How do you rate your stall? At 0 PSI?

[Six_Silver]

When you say your convertor is a 3500 stall (or whatever), what psi is that at? My convertor stalls to 2800 at 0psi, but 4800 at 20psi on the transbrake (goes up about 100rpm per PSI).

So do I have a 4800 stall, or a 2800 stall??

 

[Six_Silver]

 

[WSLN 6]

I would say the honest stall would be 0 psi. Mine stalls at 3500 rpm at 0psi boost. JMO.

 

[Six_Silver]

Well if that is the case, why are so many of you guys running 3600 stalls at 0psi? I bought a "3400 stall" last year, and on the transbrake it went to 5400! So I went to a 2800 @ 0psi and now its much better.

Are all of you 10 sec guys really running a 3400-3600 stall at 0psi???

 

[Otto J]

Mine is only about 2400 at 0 boost
but 5900 at 26#s

 

[chris718]

the more boost you build the more torque you make.what that means is stall speed is based on a specific amount of input torque.therefore it is mandatory to know torque band in selecting a converter. the turbo in use and the specific mechanical limitations of the parts used at a given engine speed will dictate a particular rpm range and torque band for a given combination .it is this information that should be used to select a starting line rpm that will launch the car properly based on what rpm the car will leave.obviously an engine makes more power as the rpms increase however a motor that makes maximum power at 5500 rpms cannot leave the starting line at that rpm r youd red line as soon as you took off and have no rpm range to be used to accellerate the car from a dead stop.we rate our convertors at 400 lbs ft input torque and if the engine in question needs to leave at 3400 rpms and it makes 500lbs ft than we would use our 3200 rpm converter part number but it would yield the extra stall based on the effects of more torque more stall more stall more boost more boost more torque.it is wisse with the buick gns to understand operating ranges of 3500 to 5500 rpms in slightly modified form and understand thatwe will try tio leave at 3500 rpms and use 2000 rpms until redline to accellerate the vehicle against operating resistance in the form of vehicle weight drag coefficient and friction etc.if the converter will hold 8 psi at 3300 and jump 200 rpms as the brake is lifted or dumped then the selection is correct.if it wont build 12 or 15 or whatever on the br4ake it will when you dump the brake without effort .get the point.sometimes leaving with excessive boost is counterproductive to maximum accelleration.

 

[bird]

looking over some log files from my previous trip to the track (see sig for times) these are the readings i got, this is without a trans brake, on a 9" slick.
1 psi boost at 2250 rpm
6 psi boost at 3000rpm
8 psi boost at 3250 rpm
10 psi boost at 3350rpm
15 psi boost at 3800rpm (already moving at this point).
this is a 9" a/c non lock up convertor. its supposed to be 3800stall ??? i held the foot brake until about 7-8psi mashed the gas to the floor then the brakes would give and away i went. i wonder if i could use a little more stall?

 

[Razor]

My car has a 3600 9x11 L/U. At 3400 RPMS it will read 2 PSI boost. When the lights come down leaving at 2 PSI has netted me low 1.5 60 foots on multiple occassions. This is with 100% OEM suspension. Letting the converter flash. On the tree I can cut .500 lites of the foot brake.

Vs the 2800 I had that required me to stand on the brakes to get it and build boost then launch. And bring out the egg timer.

HTH

 

[bird]

what tachs are you guys using to take these readngs? im using the FAST system or my autometer tach. im startng to think ive got too low of a stall. i was under the impression that stall speed rating was at max engine speed before you couldnt hold the car and had to release the brakes (footbrake in my case), any opinions

 

[chris718]

stall speed is the maximum rpm the engine can reach with the transmission in gear ,and the car being held stationary by the brakes or the transbrake.some combinations will have so much energy stored in the driveline that the converter can not reach maximum stall speed without pushing through the brakes and tires.if your brakes can hold the energy that is stored in the driveline then whatever rpm the engine reaches can be accurately used to give you a stall speed for the combination in question.if the brakes cannot hold the energy that is stored in the driveline ,maximum stall speed will never be reached without the use of a transbrake.this device applies forward and reverse gears simutaneously to lock the transmission internally.this does not allow any stored energy into the drive line therefore maximum stall can be reached without overpowering the brakes and tires.

 

[bird]

chris, thanks for the info, so because im not using a transbrake in my particular situation my max stall speed would would be limited by the foot brake which i can hold for about 7-8psi at 3200rpm before the stored driveline energy overpowers the brakes. therefore as it stands right now with an aproximate 200rpm flash when releasing the brakes my current max stall speed is aprox 3400. if i was able to hold more boost or installed a transbrake these figures would be considerebly higher. do you think i could benifit from a looser convertor (currently using an a/c n/l 9")? ive been considering upgrading to a billet.

 

[chris718]

how much torque does the engine make and at what rpm?what is the 1/2 shift rpm?

 

[bird]

unfortunately ive never had it dynoed. its a full weight t-roof car that runs over 130 mph(see sig). id be guessing at the torque but im sure its over 500lbs. the cam is a small roller 210 210. i think pte recommends a min 3600 convertor with this turbo. i was running a 69a/r 4bolt on center exh housing last year but will be trying a larger 81a/r this year. i let the trans shift 1/2 itself at 5600-5700rpm. any recommendations based on this vague data

 

[chris718]

if you change converters,i think youll have a coupling efficiency problem unless you go to a lock up.i think that the 3350 you see shouldlnt be a problem with a 5700 rpm shift point.any higher you wont have rpm to move the car through first gear.if you can build 10 psi on the foot brake your doing okimo.the car would leave harder at 3600 or so but you can do it with that converter if you add a transbrake or change the gear ratio in the transmission to a 2.40 first gear.if this is not what you want then tou must replace or restall the converter which will be the cheapest way out.

 

[bird]

thanks for the advice, i really appreciate your honesty, looks like i have a few options to consider.

 

[evil666]

I have a red stripe torque convertor which should be a 2800 stall. I have never tried stalling the car at 0 lbs of boost to see at what rpm my torque stalls at. The only thing I can tell you is that when I crank the boost up to 5lbs the torque stalls at about 2600. When I Crank the boost up to 9lbs the torque stalls at 2900+ rpm. I haven't tried more than 9lbs of boost, but I did my best 60ft this way.(1.52) I don't have a trans brake on my car, I use the foot brake with the RON CUSTOM MAX BOOST BRAKE MODULE which works extremely well for me. I was never capable of holding more than 5lbs boost on foot brake before, until I installed the brake module from ron customs and rebuilding my master cylinder. I have never tried launching the car at more than 9 lbs of boost but I am positive that with this brake module you can hold up to 12 lbs+. For my set up I am satisfied with the RON CUSTOM MAX BOOST BRAKE MODULE, I have done my best 60ft times with this brake module.

86 Grand National t-top (59000km)
stock long block,stock suspension, red stripe convertor, te44, smc alk injection, 24lbs boost, 94 octane, hooker cat back with dyno max ultra flow muffers, tomco 30lbs injectors, dyno stage 4 street chip, thdp, mease 24 row IC, MT drag radials (275/50/15) 3800lbs race weight.

best ET
60FT=1.52
1/8= 7.38
I/4= 11.74
MPH=113
BEST MPH= 114

 

[jsta6]

What is "RON CUSTOM MAX BOOST BRAKE MODULE"?

==HIJACK THREAD HERE:==

What difference will a line-lock have, if any, on how much boost you can hold?

 

[evil666]

What is "RON CUSTOM MAX BOOST BRAKE MODULE"?

==HIJACK THREAD HERE:==

What difference will a line-lock have, if any, on how much boost you can hold?


__________________

The difference with a line-lock is that it will lock only your front brakes and release any pressure going to your rear brakes so you don't damage your brake drums, and it also makes it much easier to heat up your tires. The Ron Custom Max Boost Brake Module works differently from a line-lock. The way it works is that when it is engaged by a momentary switch it bybasses the stock brake proportion valve and sends alot more pressure to the rear brakes which makes it alot easier to create boost off the line. I have done my best 60ft (1.52) at 9 lbs of boost, but I am sure that I could hold up to 12 lbs or even more but still haven't tried it. The only thing I know is that this brake module works well for me, and if you want to know more about it you should do a search and see other people's opion.


86 Grand National t-top (59000km)
stock long block,stock suspension, red stripe convertor, te44, smc alk injection, 24lbs boost, 94 octane, hooker cat back with dyno max ultra flow muffers, tomco 30lbs injectors, dyno stage 4 street chip, thdp, mease 24 row IC, MT drag radials (275/50/15) 3800lbs race weight.

best ET
60FT=1.52
1/8= 7.38
I/4= 11.74
MPH=113
BEST MPH= 114