Pretty clear in that chart!

 

The car felt JUST AS FAST with the T56, so I didn't "gain" any speed. It's weird, but that's how it worked out.

The converter was a locking 2,600 stall Pro Torque...maybe there was something wrong, I don't know. Also, the stall was set before the new motor. With the new motor, it probably stalled 2,700 - 2,800 RPM. I honestly don't recall if it was locked in that run or not.

-Alex

 

I have also seen up to 50rwhp difference in a M6 car who swapped to a stalled Th350. My car only made 370rwhp and ran 11.15@121mph N/A @3,450lbs,3.55's and 26" ET streets. You can't get too caught up in dyno #'s esp. when the trans is an auto and chassis dyno's are involved. A change in tire pressure can change readings. A dyno is a tuning toll guys. Later Clint

 

When I had my auto, stock stall, I dyno 322rwhp. With the only change being a 6-spd, I put out 356rwhp.... I went from 111.0mph traps to 115.0mph traps in the 1/4....

 

I went from 405 SAE (manual) to 370 SAE (stalled auto), back in the day....
I figure I lost about 2.5 miles per hour trap speed...

 

Hmmmmm, that is a little over 9% difference between the stick and the auto. That is more than I would have thought.

 

Actually, I'v found an old dyno that I had after the swap....
400 locked...370 Unlocked.....So, that's was only 5 loss tranny to tranny(locked) after the swap. I never run my car that way but it makes a good comparison....30 rwhp is what I lost on unlocked verter back then (rather high, but my stroker knocks the stall right out of then).

The 9% difference you calculated is mostly the converter slip. There is some numbers that would not change with more hp...(the internal friction and pump turning loss would almost always stay the same, no matter how much hp you throw at it) and these two together = the big loss....Inertial style dynos do have a hard time loading stalled autos so, the real loss through the unlocked verter is hard to calculate. The 2 1/2 mile per hour loss does speak for itself.....

 

Did you open up the tranny, sounds like it was slipping to me

 

FYI: mine lost ~100rwhp (from ~700 to ~600) going from a T56 to a TH400 with a race converter. However, it went ~0.2 seconds quicker and a tad faster with the swap. Sucked for street driving however.

Rich

 

Never opened her up...sold it right after the swap.

-Alex