...I know these two comanies taylor their converters to your car/engine/cam/trans/gears/intended use.....but just wondering how much slip (percentage-wise) does one usually have when custom made for your car?

Also what amount of slippage on average is generally acceptable on any given vehicle?

...I know these two comanies taylor their converters to your car/engine/cam/trans/gears/intended use.....but just wondering how much slip (percentage-wise) does one usually have when custom made for your car?

Also what amount of slippage on average is generally acceptable on any given vehicle? I don't know what's supposed to be "acceptable" in the way of converter slippage, so I cannot offer you a direct answer on that, but FWIW, TCI told me that the converter that they sold me which happens to be one of their competition models, will have less than 5% slippage. However, this might be one of those topics that's merely is heresay anyway, because when a company tells you that their converter has X amount of slippage, who's to say that what they're telling you is true or not? I mean, how will you ever know weather it's providing 5% slippage or 10%???

And again, FWIW, I've heard good things about ATI converters, althugh I've never had one myself, so I cannot honestly speak from experience on those. I hope this helps you.

Thanx....FWIW I run a Hughes converter, several others here have it as well and are reporting in excess of 10% slippage while some others use a custom converter and have like 6%....

Thanx....FWIW I run a Hughes converter, several others here have it as well and are reporting in excess of 10% slippage while some others use a custom converter and have like 6%....Well then maybe I can learn something here. Can you explain exactly how they're measuring the exact amount of slippage? can that be done on a Dyno or something? Or do people attempt to determine that by using online RPM calculators? But if that is the case, then can we be sure that none of the slippage is coming from the transmission itself? maybe I'm missing something here. But if I'm not, then it just seems to me that w/out very sophisticated equipment, this is anything but an exact science. I mean, how would I be able to tell if my converter is supplying 10% slippage, or 6%??? Even a fraction of an inch of error in the tire height spec can throw the math off. And for that matter, I don't doubt that some tachometers can easily be off by 3%. And a number of speedometers are definately off by 2% or so. There sre so many variables here. So how can your average Joe amatuer racer determine the exact amount of converter slippage? This is a sincere question on my part.

http://www.tciauto.com/Products/TechInfo/Calculators.asp

http://www.tciauto.com/Products/TechInfo/Calculators.aspUhmm, like I said, those calculators will only furnish answers that are as accurate as your speedomoeter and tachometer errors are. There are many variables, so how can you possibly determine 10% slippage from 6% slippage? I don't think equations that are based on tachometer and speedometer readings can be that accurate. There will always be a certain degree of error, and how much that error is, will be unknown w/out the use of sophisticated equipment. So if we cannot even determine for ourselves what the actual converter slippage is with accuracy, then why even worry about it?

Uhmm, like I said, those calculators will only furnish answers that are as accurate as your speedomoeter and tachometer errors are. There are many variables, so how can you possibly determine 10% slippage from 6% slippage? I don't think equations that are based on tachometer and speedometer readings can be that accurate. There will always be a certain degree of error, and how much that error is, will be unknown w/out the use of sophisticated equipment. So if we cannot even determine for ourselves what the actual converter slippage is with accuracy, then why even worry about it?

i see where you are coming from. and completly agree. but this is a way to give an idea of what your stuff is doing. accurate maybe not, but sometimes hotrodding is horsehoes and hand gernades. "sometimes"

i see where you are coming from. and completly agree. but this is a way to give an idea of what your stuff is doing. accurate maybe not, but sometimes hotrodding is horsehoes and hand gernades. "sometimes"LOL....that's well put. :D

The only truly accurate way I can see is using a data logger to monitor driveshaft rpm vs engine rpm. Even then, I guess you are at the mercy of the tach output on your ignition, and the inputs on the data logger as far as accuracy goes.

If you run on a dragstrip, you get a very accurate measure of trap speed on your timeslip. If you have a good quality tach, know your rear gear ratio, and measure circumference of your rear tires with a tape measure, you should be able to calculate converter slippage pretty accurately.

The only truly accurate way I can see is using a data logger to monitor driveshaft rpm vs engine rpm. Even then, I guess you are at the mercy of the tach output on your ignition, and the inputs on the data logger as far as accuracy goes.

I've used my playback tach for this very purpose. I record a run, then plot it on my laptop. You can scroll through the run to the elapsed time that was on your time slip for the pass and look at the exact RPM at that point in the run. I agree with tach accuracy being a factor. Another factor is tire growth for bias ply tires. You can get a pretty reasonable ieda of what your converter is doing this way. My last converter (8" ATI Treemaster) showed between 8.5%-9% slippage consistently. We'll see what the new Coan 9" does :)

I've used my playback tach for this very purpose. I record a run, then plot it on my laptop. You can scroll through the run to the elapsed time that was on your time slip for the pass and look at the exact RPM at that point in the run. I agree with tach accuracy being a factor. Another factor is tire growth for bias ply tires. You can get a pretty reasonable ieda of what your converter is doing this way. My last converter (8" ATI Treemaster) showed between 8.5%-9% slippage consistently. We'll see what the new Coan 9" does :)I didn't even think of the tire growth factor. That's another variable.

KJETT elaberate more on your tach and lap top part # etc.

KJETT elaberate more on your tach and lap top part # etc.

I use an Autometer Ultimate I playback tach. It stores up to 4 runs. It can record your burnout/staging with the use of an auxilary trigger/switch. I have mine wired to my brake pedal and use a toggle switch to enable/disable it. Autometer sells a model up from this one (Ultimate II) that will also measure driveshaft speed. It comes with a software program called TachFacts. The software is decent, but doesn't provide the same level of granularity that you might get with the Edelbrock Qwikdata or similar high end data acquisition systems. They are a little pricey ($399 for the Ultimate I, $575 for the Ultimate II), but significantly cheaper than a full on data acquisition system (and the associated plumbing). It does all that I need it to do. The tach comes with a cable and can be connected to the serial (com) port on any laptop PC. Here's a link:

http://www.autometer.com/cat_data_tachdetail.aspx?pid=5

HTH...

Ken, thanks for that info. :thumbsup:

I can tell you of my experience with three converters:

1. El cheapo no name brand 2400 12 %

2. TCS quality 10 inch converter 7.5 %

3. Unknown brand 8 inch converter 12.5 %

I had a boss Hog 3500 that calculated 18% slip through the lights.
Changed to a Coan 3000, it calculated 4% through the lights

Et went from 14.0 to 12.75 and mph from 94 to 107.

The calculation formulas may not be perfect, but they can sure get you in the ball park and let you know when you have a total piece of crap for a converter. You could hardly tell the difference in my two converters on the street, but it was night and day at the track.

It you are going to use your car at the track some and want to ET to your cars potental....get a VERY good converter. If all you want to do is brag about how far you can spin the tires in front of your house and guess at your ET, just about any old piece of junk will work.

I used the word YOU as people in general, not as a specific person.

I run an 8" ATI flashing between 5900-6150 rpm.

I also have an RPM Performance data logger on board which measures engine & driveshaft rpm as well as WB02.

At the end of each race day i print out each run and calculate the converter slippage using engine & driveshaft rpm values at the finish line.

This converter has shown slippage as low as 5.2% or as high as 6%.

Using the data logger takes out all other variables like tire growth, accuracey of tire diameter & rollout, etc.

I'm sure there are companies that have a tendency to build better performing torque converters than other ones do, but have you guys found in your experience, that for the most part you get what you pay for, and that a $600 converter just won't perform like an $1,100 converter will?

I am totally satisfied with the 8" ATI in my car, IIRC, it was around $700. I prefer the standard Treemaster over the MRT.

I am totally satisfied with the 8" ATI in my car, That doesn't surprise me since I've heard good things about ATI converters. A guy who I work with who used to race quite a bit told me that someone at ATI told him that if he bought their converter, his car would launch real hard, and after he bought it and installed it, his car did launch fantastic just like they said it would.