The question on everyone's mind.

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1X83Z

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Will it wreck my automatic transmission if I rev up to 3000 or so before I floor it? Not drop it into neutral, but one foot on the brake, one on the gas until it gets to 3000 or thereabouts then pedal to the floor.

I'm trying to eliminate turbo lag, since you're going to ask.
 
If anything, I would think that it would do most harm to the brakes since that's what's keeping your car in place. So I dont think it would hurt your transmission, but I'm not 100% sure.
 
It obviously won't do it any good. Brake torquing as it's called doesn't really cause any damage to the brakes since it's stationary. But it does cause a hell of a lot of heat to build up in the transmission. I'd imagine it gives your transmission's torque converter a ****-kicking.
 
I know road testers hold revs in neutral (e.g. 6000 rpm) and then slam the car in to drive to achieve better acceleration times.

Is turbo lag really that pronounced in first gear though?

BTW, what car is it?
 
Brake torquing wont put you on the side of the road. Just try to eliminate how long you do it before a launch. It does build up alot of heat in your torque converter. But obsorbing engine and transmission speeds that dont match up is what your torque converter is supposed to do. It really is the only "good" way to launch an auto. Some aftermarket companies, depending on your car, make aftermarket torque converters to be able to rev up to as much as 4,500 rpms.
 
RacyBacy
I know road testers hold revs in neutral (e.g. 6000 rpm) and then slam the car in to drive to achieve better acceleration times.
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Thats bad news for your tranny. A freind of mine did that, pretty soon he had teeth from reverse gear floating around in the tranny fluid. Yes, this was probably the result of more general abuse, but brake-torqueing is the only "good" way to launch an auto tranny. I believe that this is the method that road testers actually use.
 
The turbo in Dad's Skyline kicks in at about 2,900rpm or something (it is an automatic) so when he goes to drag a boy racer at the lights (he always beats them - he and the car have a reputation around his town :D) he holds his foot on the brake and revs it up to the turbokickyinyrange then lets off the brake and it flies down the road leaving the boy racers at the lights spinning his wheels. Of course being a 4WD Skyline helps a bit. ;)

He's even dragged off a new BA Falcon XR8 and won. The guy in the Falcon (about 45 years old - same as Dad) pulled up alongside him at the next set of lights, looked over, shook his head and was smiling the whole time.

Before you go off at me, this isn't 'proper' street racing.
 
Doing that over and over again will fry the tranny. It will take a while but it is not good for it. Just get a stall converter if you want to do that all the time.
 
RacyBacy
Is turbo lag really that pronounced in first gear though?
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I'm pretty sure with the engine being under load (launching off the brake) the engine should reach full boost before you launch (unlike neutral).
 
Sorry to hijack the thread for a second, but does shifting into drive whil going backwards in reverse and gunning it hurt the tranny a lot? I know it's not good for it, but Is is really bad? I think my tranny has 158,400 miles on it :indiff: ...It's the only way I can make any smoke in my car. I can make a fairly large ploom.

btw, i obviously have auto.... :dunce:
 
I brake-torque the 323 every now and then...basically it allows the 323 to peel out more efficiantly than if I just slam on the gas. Plus, flat out brake-torque in the 323 puts it at around 2,500rpm, which is the torque peak.
I've also brake-torqued our MPV, and several cars at work(auto RX-8s mainly). Ofcourse when I do it, it's just for fun, not a wanna-be sense of actually accelerating faster...though in a turbo car you can get boost going and accelerate faster.
 
Well, holding the brake and reving thing engine isnt nearly as bad for your car as reving it up in neutral then slamming it into drive.

Find a good aftermarket torque converter is the way to go. If you search around, you can find one that fits your specific needs. IE: have a stall converter that revs up to the 4500-5500 range is completely unstreetable. The highest i would recomend is a 3,500 rpm stall converter. But, you will notice a big difference in regular driving.

You can also look into rev limiters and trans brakes. There are many options.

Hope it helps.
James-

PS, there are torque converters thatgo all the way up to 6500 rpm. Of course, full racing application.
 
Event Horizon
does shifting into drive whil going backwards in reverse and gunning it hurt the tranny a lot? I know it's not good for it, but Is is really bad?
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Not if you wan't to leave your tranny on the ground behind you :lol:
 
I suppose it depends on how old the car is, whether it has any kind of traction control, whether its AWD, RWD or FWD, how much grip you expect to get from your tyres (325's compared to 185's etc) and most importantly - how oftern do you expect to be doing it?

If your going to be doing it regularly, in a competitive enviroment for example, maybe a manual transmission would be a better option?
 
TheCracker
If your going to be doing it regularly, in a competitive enviroment for example, maybe a manual transmission would be a better option?
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Yes it would. IMO automatics are in general faster then their manual equivalents since the driver doesn't need to change gear while accelerating hard.

Professional race drivers can't match the gear change speeds of the most advanced semi autos/autos of today. Hell, all the new stuff coming out is pretty amazing. Audi's DSG system is getting excellent write ups. The Ferrari F1 shifts are supposedly blisteringly fast too.
 
When i buy the Skyline off Dad (hopefully before the end of this year) i wil start saving up for a manual gearbox as i like to have more control over the car. And it's not doing the engine any favours with a auto. :/

It has over 201,000km's on the odometer and its still going strong! :D
 
RacyBacy
Hell, all the new stuff coming out is pretty amazing. Audi's DSG system is getting excellent write ups. The Ferrari F1 shifts are supposedly blisteringly fast too.
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SMG's in general are very fast, exponentially faster than their standard counterparts. Imagine motorcycle transmission speeds. I had the actual numbers a while ago (well below a tenth of a second), but can't find them now.
 
RacyBacy
I know road testers hold revs in neutral (e.g. 6000 rpm) and then slam the car in to drive to achieve better acceleration times.
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This is totally, completely, and utterly incorrect, and it will quickly lead to a broken CV joint, driveshaft, or internal damage to the transmission. No road tester would ever do that, certainly not if they ever expected a manufacturer to lend them a car to test ever again.

A durability tester working within a company might do so in order to make the drivetrain fail, but that's not what you're talking about at all.

In answer to the original question, Doug, as others have said you won't hurt the car doing that as long as you don't hold it for more than a few seconds at a shot (10 or so). The main thing is heat buildup - heat kills an automatic trans (though not as quickly as a neutral drop will).
 
neon_duke
This is totally, completely, and utterly incorrect, and it will quickly lead to a broken CV joint, driveshaft, or internal damage to the transmission. No road tester would ever do that, certainly not if they ever expected a manufacturer to lend them a car to test ever again.
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All road testers aren't saints! If anything, doing that sort of start will have an effect on the transmission or the stall converter. Not the CV joint. The transmission would probably be sitting on the ground if you did that with an auto. This technique can be done with a manual though. You just smell a burnt out clutch afterwards.

In my original post duke I was referring to manual transmission cars, not automatic. When I said drive, I really meant forward gears. Sorry for the confusion. :dunce:

There is really no point in holding an automatic car at say 3000 rpm with your foot on the brake unless you want to shave a few tenths off your acceleration times. Not worth it IMO. It's just premature wear of the transmission components.
 
I would have thought that revving any car to 6000rpm and dropping the clutch/slamming it into drive would produce a huge amount of wheel spin and smoke and very little forward motion, rather than any meaningful exceleration.
 
Exactly, unless you have slicks or a really weak car. I launched at the track at 3,000rpm and still spun huge drag slicks at least 3 full revolutions then pulled the front tires off the ground about an inch both sides when it did hook.
With street tires I cant launch over 1,500RPM without frying the tires.
This is why an AWD vehicle has a huge advantage over a RWD car when launching.
Similar to why a WRS STI will own a Corvette Z06 taking off from a light. 4 tires giving traction instead of 2.
 
Yeah that's true. But a little wheelspin can actually make for a quicker getaway. Most people dump/slip the clutch to achieve marginally better times.
 
RacyBacy
Yeah that's true. But a little wheelspin can actually make for a quicker getaway. Most people dump/slip the clutch to achieve marginally better times.
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The idea is to get a little closer to the engine torque peak. The old drag racing rule of thumb, I believe, is to to set your stall speed a little under the RPM where the torque peaks, and shift at the horespower peak (assuming that the gearing won't drop you well below the torque peak after you shift).
 
Thanks everyone!

The car's a 2000 Audi A4. We just had the automatic transmission replaced a few months ago, but the lag seems to be getting worse by the day. Literally, you press the gas and a second later, it goes. If you pay attention at intersections you can time it so that you press the gas and when the light turns green, the car goes, but I hate doing that. So this is really the way to do it. Anything's better than starting from 1100 or whatever idle is.
 
If the lag is actually getting worse, then you might want to have the car looked at. Maybe you have an ignition related problem like plugs or coils or the throttle position sensor is messed up.

BTW, don't take this advice too seriously, I'm three sheets to the wind. :dopey:


M
 
Perhaps coming off the brakes a little first to start the car gently rolling forward might help? - but i don't know, its been years since i last drove an auto!
 
///M-Spec
.....or the throttle position sensor is messed up.
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That may very well be the case especially if Audi is using "Throttle by Wire."

I know that a few auto IS 300's are experiencing some "lag" issues with it's throttle by wire system. The issue was easily fixed with a new patch, or whatever the hell they call it, on the ECU.
 

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