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Converter slippage... #2630834
03/09/19 05:30 PM
03/09/19 05:30 PM
Joined: Jan 2003
Posts: 338
Montreal Quebec
STROKIE Offline OP
enthusiast
STROKIE  Offline OP
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Joined: Jan 2003
Posts: 338
Montreal Quebec
There a way to figure the converter slippage...
Some say slippage can add 300 to 500 rpm or more.
Logically the slippage must be more at full throttle than cruising speed.
By the way I use B&M 10415 Holeshot 2400 Stall.
Thanks

Re: Converter slippage... [Re: STROKIE] #2630835
03/09/19 05:40 PM
03/09/19 05:40 PM
Joined: Dec 2005
Posts: 8,512
Fulton County, PA
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CMcAllister Offline
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CMcAllister  Offline
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Fulton County, PA
Tire size - gear ratio - MPH - RPM. If you know three, you can figure the forth. Typically trap speed at the track is used with the car under power. However much more the RPM is than what the formula says it should be, is how much slippage there is.


If the results don't match the theory, change the theory.
Re: Converter slippage... [Re: STROKIE] #2630884
03/09/19 08:05 PM
03/09/19 08:05 PM
Joined: Aug 2003
Posts: 39,049
Bend,OR USA
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Cab_Burge Offline
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Bend,OR USA
Originally Posted by STROKIE
There a way to figure the converter slippage...
Some say slippage can add 300 to 500 rpm or more.
Logically the slippage must be more at full throttle than cruising speed.
Thanks

A good street and strip converter will drive like a stock converter at light part throttle driving and then slip if you go to WOT below the stall speed, it should lock up and have less than 10% slippage at or above the stall speed, especially in high gear above 5000 RPM
Measure the circumference of both rear tires and inflate them so they are within 1/4 inch of each other on the circumference and then do the math for your RPM at the finish line in the 1/8 or 1/4 mile and see how much more or less your calculations show.
IE if you see 6600 RPM in high gear in the 1/4 mile and your calculations how 125 MPH and your time slips says 120.0 MPH your doing good, if it shows 125 MPH and your time slips says 105 MPH your not doing so good.
Anything more than 10% is not good, less is better.


Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
Re: Converter slippage... [Re: Cab_Burge] #2631178
03/10/19 07:01 PM
03/10/19 07:01 PM
Joined: Jan 2003
Posts: 338
Montreal Quebec
STROKIE Offline OP
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STROKIE  Offline OP
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Joined: Jan 2003
Posts: 338
Montreal Quebec
How can I figure the RPM at the 1/4 mile finish line.
I went to the the track a few times but I don't to know exactly the rpm at the finish line... shruggy
Thanks

Last edited by STROKIE; 03/10/19 07:03 PM.
Re: Converter slippage... [Re: STROKIE] #2631183
03/10/19 07:11 PM
03/10/19 07:11 PM
Joined: Mar 2006
Posts: 8,875
MI, usa
dvw Online content
master
dvw  Online Content
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Joined: Mar 2006
Posts: 8,875
MI, usa
Originally Posted by STROKIE
How can I figure the RPM at the 1/4 mile finish line.
I went to the the track a few times but I don't to know exactly the rpm at the finish line... shruggy
Thanks

Here you go.
Doug

http://www.wallaceracing.com/mobile/converter-slip.php

Re: Converter slippage... [Re: STROKIE] #2631204
03/10/19 08:16 PM
03/10/19 08:16 PM
Joined: Oct 2007
Posts: 3,941
New York
polyspheric Offline
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polyspheric  Offline
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New York
If you experience 10% slippage for any significant length of time, you'll know about it.
Your transmission will spout flames.


Boffin Emeritus
Re: Converter slippage... [Re: STROKIE] #2631221
03/10/19 09:09 PM
03/10/19 09:09 PM
Joined: Aug 2003
Posts: 39,049
Bend,OR USA
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Cab_Burge Offline
I Win
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Joined: Aug 2003
Posts: 39,049
Bend,OR USA
You need to watch a good tach at the finish line and use that for your calculations and use the calculator to figure the calculated MPH with your RPM, gears and tire sizes and then use your MPH to figure how much differences you have between the calculated MPH and your actual MPH.
Not all tach are as good as the better ones so choose quality over cheaper prices on buying your tach
BTW, I've seen and race with good race converters that slip over 10 % in the 1/4 mile, a really good one will slip around 2 to 5% at the finish line.

Last edited by Cab_Burge; 03/10/19 09:10 PM.

Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)






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