34% converter slippage??

[Kevinmach1]

I've been trying to figure out why my 1/4 mile speed is only 15-18 mph faster that my 1/8 mile and I'm wondering if this is in an acceptable range or not. When I fiqure my trap speed, the rpms I trap at, with 3.73's and assuming 4 gear is 1:1, the handy little online calculator comes up with 34% converter slippage.
Seems to me there shouldn't be any slippage, but that's what I am asking..
Whats normal? I would guess if I had a manual I would have 0% slippage..

I have the TCI 3000 stall currently, but I do have a PI triple disk on the bench waiting to be installed...

My 1/8 mile is 85ish, and I get 100-101 mph at the 1/4.

 

[BAKnBLK2010]

34% slippage is fucking terrible. With a good 3000 converter you might see 10% or 15%. Most converters in that size range are at least 90% efficient. I'd get the new one installed and throw that piece in the trash.

 

[US-1]

Pull the TCI out. Put the PI converter in the car. Take the TCI to the curb, toss it into the street, laugh hysterically as people run over it.

 

[fdjizm]

Pull the TCI out. Put the PI converter in the car. Take the TCI to the curb, toss it into the street, laugh hysterically as people run over it.

 

[Germeezy3]

Pull the TCI out. Put the PI converter in the car. Take the TCI to the curb, toss it into the street, laugh hysterically as people run over it.

With that converters slippage don't you think people will just spin like tops as they run it over?

 

[US-1]

Where do you think the laughter comes from?

 

[Steedman07]

What does your dyno sheet look like? I am having a problem between 4,500-5,500 rpm's..power and torque are dropping some, then it feels like a nitrous hit at about 5,500 rpm's...

 

[psfracer]

If the car is hunting for rpms on the big end---your converter is locking / unlocking and it either needs to be corrected in the tune, or the converter is going bad.

As far as the OP, yes 34% is just flat out sad, and explains why your car does not mph. Did you confirm the tune is locking the converter in 4th? If it is, then you have a bad converter.

 

[Five Oh Brian]

34% slippage is fucking terrible. With a good 3000 converter you might see 10% or 15%. Most converters in that size range are at least 90% efficient. I'd get the new one installed and throw that piece in the trash.

I just did the math for my converter (from Fuddle Racing) and my trap speed vs the theoretical speed is 89.9%, so it looks to be slipping 10.1%. It has twice the clutch area of the stock converter per Fuddle and they claim it can stay locked up at WOT even with forced induction. Plus, I have it tuned to lock up 1/2 second after upshifts at WOT.

If your converter is showing 34% slippage, then follow everyone else's advice and check the tune or just plain toss it in the garbage.

 

[TexasKyle]

Out of curiosity, how are you figuring this? What's the math?

 

[Kevinmach1]

I made a mistake when I posted, I did it from memory and my memory again proves to be getting worse. The slippage was 24% not 34%. Still sounds like that is too much. I haven't checked with the tuner guys yet, but I will be ordering a tune over the winter from JDM and when I do, I will make sure to ask the that the tune has the converter locking.
I will also put My PI converter in along with some long tubes if everything goes according to plan. I have a zex wet kit in the garage also, but I am in negotiations with my wife to possibly go a different route (supercharger)..

I used this calculator
http://www.wallaceracing.com/converter-slip.php

 

[Kevinmach1]

Pull the TCI out. Put the PI converter in the car. Take the TCI to the curb, toss it into the street, laugh hysterically as people run over it.

I can get 3 cents a pound at the scrap yard...

 

[Five Oh Brian]

Out of curiosity, how are you figuring this? What's the math?

Assuming 100% lockup (as in a manual transmission), the formula for mph based on a particular RPM is...

RPM * Tire Height in inches / gear ratio / 336.135 = MPH

For example, my car at 6800 rpm's in 4th gear (1:1 trans ratio and 4.10 rear end ratio) would be...

6800 * 25.68 / 4.10 / 336.135 = 126.7 mph

However, my car is only going 114 mph @ 6800 rpm's in 4th gear, so...

114 / 126.7 = 89.9% efficiency (or 10.1% slippage).

 

[psfracer]

I made a mistake when I posted, I did it from memory and my memory again proves to be getting worse. The slippage was 24% not 34%. Still sounds like that is too much. I haven't checked with the tuner guys yet, but I will be ordering a tune over the winter from JDM and when I do, I will make sure to ask the that the tune has the converter locking.
I will also put My PI converter in along with some long tubes if everything goes according to plan. I have a zex wet kit in the garage also, but I am in negotiations with my wife to possibly go a different route (supercharger)..

I used this calculator
http://www.wallaceracing.com/converter-slip.php

Yeah, make sure you tell JDM of the issue you are having---when it comes to tunes and the 5R55S transmissions, JDM is one of the best--you won't go wrong there. If you are still having issues after that new tune, its definitely time for a PI multi disc converter (or equivalent)

 

[US-1]

I can get 3 cents a pound at the scrap yard...

Beer money!