this topic has always bugged me.

I had my car chassis dyno'd with a stock 12" converter that made 460tq at 2k rpm ( I talked with the owner of the shop and he said his employee made a mistake of not printing the entire run, they just printed what people usually want as the power band). That is why it looks like my torque peak is like 425. I had the owner fax tthe full dyno run (2000-6200+) to my dads office, i will get it this weekend and post it.
This is my question. My converter is on its way back from being inspected. If I were to go back to the chassi dyno, my HP would stat about the same, but what if my instant torque multiplication jumped like 50 ft-lbs, or something crazy like the 587 ft-lbs ken jet got (not a personal poke ken, I am under the assumption your torque at that RPM is from the converter and not power power).
But is this REAL power? Do your tires and the pavement feel it? Or is this number just some fluke of how chassis dyno's interact with converters?
Like this isn't about numbers.. 587.. 460.. whatever. This about does the pavement really feel these multiplied torque values or is it bogus?

Any ideas?

matt

Matt,you think too much smile.gif
..but that's OK graemlins/thumbsup.gif

To your question, if the dyno rollers see it why wouldn't the pavement see it? If you're saying your peak torque was at 2k then you're either seeing multiplication from the converter (i.e., it's not locked up) or I would find another dyno operator. BTW, my dyno data is in my signature ;)

You are not upping your power/torque any with a higher stall speed, but rather letting the engine operate more in the band where it makes its best torque and power at. Get the stall speed right about at the torque peak for a street or street/strip car with a 3 or 4-speed auto. If you had a Glide it would run the best with stall speed 300-500 over the torque peak. The numbers you are seeing is due to the chassis dyno method of testing. You will see torque multiplication (in the area of at or a bit over 2:1 with some stators) as the reason for this.....or you would have the rest of the world beating a path to your door for info on how to make that kind of torque at 2K, lol.

Thanks for clearing that up Steve.

I got my inspected converter back from precision industries today (I bought the converter before I had heard of team chevelle, so I didn't know who the real names were. Not to say its a bad converter, I just can't compare it to anything other than my direct-drive 12" loaner :D )
Included in the box was a sheet of paper directing people to this link:
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All late model dynamometers have a software program that commands the loading and speed of the vehicle over a certain period of time while making a test pull. The software used in these dynamometers is setup to be used with a locked 1:1 connection between the engine and the rear wheels, such as using a standard shift transmission in 3rd gear or when an automatic transmission has the torque converter clutch
locked. When an unlocked high stall torque converter is used to make the pull and the dynamometer software has not been changed to allow for the fluid coupling differences the dynamometer readings will all be bogus. For instance, the low rpm torque readings will be high due to the torque multiplication of the torque converter being run in partial stall. Likewise,
the high rpm torque readings will be low due to the long period of time the dynamometer takes to allow the torque converter to transition from partial torque multiplication to a hydraulic locked condition. The only cure for this phenomenon is to rewrite the dynamometer software to prevent this from happening. Torque converters with a low STR or low stall are not as adversely affected by this phenomenon. The high rpm transition problems
never occur when the vehicle is being driven or raced normally. Therefore, worrying about what the dynamometer numbers are is a total waste of time. If your dynamometer operator refuses to alter the software to give correct readings then the only things you can do is (1.) lock the torque converter clutch and do the testing, (2.) use the readings you get with an unlocked torque converter as a baseline and continue to tune the car like normal
until you get the best numbers remembering these are just numbers and not the actual horsepower and torque or (3.) use a dynamometer shop that gives you the service you deserve for your hard earned money. The only really true test of the performance of a vehicle is to take it to the track and see what
ET and MPH the car will run.
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Seems to clear up any confusion for me anyway.

Matt