converter slippage

-
aaronk785

aaronk785

Well-Known Member
Joined
Apr 21, 2013
Messages
1,021
Reaction score
851
Location
westmoreland ks.
Is 16% slippage excessive. Purchased a new 8 in. custom converter from a reputable company not a cheapie. This is in the 1/8 mile. Will it lock up more in the 1/4 since it should be past its max hp rpm. Still pulling hard on the converter in the 1/8. I'm at 6200 in the 1/8 at 103 mph. Going to run the 1/4 this weekend and don't want to run out of rpm. 7200 is the max I want to turn. Car has 4.56 gears and 29.5 slicks. How much rpm approx. will I gain in the last 1/8 mile. I know there a lot of other factors. Just want to know from your experiences. Thank you.
 
I dont think the % of slippage is going to change regardless of the length of track....
 
You're gonna need less gear. 7200 is plus 16% rpm(over 6200). and Plus 16% rpm should be plus 16% mph; so 7200 is good for 120mph. Ima thinking you will be out of rpm before you are out of track!
Stated another way; 103 @6200 is 103/(6200x1000)=16.613 mph per thousand rpm. So 16.613x(7200/1000)=119.613mph

4.30s would get you;4.56/4.3=1.0605 more mph @7200 or about 127mph
4.10s would get you;4.56/4.10=1.1122 more mph@7200 or about 133mph

trapping at 7200,suggests a power-peak at/or around 6800;That's a heckof an engine!
 
Last edited:
dont know what the slippage is on our Turbo Action converters.. but with 4.56 gears...29.2 diameter tires...worse case we would hit 7100 at 128 mph...
 
Same converter size and gears here. You're going to cross the 1/4 around 7400-7600 with that gearing and tire size depending on your shift point.
 
Thanks for the replies. Thanks for the formulas a/j . And thanks for the comparison Rockin. Going with 4.30 gears. 90% of my racing is 1/8 mile otherwise I would do 4.10s The 7200 is well past power band. I would guess max hp at around 6300 or so. Shift at 6500 to 6600 for best E.T. That's just the max I would want turn the engine. Thanks again.
 
I dunno man,
(6500x29.5x3.1416)/(1056x4.30x1.00)=about 133mph,less TC slip.
If your TC is slipping 16%, then the speed is reduced by that same slip; so 112mph.
Or you can take it off the rpm; 6500 less 16% is 5460; and
(5460x29.5x3.1416)/(1056x4.3x1.00)=about 112mp.
16% seems like a lotta slip....
I did the math on your numbers in post#1, and I too get about 16% slip.Here's what I did;
(103x1056x4.56)/(29.5x3.1416)=5352rpm......and 6200on the tach/5352=1.158 or about 16% over.
If you have the power to go 103 in the 1/8, I think you're gonna need even less gear for that TC...I don't know the conversion factor for 1/8 to 1/4, but to hit say 128@6500 with 16% slip, you will need;
(128x1056x1.00)/{(6500/1.16=5603) x29.5x3.1416}=1/.260=3.84s ..That's about half way between 3.73s and 3.91s.
Going with the 3.91s and re-arranging the formula, I get;
(128x1056x1x3.91)/(29.5x3.1416)plus 16%=5702x1.16=6615rpm
Did I get that right?
 
Last edited:
Thanks A/J. I can see you are way better at math than me so ill take your word for it. I have the 4.30s so that's what I will use. Not optimum but better than 4.56s. I'm going to send the converter back this winter. 16% is way to much. From what I've heard this company will try to make it right. And I cheated and used the Wallace calculator to get my %.
 
Just got back from battle of the brands at hpt Topeka. Ran a 10.53 at 126.54 tonight was test and tune. Any way my torque converter slippage came out to 10% down from the 16% I figured in the 1/8 mile. With the 4.30s I am at 6800 at the stripe. So about perfect. Didn't hurt my 1/8 mile times with the 4.56s so I am pleased. I am at a loss but that's OK it worked out well.
 
You must log in or register to reply here.
-

Back
Top