IMO L/U versus N/LU

[Lee Thompson]

@ BG and Indy I was running Precision Industries multi disc L/U. 3600 stall
@ BG the car went 10-0's @ 139 MPH
@ Indy (a little hotter and humid) car went 10.23 @ 137 MPH. About what I expected. 1.55--1.60 60 ft. both places.
I have had many people who I respect their opinion, tell me to go to a N/LU--One even swore I would pick up MPH. All of them said it would 60 ft. better and E.T. better. I doubted the MPH increase but could buy the et thing.
Recently I installed an AC N/LU and last night I got to the track.
No changes in boost or fueling or anything.
Best I could muster was 10.26 @ 133 MPH--had to go from 22 psi of boost to 24 to get that. Air was better than @ BG or Indy.
Car had a better 60 of 1.47 and ran a better 1/8 but would not pull the last 1/8 like it would with the convertor locked.
I am going back to my L/U.

 

[Sweet6]

Good info. I was debating going to a NL when I had my trans done. I stayed with my LU. But I am sure we will hear other stories of how NL is better than LU. I think it is a crap shoot either way. My LU has performed well so I kept it.

When do you lock your converter? I have a multidisc and have not locked it yet. Also what kind of RPM drops do you see?

TIA

 

[Lee Thompson]

Info

I am sure many things come into play.
I was locking mine @ 6000 RPM in 3rd.
It would drop to 4500 and then pull back to 5500 @ the end all because of the convertor being a higher stall.
I am sending it back to be tightened up. (hopefully they have found a way to take some of the rattle out--it is almost embarrasing)
@ 4500 it would feel a little sluggish untill it pulled out of that RPM range.
When my car was a low 11 car it would drop from 5600 to 4600.
If I turn the boost down to say 17 psi it does not drop as much.
More power makes my convertor looser.

 

[TurboDave]

I've loved my Vigilante from day one. Any time I don't lock it (for whatever reason) I always seem to loose at least 3-4mph at the top end.

My only complaint is: My converter is one of the early 7 disc units. I have always been plagued by a cold engine "stall when shifting into gear". I'm assuming it's because there are so many discs crambed into the unit that they just hang up with the fluid being cold. Precision probably would never openly admit it, but I'm convinced that's why they have gone to a 5 disc unit.

I must add though that I've stuck with it because of it's obvious indestructability (5 disc units are just as strong though too), and extremely positive lock at WOT!!!!

 

[Sweet6]

Yes, I had a 7 disc in my GN. I suffered the cold start stall as soon as the converter was put in. I got mine in May 99. Then last year after about 60 passes and 6000 miles, it locked up on me. I paid $400 to get it freshen and turned into 5 disc. I never locked the 7 disc at WOT either. I am going to try locking the new 5 disc. The 5 disc I have not feels a lot better than that 7 disc ever did. Not sure why. Maybe I had a bad one.

TurboDave
What MPH do you lock you converter?

 

[Lee Thompson]

Sweet6

It is not possible for you to get a bad product because no manufacture ever makes one. It is always the stupid consumers fault. I'm in a good mood today !!!!

 

[Sweet6]

I hear you. Now I have $1500 in my converter. :biggrin: Hopefully this one lasts longer. I knew I could not make much of a beef since the converter was 6 years old when it broke. Even though my car is a garage queen.

For whatever reason the new 5 disc I have feels night and day better than the old 7 disc I had.

 

[Sly87]

I've loved my Vigilante from day one. Any time I don't lock it (for whatever reason) I always seem to loose at least 3-4mph at the top end.

My only complaint is: My converter is one of the early 7 disc units. I have always been plagued by a cold engine "stall when shifting into gear". I'm assuming it's because there are so many discs crambed into the unit that they just hang up with the fluid being cold. Precision probably would never openly admit it, but I'm convinced that's why they have gone to a 5 disc unit.

I must add though that I've stuck with it because of it's obvious indestructability (5 disc units are just as strong though too), and extremely positive lock at WOT!!!!

Im thinking about a Vigilante 3200 L/U.When I emailed Precision they recommended the single disc converter.My car is driven mainly for the street.What's the difference between the Vigilante Single Disc and 5 Disc converter??

 

[c&cgn]

Intersting thread Lee.

I just recently switched from my AC n/l to a custom race L/U converter that a local company builds. I went 10.71 on it a couple of years ago then tried going non-lock as I was told that was better.....

This year I went a best of 10.40 @ 129 with 1.46 60' with the AC nl @ 6250 rpm

Last weekend I went 10.33 @ 130 with a 1.44 60' on the L/U and the rpm was 5750. Went 128 mph unlocked @ 5950 rpm. I may just stick with the L/U.

I know the Art Carr convertors work very well for some people, and my car ET'd and MPH'd pretty good with it ( I made many mid 10 @ 127 -128 passes), but I feel for my combo the L/U seems to be a better fit, at least so far.

 

[Ttype6]

My only complaint is: My converter is one of the early 7 disc units. I have always been plagued by a cold engine "stall when shifting into gear". I'[/QUOTE] This is the first time I've heard someone mention this. It's nice to have confermation of this problem. My 3200 five disc has done this from day one.I replace it with a ten inch n/l and the problem went away. Then I put the five disc back in and the stalling returned. I know it's the converter. When I first installed the five disc,it rattled quite a bit. After a relatively short period of time running in park the rattle suddenly diminished to a very tollerable but still noticable level.Dispite the stalling,I'm very pleased with it. When it locks,it locks now.

 

[TurboDave]

Im thinking about a Vigilante 3200 L/U.When I emailed Precision they recommended the single disc converter.My car is driven mainly for the street.What's the difference between the Vigilante Single Disc and 5 Disc converter??

The multi disc converters, when they lock, are going to LOCK HARD!!! Even during normal driving. This may be too annoying to some folks. Most of us that run the multi disc units understand it's just something that goes with the territory.
If MOST of your driving is street and not race, then the single disc is probably your best bet.