I know there's another topic under technical that asks information about double clutching, but I'm looking for something much more specific.

I recently decided to do some research on double clutching because I wasn't sure exactly what it was refering to. From what I read it appears to be a technique where by you can keep up the RPMs as you go into a turn so that you can get a good launch after coming out of the turn. According to what I read it can be used in conjunction with heal-toe braking. Basically if you need to slow down when going into a turn you can kick the clutch and apply pressure to the brake using your toe. At the same time you press on the accelerator to keep the engine RPMs up. You also shift to the proper gear (most likely a downshift because you have slowed down) and release the clutch after the turn as you take your toe off the brake. It is also much easier on your clutch when you're down shifting.

As for misfiring system. I'm pretty sure they are only present in cars with turbo setups. According to what I know they have been used in rally cars for quite some time because they allow the turbo to be spooled up even when the car is slowing down. Basically it's retarding the combustion sequence to the point where some fuel/air mixture will not be combusted, but instead is pushed out into the exhaust manifold. The next fuel/air mixture is combusted and the heat from that combustion ignites the fuel/air mixture in the exhaust which then spools up the turbo. This allows you to get boost from the turbo after the turn if you've had to slow down.

Now for my question. I was wondering if you could use the double clutch technique to spool up the turbo instead of installing a misfiring system. If you know anything about this or can point out any mistakes or missing information I would be very thankful as well.

finally, someone explains what a misfire system is. Sorry i can't help with your other questions though.

finally, someone explains what a misfire system is. Sorry i can't help with your other questions though.
I got curious after watching Initial D. So no one out there has any idea what I'm talking about?

finally, someone explains what a misfire system is. Sorry i can't help with your other questions though.
I got curious after watching Initial D. So no one out there has any idea what I'm talking about?

I do. You probably got everything right. The ignition basically just retards the combustion, and the mixed shtuff gets ignited when the next ignition occurs. This in turn keeps the turbo spooled up and in the end, you get the responsiveness of a n/a engine and the power of a turbo'ed one

Btw...i've heard that this tuning is hella bad for turbos (gotta be the heat), and the turbo has to be replaced every now and then

Yea I figured that the heat would be a big problem, but uh..my question was whether it's possible to spool up a turbo when you're double clutching. Meaning do you guys think it's possible to build enough pressure from reving the engine while in neutral as you're braking and downshifting into a corner? Or is all that more than any one human could accomplish on his own?

It would be feasible, but VERY difficult even for a good driver. I mean, you'd have to keep the clutch pressed, apply the brakes and at the same time press the gas to keep the revs high. Plus using your hand to shift and to turn the steering wheel!! Doesn't sound quite easy to me... :lol:

Btw you guys should watch some Best Motoring videos to see how these guys use the right foot to press both the brake and the gas in order to downshift... It's really awesome. I have tried it with my car too but the brake and the gas pedals are too far from each other. :P

It would be feasible, but VERY difficult even for a good driver. I mean, you'd have to keep the clutch pressed, apply the brakes and at the same time press the gas to keep the revs high. Plus using your hand to shift and to turn the steering wheel!! Doesn't sound quite easy to me... :lol:

Btw you guys should watch some Best Motoring videos to see how these guys use the right foot to press both the brake and the gas in order to downshift... It's really awesome. I have tried it with my car too but the brake and the gas pedals are too far from each other. :P
And if you look at the old rally car footage, they did it as well, obviously not as necessary now with the newer misfiring systems...

Do all the turbocharged rally cars today use misfiring systems?

i would think so. i mean, its a legal advantage...i see why not?

I was thinking that the heat would could be a factor that would compromise the reliability of the engine. Then again they probably provide sufficient cooling. Do you think those systems could be made street legal?

I was thinking that the heat would could be a factor that would compromise the reliability of the engine. Then again they probably provide sufficient cooling. Do you think those systems could be made street legal?
All the components in a Rally car are street legal, each rally car is registered as a prototype, so there are some more lenient rules for road use, but I knew of someone who could not afford a second car, so he used his ex-WRC team Grp A spec EVO 6 to commute to work and back daily, and then rallied it at weekends and in competitions 8) as a Privateer :P
So anything off a Rally car can be used in a street car (but then again, the rules might be different in the US ?)

I was thinking that the heat would could be a factor that would compromise the reliability of the engine. Then again they probably provide sufficient cooling. Do you think those systems could be made street legal?
All the components in a Rally car are street legal, each rally car is registered as a prototype, so there are some more lenient rules for road use, but I knew of someone who could not afford a second car, so he used his ex-WRC team Grp A spec EVO 6 to commute to work and back daily, and then rallied it at weekends and in competitions 8) as a Privateer :P
So anything off a Rally car can be used in a street car (but then again, the rules might be different in the US ?)
The US has some very strict emissions regulations so not all car parts can be deemed street legal here. I know there are a lot of turbo systems that are considered to be illegal out here so I'm guessing that something like a misfiring system might have difficulty passing emissions testing.

I was thinking that the heat would could be a factor that would compromise the reliability of the engine. Then again they probably provide sufficient cooling. Do you think those systems could be made street legal?

Anything that causes fire to come out of the exhaust is always illegal in the US :D

Double Clutching... I think you are missing some steps. Remember, DC'ing was originally used for cars with transmissions w/o sycro's. In initial D, that is NOT true DC'ing. What you hafta do is:
1. Press on clutch
2. Shift into neutral.
3. Let go of clutch
4. Gas it to the right RPM (to keep the gears from 'jamming'... bak in da old days)
5. Press on clutch AGAIN.... hence the name 'double' clutching
6. Shift into the next gear u wanna go into
7. Finally let go of clutch and go!

Sounds purday complicated... dont u think??? Amzing that ppl use to hafta go thru all those steps for each gearshift... especially in racing!
Let me know if something i wrote above is wrong.

So that misfiring system + duble clutch combo wuld only work for downshifts.

nah, cars with no syncro needed it both ways

nah, cars with no syncro needed it both ways

Can u explain wat u mean? I am now officially confused by wat u mean by 'needed it both ways'
:shock:

nah, cars with no syncro needed it both ways

Can u explain wat u mean? I am now officially confused by wat u mean by 'needed it both ways'
:shock:
changing up and down throught the gears :?

yea they did... but for the 'misfiring system' idea i think it wuld only work for downshifts since it wuld up the revs while ur shifting

THERE IS NO MISFIRING SYSTEM..... THE SO-CALLED MISFIRING IS AN ANTI-LAG SYSTEM. The Misfiring system is just something created by Initial d. Its illegal in some states because of the loud noises made by the antilag system,it disturbes peace in residential areas. Also you can't put that thing in a normal car.... the Anti-lag system ruins 75 % of the car's engine thus ruining engine life Immensly. WRC uses it but they change their engines after every competition/ tournament , so its okay for those guys to use it.anymore info is at this link http://www.rallycars.com/Cars/bangbang.html

Hahaha Initial D... Yea the name 'anti-lag' system actually makes sense.

isnt double clutching skipping a gear. so..

1. engage clutch and switch for 1st gear
2. disengage clutch and shift to neutral.
3. rev it up to the right rpms
4. engage clutch shift to 3rd.

isnt that what double clutching is???

I recently decided to do some research on double clutching because I wasn't sure exactly what it was refering to. From what I read it appears to be a technique where by you can keep up the RPMs as you go into a turn so that you can get a good launch after coming out of the turn. According to what I read it can be used in conjunction with heal-toe braking. Basically if you need to slow down when going into a turn you can kick the clutch and apply pressure to the brake using your toe. At the same time you press on the accelerator to keep the engine RPMs up. You also shift to the proper gear (most likely a downshift because you have slowed down) and release the clutch after the turn as you take your toe off the brake. It is also much easier on your clutch when you're down shifting.
I guess Vin Diesel was very very wrong when he mentioned the need to double clutch during a drag race in The Fast and the Furious. :lol: Anyways thanks for explaining that. I occasionally ponder things like that and heal-toe braking...

O when i read the last post i just remembered something.( It dosent have anything to do with double clutching or anything). The new fast and the furious movie is coming out and Vin-Diesal comes back from.... mexico :) sry if this is a little off topic ... just had to bring it up.

Oh great, another Rice & Ricious film.. :roll: :lol: What do you mean by "double clicking"?

Oh great, another Rice & Ricious film.. :roll: :lol: What do you mean by "double clicking"?

:lol: :lol:

O My Lord.

There is so much misinformation on this thread it's not even funny. The only reason I registered was because of this thread and for the sole purpose if enlightening you noobs.

First of all, double clutching does NOTHING to make your car faster!
On the older american cars that were 5 speed, some of them required you to double clutch one every single gear shift.
So you would have to :
- let off gas
- push clutch in
- shift to neutral, re-engage clutch (let it out)
- push clutch in
- shift, and engage clutch to accelerate

And you can also do this on newer cars as well, BUT, only if you need to. Sometimes older cars don't shift as easy (bad synchros), and with double clutching, it makes the car go into gear easier (on cars that have problems).

It is in no way, a racing maneuver.

And when you push the brake while tapping on the gas and downshifting..

That is called, "HEEL-to-TOE" down shifting.

The whole purpose of heel-toe is to be able to downshift faster, put less stress on the syncrhos/transmission, prevent weight shift of the car (while downshifting), and slow down faster.

When I say downshift faster, step into any 5speed car today. If you are slowing down, and down shift the car into a lower gear, you have to let the clutch out slowly into the lower gear. Or if you let it out fast, the car willl jerk and downshift roughly (on some cars, if you downshift into 2nd and not let the clutch out slow enough, the tires lose traction because of harsh clutch engagement).

When you downshift, either way, it's going to make your car jerk (weight shift forward) and put stress on your clutch and transmission.

You're not really slowing down as fast as you can when you just downshift normally.

Here's an explanation of heel-to-toe.
let's say you are in a 240SX. 4th gear going 3,000RPM (cruising). If you were to downshift into a lower gear (without slowing down, constant speed), if you shifted into 3rd, the car would be in 4,000RPM.

That's the whole reason your car downshifts with a jerk.. because your suddenly engaging the clutch from 3000RPM to 4000RPM.
As soon as the engine gets to 4,000RPM, the clutch is engaged fully and your are done downshifting of course.

People can prevent this harsher downshift gear engagement by Heel-to-Toe.
It's also called "Rev-Matching".
Basically if you were to rev-match, the car would go into a lower gear faster and smoother.
What you do is, in the case above (4th gear 3000RPM). Put the car in neutral/clutch in.
BLIP the throttle (tap on the gas really hard. JUST ONCE).
While blipping the throttle, put the car into lower gear, and engage the clutch really fast.
(If you blip the throttle to 4000RPM, the clutch should just slip into gear EASILY).

But, lets say you're slowing down.. HOW DO YOU BLIP THE THROTTLE WHEN YOUR FOOT IS ON THE BRAKE?!?!?
That is when you heel-toe.

You keep the top part of your foot to brake, and the bottom part of your foot (the heel) to blip the throttle.
It's hard, but takes practice to learn.
You have to be careful not to push to hard on the brake, and you have to downshift really fast or else you will not downshift correctly.

For me, i go to the canyons alot (with my 1990 nissan 240sx) and when you are going on the downhill... you are FORCED to heel-toe.
Meaning.. if you don't do it right, you will not be able to slow down fast enough and will understeer.
So, it's 2nd nature up there.

You can even use it in daily driving.. (except it's harder.. because when you're cruising at lower RPM's, you have only lie 500-600 RPM of gear separation).


You all need to research and maybe own a car before talking about alll your stupid Fast and Furious bulllshit.

Infact dude you ****ed up there as well, double de clutching is when cars lacked syncromesh all together and required you to manualy match revs not just on old american 5 speeds. But yeah, you did clear up alot for some other people but calm down dude.
And by the way, the instructions are
- let off gas
- push clutch in
- shift to neutral, re-engage clutch (let it out)
- Blip the gas to match revs
- push clutch in
- shift, and engage clutch to accelerate

I'm kind of mad that fast and furious crap and Initial D stuff was on here...

As for "blipping" the throttle, you better have some serious frickin' foot control to match them perfectly. Because unless you're really good at it there's either going to be too many revs or too few, and too many revs causes a momentary loss of deceleration because the engine revs are too high, almost as if you downshifted in order to accelerate. ON the flip side, downshifting while braking and blipping the throttle too lightly causes a forward jerk as the engine is going too slowly to match the correct revs for that speed.

My point isn't to argue, but that it's very hard to match the revs perfectly unless you've driven pretty damn hard for a long period of time. I still get a slight jerk even after a good year of "sporting" fun.
And as far as heel toe dowshifting you've got your feet position wrong, or at least that's not how I've done it. I use my heel to brake and my toes to blip the throttle. The reason being you have more control with your toes than you do with your heel.

And btw, don't just show up like an ass and call us all noobs. Most of us know quite alot about cars, and if you've browsed our site you'll see we're all here to enjoy them. Not to point out who does and doesn't know certain things.

Yeah blipping the gas is hard bus before syncro and if you didnt have constant mesh that was the only way

I always blip the throttle when I downshift but I have never tried heel-to-toe downshifting... the brake and gas pedals are too far from each other.

I just got back from a little excursion, shall we say... :wink:

And I realized when I'm "heel-toing", I'm actually working the sides of my right foot only. Because in my car the pedals are so close together I can hit both with my right foot, and this is while wearing running shoes!

So I'm using mostly my arch to do the blipping.

this may be a little off topic but i was wondering if it would be possible to install a mis firing system (sorry this just sounds cooler than 'antilag') in a rotary engine?

im a noob so my question may seem stupid but im looking for an answe....thanks in advance

I would assume it could be done. I don't think there would be any major problems that I could think of.
But it probably wouldn't be street legal.

Just for your info your not ment to post in threads that havn't been used for a while. Its somewhere in the rules.

isn't misfiring really bad for ur engine? i don't really know myself but it seems like it

Old.

But, a misfiring won't reduce engine life. Just your turbo and exhaust manifold really, that's where it's happening. All a misfiring system is doing is increasng the amount of exhaust gases fed to the turbo and it does this by simply ******ing (holding back, so to speak) the spark timing so that most of the combustion happens in the manifold. This is only happens whilst not on the throttle and returns to noraml when you are.

Not good for turbine blade longevity.

.dlO

thank god, this cleared up most of my questions
i was about to start a new one.

I got curious after watching Initial D. So no one out there has any idea what I'm talking about?

After reading your first post i had a suspision that you watched Initial d (I do too). It was from the part were they have to race the evos isnt it?

Engines that have this so called MFS (anti-lag), especially rally car engines, are either rebuilt or replaced. I read up on this a while back.

This is over a year old and PancakeBoy is asking someone a question who is looong gone.
I learned something though. I didn't know such a thing as misfiring systems existed.

You are mixing heel/toe rev matching, and double clutching... With modern cars there is little to no advantage to doing a double clutch. Synchros are made to take the place of this...

You never want to drop out of gear while corning because it will upset the balance of the car and make it unstable. So the technique is to use your right toe on the break and blip the gas with your right heel while clutching, then hit the gear. This allows you to use a combo of engine breaking, foot breaking, and puts you in the correct gear for exiting the corner. If you wanna learn, best thing is to do it at slow speeds while coming to a stop on the street... just start doing a heel/toe downshift when coming to a light or stop sign. I wouldn't recommend a track being the first place you practice...

Another good thing to learn is left foot breaking which is nice to do a trail braking on a long sweeper... helps keep rev's up a bit to exit a turn while holding a line.

I love doing this stuff whenever I drive, to me it makes my commute to and from work more enjoyable... ALso makes it second nature when I hit the track and am really pushing the car.

For the record, it is entirely possible to do this on the street while abiding by traffic laws and not being dangerous... Just use a bit of good judgement about when you start practicing! :)

I'll leave this open because it's a good topic but it should be closed.

Good explanation 2k...

missfiring is bad for your turbo..it doesn't affect the engine in any negative way aslong as it's running in "good trim"... and it's not even really BAD for the turbo..just drops it's life expectancy.

its just basic solution on turbo lag. when you lifts your foot off the gas to make a shift, there is a drop of pressure or turbo lag,when the turbine loses this power, it slows down and needs time to spin up again, which creates the lag.the way a misfiring system works is, when this happens, it senses it immediately and injects fuel directly into the exhaust system itself. The fuel is detonated in the exhaust manifold, creating that pop and a kick when you hear and the force of this mini-explosion is enough to maintain boost pressure needed to keep the turbo up to speed even when the car is slowing down, thus virtually eliminating any lag and maximizing power coming out of a turn. However, these are illegal on street cars, and eventually ruins the turbo and exhaust system...

I have found two things wrong here. First double clutching was not used on American 5 spd trannys. This was used on the old 3 spds, and some 4spds (I am refering to passenger cars not comercial trannys) By the time 5 spds came out, they were syncroed. Secondly, returding ignition to gain more turbo boost is very hard on an engine, not just the turbos. Because of the greater amounts of pressure in the exhaust, the pressure flows back into the cylinders every time you let off the throttle. This does not allow fresh air to enter the cylinders at low RPMs. Bottom line is that this only works at constantly high RPM ranges, like what is used for racing. This also results in greater heat ranges than what the engines are built to operate in, that never helps engine life