any news on this ?

Whilst playing with this I thought of a form of launch control using one of the PGM outputs, set at the optimum rpm for starting, wired via a button on the gearlever to enable the hard cut circuitry under development. Hold the button on the line to limit wheelspin.

A mate has got an expensive version of this which seems quite effective, on the face of it it would be a cheap and easy solution. Any thoughts on this ?

[David Withers]

Circuit for rev limiter is here. Please let me know if it works on your setup.

http://www.with.nildram.co.uk/MJLJ/Limiter.htm

[zetecmike]

David, thanks for the reply but I can't seem to get onto your site. I can get to the with.nildram.co.uk and get a blank page with " OK " in the top left corner but can't seem to connect to anything else, any sugestions. I've now tested the soft rev limit and have only set it at 7000 for testing and it works a treat so probably will not use the hard cut at the top end but will try it out for launch control.

[David Withers]

Strange that you can't access it. It works for me at home and work. Everything after the with.nildram.co.uk is case sensitive so that may be the problem. If the file upload facility is working I will try to post it to the contributed files section in the next few days.

On my Pinto engine, the soft cut limits the revs well when the engine is under load. It will easily rev through the soft cut with no load, eg missed gear change so I think the hard cut is worthwhile.

Edited to add that I have now uploaded the experimental circuit and parts list to the contributed files section.

[4600cc]

Can you draw something similar for 8 cylinders and two coils? Each coil on mine feeds four cylinders.

[David Withers]

The limiter was designed to work with a 4 Cylinder engine. For 8, I would probably make the limiter as drawn and apply it to just 4 cylinders, making sure that alternate cylinders in the firing sequence are cut, if possible. The ignition retard combined with this will probably be sufficient. If it still revs past the limit, I would construct a second circuit and drive it from one of the programmable outputs set 100 rpm higher than the rev limiter output to give a form of progressive hard cut.