rev limiter

[simon 16i]

ive got the rev limiter output simply connected to a relay which interupts power to the coils, havent driven it yet with the limiter set but on trials in the garage the relay cuts in as expeted when the limit is reached but as the revs drop i would expect the revs to pick up again as the throttle is still open but th engine just dies is this normal???

if it is normal is there another method i can use

[MartinM]

... but th engine just dies is this normal???

No - not normal at all...your relay should be energised at the rev limit and de-energised when the revs drop to 100rpm below that level.

What rpm are you setting the rev limit at?

Presumably it restarts OK?

Cutting the coil power via a relay is generally frowned upon, as it can produce sparks in the cylinders at inappropriate times, which may not be a grand idea at very high rpm, but it does work. Your risk though....in the worst case, extended periods of sparks at inappropriate times might damage your engine, such as driving the car "on the rev limit" all the time

As to why it's happening? Not sure - are you sure it's only the coil power that the relay is cutting...?

[simon 16i]

oh worrying that, definatly only cuts the supply to the coils (runs twin coils) restarts fine though, ive tried various limits starting with 3000rpm as a trial, this has only been tried stationary so far so not sure if it makes a difference when driving or not.
im happy to buy the proper rev limit board and install that but cant find one thats pre assembled only the kit form one?

thanks for the reply

[brentp]

Hello Simon,

You should find the rev limiter modules here (kit and assembled)

http://www.autosportlabs.com/-c-1.html

Regards,

[simon 16i]

just bought one thanks for the link, hopefully this will solve the problem

[Ivan]

I just read about the rev limiter that megajolt itself doesn't do
anything , it only commands the output.
I forgot there was an output in the first place
and thought the ingnition was retarded when the limit reached.

Could you point me in the right direction in the manual
or explain some more?

Ivan

I hope I haven't run it without rev limit until now because
I've pushed it as far as possible already.

[brentp]

Hi Ivan,

The rev limiter capabilities are covered in the various guides:
http://www.autosportlabs.net/MJLJ_V4_Operation_Guide
http://www.autosportlabs.net/MJLJ_V3_ve ... tion_guide

[brentp]

And of course, the documentation for the hard rev limiter:
http://www.autosportlabs.net/Hard_rev_limiter_1.2.0

[Ivan]

I just read it again and plaese confirm it for me
I'm still runnin 3.0.0 version (need to update )
The MJLJ retards the advance to 0° 100 revs befor the
set limit acting as soft limiter befor the output get activated.
I'snt this enough not to risk damages?
Doe's one really need the hard rev limiter?
It seem for the 3 years that I've been using the MJLJ
and always racing WOT there is no problem in my case.

Ivan

[brentp]

It all depends on your engine.

Our test platform, which has a turbocharged toyota 4AG motor with upgraded cams, can easily push past the soft limiter. Some engines experience a natural power drop-off at high RPMs, so the soft limit provides enough power loss to prevent RPMs to climb further.

[Ivan]

I see that this could become a problem as from now on
I had to rebuild the timingwheel becous it whent flying
off at more than 7000 rpm and destoyed th vr sensor
and oilfilter on its way out!
In the mean time i've installed new camshaft pulleys
to adjust the cam timing.
I'm driving more and more towards the limit with the car
and the hard revlimiter seems a wise idea.

Regards

Ivan

Only two more weeks for the next race on my birthday 12/07 !!!