How much slip with Art Carr 9"

[Richard Inglett]

Currently running single disk 9.5" Precision torque converter. Has been durable and reliable but appears to have about 15% slip (5800 rpm @ 112 mph). This is with the converter unlocked (single disk design does not permit lock-up at full throttle). Courious about how the slip compares to an Art Carr 9".

 

[UNGN]

Switching to 28" tires is cheaper than swapping converters at this point. At the same RPM they are 7% faster, so 5800 RPM would be 119+ mph.

 

[lazaris]

Not quite. The taller tire will also in turn make the converter slip more. This happens because the gear ratio is effectively reduced putting more load on the drive train which tends to increase converter stall.

 

[V6 Beast]

with my AC 19930 and 28" slicks I am around 5600-5700 @ 120-121.


Sully

 

[Richard Inglett]

True

Originally posted by UNGN
Switching to 28" tires is cheaper than swapping converters at this point. At the same RPM they are 7% faster, so 5800 RPM would be 119+ mph.

Thanks for your reply. However, still courious about how the slip of my converter compares to an Art Carr 9". Just looking for information. Have no plans to replace a converter that is not broken. As you have indicated, 28" tires are cheaper.

 

[Richard Inglett]

Thanks

Sully - V6 Beast,
Can determine the slip from what you have provided.

lazaris,
I'm nervous now. Slip number observed is with 93 octane pump gas. Sounds like my engine will be screaming with C116 and 28" tires.


Thanks for the replies,
Richard

 

[TurboBob]

Which configuration Vigilante do you have?

If you have access to direct scan you can calculate slip very accurately.
Just ensure that DS is set to the defaults of 3.42 gear and 26.1" tire.

The do the math: (MPH in third gear) X 47 = torque converter output RPM (TCO).

(TCO / Engine RPM) X 100 = coupling efficiency

100 - coupling efficiency = slip %.


If your numbers are from DS the you are at about 91% (9% slip). The Vigilante's have
a "short extension" stator which means that your slip is just lost power at that
RPM.

I don't think the Art Carr converters will be any tighter at that RPM since they are
so small (diameter). The 9.5" Art Carr is basically equivalent to the Vigilante.

Hopefully someone will post some data from an ArtCarr.

Bob

 

[Richard Inglett]

TurboBob,
Converter has a "0" pump trim and for the street I have P275/50/R15 BFG tires. Do not have a DS but will keep your information for future reference.

On basis of what Sully (V6 - Beast) has provided, the Art Carr's 9" converter appears to have less slip. Will calculate the numbers tonight.

Thanks,
Richard

 

[buickboy]

I have run a AC 9" 3500 stall for 2 years. I can tell you that your MPH will suffer a couple of MPH, but i like the fact that it has no clutches and is cheaper to buy and repair.
Mitch

 

[lazaris]

Richard,


Also if you use a 28" tire the 47 in Turbobobs equation changes. I believe the 47 equates well for a 26" tirewith a 3.42 gear. Another good one is:
RPM= (336 X GEAR RATIO X MPH) / TIRE DIAMETER This will tell you what rpm you should be crossing the finish line with if you had no slip.

 

[TTA850]

Richard Inglett,just so you know your not alone here my PI converter is doing the exact same thing.It was slipping around 17% before I sent it back.They tightened it up but it's still slipping 13-14% - which means almost 10% of my power(and yours)is getting lost compared to a proper converter.

Also from talking to people using ATI converters they seem to be getting 3-5% slip(3500 stall,non lockup)so you might want to think about them too.

My converter slip figures are also on just 94 pumpgas,I will be trying C16 this weekend,I just hope I don't run out of RPM's.

HTH,
Steve

 

[Louie L.]

Originally posted by lazaris
Richard,


Also if you use a 28" tire the 47 in Turbobobs equation changes. I believe the 47 equates well for a 26" tirewith a 3.42 gear. .

So what does it change to with a 28 in tall tire?

 

[3.8vsix]

Guys, I am not that smart I hope someone will clear something up on the math above
(tco/engine rpm) does this mean divide, add together or what??

 

[TurboBob]

Using DS. if you have a stock speedo, stock speedo drive gear, and set the defaults to 26.1 and 3.42 then my equation will work regardless of the tire size. DS reads the speed of the transmission tailshaft. It works.

If the components have been tweaked you can recalibrate the equation by driving around locked up in third gear. Take some data and work the equation backwards.


The other equations rely on data you can't test or measure. Track trap speed accuracy, tire growth/rolling diameter.

Bob

 

[lazaris]

Bob,

Why couldnt you measure track trap speed? Wouldnt tire growth diameter effect the 26.1 you set as defaults as well?

 

[UNGN]

Originally posted by lazaris
Bob,

Why couldnt you measure track trap speed? Wouldnt tire growth diameter effect the 26.1 you set as defaults as well?

Bob is using 26.1 because that is what the stock speedometer gear expects the tire size to be. No matter what the tire size is the mph that direct scan will show (an the speedo) will be the same for a given RPM (except for slip). The actual mph (trap speed mph) may be different.

As for tire growth, the tires will eventually grow into 26.1 at speed. At low speeds, the tire height is actually less than 26.1.

 

[Steve Wood]

Richard, Sully above seems to have about 10% slippage which is in the ball park for an AC 9". Depending upon the stall, 9" converters seem to often be around 9-11% in slippage.

My experience with a multi-clutch 9.5" converter, unlocked, was similar to yours.

I changed to one of Bruce, the Toelle House Cookie Man's 9/11s because I got tired of the 9.5" and it's unlock, slip, relock with a bang characteristics everytime I lifted off the pedal for a moment cruising down the road.

 

[Richard Inglett]

Thanks to Everybody

The information provided is greatly appreciated. On basis basis of information provided by Sully (V6 Beast), his Art Car 9" has between 11 & 12% slip. But using the clarification provided by lazaris, slip number may be as little as 9% with smaller tires and pump gas. My numbers do not have the accuracy of a direct scan but they and the experiences by Steve Wood and Steve (TTA850) confirm that an unlocked Vigilante has more slip than an Art Car 9".

To get my rough numbers, compared actual rpm numbers to ideal (locked) rpm numbers with the following:

Speed = (RPM x Tire Circumference x 60) / (Transmission Ratio x Rear End Ratio x 63360)

RPM = (Speed x Transmission Ratio x Rear End Ratio x 63360) / (Tire Circumference x 60)

Tire Circumference = 3.14159 x Tire Diameter

DS method is definately more accurate.

Thanks again for the replies,
Richard

 

[3.8vsix]

The do the math: (MPH in third gear) X 47 = torque converter output RPM (TCO).

(TCO / Engine RPM) X 100 = coupling efficiency

100 - coupling efficiency = slip %.


I hate to be so dumb, but this formula does not make sense.

This is my mph, rpm, etc:
mph is (113)x47=tco 5311
tco/rpm is 5311x100=531100
100-531100=-531000 is this right?

Did I figure this right?

 

[ijames]

Originally posted by 3.8vsix
The do the math: (MPH in third gear) X 47 = torque converter output RPM (TCO).

(TCO / Engine RPM) X 100 = coupling efficiency

100 - coupling efficiency = slip %.


I hate to be so dumb, but this formula does not make sense.

This is my mph, rpm, etc:
mph is (113)x47=tco 5311
tco/rpm is 5311x100=531100
100-531100=-531000 is this right?

Did I figure this right?

First step is okay. In Bob's lingo, tco output rpm is the torque converter output rpm and is 5311 as you calculated. On the next line, tco/engine rpm is the torque converter output rpm divided by the actual engine rpm so in your case you need to have the actual engine rpm. If that were 5500 rpm, for example, then tco/rpm would be 5311/5500 * 100=96.6% coupling efficiency, and the slip would be 100-96.6% = 3.4%. Clearer?