[Jim Robertson]

For the guys with data acquisition equipment...
How much convertor slip do you actually see on the top end? I am looking for simple engine rpm to driveshaft speed difference. Guessing and speculating does not count.

We cannot get our convertor guys to commit to a number that they would consider good or acceptable. The best drive shaft speed we are seeing is around 85% of the engine rpm. It seems this could be improved.

Thanks,
Jim

[rompn63]

I had a 4 speed Jerico in my car and I let myself and other people convince me my car would go faster with an automatic and have less breakage. Boy, was that a mistake.
I have a Racepak V300 I use to moniter clutch slip and engine functions. It was worth its weight in gold when I put the turbo 400 in my car. I tested 6 different converters that slipped from 12% to 5%. I finally gave up on the turbo 400 and put a 5 speed in my car. I picked up 3 tenths and 3 mph.

[Jim Robertson]

rompn63,
Good info...about convertor slip and the manual vs auto shoot out. Who's convertor produced the least slippage (5%) and who's resulted in the quickest et? Were they the same convertor? Thanks for sharing.

Anyone else with good data willing to share?

Thanks,
Jim

[dammen8]

My dynamic convertor has 5% slippage...not confirmed from data equipment but this was done with a calculator....

Chad

[rompn63]

All my converters were built by Jim Paquet's JPT Transmissions in Eaton Rapids MI.
Jim has the ability to build any type converter you want.
He worked with me for over two years trying 8", 9", and 10" converters. He would cut them open to modify the stall and weld my converter back together while I waited.
The 8" gave me the best 60' times but slipped 10% thru the lights.
The 10" slipped 5% but stalled too low for my car. The 9" was the best compromise it gave me good 60's and slipped 5% thru the lights.

[lust4speed]

Don't think I need electronics to confirm your suspicions that 15% slip is way too much. I also have only worked it out using the Wallace Racing website calculator, and for what it's worth, my old but still working 8" Art Carr converter has 8% slip.

[TOP 452]

Jim It was a pleasure talking with you last night. Don

[Jim Robertson]

Don,
Likewise. Thanks for sharing your info.
Best of luck on the new combo. Update us all on the progress as it nears completion. It will be significant. :-)
Jim

[455-4+1]

I ran the data logger and fuel on a BBC rail here up until a year or so ago

Alcohol 530 BBC, Big Cheif heads, 14-71 producing around 40lb, Iron block

Trans was 2 stage PG (aftermarket case, all the goddies etc)

Prior to blower ran 7.30 @ 180 and had around 6% slip at the the top end
Would flash to around 7000 at launch and go through the traps at 8800

Now with the blower, new shortblock, trans, covertor, gears tyres etc as follows
The lauch is off around 3000 rpm and flashes to around 5k. Rpm is down to around 7800 and runs around 6.70 @ 215 (convertor is at around 8% at end of run)

I will try and track down a scan of a old N/A trace and post