Rev Limiter Bouncing

[Grundy]

Okay, don't all jump on the hate train here

 

I just want to get a little understand on a few things.

 

 

Firstly if you don't know what I mean, here's some clips of what I'm on about.

 

(start at 35secs)

 

 

http://youtu.be/DA_zxodsDI8?t=25s (Start at 25secs - short clip)

 

 

I've just been doing a little reading and wanted to find something out.

 

Our cars, if you hit the Rev Limit, it cuts off the fuel, like an anti climatic end.

Now I'm just going on a guess here, but are these cars (there's a chance they are modded to do this, so I'll broaden it to other cars) I read somewhere about the spark cutting out.

 

So are there two types of fail safes on cars? Some cut the fuel, and some cut the spark?

 

Because I'm guessing these bounce the rev because the spark cuts out, fuel carrys on, and then it sparks up igniting the over fuel?

 

 

 

Or am I just talking @*!#?

 

 

I'm not being a little Car park gangster here, I'm just curious, as it makes me think about the 350z on drifting, does it not just bog down when you hit the limit, cutting the drift short?

[brillomaster]

just this question came up a little while back, have a quick read through the second half of this:

 

http://www.w8ji.com/rpm_limiters.htm

 

nearly all modern cars cut fuel, rather than cutting ignition, since air and fuel will still ignite in a hot exhaust, but air and spark will do nothing at all without fuel.

Edited February 5, 2015 by brillomaster

[mouthwash]

I'm going to have to review our friendship.

[Grundy]

I'm going to have to review our friendship.

Not bad timing, our contract is up for renewal soon, and there is a cancellation fee

[StevoD]

I'm going to have to review our friendship.

 

yea same maybe time to cancel that subscription

 

normally it will cut the fuel and spark

 

the likes of '2-step' (not the dance) will just cut the spark and dump all the unburnt fuel into the exhaust or turbo if you have one

 

and do this

 

 

 

now Regarding the Z and drifting, for me at least im comparision with my s14 the gearing is to close on the 1st/2nd/3rd for me anyways which is why im looking into adjusting the final drive

 

but i wouldnt say the rev limiter just stops you drifting

 

[Grundy]

I'm going to have to review our friendship.

 

 

 

 

That scooby though has the addon rev limiter.

 

So was it like a zed before that? Did it cut the fuel? or was it pre-fuel cutting and just cutting the spark?

As that will answer my next question of - The rev limiter addon allowing you to change how it's cut off?

 

If that makes sense.

[StevoD]

im not going to lie now im confused on what your actually asking

 

are asking how standard cars use a rev limiter?

[Grundy]

im not going to lie now im confused on what your actually asking

 

are asking how standard cars use a rev limiter?

Yeah sort of, it was onto my next question.

 

Take the Zed for example - Cuts of the fuel, rpms drop until the fuel cuts back in.

However take Andy Jame's race logic for instance, once that's fitted, he now has Launch control, ready hold it on a set limit without cutting the fuel.

 

So do these kits, B'rev, Utec ECU (Piggy back thing) work by essentially switching the cut off around? (No longer shuts off fuel, shuts off spark)

 

- May of answered my own question, do they just set the rev limit on the device so it's not at say 6600rmp, therefor the fuel doesn't cut off?

 

 

 

I know i'm waffling a bit, and I apologise, just trying to learn some things as it's always baffled me some cars do this some cars don't etc.

 

Thanks to Brillo, I was on the right line with the Fuel/Spark theory. Does make sense.

[StevoD]

i think it depends on the kit

 

i think your heading down the route if getting antilag and lanch control mixed up

 

i think the launch control on andys will just hold the revs at a set level untill the clutch is released (or brake is auto) just like say on a GTR

look how its sits at 4k it doesnt *bounce*

 

Edited February 5, 2015 by StevoD

[Tricky-Ricky]

Yes as already said all modern cars from the mid 90s use fuel cut rather than ignition cut, but not all, a lot of Japanese cars previous to this used ignition cut, however if you fit a stand alone ECU most will allow you to set fuel or ignition for RPM limit and or launch.

[Ekona]

The 350Z I believe (and I do stand to be corrected on this one) will cut fuel at the rev limiter, but will cut the spark for the TCS.

[Tricky-Ricky]

I think you will find that the TCS uses a combination of the ABS and the electronic throttle to provide the control, and no fuel or ignition cut.

[mouthwash]

Yeah, Ekona.. Have some of that.

[Ekona]

I know the stability uses the ABS to brake individual wheels, but I always thought the traction was done by spark cut as it always felt so incredibly harsh. Throttle body control could do that too though, so I bow to your superior knowledge on this one, thanks

[Tricky-Ricky]

Not saying I'm 100% but pretty sure, its a common system, and has been use in one form or another on lots of cars, the worst one being the Toyota Supra MK IV they fitted a separate electronic throttle butterfly which was horrendous, as it would sense wheel spin if you try and squirt quickly out of a junction or roundabout and close the throttle plate, leaving you stranded in front of oncoming traffic.

[Voodoo Vix]

Not saying I'm 100% but pretty sure, its a common system, and has been use in one form or another on lots of cars, the worst one being the Toyota Supra MK IV they fitted a separate electronic throttle butterfly which was horrendous, as it would sense wheel spin if you try and squirt quickly out of a junction or roundabout and close the throttle plate, leaving you stranded in front of oncoming traffic.

 

That's why my boyfriend disconnected his in his supra, it was more dangerous having it on sometimes (if you know the car's responses anyway).

[Tricky-Ricky]

Not saying I'm 100% but pretty sure, its a common system, and has been use in one form or another on lots of cars, the worst one being the Toyota Supra MK IV they fitted a separate electronic throttle butterfly which was horrendous, as it would sense wheel spin if you try and squirt quickly out of a junction or roundabout and close the throttle plate, leaving you stranded in front of oncoming traffic.

 

That's why my boyfriend disconnected his in his supra, it was more dangerous having it on sometimes (if you know the car's responses anyway).

 

 

I think most owners do, once they have a taste of how it behaves, apart from removing the traction control ECU I also removed the actual secondary throttle, as its all more trouble than its worth, and once you go BPU or fit a single turbo its down right dangerous.