spearfish3

Also with diesel, you can just plug in another 120+ rwhp and put some propane or nos for even bigger gains. All that extra torque and hp may change the way the stock converter stalls at.

F8L Z71

Your stock converter is rated at either 1600 or 1800. Most definately not 900.

Brake stalling it to see measure stall point is not an accuate way of doing it. Too many factors are involved such as TQ and traction. In my T/A with a PT4400 I could only brake stall it to about 3200max before the tires would break lose or push me forward. Yet if I stall it too 2800rpm then floor it I can see it flash to somewhere around 4200-4500 (it moves to fast).

I am not sure about a higher stall being better for towing or not BUT a higher stall will get you into your powerband faster even at part throttle AND most units have a higher STR rating which tightens the converter up and makes part throttle easier to drive in, kinda like having gears even though the converter is slipping up until near the stall point.

In all I htink the otherall opinion here is don't go too big, stay under 2600rpm. Get a very good trans cooler (anything less than $150 is not good), keep your stock fans etc etc.

Mr. Sandog

I guess I always want to look at the application. Let's assume that there is a 5,000 lb trailer behind my Avalanche with the stock converter. Are you saying that I won't start moving until 1800 RPM's? I find that really hard to believe. I haven't towed yet with the AV, but I would bet it would start moving maybe around 900-1000 RPM's, because right now it starts moving right off idle at around 700 RPM's.

Next, I would like to know at what RPM a TT2600-equipped vehicle begins moving. I have no knowledge or experience in this area, so others with a TT2600 should really chime in here. Even if it begins moving at 1800 RPM's, it's making double the heat of my stock converter, correct? Everyone talks about torque multiplication and all that, but whatever increase in torque is experienced is at the cost of increased heat, yes?

Like you said, though, if that extra heat can be addressed properly, then perhaps there need be no issues.

F8L Z71

I thought you had a converter in one of your vehicles before? I thgouth you had that's why I left out some mundane facts about a TQ converter.

If not then let me explain better.


A higher stall TQ convertr will start moving the vehicle at nearly the same RPM as a stock converter. IE you give it gas and by 700-900rpm your vehicle will start moving wether you have a stock stall or a 4400stall. Now, how quickly it starts moving (at part throttle) is dependent on the weight of the vehicle, torque, stall ratio of the converter etc. A 3000 stall with a 2.0 STR (as Yank and PI call it) will require more throttle to get up to 35mph than say a 3000 stall with a 3.0 STR BUT both will start MOVING at nearly the same RPM.

My PT4400 stall would start moving as soon as I pressed the throttle; albeit it felt like a slipping clutch. Toattain a speed of 45mph I generally would hang at 3000rpmtill I got there. Meaning I would give it gas, the car starts rolling forward. I can slowly get up to 45mph and still keep the revs around 2000rpm but it would take a long time (I had to do this around cops because the car was so friggin loud). Normally I would just take off from a light and the car would act just like someone slipping the clutch and holding it at 3000rpm till I reached 45mph then it would drop into the proper gear and rpms woiuld drop. I hope that made any sense.

The main point being, you don't have to wait till 1800 or 2600 or 3000rpm for the truck to move when you have a high stall converter in it. That stall speed is just the point at which the converter is not slipping anymore.

Liek I said above, the easiest way to understand what I am saying it to realize that the stock converter in most cars and trucks is right around 1600-1800rpm, yet at what rpm does you car actually start to move when you give it gas?

Hardtop

iTrader: (3)

That cooler looks nice. I have a question though for us folks that get cold weather. Tying a cooler in series with the radiator will help keep some heat in the tranny fluid for those days that you get under 20 degrees. If that cooler was used, and you bypassed the radiator, is it possible that the trans fluid wouldn't get hot enough in the winter?

Bruce

James B.

iTrader: (1)

That's hard to say. I would think that the coolant would be ice-cold by the time it reaches that side of the radiator anyway. I think I would be mounting a self-contained cooler like that underneath, out of direct airflow. It should be possible to make a braket that uses the space behind the lower radiator support so the cooler sits nearly horizontal at just below crank level.

marc_w

That's not it at all...

Brake stalling the stock converter, I'll hit about 1,800... I won't be surprised to brake stall the Yank 2600 and see it flash to 2,800. It's just that even with the stock converter, you don't hit the rated stall speed unless you give it enough throttle. I can ease into the throttle with the stock 'verter, and get rolling along at 1,400rpm easy enough.

The higher the STR of a converter, the tigher it feels... So the stock converter is actually more loose feeling than the 2600, in it's smaller range of RPM where the slip occours. That's why some people call the stock converter kind of "sloppy". It doesn't stall high, but it's easily slips in that small range.

The 2600 or 3000, or any other aftermarket converter has a wider rpm range where slip occours, but the feel of looseness isn't DIRECTLY proportional to the stall speed.

I don't know about the EXACT correlation of STR to rated stall speed, in the feel of looseness or tightness. IE: Where the tradeoff point is. IE IE: If a 3600 stall with a 2.8 STR will feel tighter or looser than a 3000 with a 2.1 STR. I'm not sure if there is a little formula out there for rough estimates on the feel of a converter.

marc_w

From what I've been told, I'll see a few hundred more RPM than normal from a dead stop takeoff, with "normal" every-day throttle. It's supposed to be VERY easy to adjust to.

Anything more than an agressive half throttle stomp from a stop, will start to push the converter up to the 2,600 range.

I noticed that my girlfriends Olds Alero, and my mothers Cavalier both have converters that really compliment the motors. Both of them are rather lacking in the motor department, and the converters have a good amount of slip to them to help. Both are so well behaved, with such good feel, you'd never notice unless you drove one and had converters on your mind. They're nothing like the quick slip, snap/jerk reaction of our truck converters.

marc_w

Yeah, I think it's possible. I heard that ATF starts to gel around -40*F or so.

I heard a few different arguments about minum tranny temp. Some say that they'd never run a tranny hard that's under 100*F. My gauge never moves off the bottom (100*F mark), in the winter months, so I'm not much of a believer in that.

I'll have to scan it this winter and see what temps I'm *really* running at.

spearfish3

Thanks for all of yalls help. Are all brands fairly equal in quality or is there some that I should avoid? A lot of people have yanks, but how are vig, tci and others