Lock Converter or Shift into Overdrive?

[MNwe4]

Last year the car was crossing the traps at 120mph and 6100rpm in 3rd gear. This year it's running quite a bit better. I've already picked up 4mph in the 1/8th mile, but haven't been to a 1/4 mile track yet. Going next weekend though. So, I was wondering what people think: should I have the chip lock the converter while in 3rd gear and at what mph or should I shift into OD toward the very end of the run? Is locking the converter hard on the transmission? With no real tach, deciding when to shift to OD may be a bit of a challenge. Opinions?

 

[bison]

How about getting a converter in there that will make use of the engines power? You will pick up even more with a 9.5". That converter wont take WOT locks

 

[Dusty Bradford]

It won't handle WOT locking. It needs to be tightened up some or it's time to swap to a non lock.

Is it still stalling at 3000 rpm at 0-1# of boost? I ask this because I have some cars running 124-125 at less rpm with that same converter.

 

[WSLN 6]

Change to 28" tall tires and if serious, a PTC 9.5" NL. Best upgrade ever.

 

[VIN7]

Just out of curiosity, and I know Bison has talked about it before, but what about dropping the gear down to 3.23 or 3.08?

This would address rpm at the line but my question is how will the rest of time slip be affected? Is this something (gear change) that is cost effective and worthwhile. I guess it costs about the same as getting new tires and less than swapping converters.

 

[Dusty Bradford]

The 28" tire is the best thing to do for any car that's running the drag strip.

 

[bison]

Just out of curiosity, and I know Bison has talked about it before, but what about dropping the gear down to 3.23 or 3.08?

This would address rpm at the line but my question is how will the rest of time slip be affected? Is this something (gear change) that is cost effective and worthwhile. I guess it costs about the same as getting new tires and less than swapping converters.

The converter still needs to be addressed. It's cost effective and worthwhile if the car can pull it. It might give you an extra 100ft out the back or hold the engine at peak power longer

 

[MNwe4]

BISON,
I do realize the 9.5" is the way to go for a track setup. You and Dusty have been very informative in previous conversations. Unfortunately that converter requires some serious dough which I need to keep in my pocket for now.

WSLN 6,
A taller tire is a good idea. I'm currently running 275/50 Nitto 555R's which are just shy of 26". Until last weekend they have performed well for me, but now I'm spinning the crap out of them at the track. If I run into the same problem this weekend I was considering taking a look at Hoosier's 27" DOT slick or whatever other vendor is at the track.

DUSTY,
Yes the converter is still stalling between 2900-3000 rpm at 0-1 psi. From the logs it also looks like 3400-3500 at 5 psi. Attached is my best run from the 1/8th mile if you'd like to take a closer look. I'm just concerned about running out of rpm toward the finish and from what I understand will be giving some up if I have to shift to OD. I'm comfortable running the motor to 6100 rpm but have no idea how much further it can be pushed. Everything is built but it still has the stock crank and rods.

Also, could someone explain in more detail why this converter can not handle a WOT lock? I believe what you guys are saying, just would like to know some of the technical reasons. There seems to be a lot of people that do lock their converters. Are they being foolish?

 

[Dusty Bradford]

Put a 275/60 M/T radial or a 28x10.5S slick on it. You need a 28" tire on it...that will really help your trap rpm.

The 10" PTC is a single disc converter. The single disc 9.5" and 10" converters don't have enough surface area to support a WOT lock like a 12" clutch or a multi disc converter can. Once you reduce the size of the clutch to fit it inside the smaller converter you don't have enough holding power. They are intended for lock-up at highway cruise only.