skittle?

[NAZCA C2]

Could'nt the differentials cause a similar sound?

[paul]

they would not do it into corners i don't think depends what rally cars run> lsd? but it normally only happens when against compression so is bound to be that anti lag technique / but the dif could make a skitting sound but would only happen at high speed i would think ?

[Alastor]

Although I am relatively new to the board, I know that it is foolish to question Matra et Alpine’s wisdom. Nevertheless, I have my doubts as to whether or not what the original poster described as a “skittle” is in fact the AL system.

The following link is a video of a Subaru WRC car entering and exiting the equivalent of a hair pin (900Kb avi file).

http://jupiter.walagata.com/w/alasto...mpreza.WRX.zip

Well before and most of the way through the corner a high pitched squeak (I am assuming this is the “skittle” noise) can be distinctly heard. Upon existing the corner the squeak is no longer present. Once on the straight a pop or bang can be heard during the up-shift, and then several more again at the end of the video (presumably from lifting off the accelerator).

It seems to me that the initial squeaking sounds more like a BOV or similar device. While the popping/banging could be caused by a AL system.

Even though there are not any question marks above, it is a question ;-)

[Matra et Alpine]

Although I am relatively new to the board, I know that it is foolish to question Matra et Alpine’s wisdom. Nevertheless, I have my doubts as to whether or not what the original poster described as a “skittle” is in fact the AL system.
....
It seems to me that the initial squeaking sounds more like a BOV or similar device. While the popping/banging could be caused by a AL system.

Even though there are not any question marks above, it is a question ;-)

I agree the sound is NOT the same as the "classic ALS".
I checked and ALS are no longer the only method.
They also use a modified verison of the standard Exhaust Gas Recirculation.
However, I've not ben able to find any technical articles from any of the teams on their implementation of EGR and ALS.
I think you're right that it's the BOV we're hearing but that it's in a programmed mode as an EGR woudl need. So instead of jsut opening and releasing all the pressure, it's useing a slower controlled release and that woudl surely make a squeaking noise as heard.
I'll ask around guys at the next event, some of them work for the big guys

PS: It's never a problem to question my knowledge, I do it all the time.
AND this is a prime example of things moving on from the setups I'm experienced with and not hearing it first hand. The vid was a help. Hadn't released noticied it as a 'squeak' till then. Still not sure if that's the "skittle" though

[KnifeEdge_2K1]

i know burning too rich a mixture is bad for teh cat because the unburned fuel is really hot and will prolly ignite as it reaches the air at the end of the exhaust bla bla bla but what if there was too thin a mixture, like too much air and not enuff fuel, now this i imagine would only happen when a) u run outta fuel or b) ur ecu is playing tricks on u

i cant imagine there being any harmful effects since extra air is .. air
the only thing bad i can think of is bad economy because u waste energy compressing the air u dont need and blowing it out, oh that and the engine being seriously underpowered but that fits in to the other thing

but emmissions rating will be phenomenal

[KnifeEdge_2K1]

oh and ive never heard of it being reffered to as skittling more of a popping sound, like when u microwave popcorn

its basically an engine misfire but deliberately caused by the ecu to keept the turbo spinning (i came to the same conclusion as matra)

as the car goes up to a corner a driver would lift off which means the revs drop, and the turbo's turbine's rpm dropping as well, now this is really bad when you exit the corner cuz u want the torque made by the turbo to get out fast, but here in lies the problem
if you want the turbo to keep spinning you have to add throttle, but if u add too much throttle u run into a tree, so you back off the throttle but that means your turbo slows down
what the anti lag system used by wrc cars is time the spark plug to fire right when the exhaust cam begins to open the exhaust valves, this causes the air fuel mixture to litterally explode out the manafold into the turbo and out the back of the exhaust, this keeps the turbo spinning while the bov is open to prevent the pressure from getting too high and stalling the turbine (VERY BAD THING)

now as you can imagine having air fuel mixture explode out the entire exhaust system and your turbo charger all the time cant be good so thats why its mainly used only on competition spec cars and also because they're so loud they're illegal on the streets, n even if you tried to get one on the streets ur car would start smoking cuz the explosions will melt ur catalytic converter and then ull have a hole in ur exhaust and the cops will come after u

[megotmea7]

i cant imagine there being any harmful effects since extra air is .. air

a very sevire problem comes of running a car to lean, this is also effected by the ambient tmpertature and temp. drop after the intercooler, air pressure, and octane of fuel used. detonation is when the a:f ratio is so high that there is not anough fuel to prevent preigninition. when the a:f mixture goes off before the piston reaches tdc and the expanding gasses are pushing against the piston as it is going up or just reaching tdc. this is very bad for piston engines and even worse on rotaries(the explanatin is also slightly different on rotaries also) cars usually make more power whern running lean but there is the point where you stop making power and start detonating(usually tuned with ignition timing) and detonation is not good

[crisis]

It's an anti-lag technique employed to keep the turbo spinning.

Basically it adjusts the ignition timing to ignite fuel in the chamber AS the exhaust valve opens, so the burning fuel spins the turbo.

The noise you hear is the retarded combustion through the turbo.

All explained - and warnings on the impact it has on the parts - at http://www.rallycars.com/Cars/bangbang.html

Very informative. +3. Also because Ive been mean to you.

[Blue Supra]

Is that system being referred to here the same as a misfiring system used in WRC?

[Blue Supra]

anybody?

[paul]

yes it is

[KnifeEdge_2K1]

anybody?

no body calls it a misfiring system
misfiring is synonymous with the word bad

uve been watchign too much initial d

and thanks for the explanation about lean/rich ratios and thier effects on premature detonation to whoever wrote it im too lazy to check

[Blue Supra]

Initial D owns me
i love it!

[whiteballz]

i will ask in with shiftys dad when i next see him, he rallys STI's and im sure he will know.

[Ferrari Tifosi]

no body calls it a misfiring system
misfiring is synonymous with the word bad

uve been watchign too much initial d

and thanks for the explanation about lean/rich ratios and thier effects on premature detonation to whoever wrote it im too lazy to check

Premature Detonation, isn't that a bit redundant? Anyways, I believe only a lean mixture will cause detonation, I may be wrong though.