Convertors???????????

Bobtempest

Moderator
Staff member
Torque convertors are seldom mentioned here. I have a ATI from Bill Anderson, it is a well made convertor, top quality. What kind of stall you guys run with a 3600-3700lb, 272, GN1s and a 76 Q-trim, 3.42 gears. I still run a 200 by Bruce T. It its holding up well. How much RPM shift drop do you get or should see? What does it flash to at launch? Come on guys give some feed back.
 
What, no one runs a convertor? Yea. Cannot believe no feed back on this. I know all combos are different but a little imput might help someone.
 
I ran a very tight TCI 8 inch. It stalled to 3000 as soon as I floored the gas on the transbrake. Took a little while to build boost, something like 2.5 seconds to get to the 4400 rpm two-step. Drove pretty good on the street though. With the 8000 rpm capable solid roller boost was only a downshift away. If I was to want to race it in competiton of any kind I would have changed it to a 3500-4000 stall. Same combo as yours but with T400 and 3.7 gears. Car went 1.50 sixty foots and 138 in the quarter.
greg
 
I like my ATI 9"!

Bob,

I also have an ATI converter. I bought it through Alan Roehrich, he was a good guy to work with. I run a TH350. The converter is a 9" and I requested a stall of 3500. I'll be damned if it doesn't stall at exactly 3500 (about 10psi boost). My combo is newer, so I haven't fully explored the capabilities. The last time out, I was shifting at about 5300 and it would drop 400rpm at each shift. I know I can shift higher with my combo, I just haven't got there yet. This convertor only has about 3% slip. I was doing 120mph at about 5500 with a 25.5" tall tire and 3.42 gears.
I really like this converter, its a quality piece.

Eric
 
Bob,

Hows it going? We talked a while back. if you like I can send you some DS runs to see the shift rpm drop and what rpm i left at with my Yank conveter. did you ever find out out if you had a 74 or a 76 turbo?
 
Just checked out a post on another board Bob, and I dont agree with the response you got.You have the "Right" convertor. Compare apples to apples (weight vs boost vs launch vs shift rpm vs turbo size vs gears vs tire size!). Any way to tell if the trans was slipping or the tires were spinning on the 1-2 shift? I do agree you have not fully tapped your combinations potential. You will probably run as fast or faster with your 76mm wheel at the same boost stated with ALOT more weight and no balls (bearings)!
Keeping the rpm drop to a minimum without excessive slippage is the key to lo ET's, 400rpm is reasonable, shifting higher as well as more gear will give you a greater rpm drop as well. Call me directly if you wanna tighten it up but you may not be happy with the results!! I am positive that anyone who knows the weight and level you have it cranked to would be foolish to say they are not impressed with what you have accomplished!
Thanks,
Bill
 
Thanks for the post Bill.
The Trans is fresh and I am not slipping. I did not detect the tires slipping. I just keep being told by other guys in the 9's that I was "driving over the convertor." I was told this by a trans guy/ racer also. All these guys planted the idea that I was 600-800 too loose. That is why I had the uncertainty. I understand what you are saying, makes sense.
You are just the only person that told me about keeping the rpm drop to a minimum without excessive slippage is the key to lo ET's. I guess everyone thinks I am losing a lot of HP due to excessive slippage. But maybe I am not.

I always thought, one also wanted the convertor to keep the engine in it power band. Guess I am.

At 134.44 and 6300 RPM with the 3.42 gear, 28.5 slick with a 200 trans - what is the slippage. I remember someone saying they knew how to calculate it.
Thanks for the help.
 
Looks like about 9-10% accoring to my calculations. On the looser end of the scale but not unreasonable for a turbo car. Several ways to resolve this. Obviously tighten the convertor, reduce the vehicle weight, shift higher, put more gear in the car. I think if you tighten it up, you wont really be satisfied with the spool up or the launch. If you wanna give me a buzz at the shp and we can discuss it.
Thanks,
Bill
 
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