So what is my stall??

[imjoesnuffy]

I picked up my torque convertor in a package deal a while back. At the time I was told that it was a 3000 rpm stall, but the guy I got it from didn't know much about turbo buicks as far as I could tell. No noticeable markings/numbers on it. It is a purplish/pink looking color and is full size.

When I had it flushed by Brad at Bradco engineering, I asked him about it and he said it looked like a Precision TC, but couldn't be sure. He did say it looked well put together as far as he could see. He said he would have to cut it open to determine the stall on it and could restall it for me if needed at that time. I didn't have him do it.

Was checking out my runs on my Powerlogger and noticed it is stalling as high as 3700-3900 rpms before I see the mph change from 0. This is on a 15psi launch off the footbrake.

I don't consider it to be laggy, but from reading others descriptions of their cars, it may be??? From a complete stop, without building boost if I floor it, the tires do not break loose until 1 sec before the 1-2 shift. Under higher rpms in 3rd gear it will go from 0-15 psi in about a second or so if floored.

As the saying goes, if it aint broke, dont fix it. I am happy with it, just wondering what it is.

 

[imjoesnuffy]

Not even a guess?

 

[Kip]

John, the best thing to do is check the rpm at one pound of boost power braking the car.
See ya, Kip

 

[GNVYUS 1]

Couple things come to mind, you needed to find out the converters # so you can figure out what pump it is, doesn't sound like the 0 pump like you were told.

Holding 15psi at 3700 is pretty impressive, what is your rear brake setup, Powermaster I assume?

I'd be concerned with your converters efficiency, you need to know what RPM you went through the traps at and then the rest is easy to plug into the TCI calculator with. That converter IMO sounds too loose from your description, especially for that turbo.

BTW, you can lock the converter at the track in 3rd if it has a lock up clutch, especially if it's the 5 disc.

 

[imjoesnuffy]

Couple things come to mind, you needed to find out the converters # so you can figure out what pump it is, doesn't sound like the 0 pump like you were told.

Holding 15psi at 3700 is pretty impressive, what is your rear brake setup, Powermaster I assume?

I'd be concerned with your converters efficiency, you need to know what RPM you went through the traps at and then the rest is easy to plug into the TCI calculator with. That converter IMO sounds too loose from your description, especially for that turbo.

BTW, you can lock the converter at the track in 3rd if it has a lock up clutch, especially if it's the 5 disc.

I have the powermaster and upgraded the rear brakes to the S-10 set up with the soft pads. I also use the Line lock to not heat up the rear brakes while doing the burnout. I am happy with them.

My RPM at the end of the 1/4 mile is around 5700-5800 according to the powerlogger. That was my peak RPM in 3rd but that was after the traps, I don't let out until I am past the signs, LOL. I do lock up the TC a second or two after it shifts into 3rd.

Using the TCI calculator: RPM(5700), Tire height(26), Rear ratio(3.42), Trans ratio(1:1 for 3rd Gear correct??), MPH(123.23) = 4.66% That seems too good.

Thanks Kip. I will give that a shot. We didn't get to talk much down at BG, but whenever I get back next year I have some upgrades in mind you can definitely help with.

 

[Kip]

John, I figured I would have seen you more at BG but from talking to Rickie I guess you were almost always on the track or in the staging lanes. Take care and be safe when you are gone.
See ya,
Kip

 

[imjoesnuffy]

Kip,

That's what I get for trying to cram the whole BG experience into one day. Thanks for the kind words, and I will do my best to do just that.

As for the stall: Brakeboost to 1 psi = 2500 rpm???

 

[wickedtt]

I picked up my torque convertor in a package deal a while back. At the time I was told that it was a 3000 rpm stall, but the guy I got it from didn't know much about turbo buicks as far as I could tell. No noticeable markings/numbers on it. It is a purplish/pink looking color and is full size.

When I had it flushed by Brad at Bradco engineering, I asked him about it and he said it looked like a Precision TC, but couldn't be sure. He did say it looked well put together as far as he could see. He said he would have to cut it open to determine the stall on it and could restall it for me if needed at that time. I didn't have him do it.

Was checking out my runs on my Powerlogger and noticed it is stalling as high as 3700-3900 rpms before I see the mph change from 0. This is on a 15psi launch off the footbrake.

I don't consider it to be laggy, but from reading others descriptions of their cars, it may be??? From a complete stop, without building boost if I floor it, the tires do not break loose until 1 sec before the 1-2 shift. Under higher rpms in 3rd gear it will go from 0-15 psi in about a second or so if floored.

As the saying goes, if it aint broke, dont fix it. I am happy with it, just wondering what it is.

When you say its a full size converter do you mean 12"? if so I would say 15 psi at 3700 rpm is way too loose something wrong their?

 

[imjoesnuffy]

When you say its a full size converter do you mean 12"? if so I would say 15 psi at 3700 rpm is way too loose something wrong their?

It is the same size as the D5. Brake boosting it I get 1 PSI at 2500 and 15 PSI at 3700. I end up with a convertor that only slips 4.66% though? Assuming the trans ratio is 1:1 in third gear, which is what I have read elsewhere.

 

[Rosewood T-Type]

John, the best thing to do is check the rpm at one pound of boost power braking the car.
See ya, Kip

Kip is absolutely right! 1# boost rpm is the tell.
Your stall is a little tight but not to far off. I think youd be more happy w/ a 9 or 10 inch 3200 - 3600. use your powerlogger to check rpm drop at the shift optimal is 900 to 1000 drop, any more your way to tight.

Hope this helps Doug

 

[Chuck Leeper]

" I do lock up the TC a second or two after it shifts into 3rd."
If that was done on the pass you are using in the calculations, the 4.66% number is not valid

 

[imjoesnuffy]

" I do lock up the TC a second or two after it shifts into 3rd."
If that was done on the pass you are using in the calculations, the 4.66% number is not valid

On the first run that day I forgot to lock it and still managed 120 mph. 5900 rpms at the end of the run, but like I said I didn't let out till after the billboard. Convertor slip% 11.2 that sounds more accurate to me. RPMs drop from 5553 to 4427 on the 1-2 shift and the 2-3 shift was 5811 to 4639.

So in other words, I need more stall as this is too tight?