Average RPM slippage on a conv

S/ST 3040 · 03-26-2017, 08:01 PM

Quote:

Originally Posted by ken robinson

Whats the average rule of conv. slippage = in RPM +/- ? I'm trying to see what the top end RPM is with different rear gear ratio's .... RPM x tire dia. / by MPH X 336 = ring & pinion ratio . That formula dosen't account for conv. slippage , and is giving me the wrong gear ratios ....The car goes thru at 6750 x 28 tire / average 115 mph x 336 = 4:85 gear . But thats not true because it runs a 4:30 not a 4:85 . What would it go though with 4
:56 like 7150 rpm in average air ? My math / formula is wrong or I'm missing some thing .

115 x 4.30 x 336 / 28 = 5934 RPM (drive shaft RPM)

5934 x 100 = 593400 / 6750 = 87.9% (or 12.09% slippage)

115 x 4.56 x 336 / 28 = 6293 (drive shaft RPM)

6290 / .879 = 7159 RPM

The 4.56 gear should let the converter show better efficiency but, no way of knowing
exactly how much. Like was already stated, tire growth will affect the final number.

Dyno · 04-11-2017, 10:27 PM

5% slippage is a good number to shoot for.

jaf2021 · 04-14-2017, 06:38 PM

What if your % is 112?

Dyno · 04-14-2017, 09:39 PM

you are slipping 12 %

jaf2021 · 04-15-2017, 09:10 AM

Converter too loose????
I would have to double check but I think there is about a 1200 RPM drop between gear change(PG)

Mark Yacavone · 04-15-2017, 12:24 PM

Ken, Ever try a 4.10 with that converter?

ken robinson · 04-16-2017, 11:55 AM

I have not tried the 410 gear yet . I need to try the lower 1st gear before I try the 410 . Its a low rpm torque combo mainly so I see your point Mark . Thanks

04-11-2017, 10:27 PM	#2
Dyno Senior Member Join Date: Dec 2002 Posts: 912 Likes: 1,123 Liked 674 Times in 201 Posts	Re: Average RPM slippage on a conv 5% slippage is a good number to shoot for.

04-14-2017, 06:38 PM	#3
jaf2021 Member Join Date: Oct 2004 Location: selmer,tn Posts: 111 Likes: 13 Liked 5 Times in 5 Posts	Re: Average RPM slippage on a conv What if your % is 112?

04-14-2017, 09:39 PM	#4
Dyno Senior Member Join Date: Dec 2002 Posts: 912 Likes: 1,123 Liked 674 Times in 201 Posts	Re: Average RPM slippage on a conv you are slipping 12 %

04-15-2017, 09:10 AM	#5
jaf2021 Member Join Date: Oct 2004 Location: selmer,tn Posts: 111 Likes: 13 Liked 5 Times in 5 Posts	Re: Average RPM slippage on a conv Converter too loose???? I would have to double check but I think there is about a 1200 RPM drop between gear change(PG) Last edited by jaf2021; 04-15-2017 at 09:14 AM.

04-15-2017, 12:24 PM	#6
Mark Yacavone Veteran Member Join Date: Mar 2002 Location: Miles From Nowhere Posts: 7,790 Likes: 2,882 Liked 5,080 Times in 1,936 Posts	Re: Average RPM slippage on a conv Ken, Ever try a 4.10 with that converter? __________________ "We are lucky we don't get as much Government as we pay for." Will Rogers

04-16-2017, 11:55 AM	#7
ken robinson Member Join Date: Dec 2001 Location: tomsriver nj Posts: 477 Likes: 72 Liked 213 Times in 85 Posts	Re: Average RPM slippage on a conv I have not tried the 410 gear yet . I need to try the lower 1st gear before I try the 410 . Its a low rpm torque combo mainly so I see your point Mark . Thanks