DIYPNP false rev limiter/speed limiter
 

Ive searched, maybe my search skills are b0rked.

I realize the DIYPNP can tackle such things as launch control and flat foot shifting, and those are somewhat useful in a track only application.

My question is about having a false rev limiter, one that can be initiated with a button on the steering wheel. Yes, the classic pit road speed limiter. The math of x RPM = y MPH is pretty easy, but can the DIYPNP handle this? Ive been searching this evening and finding very little discussing anything like this...

Thoughts?

Add a switch in series with the clutch switch to activate the launch/flatshift. Then hope that the lower rev limit (the launch limit) gives you a proper speed at some gear.

I wish I could do that, but I need it to be specific to a certain RPM, which is going to be different from launch control or a flat foot shift RPM.

The current code only has one switchable RPM limiter; I don't see a good way to do this without modifying the firmware.

So, if Im reading this correctly, Id have to choose between A) flat foot shift, B) launch control or C) a pit limiter?

And pardon the n00bish question, but how involved is making that kind of firmware change?

The flatshift and launchcontrol is combined by using two set rev limits depending on from which Rpm you are coming from.
The function is actually switch from one to another when you pass a trigger rpm, between the two limits. This means tat the launch rpm must be lower than the flatshfit one.

I see no simple way to combine this dual function with a speed limiter. You would like a switchable basic Rev limit.
Someone of the few that modify the firmware might think it's a decent idea.

You could choose between launch/flat and a speed limit (using the flat/shift function in a different configuration). Maybe the flatshift could work at the rpm you get the correct speed (flatshift rpm is less critical than the launch in my experience).

If thats the case, I could probably live without the LC. Below the switch, it could be pit speed limiter, above for FFS.

Id just need to figure out some way to switch it for the pit limiter.

You could possibly use the table switching to cut your spark advance to -10 above the speed limit RPM.

There are more experienced people in here but as long as they are silent I can keep thinking out loud.

if you wan to use the LC limit as a pit-limiter you need to go below the FS-trigger rpm at pit entry to get the lower limit.
Activation is then done by a switch in series with the clutch switch.

One drawback is that accelerating from the pit box is limited to the same rpm (e.g. if 3000rpm in 2nd is the pit limit, you will only get 3000 in first too).

Electronic speedo (NB)? Then there could be an opportunity for a real speed limiter. Is there anyway for activating a soft/hard limit based on external input (not now I guess)?

I did not think about table switching for preventing running over a set RPM, a bit cumbersome but the car would not sputter that much as on LC-limit, and you would keep LC+FS.

Bringing this back to life. DIYPNP is done, probably going in the car with a base map next week, then its off to the dyno. Looked at the launch control documentation, seems to me like I just need a grounded switch that connects to Input 1. Grounds the input, OUT connects to the PE1 input for table switching, no? If thats right, piece of cake...

yep............