Drag racing stall converters, hold in rpm slip?
#594156
01/25/10 11:33 PM
01/25/10 11:33 PM
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mark7171
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When racing do you want to hold the vehicle at peak torque with the stall slip?
My blocks torque peak at 4000rpm, so choose a stall converter that will multiply torque( sometimes x 2.5 torque at stall) in the stall lock up range(4000 rpm). Then use a staged rev limiter, and drivetrain gearing, to hold the engine rpm in the torque multiplications .
Just looking for advantages. If your making your peak torque late, was hoping you could keep slipping and rev limiting to hold yourself in a sweet spot. After the launch.
Last edited by mark7171; 01/26/10 02:17 AM.
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Re: Drag racing stall converters, hold in rpm slip?
[Re: mark7171]
#594157
01/26/10 09:47 AM
01/26/10 09:47 AM
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Anonymous
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Anonymous
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For max ET, the rule of thumb is to use a converter that stalls 800 to 1,000RPM below where your motor wants to be shifted..........In a drag race only situation, you don't worry about torque because you can make up for it with the rearend gear and transmission ratios multiplying torque.......  Wayne
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Re: Drag racing stall converters, hold in rpm slip?
#594158
01/26/10 01:12 PM
01/26/10 01:12 PM
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Florida
Locomotion
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I think you may be confusing "stall" and "flash". My converter "flashes" to 5-5,300 at launch. I shift around 66-6700.  I forgot at the moment what my rpm's drop down to when I shift, but if it's too low, it will get into the converter and slip, hurting accelleration. I can footbrake my car up to 3,500, usually a little below that. I've had it to 4,000. But a lot has to do with the brakes, gearing, torque, etc. But each car is different. I've seen more detailed explainations of "stall" and "flash", just don't recall where and don't have time to look. How well a car leaves at a certain rpm also has a lot to do with how the carb is set up. The higher the rpm, the less pump squirt is left for the rest of the pedal travel to open the carb all the way. But it also starts the main metering system flowing. Many say that a lower launch rpm can help flash the converter higher for a harder launch. Again, a lot of variables.
Last edited by Locomotion; 01/26/10 01:16 PM.
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Re: Drag racing stall converters, hold in rpm slip?
[Re: Locomotion]
#594159
01/26/10 02:04 PM
01/26/10 02:04 PM
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Anonymous
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Anonymous
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Quote:
I think you may be confusing "stall" and "flash"..........
If you're talking to me, I'm not confused about anything....... 
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Re: Drag racing stall converters, hold in rpm slip?
#594160
01/26/10 04:43 PM
01/26/10 04:43 PM
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Joined: Jan 2003
Posts: 5,894
Florida
Locomotion
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Quote:
Quote:
I think you may be confusing "stall" and "flash"..........
If you're talking to me, I'm not confused about anything.......
Well, actually both!  But I'm just saying that there needs to be a little more clarification so others can understand better what's trying to be said.
If a converter lets one hold the car against a footbrake to 800-1000 rpm below shift point, it will probably flash too high and be a dog. If it flashes at least that far below the shift points, it will work much better. But it doesn't hurt to discuss the car and application with the manufacturer of whatever brand one chooses.
competitionplus.com torque converter article
Car Craft torque converter article.
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Re: Drag racing stall converters, hold in rpm slip?
[Re: Locomotion]
#594161
01/26/10 11:38 PM
01/26/10 11:38 PM
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Anonymous
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Quote:
Well, actually both! But I'm just saying that there needs to be a little more clarification so others can understand better what's trying to be said.
That's why I wrote "rule of thumb"...to leave myself some wiggle room...... 
Quote:
If a converter lets one hold the car against a footbrake to 800-1000 rpm below shift point, it will probably flash too high and be a dog. If it flashes at least that far below the shift points, it will work much better. But it doesn't hurt to discuss the car and application with the manufacturer of whatever brand one chooses.
I haven't experienced that.......
I used to have a 3,920LB race weight '66 Belvedere that had 3.54 gears, 28X9 slicks, pump gas stock stroke 440 with stock 906's, small solid cam, small tube headers, M1 single plane, 850 carb, and a 9.5" Dynamic converter.......I could go wide open throttle (and hold the car there) when the first amber came on foot braking.....it would stall right at 5,500 and I'd just let go of the brake on the bottom amber......I'd shift at 6,200 on the first shift and 6,400 on the second and it ran 11.60's @ 115 pulling the front wheels off the ground.......With tighter converters it would go slower (I tried all kinds of crap with that car trying to pick it up).......
I also had a '69 GTX that weighed 3,940LB race ready.....had 3.55 gears.......496" 440 with a turd hydraulic cam, headers, Torker 2 intake, 850, and a 9.5" Dynamic........converter would foot brake to 5,000 (that was WOT)....I'd shift at 5,800.........and it ran 11.70's @ 113........and it too was slower with tighter conveters.......
Wayne
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Re: Drag racing stall converters, hold in rpm slip?
#594162
01/27/10 02:53 AM
01/27/10 02:53 AM
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Joined: Jan 2003
Posts: 27,421
Balt. Md
383man
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Quote:
Quote:
Well, actually both! But I'm just saying that there needs to be a little more clarification so others can understand better what's trying to be said.
That's why I wrote "rule of thumb"...to leave myself some wiggle room......
Quote:
If a converter lets one hold the car against a footbrake to 800-1000 rpm below shift point, it will probably flash too high and be a dog. If it flashes at least that far below the shift points, it will work much better. But it doesn't hurt to discuss the car and application with the manufacturer of whatever brand one chooses.
I haven't experienced that.......
I used to have a 3,920LB race weight '66 Belvedere that had 3.54 gears, 28X9 slicks, pump gas stock stroke 440 with stock 906's, small solid cam, small tube headers, M1 single plane, 850 carb, and a 9.5" Dynamic converter.......I could go wide open throttle (and hold the car there) when the first amber came on foot braking.....it would stall right at 5,500 and I'd just let go of the brake on the bottom amber......I'd shift at 6,200 on the first shift and 6,400 on the second and it ran 11.60's @ 115 pulling the front wheels off the ground.......With tighter converters it would go slower (I tried all kinds of crap with that car trying to pick it up).......
I also had a '69 GTX that weighed 3,940LB race ready.....had 3.55 gears.......496" 440 with a turd hydraulic cam, headers, Torker 2 intake, 850, and a 9.5" Dynamic........converter would foot brake to 5,000 (that was WOT)....I'd shift at 5,800.........and it ran 11.70's @ 113........and it too was slower with tighter conveters.......
Wayne
Your 66 Belvedere is very close to the 440 in my 63. I use 906 heads and the MP .557 cam. An 850 DP with the Holley SD intake. I also use a 9.5 Dynamic converter and I have 4.30's with a 30 x 9 tire. I foot brake it to about 2500 on the line . Leave as the last yellow comes on and shift it at 6200. Traps about 6400 running mid 11's. I have the stock power drum brakes so I dont think I could hold it on the line floorboarded if I tried.  It drives like a stock converter and flashes about 4200. Ron
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Re: Drag racing stall converters, hold in rpm slip?
[Re: 383man]
#594163
01/27/10 09:15 AM
01/27/10 09:15 AM
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Joined: Feb 2007
Posts: 6,295
U.S.
moparniac
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for you guys that leave off the 2 step to you hold the pedal to the floor and let the chip bounce or hold the pedal where the chip is gonna bounce then hammer the pedal on go ??? thx
Mopar Performance
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Re: Drag racing stall converters, hold in rpm slip?
[Re: moparniac]
#594164
01/27/10 09:38 AM
01/27/10 09:38 AM
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Posts: 52,972
Romeo MI
MR_P_BODY
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Quote:
for you guys that leave off the 2 step to you hold the pedal to the floor and let the chip bounce or hold the pedal where the chip is gonna bounce then hammer the pedal on go ??? thx
That would depend on RPM... if its too low of a RPM and
your foot is on the floor you wont have enough/ if any
pump left... if its higher RPM it would have enough
air passing to be on the WOT circuit and not bog.
I tried some lower RPM launches on the T-brake and
the car fell on its face... gave it a quick let off
and hit it again and it took off
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Re: Drag racing stall converters, hold in rpm slip?
[Re: MR_P_BODY]
#594165
01/27/10 10:38 AM
01/27/10 10:38 AM
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Joined: Jan 2003
Posts: 3,616
Riverside, Ca
G_bob
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My motor made peak torque at 5000 on the engine dyno, hp at 6500. My converter flashes 5800-5900 and I shift at 6700.
4.56 gear and a 32" tire.
I'm using a brake and a two-step, but I've found that my car launches harder with the two-step set at 3000 than it did at 4800.
4800 netted 60 fts at 1.45-6.
3000 has it consistently in the 1.39's.
Oh, and I mat it on the first amber and just let the two-step do it's work.
Your results may vary.
Last edited by G_bob; 01/27/10 10:40 AM.
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Re: Drag racing stall converters, hold in rpm slip?
[Re: 383man]
#594166
01/27/10 01:45 PM
01/27/10 01:45 PM
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Anonymous
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Anonymous
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Quote:
Your 66 Belvedere is very close to the 440 in my 63. I use 906 heads and the MP .557 cam. An 850 DP with the Holley SD intake. I also use a 9.5 Dynamic converter and I have 4.30's with a 30 x 9 tire. I foot brake it to about 2500 on the line . Leave as the last yellow comes on and shift it at 6200. Traps about 6400 running mid 11's. I have the stock power drum brakes so I dont think I could hold it on the line floorboarded if I tried. It drives like a stock converter and flashes about 4200. Ron
I used to leave at WOT all the time with 4 wheel drum brakes......I did that when racing 12.0 index.......I'd slow it down by capping it up and running through the air cleaner.......My car wasn't any faster than foot braking it to 3K, but when racing 12.0 index on a 4/10's tree I could cut .470 to .490 lights by doing it that way.........
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Re: Drag racing stall converters, hold in rpm slip?
#594167
01/27/10 01:56 PM
01/27/10 01:56 PM
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Joined: Jan 2003
Posts: 27,421
Balt. Md
383man
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Too Many Posts
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Posts: 27,421
Balt. Md
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Quote:
Quote:
Your 66 Belvedere is very close to the 440 in my 63. I use 906 heads and the MP .557 cam. An 850 DP with the Holley SD intake. I also use a 9.5 Dynamic converter and I have 4.30's with a 30 x 9 tire. I foot brake it to about 2500 on the line . Leave as the last yellow comes on and shift it at 6200. Traps about 6400 running mid 11's. I have the stock power drum brakes so I dont think I could hold it on the line floorboarded if I tried. It drives like a stock converter and flashes about 4200. Ron
I used to leave at WOT all the time with 4 wheel drum brakes......I did that when racing 12.0 index.......I'd slow it down by capping it up and running through the air cleaner.......My car wasn't any faster than foot braking it to 3K, but when racing 12.0 index on a 4/10's tree I could cut .470 to .490 lights by doing it that way.........
That makes sense. I found on the .5 tenths tree if I leave as the last yellow comes on I cut real good lites (.004 and .018) last time out. I know I would have to adjust with my car on a .4 tenths tree. So I can see how and why you do it. Ron
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