A little RacePak tech

[pittsburghracer]

I have been meaning to do this all winter and finally got around to it. Late last year my five year old engine was finally showing signs of slowing down a little. I had a couple of cylinders down some on compression (one more than others), the converter was way past rebuild time, and it was over three years on my first powerglide build. Car was running 6.10@111mph at Quaker City and probably should have been 6.05@112mph. This was a spragless Transmission Specialties 8 inch converter that I had the stall of 5800. Here’s the graft and specs with the crosshairs set when I had the car floored and the transbrake just released.

 

[pittsburghracer]

Just feeling that something wasn’t right and John being John on a coronavirus filled year I decided with one race left (a three day Halloween Race at Keystone) I would pull the transmission and throw in another brand new ATI cased powerglide I just built. While it was apart I decided to throw in another converter that I couldn’t recall it’s history. It was at this time I happened to notice my flywheel was cracked over 3/4 way around it so that would have probably came apart on its next pass. I was also nursing a couple oil leaks that happen on five year old race engines. Well my very first pass was a disappointing 6.32 in some great October air. Then a 6.31 so I checked the RacePak info and as I thought the stall was very low. I went from around 5800 stall to around 4850 with the car slowing down .30 in the 1/8 mile. I also couldn’t cut a light worth crap and with limited time trials because of the weather and car count I parked it and enjoyed the weekend with friends. I figured the converter was bad so I sent it to Transmission Specialties to have it rebuilt and stall raised to 5800 so I had a good spare. It was found to be good and is a 9 inch converter not an 8 inch converter so he couldn’t raise the stall to the requested 5800 stall. I may call him tomorrow to see what it would stall at on my approximate 900-950 horsepower 572. I mainly posted this to show guys why I push high stall converters. They do make a difference. Here’s the readout from to second converter. Look how low the stall is.

 

[448Scamp]

High stall converters and data logging.

 

[LO23M8B]

High stall converters and data logging.

You need both! Ya love it.

 

[moparstud440]

Just feeling that something wasn’t right and John being John on a coronavirus filled year I decided with one race left (a three day Halloween Race at Keystone) I would pull the transmission and throw in another brand new ATI cased powerglide I just built. While it was apart I decided to throw in another converter that I couldn’t recall it’s history. It was at this time I happened to notice my flywheel was cracked over 3/4 way around it so that would have probably came apart on its next pass. I was also nursing a couple oil leaks that happen on five year old race engines. Well my very first pass was a disappointing 6.32 in some great October air. Then a 6.31 so I checked the RacePak info and as I thought the stall was very low. I went from around 5800 stall to around 4850 with the car slowing down .30 in the 1/8 mile. I also couldn’t cut a light worth crap and with limited time trials because of the weather and car count I parked it and enjoyed the weekend with friends. I figured the converter was bad so I sent it to Transmission Specialties to have it rebuilt and stall raised to 5800 so I had a good spare. It was found to be good and is a 9 inch converter not an 8 inch converter so he couldn’t raise the stall to the requested 5800 stall. I may call him tomorrow to see what it would stall at on my approximate 900-950 horsepower 572. I mainly posted this to show guys why I push high stall converters. They do make a difference. Here’s the readout from to second converter. Look how low the stall is. View attachment 1715779449View attachment 1715779450

What RPM do you shift the car at?

 

[pittsburghracer]

What RPM do you shift the car at?

I shifted at 7000 for three years then lowered it to 6800 for two years.

 

[moparstud440]

I shifted at 7000 for three years then lowered it to 6800 for two years.

I was always told you should have around 1000 rpm fall back when shifting. I'm guessing with the 5800 convertor you had that and with the tighter 9" if was dropping back more than 1000 rpms bogging the engine down. I have a 5000 stall in my car, but only shift at 6,000. Switching to a 8" I picked up several tenths as well.