stall speed

One of the most critical areas of a automatic race car

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fishman
Posts: 56
Joined: Sun Nov 05, 2006 4:51 pm
Location: alberta,canada

stall speed

#1 Post by fishman » Wed Oct 01, 2008 10:46 pm

My convertor stalls at 4900 rpm and on the dyno my motor made its peak torque from 5100-5300 rpm....i am going to send it in to get loosened up was thinking about getting it set up somewhere around 5800 rpm....i also have another question as this convertor was used in my old motor and with 75 less horse my 60 foot times were better because of peak torque was down lower, by loosening up the convertor will this change my shift points as right now when it shifts from 1st gear to second my tach drops close to 1500 rpm.....the tranny is a pg with 1.74 gear......car weight is 2460 with me in it........peak horse power was at 6700 rpm....shifting it at 7000 rpm........my last pass it ran 9.81@133.6 mph my 1/8 was 6.26@108 mph..what will loosening the torque up do to my top end........the reason i am asking was thinking about going with a bigger cam as seems like last 100 feet does nothing for me........have 4.86 gears and 32x14x15 tires in 98 inch wheel base car......thanks in advance
Last edited by fishman on Sat Oct 04, 2008 8:32 pm, edited 1 time in total.

Marty Chance
Posts: 193
Joined: Fri Sep 19, 2008 6:34 am
Location: Cheney, KS

Re: stall speed

#2 Post by Marty Chance » Sat Oct 04, 2008 6:08 pm

1500 rpm drop on the shift is a bit too tight , so you are correct about raising the stall but i would be cautious about raising it too much , because if you are bracket racing you may loose some consistancy if the car launches too hard , but if you do some heads up racing then 5800-6100 would be ok and when you bracket race you could use an msd digital box to pull timing out on the launch and control how hard it hits the tires. As far as the effects of loosening the converter has on top end performance it will most likely work better and not have much if any increase in slippage and this is because slippage is relative to how the car accellerates , in other words because the converter is too tight it labors the motor right after the launch and after the shift so if we raise the stall (slippage) the motor will accellerate faster and get to the lock up mode of the converter sooner there for not increasing the slippage (we call this "keeping the motor happy") hope this helps , Marty Chance
Neal Chance Racing Converters
Home of the World's Fastest Automatic Doorslammers!
www.racingconverters.com

rich
Posts: 107
Joined: Mon Aug 18, 2008 6:37 pm
Location: kennewick wa near hanford

Re: stall speed

#3 Post by rich » Sat Oct 04, 2008 7:04 pm

Marty Chance wrote:1500 rpm drop on the shift is a bit too tight , so you are correct about raising the stall but i would be cautious about raising it too much , because if you are bracket racing you may loose some consistancy if the car launches too hard , but if you do some heads up racing then 5800-6100 would be ok and when you bracket race you could use an msd digital box to pull timing out on the launch and control how hard it hits the tires. As far as the effects of loosening the converter has on top end performance it will most likely work better and not have much if any increase in slippage and this is because slippage is relative to how the car accellerates , in other words because the converter is too tight it labors the motor right after the launch and after the shift so if we raise the stall (slippage) the motor will accellerate faster and get to the lock up mode of the converter sooner there for not increasing the slippage (we call this "keeping the motor happy") hope this helps , Marty Chance
that was a great reply easy to understand love it when someone can speak to all of us without needing a degree or an interpeter to try and figure out if what you think was said is what was meant

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fishman
Posts: 56
Joined: Sun Nov 05, 2006 4:51 pm
Location: alberta,canada

Re: stall speed

#4 Post by fishman » Sat Oct 04, 2008 8:31 pm

Marty Chance wrote:1500 rpm drop on the shift is a bit too tight , so you are correct about raising the stall but i would be cautious about raising it too much , because if you are bracket racing you may loose some consistancy if the car launches too hard , but if you do some heads up racing then 5800-6100 would be ok and when you bracket race you could use an msd digital box to pull timing out on the launch and control how hard it hits the tires. As far as the effects of loosening the converter has on top end performance it will most likely work better and not have much if any increase in slippage and this is because slippage is relative to how the car accellerates , in other words because the converter is too tight it labors the motor right after the launch and after the shift so if we raise the stall (slippage) the motor will accellerate faster and get to the lock up mode of the converter sooner there for not increasing the slippage (we call this "keeping the motor happy") hope this helps , Marty Chance
Thanks for the reply Neal very informative and helpfull.....so i will send it in and get it loosened up to 5800 rpm....under my combination by changing stall speed what should i expect for gian 1 tenth...2 tenths...........as i am looking at changing the cam to suit the motor more and to have more grunt on the top end and also to knock the et down

Marty Chance
Posts: 193
Joined: Fri Sep 19, 2008 6:34 am
Location: Cheney, KS

Re: stall speed

#5 Post by Marty Chance » Mon Oct 06, 2008 7:38 pm

impossible to accurately forcast how much faster the car will be and you may want to hold off on the cam change until after you make the converter change and test it , making two changes at once can give you hard time figuring out if one helped and the other hurt because it usually results in less gain than you expected and you dont know if one slowed you down and the other picked you up or vise versa (just a suggestion) marty chance
Neal Chance Racing Converters
Home of the World's Fastest Automatic Doorslammers!
www.racingconverters.com

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fishman
Posts: 56
Joined: Sun Nov 05, 2006 4:51 pm
Location: alberta,canada

Re: stall speed

#6 Post by fishman » Thu Oct 23, 2008 11:07 pm

Hi Marty

First of all i am going to take your advice and just do the torque converter and leave the cam change...i got the converter back today i sent it out to get loosened up and they set it up to stall at 5800 rpm.....were i live no more races until the end of April so will have just try it on the brake and no two step to see what it stalls at in my garage. It will be a long winter not doing to much to the car,, just changing the upper and lower control arms to tubular and going to a coil over shock to help my launch from the stock front end that has stock springs and 90-10 drag shocks

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