I installed a new converter in my car a couple weeks ago. I went to the track today to test it out.
Ran into some trouble. Nothing big, but I need some analysis to help me along my way here.
It never occured to me that changing the converter would change the shift points when in full auto mode (shift points by the governor). I haven't got good enough at shifting with the staple shifter to not make mistakes (missing gears, going into neutral) at the track to do that. So I leave it in auto (complaint dept. can take a # :D ).
It used to shift at about 6100 and 6250 last time I went up, with a trap speed of 116.03-116.62.
This time, I went my first run, and noticed the shift light never went on until I was in the traps, which means that the motor never hit my old shift light rpm of 6100. Using the recall function on my tach, the max RPM I hit was 6300.
Because its hard to pay attention to the tach, I dropped my shift light to 5000rpm, and did another run.
1-2 happened at 5900, 2-3 at 5400. Both 60's were low 1.9's, not the 1.8x's I was getting with a good burnout before, but my 60's are usually low 1.9's because I can't stab the throttle off the line or I will smoke the tires. (very small, short ET streets).
On a chassis dyno with my old converter, 116mph is equal to about 6600rpm.
Today I went through the traps at 114.98 @ 6300 max rpm.
Now obviously I am not getting my full power here-- I should be shifting at around 6100-6300 both shifts for max power. 2-3 at 5400 really took away my sweet spot for hp, 5200-6300.
Now I have to go and fiddle with that gosh darn governor again. But aside from that..
As I understand it (and I may be wrong), the 114.98 is an average of the last 66' of track time. Does anyone know a way to at least guess what actual MPH I was doing so I can take a stab at converter slip w/o having to pay for another useless no-load chassis dyno run?
I am just trying to see at this point whether I bought myself a converter that slips less, and for what its worth, try to get as accurate as possible a % for this w/o going back to a chassis dyno.

Any thoughts appreciated. I was hoping I would be able to make this my last run of the season because I am moving (and hit 120mph doing it), but obviously that didn't happen.

Thanks..
Matt

I did a little math myself, and using a constant acceleration (I know thats not the case), I came out with a max mph of 115.5.
That dropped my theoretical slip from 10.86 (on a chassis dyno) to today's guesstimate slip of 7.5-7.8%, or a drop of about 3%.
When I get my shift points right again, is this gonna be worth anything, mph wise?

Thanks..

matt

matt,
is the car dead hooking? are you flashing the converter? sometimes track prep on saturday at ne dragway is marginal. any tire spin?

The car is far from dead hooking.. I am running 26*10.5 ET streets and a 3.90 gear behind a solid roller 462 that made 565/550 running its accessories (minus PS) and my full exhaust on an engine dyno.
I have to feather into the throttle. The tires weren't spinning but I wasn't hard into the throttle until the car got moving to a pretty decent mph. I have to ease into it, I have to disconnect the kickdown because 1) it doesn't work right, and 2) if I leave it on, I have to ease in so slowly that when I do get to the floor, the trans tries to kick back down, making for a screwy run.
8" of ET street tread is not dead hooking with this car.
I felt my converter had excess slip, and I was hoping this time to see if it was or not, but with such low shift RPMs, there is no way to tell aside from my guess a 3-3.3 % slip reduction @ 115 vs the old converter.
I don't have a roll bar and won't hack up my car to do it, and I was running 11.8's with a 1.8x 60' with the correct shift RPMs, and NED requires a bar at 11.50, so spending $800 or whatever on 28*12.5 ET streets and wheels that would fit with them doesn't make sense.
I can feather a 1.8x 60' out of these tires if I get the burnout right and hit it just hard enough not to spin, but I am a ways away from flooring it when the lights drop..

matt

matt,
you might want to plan a trip to the track the next time they run a quick street event. they do an awesome job prepping the track and they also spray everytime the class is called. many of these cars are in the 8's and 9's with a 10" slick. i think that would be the best to see what the potential is of such a small tire on a big heavy car with so much torque. last year a guy with a 70 vette was running the same tire and easily was pulling 2-3 feet of air and running 10.20. i know the vette is a different animal but you know my point. good luck mike