Stalling Stageas

[DaveB]

Hi all,

I'm looking for advice on 'stall launches'. I've read the DIY question on 'getting it off the line', but this seems to have been written for S1's, and I have a S2.

What's the deal with the brakes "creeping" - ie. the car "driving through the brakes"? Mine doesn't do that, no matter how much throttle I give it. And since upgrading my turbo by getting it hi-flowed by GCG and getting the full 3-inch exhaust/hi-flow cat/dump, 500hp in-tank walbro etc. and Nistune and tune, my stall launches are much **less** impressive... what's going on? How many rev's do you need to stall it to? Or doesn't it matter - full throttle will do? 'Cause in the R34 service manual it describes a 'stall test' of the transmission where the accelerator is held at full throttle for 5 seconds to determine stall speed. I don't know what's going on when you guys say it drives through the brakes... mine just doesn't. Maybe this is a series 2 thing.

[kidafa]

deff not a series 2 thing........ If you put your foot on brake hard and apply the go pedal, keeping applying the go pedal till the car tries to creep forward through the brakes. (your rears might do slow revolotions at this time) take a tiny bitt of go pedal to stop it creeping and hold it their till you want to fly then remove left foot and flat to the floor! I wouldnt hold it for too long cos i cant see it being good for your trans!

[munchstagea]

If you are bogging down, either not enough herbs, or your transmission is slipping. Got a boost gauge? What are you boosting to when stalling it up? I have seen this don properly by the original author and it works well. Quick tyre chirps on dry road before heading for the horizon.

[lachlanw]

are you saying if you floor the brakes then floor the gas your car will not start to move ? does it build boost ? are you jus leaving it in D and not 2nd in tiptronic or anything?

[QWK32]

works well for me dave, stock turbo running 12psi. launches really hard, sits up just over 2000rpm and boost is right up there, often will spin the rear while stalling it up and on take off, and like you have read, it does tend to overcome the brakes sometimes. maybe because you have a hiflow it needs more rpm to get the turbo going and therefore you aren't making as much power down low as us with the stock turbo that would spool full boost with a fart. you may need a higher stall convertor if hard launches are what your after.

Edited September 3, 2009 by QWK32

[Stinky Rooster]

The reason you cant launch like that, is because the true stall speed of your converter is too low. Now that you have a hiflow, and the resultant shift in the torque band (ie higher up the rev range) what you are actually doing is building up a crapload of excess heat in your tranny and running the risk of ballooning your converter. I dunno what "test" the manual is supposed to replicate, but just keep in mind that most stuff like that in the manual is for stock, and stock only. The true way to figure out the stall speed of your converter (as a rough guide) is to hold the car in second gear at a slow roll - less than 20kph. Stand on the accelerator and watch the tacho closely. The revs will rise before the car actually surges forward, and the rev range you reach as you feel the car surge is pretty close to the true stall speed. (this is usually anywhere between 500-1500rpm higher than the flash stall speed)

For the launches you want with the hiflow, you can either get your converter modded for a higher stall speed (awesome takeoff, but it will kill your fuel economy, not to mention the costs involved. A torque converter has to be cut apart and then welded back together) or use a transbrake, but the shock loading this would put on the trans, diffs and attessa systems would be horrific.

[RBPOWA-(TJ)]

hey Dale, im looking into a torque converter. but very confused about how they work, i know your rev it up to say 3500rpm before the car starts to creep. but how do they work in normal daily driving,

and if im driving along and overtake by putting my foot down, with the thud or is it just like driving without one, only on the stall up stage :S

if that makes sense, anyone is welcome to answer

[QWK32]

hey Dale, im looking into a torque converter. but very confused about how they work, i know your rev it up to say 3500rpm before the car starts to creep. but how do they work in normal daily driving,

and if im driving along and overtake by putting my foot down, with the thud or is it just like driving without one, only on the stall up stage :S

if that makes sense, anyone is welcome to answer

just think of it as like a clutch that slips unit you hit a certain rpm, then it grabs. a high stall will drive just like the standard one, if you watch the gauge when you put your foot down the rpm rockets up to about 2000rpm before slowing up and reving out normally. with a higher stall convertor say 3500rpm. when you plant the foot the rpm will very quickly hit 3500 then rev out as normal.

Edited September 3, 2009 by QWK32

[Stinky Rooster]

dude, it would take me waaay too long to explain it in fully, so read this

http://automichanic.wordpress.com/2009/06/...rque-converter/

The "stall speed" of the converter is controlled by the pitch angle (and ergo the amount of directional change and speed the fluid is moving at) of the blades in both the turbine and the impellor.

Basically, what you want to acheive is the point where the engine is making most torque, at the point where the converter is closest to lock up, where the turbine and pump are spinning at closest to the same speed as possible. This is so the torque multiplication effects are strongest where you need them, and have the least amount of convereter drag right when you dont want it.

[RBPOWA-(TJ)]

. . . . i'll read the link thanks

[DaveB]

Thanks for all the info and tips guys... especially advice on checking boost at stall - hadn't even thought of that (I haven't had a boost guage very long and it's mounted a bit low lol).

Since the turbo upgrade it still launches *hard*, but it's not *violent* like it used to be stock... when the passenger struggles to keep hold of the stopwatch at launch.

RBPOWA-(TJ) - I have in fact investigated high stall convertors... we are lucky enough to have one of the nation's most awesome transmission shops here in sleepy old adelaide and I spoke to them a while ago now. I had them fit a 'heavy-duty high-stall convertor' just this week, picked the stag up yesterday in fact. Apparrently stock stall is only around 1,800 (!!!!?!?!) and it has now been upped to around 2,800. I'll have to see how the fuel goes yet lol... but basically it feels quicker everywhere at the moment. Just a stall launch still not like stock

I dunno if new torque convertors need running in... So going easy on it for the moment... only done about 50 k's.

However, just did a brief 'check boost at stall' test and noticed boost reads 0psi (no boooost!!). At ~3,500-4,000 I get about 18psi so I think a boost controller is in order (I have *no* boost controller atm)... what do you guys think?

Edited September 3, 2009 by DaveB

[BensDR30]

Dave, it sounds like you're approaching the point of diminishing returns in regards to the streetability of your ride. Eventually the HP increase (and supporting modifications) are outweighed by the decrease in practicality.

Having said all that, I've got a 4-cylinder converter in my Z, which has a stall speed about 400rpm higher than the 6-cylinder one, and it's a pretty good thing. I'm not sure if fitting a CA or SR converter would be feasible or achieve the same outcome behind an RB, but it might be worth talking to MV's about your options.

But do have a care about the well being of your gearbox - heat kills and stalling up makes lots of heat...

[DaveB]

The reason you cant launch like that, is because the true stall speed of your converter is too low. Now that you have a hiflow, and the resultant shift in the torque band (ie higher up the rev range) what you are actually doing is building up a crapload of excess heat in your tranny and running the risk of ballooning your converter. I dunno what "test" the manual is supposed to replicate, but just keep in mind that most stuff like that in the manual is for stock, and stock only. The true way to figure out the stall speed of your converter (as a rough guide) is to hold the car in second gear at a slow roll - less than 20kph. Stand on the accelerator and watch the tacho closely. The revs will rise before the car actually surges forward, and the rev range you reach as you feel the car surge is pretty close to the true stall speed. (this is usually anywhere between 500-1500rpm higher than the flash stall speed)

For the launches you want with the hiflow, you can either get your converter modded for a higher stall speed (awesome takeoff, but it will kill your fuel economy, not to mention the costs involved. A torque converter has to be cut apart and then welded back together) or use a transbrake, but the shock loading this would put on the trans, diffs and attessa systems would be horrific.

Sounds like good advice Stinky'... did just what you have suggested, and got a hi-stall convertor. Couldn't believe the poxy 1,800rpm stall on the stock one! Still guess that's good for fuel economy.

Edit: yes Ben, you're right there... on all accounts I figure at least I haven't got a huge turbo, FMIC and 1,000cc injectors... but yeah I like to take the car places and the 'wagon-ness' is handy... oh, and I don't want to come across like some traffic-light-drag-crazed nut who stomps on both pedals at once at every opportunity!! It was just an experiment, when I got the car and it was on the road and running well, to try a stall launch - after hearing about how good attesa was at keeping the wheels from spinning and how good a 'real' 4wd launch was - and I was so impressed, I was kinda hoping that the turbo upgrade (sort-of necessary since the turbo was whining so loud that passengers were complaining!) wouldn't kill that. But it has a little... still, it's an awesomely fun car to drive, and I have taken it as far as northern vicland a couple times... still plan to 'use it' for the forseable future.

Edited September 3, 2009 by DaveB

[kidafa]

did they fit a shit kit aswell while you were their dave? Yeah your correct about Mike at MV automatics knowing his shit..... Im going to get a shift keen soo installed by them and bands tightened ect ect.... If i dont buy that uncompliable manual s1 thats for sale with chef.

No boost when its stalling up seems a bit weird to me. as for what boost controller to get, i highly recomend a profec b spec II by greddy. Nice and small, easy to install and self tune, stealth hi low button easily made. will get plenty of change from 500 if you shop around aswell

[DaveB]

did they fit a shit kit aswell

lol I had a shift kit, yes "stage 1", got it installed a while ago. big difference. no. HUGE difference. I would go so far as to say that if you are upgrading your power in any way, you *need* this. My transmission was flaring a little sometimes even with stock power (130rwkw). Mind you the shift solenoid rack and pressure regulator (all get replaced together) later went faulty so that may always have been on the way out. It made it past 120,000K's though so this was probably the usual RE401B troubles.

This service they told me about some development work they'd done for the stagea; an aluminium servo in place of whatever the stock one is which controls the bands, or something like that (I know even less about it than I do the valve body upgrade/shift kit, which I had them install). They said that it would make the shifts more consistent and help with the longevity of the transmission. I had been noticing that the changes weren't always as firm from 1st-2nd, ie. the 'crispness' of the shifts would vary a little across the rev' band, and I knew how expensive an excercise it was to have one of these gearboxes removed (regardless of whether you can get a 2nd-hand one for $400, you still have to disconnect the ATTESA line etc.). So I went for the servo upgrade and I have definitely noticed that the shifts are always 'crisp' and fast now. I think it felt almost as different as when I had the shift kit installed. I highly recommend both

[kidafa]

how much did it set you back?

might give them a call today and see what prices are ect for shift kit or this and then a price for the both at once.

[DaveB]

The convertor is more expensive than the shift kit 'cause they only have to drop the pan & valve body I think for the shift kit; whereas for the torque convertor will need the transmission out (somewhere around $600+ in labour I believe) and then a day or two's wait while the torque convertor is sent off to be rebuilt. Definitely ask about getting it done all together because maybe you can save some labour there. Let us know how it goes... if you have an auto you need a shift kit makes a big difference

...just don't get one if your favorite thing about the stagea is how smooooth and quiet it is, 'cause from here that starts to diminish... shift kit will make shifts harsher. But the transmission bands should last longer (now the transmission *mounts* I'm not sure of...)

[kidafa]

i do like how smooth and quiet it is but ive got all the bolt up modds ebc, safc, sitc, fmic, 3inch full zhorst ect ect so its getting upwards of 170 at the rears and the the dyno shop (boostworx) seem to thing that the auto trans is sapping a fair bit of power from it and that it might be slipping a bit.

ive got a bigger trans cooler on it but think its prob worth it.... just need to give it a view days while i um and arrr over buying that uncomplied 5speed s1 thats here.

[DaveB]

i do like how smooth and quiet it is but ive got all the bolt up modds ebc, safc, sitc, fmic, 3inch full zhorst ect ect so its getting upwards of 170 at the rears and the the dyno shop (boostworx) seem to thing that the auto trans is sapping a fair bit of power from it and that it might be slipping a bit.

ive got a bigger trans cooler on it but think its prob worth it.... just need to give it a view days while i um and arrr over buying that uncomplied 5speed s1 thats here.

Nice - sounds pretty good to me. I've only ever had mine tuned at boostworx as well and I'm only making about 15kw more than you with a neo and gcg hiflow. Tho I spose I don't have a FMIC...

I'm hoping that my trans will now sap less power with the upgraded stall convertor. Just driving it in traffic it's amazing - no need to stall, just plant your foot and it's at 3,000 revs instantly! It really takes off now. Plus I tested out what it might be like when I get my IEBC installed - I removed the vacuum hose on the wastegate actuator and at stall like that I can make at least 5psi And that's not even flooring it... awesome. Can't wait to see what it'll be like after this next tune with the IEBC.