Converter swap.. Whats it good for?

[Super73]

I know this is a very generic question as it would depend on your set up, but I'm going from a 3,200 to a 4,400. The best I was doing dead hooking at the track was a 1.87 average 1.89. If you look at my dyno, It needs more verter period. I shift at 7,400.

http://73-ls1.com/63truck/new_tune_11_27.JPG


If you had to guess, what do you think the new 60's would be?


Any of you have first hand with converter swaps and what they did for your ET?

[Bob West]

Its hard to say how much its going to be worth. I swapped from a 11" BM holeshot to a 10" ATI and gained NOTHING, I swapped from the 10" ATI to an ATI 8" converter and ended up gaining 3-4 tenths which included suspension tuning that had to be done to get it dead hooking again. If you shift at 7400 I still dont think you have enough converter. just my opinion.

[Super73]

Gonna be spraying it too.. 100 out of the hole. I might move to 200 if I can keep it hooked. That's why I went with a 4,400..

[John_Heard]

The spray will loosen it up quite a bit.

[sc racing]

I know this is a very generic question as it would depend on your set up, but I'm going from a 3,200 to a 4,400. The best I was doing dead hooking at the track was a 1.87 average 1.89. If you look at my dyno, It needs more verter period. I shift at 7,400.

http://73-ls1.com/63truck/new_tune_11_27.JPG


If you had to guess, what do you think the new 60's would be?


Any of you have first hand with converter swaps and what they did for your ET?

Just wondering...... if your peak power is at 6560 why do you shift so high?This is just my opinion (and Im not saying I correct ) but I thought shift points were about 500 rpm above peak.I would think you would pick up some et if you shifted earlier.Again just my opinion.

[sc racing]

I just looked at the graph again and your peak is actually about 6400.I would try a shift point @ 6800-7000.IMO

[Super73]

The higher I shifted it the faster it went at the track. I think using the peak to judge where to shift might be realitive to how fast the power actually falls off. But that is just a guess.

[rustbucket]

if your gonna spray 200, the 3200 converter may be better. I went from a 4200 stall to a 3000 and picked up 4/10ths in the 1/8th mile on nitrous. went from a 1.5 sixty to a 1.30.

[sc racing]

The higher I shifted it the faster it went at the track. I think using the peak to judge where to shift might be realitive to how fast the power actually falls off. But that is just a guess.

If it goes faster at the higher shift point your guess is probably fact .It doesnt drop off a lot between 6600 and 7000.

[Super73]

I'm wondering if it has to do with shift extension and TQ multplication.

Fist being a 2.48
Scond a 1.48
Third 1

Bellow are the numbers (Gears * TQ at rpm relative to shift point)

7,400 first = 682 vs 5,400 second = 559
7,000 first = 774 vs 5,000 second = 567


7,400 second = 407 vs 5,500 Third = 378
7,000 second = 462 vs 5,100 Third = 378


Being with my set up, anywhere in the RPM range the lower gear ratio has a better TQ number than the next gear. The TQ hasn't fallen off enough at 7,400 to match the TQ at 5,400-5,500.