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Discussion Starter · #1 ·
I've only owned f/r style cars (Mustangs,Camaros) before and when speed shifting my 5spd WRX I notice a bang as I hit 2nd and a little in 3rd. Is this because the tires don't spin? It also bogs slightly as I shift into 2nd. Should I lift slightly on the accelerator or slip the clutch a little? Coming off the line from a dead stop at what rpm should I dump the clutch and is that optimal for the best acceleration?
Thanks!
 

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a bang? what do you mean, sound or power?

no the thing won't chirp. today i revved the sucker to 5000+ rpms, and popped the clutch, and i just shot off the line.

bogs? keep your rpm's up. out of first, i almost always push 6000 - 6500, youll enter 2nd at about 3500 to 4000. its the only way to really jump into speed. (obviously for a smoother ride, keep the rpms a little lower, and soften the clutch release.)

off the line, i usually give her around 2000 to 2500 to make sure the turbo is engaged hard right away. you can do less, but if you want the pop, this is where to start.

also, remember, off the line, and AWD car will be a little stiffer and less responsice to your clutch work. so don't really drop the sucker unless you have the power to move the car.

hope this helps, and enjoy the new drive train. icame off a front whell drive five speed myself, and with two days of driving, im really getting the hang of her. every shift i like it more.

not ready to drag yet, but oh so soon. :)
 
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Discussion Starter · #3 ·
Thanks Dark Rex!
The bang is actually a noise, I'm just used to cars that break the back tires loose and I'm not sure where the noise is from. I'm not lifting and just speed shifting and the noise is pretty pronounced between 1st to 2nd. When I used to race my Z28 you had to be careful of letting the rpm's get too high when you dumped the clutch or you would end up with a crotch full of shrapnel. We used to wrap the flywheel housing to keep from killing us. Since you can't really break the tires free I was just wondering if there was some magic number to come off the line. I've read every test that's in the car magazines, but they don't explain how they achieve their 1/4 mile times. Thanks for responding.
 

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make sure you are double clutching! adjusting rpm's b/w gears is the only way to maximize your 1/4 mi time. plus, keep those rpms up!

have fun.
 
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Discussion Starter · #5 ·
ok, pretend i'm an idiot and explain to me how double-clutching is going to help in the quarter-mile. it seems to me that it would increase your times.
 

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first off, no one is an idiot. this place is here so that everyone can share common knowledge and therefore, we all benefit. is till have so much to learn, i barely feel qualified to talk here. blazin is a good source for info also on anything technical.

well, it would seem on the surface that longer time b/w gears would be a sacrafice to aceleration. instead of double clutching progression:

-accelerate
-depress clutch
-gear to neutral
-release clutch
-depress clutch
-neutral to gear
-release clutch.

that speed shifting wold be better, becasue there are less steps.

-accelerate
-depress clutch
-gear to gear
-release clutch.

but visualize your tac while accelerating. as you top out a gear, depress clutch and switch gears, your rpms are dropping fast, as your engine is technically in neutral/limbo. by the time you enter the next gear, your engine has slowed down in rpms, and your BOV has started to spill out some oh so valuable pressure. you enter the next gear with a slower spooling turbo (now you need to spool it up again) and lower rpms than when you left the previous gear, (need to pick those up again also)

what double clutching allows you, is time between gears to maintain/adjust rpms before the next gear. so instead of losing rpms and turbo pressure, it actually allows you to pick up a little engine reps, and keep that turbo working for the money.

the sacrafice in time b/w gears, (which i assure you, after some practice will be a fraction of a second.) is accounted for by the large difference in gear entrance rpms and lack of turbo loss.

you'll find that you are jumping into the next gear at frightening acceleration, rather than catching up to the gear. the by-products of this are many. but to name a few, DRASTICALLY shortening your gear's climb times, and therefore increasing overall acceleration times through your gear progression.

mike.
 

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Wow great explanation Mike! I'm going to need some modurators soon so keep your eyes out for the announcement becuase you seem like someone who is very enthusiastic to help and you sure know your stuff. :)
 

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Double Clutch Upshifting is a waste of time and I would have to disagree that it helps your 1/4 mile times.

However, double clutching will extend the life of your synchros and help make a smooth transition into the next gear, most importantly for corner acceleration.
 

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Ineedboost said:
Double Clutch Upshifting is a waste of time and I would have to disagree that it helps your 1/4 mile times.

However, double clutching will extend the life of your synchros and help make a smooth transition into the next gear, most importantly for corner acceleration.
Exactly. DR, sorry but this is correct. Run your WRX at the track and you'll see. For drag racing, ESPECIALLY with a turbo car, powershifting is the fastest way. I have never powershifted my car (now will I ever), but I DO speed shift as it's the fastest way (other than powershifting). You don't double clutch when racing in a straight line. That's just what they say in the F&F. ("Granny shiftin', not double clutching like ya should" :D ).

-C
 

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i hear that the best way to launch this car is to rev the engine to 5500 rpms then slip the clutch out. ive heard of people bogging when they dump the clutch. just my 2 cents

hey dark rex great description but shouldnt you adjust your rpms, using the accelerator to where the next gear would put them. that was my understanding of double clutching although i could be wrong
 

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Unfortunately your BOV opens the instant you let off the throttle. And more or less instantly release all the pressure. This allows the turbo to keep spinning, reducing lag. Otherwise you'd get a huge boost spike in the intake and the pressure wave would stop the Turbo dead, shocking the bearing and resulting in really bad lag.

Personally I can shift faster than the engine drops revs, especially if I don't release the gas completely. The double clutch does nothing in this case.
 

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GV27 said:
Unfortunately your BOV opens the instant you let off the throttle. And more or less instantly release all the pressure. This allows the turbo to keep spinning, reducing lag. Otherwise you'd get a huge boost spike in the intake and the pressure wave would stop the Turbo dead, shocking the bearing and resulting in really bad lag.

Personally I can shift faster than the engine drops revs, especially if I don't release the gas completely. The double clutch does nothing in this case.
GV27, you've hit the nail right on the head. Especially you're last paragraph. Even though I am a novice when it comes to manual transmissions I am able to keep the revs up by not letting off of the gas all of the way while shifting. I find that this practice is just one of the many "feel for the car" type of techniques that can be performed in a car with a manual transmission.

Double clutching might better at keeping the revs up, but you need Spiderman-like reflexes to actually make it work fast (i.e. for a 1/4 mile run).

-Shadow
 
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