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Conv stall difference With just a gear change
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DRR Pro
Picture of 00 DEAD ON
posted
In the same dragster, same tune up, same day, same everything. With only a gear change what will the stall do? More or less and why.
Let’s say with the 389’s it stalled 6100 rpm’s. What would it change if anything with the 430’s? WHY?
1. With 389 gears
2. 430 gears
Thx in advance


Brian Mollison
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Posts: 1024 | Location: Stafford, Virginia | Registered: October 03, 2006Reply With QuoteReport This Post
DRR Pro
Picture of TORQIN
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The 4.30 will be less stall would be my guess. The 3.89 will load the motor more to cause more stall.

JMO, would like to know the results?
 
Posts: 1569 | Location: Houston, Tx. | Registered: November 27, 2008Reply With QuoteReport This Post
DRR Trophy
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^what he said. 4.30 makes car easier to move so less stall.. I saw roughly 100-125 rpm between 4.10s and 4.30s in 1900 lb dragster all else the same.
 
Posts: 101 | Location: Ohio | Registered: December 19, 2014Reply With QuoteReport This Post
DRR S/Pro
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The converter is just a load cell, more load equals more stall. With the gear change you listed, it will reduce the load. As for how much, it's a guess,,, not a bunch though.
In a TS car, we went from 4.56 to 4.12 (the 56's broke in TT's, got it fixed for first rd), hardly saw any real difference on the racepack files. 60' certainly suffered though!
 
Posts: 1942 | Location: Tewksbury, MA,USA | Registered: November 03, 2000Reply With QuoteReport This Post
DRR S/Pro
Picture of Mike Rietow
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Depends on the power. The closer the rpm is to increasing at a rate higher than the torque is diminishing, the lower the stall, due to power. The opposite also holds true.

Power (rate of doing work dependent on torque and rpm)

Only power effects stall.


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Posts: 8834 | Location: Madeira Beach Fl. | Registered: June 12, 2018Reply With QuoteReport This Post
DRR S/Pro
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quote:
Originally posted by Mike Rietow:

Only power effects stall.


Not sure why I even commented on this one knowing there's an expert in the house...

But that aside, no, more than power effects stall, load does also!

You can carry on now... Ibbadee Bibadee!
 
Posts: 1942 | Location: Tewksbury, MA,USA | Registered: November 03, 2000Reply With QuoteReport This Post
DRR Pro
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higher number > tighter . lower > looser . et gain not worth the effort imo . loosen the converter 700 . top 38 … truth ,,,,,
 
Posts: 1144 | Location: middle georgia | Registered: July 20, 2003Reply With QuoteReport This Post



DRR S/Pro
Picture of Mike Rietow
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quote:
Originally posted by TOP38:
quote:
Originally posted by Mike Rietow:

Only power effects stall.


Not sure why I even commented on this one knowing there's an expert in the house...

But that aside, no, more than power effects stall, load does also!

You can carry on now... Ibbadee Bibadee!


So a 4.30 gear would be less load? Or more load? Confused


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Posts: 8834 | Location: Madeira Beach Fl. | Registered: June 12, 2018Reply With QuoteReport This Post
DRR Pro
Picture of rusty
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it really only affects flash right,less than 200 is my GUESS


opinions are worth what you pay for them
1.036, 6.16@ 224

 
Posts: 1235 | Location: texas | Registered: February 17, 2006Reply With QuoteReport This Post
DRR Trophy
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What does it all matter in a bracket car, 200 stall difference ain't worth losing any sleep over it. IMO that car should never of had a 3.89 gear in it anyway unless it weighed 1500 lbs and was maxxing out at 6800, that was just a dumb f'n move.
 
Posts: 40 | Location: Work | Registered: April 27, 2008Reply With QuoteReport This Post
DRR Sportsman
Picture of Mike Frizie
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getting ready to swap to a 4:30 myself after next race. will have to remember to check my logger after the swap.


Michael Frizie
ET 2471
2011 Diamond Chassis Dragster
 
Posts: 549 | Location: Winston, GA | Registered: April 10, 2002Reply With QuoteReport This Post
DRR Sportsman
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In my dragster the stall changes 250ish rpm when I leave in high gear. Can't imagine you'd see much change with one gear size


Denis LeBlanc

 
Posts: 347 | Location: Manchester, NH | Registered: February 03, 2006Reply With QuoteReport This Post
DRR S/Pro
Picture of Mike Rietow
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quote:
Originally posted by FastFreddy:
What does it all matter in a bracket car, 200 stall difference ain't worth losing any sleep over it. IMO that car should never of had a 3.89 gear in it anyway unless it weighed 1500 lbs and was maxxing out at 6800, that was just a dumb f'n move.




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https://youtu.be/I8QWEaqeFRw

1996, 1998, 2001, 2003, 2005, 2006, 2008 Super Pro Champion Sunshine Dragstrip, Clearwater Florida
 
Posts: 8834 | Location: Madeira Beach Fl. | Registered: June 12, 2018Reply With QuoteReport This Post
DRR S/Pro
posted Hide Post
quote:
Originally posted by Mike Rietow:
quote:
Originally posted by TOP38:
quote:
Originally posted by Mike Rietow:

Only power effects stall.


Not sure why I even commented on this one knowing there's an expert in the house...

But that aside, no, more than power effects stall, load does also!

You can carry on now... Ibbadee Bibadee!


So a 4.30 gear would be less load? Or more load? Confused


I can only lead the horse to water, can't make them drink.

So let's try this simple EX one for you,
take your typical RED dragster, 4 link if you prefer with a BBC that runs say 7.50 in the 1/4! Run it on the same day with and without a wing and for hell of it, say its one from a TAD car...

POP Quiz, which run has more load on the converter running down the track?
 
Posts: 1942 | Location: Tewksbury, MA,USA | Registered: November 03, 2000Reply With QuoteReport This Post



DRR S/Pro
Picture of Mike Rietow
posted Hide Post
quote:
Originally posted by TOP38:
quote:
Originally posted by Mike Rietow:
quote:
Originally posted by TOP38:
quote:
Originally posted by Mike Rietow:

Only power effects stall.


Not sure why I even commented on this one knowing there's an expert in the house...



But that aside, no, more than power effects stall, load does also!

You can carry on now... Ibbadee Bibadee!


So a 4.30 gear would be less load? Or more load? Confused


I can only lead the horse to water, can't make them drink.

So let's try this simple EX one for you,
take your typical RED dragster, 4 link if you prefer with a BBC that runs say 7.50 in the 1/4! Run it on the same day with and without a wing and for hell of it, say its one from a TAD car...

POP Quiz, which run has more load on the converter running down the track?


I'm gonna say eenie, meanie miny moe, catch a tiger by its toe,if it hollers let it go, eenie meanie miny moe!,,, The dragster with the wing has less load! No wait! Hold on! The dragster with the wing has more load! So this must mean more load, more stall? Hmmm, so this means rpm's will drop back less at the shift, meaning more stall, more load with a wing? Confused


https://youtu.be/FZ6zwnyDwUg

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https://youtu.be/I8QWEaqeFRw

1996, 1998, 2001, 2003, 2005, 2006, 2008 Super Pro Champion Sunshine Dragstrip, Clearwater Florida
 
Posts: 8834 | Location: Madeira Beach Fl. | Registered: June 12, 2018Reply With QuoteReport This Post
DRR S/Pro
posted Hide Post
quote:
Originally posted by Mike Rietow:
quote:
Originally posted by TOP38:
quote:
Originally posted by Mike Rietow:
quote:
Originally posted by TOP38:
quote:
Originally posted by Mike Rietow:

Only power effects stall.


Not sure why I even commented on this one knowing there's an expert in the house...



But that aside, no, more than power effects stall, load does also!

You can carry on now... Ibbadee Bibadee!


So a 4.30 gear would be less load? Or more load? Confused


I can only lead the horse to water, can't make them drink.

So let's try this simple EX one for you,
take your typical RED dragster, 4 link if you prefer with a BBC that runs say 7.50 in the 1/4! Run it on the same day with and without a wing and for hell of it, say its one from a TAD car...

POP Quiz, which run has more load on the converter running down the track?


I'm gonna say eenie, meanie miny moe, catch a tiger by its toe,if it hollers let it go, eenie meanie miny moe!,,, The dragster with the wing has less load! No wait! Hold on! The dragster with the wing has more load! So this must mean more load, more stall? Hmmm, so this means rpm's will drop back less at the shift, meaning more stall, more load with a wing? Confused


HMMMM
 
Posts: 1942 | Location: Tewksbury, MA,USA | Registered: November 03, 2000Reply With QuoteReport This Post
DRR Top Comp
Picture of Curly1
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On my car I went from a 4.10 to a 4.30 and it should stall a little lower due to less load and moving car easier but could not see any difference at all on logger. Your change is a larger change than mine was but I still would not expect much difference maybe 100-200 RPM?


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Posts: 3152 | Location: United States of Texas | Registered: April 02, 2011Reply With QuoteReport This Post
DRR Sportsman
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quote:
Originally posted by rusty:
it really only affects flash right,less than 200 is my GUESS


It would affect the top end slip % too, and the fallback RPM. Lower numerically “taller 3.89 gear” will make a higher flash and higher slip percentage since the gear makes the car harder to move “more load.”

Higher numerically “lower shorter 4.30 gear” makes the car easier to move so it will have a lower flash and less top end slip percentage.

I don’t have a guess on how much the flash will change, but the top end RPM won’t be altered as much as math says it will since there will be less top end slippage with the 4.30.

The math says that for a 33.5 tire 3.89 gear at 7300 with zero slip you’d go 187 mph. Change to a 4.30 gear and now you have to spin it about 8075 to go 187 mph. But like I said you’ll slip it less with the shorter gear so the RPM difference won’t be quite so high.
 
Posts: 563 | Location: Upstate NY | Registered: July 02, 2013Reply With QuoteReport This Post
DRR S/Pro
Picture of Mike Rietow
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quote:
Originally posted by 183N:
quote:
Originally posted by rusty:
it really only affects flash right,less than 200 is my GUESS


It would affect the top end slip % too, and the fallback RPM. Lower numerically “taller 3.89 gear” will make a higher flash and higher slip percentage since the gear makes the car harder to move “more load.”

Higher numerically “lower shorter 4.30 gear” makes the car easier to move so it will have a lower flash and less top end slip percentage.

I don’t have a guess on how much the flash will change, but the top end RPM won’t be altered as much as math says it will since there will be less top end slippage with the 4.30.

The math says that for a 33.5 tire 3.89 gear at 7300 with zero slip you’d go 187 mph. Change to a 4.30 gear and now you have to spin it about 8075 to go 187 mph. But like I said you’ll slip it less with the shorter gear so the RPM difference won’t be quite so high.


Now you're talking. The only thing left out of your forecast is power. The rate the torque is diminishing in relation to the rpm increasing, is the determining factor.

Only power effects stall. While at the same time, the only constant in the logger or math will be a more efficient converter with a higher numerical gear.

4 gear changes in 11 laps will validate this.



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Posts: 8834 | Location: Madeira Beach Fl. | Registered: June 12, 2018Reply With QuoteReport This Post
DRR Pro
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I like to look at things like this in extremes so as to get a better understanding.

Lets say we have an engine that makes 1000hp. But it is strapped in a 500lb go-cart. For the following lets assume no traction issues. You put the trans in 1st gear and stomp on the throttle and the converter will go up to a certain rpm and then the gocart starts moving. Since it is light and has extra gear ration it moves easy therefore the rpm is lower. In this case the go cart could be so light and the gearing so steep that it doesn't reach maximum potential stall since the load is so small.

Now put the engine in a 4000lb land yacht with highway gears and the trans in hi gear then stomp on the throttle. The rpm will be much higher before it starts moving because the load is much greater. Therefore load does effect stall.

Change the engine to a 500hp engine and in both scenarios the stall would be lower. So yes power does effect stall also.

So, Maximum potential stall is achieved when the load is heavy enough to reach the point where, to use quoted text, "The rate the torque is diminishing in relation to the rpm increasing" becomes the point where it can't be any higher rpm because the power is diminishing faster than the load is decreasing.

I have had the same car with rear gears between 3.89 and 4.33. I didn't see much stall change. About 100 rpms. And that was flash stall right after the transbrake release. I feel it didn't change much because even with the gear change the load was always enough to just about reach the maximum potential stall. That said though Fallback stall remained nearly the same for all gears. This is because the load was always enough to reach maximum potential stall. Slip percentage and the 1/4 mile finish line got better with every numerically higher gear.

Scott
 
Posts: 1838 | Location: Illinois | Registered: August 20, 2000Reply With QuoteReport This Post
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