Home Made Rev-limiter For Carby Car

[Taz_Rx]

Will hopefully get this diagram done up tonight for the people who have asked. :hmm:

[Danny]

Hi, I know this thread is a bit old, but just had to post a reply to say thanks. The rev limiter is a top idea and works great, especially for something which costs about 20 bux. One problem tho, it seems on our test motor (Holden 202) the revs keep climbing when the ignition comes back on. Not a huge problem tho, it will definitely make u change up a gear and that's what I wanted it for. We race dirt circuit, and one of our cars is a Holden 253. The cam stops making power at 6200rpm but my bro who's the driver says he doesn't pay attention to the tacho as he's got his eyes on the track all the time. So this will definitely help coz he's been revving the crap outta it and he changes gear when it revvin like crazy.

 

Haven't tried it on the 253 tho coz we've just killed a head gasket, so building up a 308 for it.....at least he won't over rev that now!

 

I followed this thread and drew up a few diagrams then just drew it up in paint now that I've successfully made it and it works.

 

 

Here's a clip of it on our other car, a HQ Kingy.

 

Cheers,

Danny.

[Taz_Rx]

Hi Danny.

 

I don't think I said this in the thread earlier, but my corolla also still climbed slightly in the revs WHILE FREE REVVING in neutral.

 

However when driving and under load it hit the limiter and didn't rev any harder.

[Danny]

Ah ok that's good to know. We've pretty much finished putting the 308 together, and on Sunday a few lads are going to the track for a bit of practise, so will wire it up in the Commodore and see how it reacts on the track. Will let ya know how it goes if everything goes ok and we make it out there. :P

[sidewaysvc]

so this limiter u speak of sounds all good and well if... u have a aftermarket tacho and shift light correct can i do it with a standard tacho and no shift light??? (4k)

[Taz_Rx]

so this limiter u speak of sounds all good and well if... u have a aftermarket tacho and shift light correct can i do it with a standard tacho and no shift light??? (4k)

 

No. The shift light is what triggers/breaks the relay.

[sidewaysvc]

so if i just chuck in a shift light somewhere or anthing that flashes it will work??

[Taz_Rx]

I don't think your quite getting the idea.

 

A tacho like the autometre one I was using has an adjustable (RPM) shift light, which you can obviously set to your desired RPM.

 

You then wire the trigger to the relay into the wiring between the tacho and shift light. This means that when the light come on, the realy breaks the circuit to the coil.

 

Only tricky bit with the autometre guages is the shift lights are actually "pull to ground" rather than power-on. This just means you need to wire the relay appropriately, like you would a fuel pump being triggered by an ECU.

 

Yeah let me know how you get on Danny.

I'm all keen for "creativity" and learning stuff, but your 308 commo race car sounds like the sort of thing I would just bight the bullet on and install an MSD 6AL - the "L" stand for rev limiter. :rolla:

[SLO-030]

probably do this on the 253 when it goes in the 30 :rolla:

[sidewaysvc]

oh i see what u mean now fully re read this whole thread which means can't do in my car with standard tacho "easily" or cheaply will do more reasearch for limited hence 4k doesnt make power after 5200rpm standard so want a limiter

[Danny]

Yeah let me know how you get on Danny.

I'm all keen for "creativity" and learning stuff, but your 308 commo race car sounds like the sort of thing I would just bight the bullet on and install an MSD 6AL - the "L" stand for rev limiter. :bash:

 

Didn't make it out to the track 2day, practice was canceled...got racing next weekend tho. Got the 308 in and ready to go last night, fired her up this morning and it's sweet!

 

Ya know the way I found this thread was coz I was googling rev limiters coz I a was looking around for one to buy lol. But yeah thought I might try it coz yeah I love getting creative as well. Even gonna run another wire from the shift light earth to ground with a push button in the middle which will be on the auto shifter. The ol trimatic doesn't change the best, but works a lot better if ya take ya foot off the accelerator when u change up a gear...so gonna use the exact same relay to cut the ignition when the button is pushed when going up a gear.

 

It might work, might not, just something else to play with lol. Apparently the V8 supercars do something similar when changing gears.

[Taz_Rx]

It might work, might not, just something else to play with lol. Apparently the V8 supercars do something similar when changing gears.

 

Funny you should say that casue thats what I was think when I read the above. Supercars don't have a button on the shifter, they have a microswitch in the shifter. The shifter will actually move a mm or two before anything happens, this is thew microswitch working.

This way the driver doesn't have to think about pushing the button, the just grap the shift and push or pull, and it all happens automatically. :bash:

[Felix]

I've seen some manufacturers use ignition retard on gearchanges to smooth shifts, soften drivetrain shocks and to aid traction.

[Hiro Protagonist]

On the Haltech E6x we used for the FSAE car (running a Honda XBR600 F4i engine) we had a flat-shift function, gearchange (was paddle-shift with a carbon-dioxide actuator on the shift lever) would send a signal to the flat-shift input on the ECU which would cut spark, and there was a microswitch on the shift-lever to cancel it (so that the ECU knew that it had actually gone into gear)

[Danny]

Only problem we got is being on dirt just about everything gets a good coating of dust, and if we start doing too much, if something jams up we're stuffed for the rest of the race. That's the reason I thought to use a button. We thought about using something like the neutral safety switch, but open it up and change it to make contact when changing from 1st to 2nd, and 2nd to 3rd.....but not sure how that will work...might go find one now and have a looksy. Another option is to chuck the B&M ratchet shifter in and wire up a button, so when ya push the lever up it taps the button, and taps another button on the downshift. But still one problem we're always gonna have not knowing how long to push the button for, or if we use an automated way of doing it, it's prolly not gonna be long enough. And I'm not THAT good at electrics to make something like the V8 supercars lol. :bash:

 

But if anyone has some ideas please share. :y: