Stall Speed vs Torque Peak for Powerglides

One of the most critical areas of a automatic race car

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BracketNova
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Stall Speed vs Torque Peak for Powerglides

#1 Post by BracketNova » Tue May 10, 2011 6:56 pm

Is there a general rule for what powerglides like. I have read 300 - 500 below the torque...I have read 1000 rpm higher than the torque peak.


My car is a little on the heavy side ~ 3250 with me in it, 4.88 gears.
"I always compare drag racing to lighting $100 bills on fire, only it's more expensive." - Craig W.

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'71 Nova E85
6.69 @ 100.2 MPH 9/6/14
1.4257 60'
1700' DA

13:1 439 BBC
3330 lbs

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Marty Chance
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Re: Stall Speed vs Torque Peak for Powerglides

#2 Post by Marty Chance » Wed May 11, 2011 7:08 am

first of all the answer varies according to your goal (peak performance or consistancy)
heads up racers will shift at a higher rpm to increase the recovery time of the shift where a bracket application will shift much sooner to increase consistancy


second it varies with torque curve (stock headed 440 mopar vs. short stroke high rpm big head sbc)
the more low rpm torque you make the more a short shift you can get by with, but even the low torque short stroke motors can short shift if the converter stall is high enough . Most motors have about 1000 rpm spread between peak HP and peak TQ so as a rule of thumb you should start out with shifting at peak HP and let the rpm drop on shift to peak TQ then you can play around with short shifting or stretching the shift out higher and see what works best for your specific combo.

Hope this helps some, Marty Chance
Neal Chance Racing Converters
Home of the World's Fastest Automatic Doorslammers!
www.racingconverters.com

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jmarkaudio
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Re: Stall Speed vs Torque Peak for Powerglides

#3 Post by jmarkaudio » Wed May 11, 2011 9:37 am

It really depends on a lot of things, but usually for a car like yours you want the stall speed just above peak torque for best performance. And usually missing the stall a little high will effect it less than if you miss low. My 461 CI SB2 engine made peak torque at 6000, peak HP at 7100, and the converter stalled 6500. Probably a little more than you want with yours, but should give you an idea.
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BracketNova
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Re: Stall Speed vs Torque Peak for Powerglides

#4 Post by BracketNova » Wed May 11, 2011 9:01 pm

Ok...the reason why I am asking - My overly generous friend has given me a converter that stalled in his car at 6000. He had a 427BBC N/A vs my 402 BBC N/A same cars (novas within 100 - 200 lbs of eachother) his ride went .2 faster than mine. My stall is currently 5200. According to desktop dyno (i know I know) my torque peak is at 5500. Last weekend my car went 7.15 and I'm desperately trying to get under 7 (no particular reason). I ditched my trac loc and went to a full spool (that was good for 10 lbs rotational gone) and an alumiinum third member (10 lbs more). So that should help.

Here are some specs (I didn't think I would take it this far - but what the heck)
71 Nova 3250 Lbs w me
4.88 gear
28 x 10.5 stiff
Calvert split monos w/ Cal-Tracs

1.78 PG w/ sportsman brake

396 BBC .030 over
crank trigger
8.2:1
800 CFM Holley on E85
Victor Jr. Intake
Good pan w/ windage and scraper
Ported 781 heads w/ large valves
Dur: 315/330
Dur @ .050: 245/255
Lift: 595/625
Lobe Center: 112
cam installed straight up
only accessory is the alternator


What do you guys think would be an optimum stall?

When I originally ordered my converter, we spec'd it out with the cam that was in it when I bought the engine - which apparently was designed to be used with a 200 shot as it fell on its face with me trying to run it just motor.

I know my compression ratio is killing me, but I didn't have the $$$ for the custom open chamber dome pistons for the 396 when I freshened things up.
"I always compare drag racing to lighting $100 bills on fire, only it's more expensive." - Craig W.

Check out my website...
http://www.findmoneyraces.com


'71 Nova E85
6.69 @ 100.2 MPH 9/6/14
1.4257 60'
1700' DA

13:1 439 BBC
3330 lbs

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jmarkaudio
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Re: Stall Speed vs Torque Peak for Powerglides

#5 Post by jmarkaudio » Wed May 11, 2011 10:01 pm

I would be VERY surprised if your engine makes peak torque that high, I would guess more like 4500. Have you tried advancing the cam? And yes, the compression is a killer, and a tighter LSA cam should help it as well.

Who did the E85 carb? I've got two Dominators running on E85, and just finished a 1250 tonight.
Mark Whitener
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BracketNova
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Re: Stall Speed vs Torque Peak for Powerglides

#6 Post by BracketNova » Wed May 11, 2011 10:41 pm

Good Call You beat me to editing my post :oops: Double checked the software...peak is claimed to be 464 @ 5k. Maybe I'm good where I'm at (converter wise)? The car ran three 7.18s back to back at the last tnt. The fourth was the 7.15 - I believe the difference was in the water temp 170° vs 180° E85 seems to like the heat...but you know that :)

Here is what dyno 2000 claims. If I am honest and plug this curve into drag2000 the time is a little over a tenth faster...7.00 1/8th. But, I may have another degree or two in the timing yet. On gas it liked 42° I'm at 41° now...just wanted to play it safe and sneak up on it.

Haven't tried advancing the cam...how would that effect things (questioning the physics not your intelligence :-) )? Lower torque higher HP?

Mark Sullens did my carb, he did a good job.

RPM HP TQ
2000 129 338
2500 178 374
3000 220 385
3500 272 407
4000 330 434
4500 390 455
5000 442 464
5500 477 455
6000 501 438
6500 506 408
7000 490 368
7500 470 329
8000 434 285
"I always compare drag racing to lighting $100 bills on fire, only it's more expensive." - Craig W.

Check out my website...
http://www.findmoneyraces.com


'71 Nova E85
6.69 @ 100.2 MPH 9/6/14
1.4257 60'
1700' DA

13:1 439 BBC
3330 lbs

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

Re: Stall Speed vs Torque Peak for Powerglides

#7 Post by Marty Chance » Thu May 12, 2011 8:28 am

if you have enough rpm left at the finish line you could put some more gear reduction in the rear end. As for advancing the cam it will usually give you a little more low rpm torque, but sometimes hurt the top end
Neal Chance Racing Converters
Home of the World's Fastest Automatic Doorslammers!
www.racingconverters.com

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supernova
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Re: Stall Speed vs Torque Peak for Powerglides

#8 Post by supernova » Thu May 12, 2011 9:19 am

How are you getting away with 4.88's and a 28" tall tire? IMO, 3.90's would better suit your combo. I'm running 3.70's with a 1.80 low gear and 28" tall tires. Changing the gear will get you in to the 6's.
Blackhoodmafia!!!! :mrgreen: :mrgreen:

1972 Nova SS
572 C.I. BBC

Best to date: 1/8
et: 5.28
mph: 134
new wt. 3340 lbs

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BracketNova
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Re: Stall Speed vs Torque Peak for Powerglides

#9 Post by BracketNova » Thu May 12, 2011 6:26 pm

That's what the rear end shop suggested...
"I always compare drag racing to lighting $100 bills on fire, only it's more expensive." - Craig W.

Check out my website...
http://www.findmoneyraces.com


'71 Nova E85
6.69 @ 100.2 MPH 9/6/14
1.4257 60'
1700' DA

13:1 439 BBC
3330 lbs

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