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torque converter pain

Posted By: nhramark

torque converter pain - 09/08/03 03:23 AM

My torque converter is so loose...... it makes Madonna look good! This motor is 3 tenths faster than the old one. The 60' is a tenth faster, and thats tripping it with the REAR tires. The mph is the same at 139, but the finish line rpm is 7600(!) instead of 7000 or so before.

I'm leaving a ton of et and mph on the table. Maybe one of you guys could figure the slippage for me?

4.56 gear
14.5 x 32w Hoosier slicks
3040 lbs w/me
139 mph
7600 rpm
9.45 et

Thanks
Posted By: clutch

Re: torque converter pain - 09/08/03 04:22 AM

I've been going through the same thing. at 0 slip you would be turning 158.58MPH at 7600 so about 12%.
Posted By: Leigh

Re: torque converter pain - 09/08/03 10:17 AM

Can't help you right now with slip %, my weather station is in the work shop, but, did you get the Hal valved QA1's for the front? They seem to have completely cured the wheelstand problem I had. Time will tell, when the super air rolls around, but, I only got about 2' for 25-30', and that was in DA of 2300'. Normally, it would be 4'+. You may want to call him!
Posted By: OhioGTX

Re: torque converter pain - 09/08/03 12:35 PM

I ran your numbers and came up with 12.39% slip. That is quite a bit of HP left on the table.

4.56 gear
14.5 x 32w Hoosier slicks
3040 lbs w/me
139 mph
7600 rpm
9.45 et

Here is a formula for calculating the percentage converter slip. The parameters are:
MPH = trap speed in MPH
RATIO = rear gear ratio
CIRC = tire circumference (diameter * 3.1416)
RPM = trap engine speed in RPM

% slip = 100 - (MPH x RATIO x 105600)/(RPM x CIRC)

% slip = 100 - (139 X 4.56 X 105,600) / (7600 X ( 32 X 3.1416)

% slip = 100 - ( 66933504 / 764037.12)

% slip = 100 - 87.605042

% slip = 12.39498


Wow that is loose, time for a tighter converter. Plenty of ET and MPH on the table.
Posted By: nhramark

Re: torque converter pain - 09/09/03 02:52 AM

Thanks for the formula, I adjusted it by figuring in rear tire growth. If the rear tire grows 1", which is probably conservative, the slippage jumps to 15.04966. Ouch!

I may try a new PTC. Have been hearing good things about them. Probly have to wait a couple weeks or so, totally tapped out on race car money right now.
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