Torque Converter Issue

[ILW84U]

Well I finally made it out to the track after my latest build (see sig for mods) & the various issues solved. To say the least, I was disappointed as my best run was a 12.19 @ 118.90. The car was leaving the line like Granny was driving! It was my first time out with an automatic. I tried leaving off the foot brake then off the transbrake & nothing seemed to help. Being used to driving a manual, the automatic wouldn't rev up like the standard. Being easy on the gas I was only able to get it up to about 2500 RPM. The converter is a 2400 stall & I think I will need to get something bigger.

With an automatic, do you have to get on the gas harder than you would with a standard to get the revs up? After a search on torque converters it looks as though the consensus is PI is the way to go. I need the car to be street friendly so I don't want to go with something too big. Torque on my car levels off at about 4000 RPM then starts to climb again at 4500. I am thinking around 3500?? Should I go lockup or non lockup, single or multi disc? What are the advantages/disadvantages?

Below is a vid of one of the runs and a couple of my timeslips.



[sfire]http://videos.streetfire.net/video/05-Mustang-Drag-Pass_697494.htm[/sfire]

 

[Chris06GT]

Triple-disc is the way to go.....

Did you happen to watch how many rpm's it dropped between shifts?

Listening to the video, it seems like the converter is real tight, and was falling hard on the shifts....We try to set our converters up where they fall between 4-600 on the gear changes......

What kind of converter is in it now? brand?

 

[ILW84U]

Triple-disc is the way to go.....

Did you happen to watch how many rpm's it dropped between shifts?

Listening to the video, it seems like the converter is real tight, and was falling hard on the shifts....We try to set our converters up where they fall between 4-600 on the gear changes......

What kind of converter is in it now? brand?

I wasn't watching the RPM's between shifts. I will check that one out though. I have no idea what converter is in it. I bought the set up used from PMP.

 

[MSgt46270]

The PI multi disk for sure. It's great on the track and on the streets. I have the 3200 stall in my car, but when I race it I lunch from idle. I tried bring the RPMs up before and my car didn't like that. Next time you go to the track try it.
Was your trans cold or hot on your first pass. The trans works better when it's warm/hot.

This video will give you an idea about the TC I have and how it is on the streets.


This video is lunching at idle and hitting about 95mph when I stopped recording.


This was my last race after two years not racing. Still banned from racing too.

 

[07 Boss]

When your revving up the engine with a stick and the clutch is in, your not spinning anything past the flywheel. With the auto, there is rotating mass beyond the flywheel (convertor full of fluid and stuff) which is why it seems like it's harder to get the RPM's up, because it really is. Just takes a little getting used to.

I'm surprised you got the motor to spin 2500 with a 2400 stall. Oh, my bad, trans brake. If you are running any kind of power, which you are, triple disc with full lock up is the only way to go. As far as stall speed, it's knda like gears, everybody has a different idea on what is ideal. You have to choose stall speed based on the application and how well you can cope with driving it. As far as streetability, most good triple disc convertors shouldn't feel much different than stock in cruise mode around town, only when you mash it. And yes, PI is probably one of best you can get without spending thousands.

 

[psfracer]

Wow, a 2.14 60' it just terrible with your set up---which is why your posting for help I know....but god damn something is wrong.

1) what rear gears are you running, and how tall a tire?
2) where do you start building boost in the rpm range?
3) multi disc for sure since your F/I and over 500rwhp
4) when does your converter go into lock up?

What track was this at (as in what was the elev and DA?) Alot of factors but bottom line, stock autos 60' in the 2.1X area. There is something definitely way wrong, with your set up no reason you shouldn't be in the low 1.5X area.

I run a 3600 stall converter and I have a twinscrew, to give you an idea. I would think the centri would need just as much if not more, but then again you have a transbrake so....???

 

[psfracer]

Wonder why it shows only three posts when there are actually 7?

 

[Chris06GT]

We run into this problem with Paul's car (my06gt)....

At first we put a 2400 in it since he was twin screwed and it was way too tight....

We then put a 3200 back in it that he used for nitrous and it should work a lot better then the 2400......I think you will find that out too......

I am gonna guess it is a 10" converter......possibly a 9.5"......It can save you some money by sending that one in and having it reworked for the stall you need if it comes down to that....

The questions Paul asked will be helpful to know though.....gear, tire, etc....

 

[ILW84U]

Wow, a 2.14 60' it just terrible with your set up---which is why your posting for help I know....but god damn something is wrong.

1) what rear gears are you running, and how tall a tire?
2) where do you start building boost in the rpm range?
3) multi disc for sure since your F/I and over 500rwhp
4) when does your converter go into lock up?

What track was this at (as in what was the elev and DA?) Alot of factors but bottom line, stock autos 60' in the 2.1X area. There is something definitely way wrong, with your set up no reason you shouldn't be in the low 1.5X area.

I run a 3600 stall converter and I have a twinscrew, to give you an idea. I would think the centri would need just as much if not more, but then again you have a transbrake so....???

1. 3.55, 28"
2. Around 3000
4. I have no idea. How can you tell?

The track was in Edmonton. Elevation is 2200 & I don't know what the DA was but it was hot & muggy.

 

[psfracer]

Do the BBR Stage II cams take away anything from the bottom of the rpm range? How did you install the cams (full advance, full retard)?

I am thinking, with 3.55s and a 28 tall tire, combined with an engine that makes all its power in the mid-range to the top with the centri, just to get to 3500 rpm is killing you. Try a much looser converter, I say 3500.

I was asking about the converter in lockup as when I had 511 rwhp (just happened to be the same as yours) I was trapping around 124mph---but I don't know how heavy your car is. With a non lockup converter you would most likely mph less.

Also, when I was trapping 119-120mph a couple years ago, my ets where normally in the 11.40 area with a best et at 11.32--to give you an idea--so you have at least 7/10ths to drop in the 1/4 mile if you can get the car in the powerband when you leave the line.

 

[forensicsteve]

A vid from our car from a couple of seasons back, with the 4r70w and I think around 16lbs of boost. maybe a little less. You have to freeze the last frame to read the time [email protected]. Think our converter was at 3400 at that time

http://s149.photobucket.com/albums/s76/forensicsteve/racecar/video/?action=view&current=loudexh.flv

 

[ILW84U]

Do the BBR Stage II cams take away anything from the bottom of the rpm range? How did you install the cams (full advance, full retard)?

I am thinking, with 3.55s and a 28 tall tire, combined with an engine that makes all its power in the mid-range to the top with the centri, just to get to 3500 rpm is killing you. Try a much looser converter, I say 3500.

I was asking about the converter in lockup as when I had 511 rwhp (just happened to be the same as yours) I was trapping around 124mph---but I don't know how heavy your car is. With a non lockup converter you would most likely mph less.

Also, when I was trapping 119-120mph a couple years ago, my ets where normally in the 11.40 area with a best et at 11.32--to give you an idea--so you have at least 7/10ths to drop in the 1/4 mile if you can get the car in the powerband when you leave the line.

Cams installed at full advance. I have done no weight reduction other than the K-member so I guess it to be about 38-3900 with driver.

I was hoping to get it down to the low 11's or high 10's. The car has more in it than the 511. It hit the 511 on a very stingy Mustang dyno @ 6000 RPM. We shut it down there because we were having belt slip on the charger & smoking the tires on the dyno. The plan was to run it up to 7000. I think I have the belt slip fixed & will put on my DR's before it goes back on the rollers (this time on a Dynojet as the other is 3 hours away).

 

[05stroker]

3500 stall and some 3:73 or 4:10s with those 28" tires would help alot at 500 rw.

 

[terry5357]

The PI multi disk for sure. It's great on the track and on the streets. I have the 3200 stall in my car, but when I race it I lunch from idle. I tried bring the RPMs up before and my car didn't like that. Next time you go to the track try it.
Was your trans cold or hot on your first pass. The trans works better when it's warm/hot.

This video will give you an idea about the TC I have and how it is on the streets.


This video is lunching at idle and hitting about 95mph when I stopped recording.


This was my last race after two years not racing. Still banned from racing too.

I have the same issue. If I bring the rpm's up any the car just falls on its face until I am almost all the way through 1st. I have a bama tune and will be getting with them to try and figure out what is going on.