page62

When I bought my 200-4R tranny from Bowtie, I had a choice between a 1900 or 2200 stall converter. Steve Holmes at Bowtie said the 2200 would give me softer shifts, so I went with that one.

But my question is: What is the difference between stock, 1900 rpm, and 2200 rpm stall converters? Pros and cons of each...?

Mystery Machine

I'd be interested too, when I decided to put in a crate motor I was told to go with a 2000rpm stall so I did...but i have no idea why, just call me retarded. :crazy:

gerry72

It doesn't mean anything other than a method of possibly comparing one converter's stall speed against another of the same manufacturer. This isn't fool proof but it gives you some idea. You need to know more than just the stall speed. You need to know how the converter achieves its higher stall such as re-engineered impeller, turbine, and or stator. What size the case is is also helpful. Many cheap converters are, well...cheap and do very little as far as converter efficiency to increase the stall speed.

The very general rule on converters is that you should get a converter that stalls at or just below the cruise rpm. This is a good rule for a daily driver but doesn't go very far in addressing a car that is a weekend neighborhood cruiser or has some other rather well defined limited use. A 2,200 rpm stall converter behind a fairly stock smallblock especially with an overdrive transmission with a locking converter is a very good target. If the engine is very stock and makes all its power at low rpm, the 1,900 rpm converter would be a better choice.

Ideally, you are trying to get a converter that will at least allow the engine to reach the rpm where you are starting to come up on the cam. You can have too much stall for a mild engine which will kill the car. It just won't be driveable since you will always be outside the fat part of your torque curve. Too little stall in a warmed up engine generally leaves you with a car that is sluggish. You also have to consider the rest of the drivetrain, such as transmission gears and rear gear. The further you go up in stall, the more gear you need.

There really aren't any significant cons if you select the right converter. You may pay a fuel economy penalty but as long as you don't go too far, it's not that bad. You also have to add a transmission cooler since the higher stall will create more heat.

This is really the once-over-lightly version and doesn't give you enough information to be smart about what converter is best for you.

page62

Okay...I get it! You want the converter to slip up until the point the cam is starting to get "on step." In my case, the L82 with the 2200 rpm lockup converter would be considered a good match.

In a more modern engine (like the 4.6L in my F150) a lower stall rpm in the converter makes sense because it's designed to have oomph at lower rpms...

By the way, the converter I got from Bowtie was from "The Converter Shop" -- that's what the box said -- and was sold to me as a "heavy duty" converter.

Nomad78SA

gerry72,
How does torque affect the stall speed? From my limited understanding, the amount of torque the engine produces has a relationship to the actual stall speed a converter will stall at...the more torque a 2200 will stall at a higher stall...
I have a 388cu with a 700R4 from Bowtie, 1800 stall and a comp 268H cam, 650 dual feed carb and a 3:55 rear gear....other mods in the signature. I went with a 1800 to stall to stay under my cruise speed RPM in the belief it will stall at a higher rate than this.
Any thoughts on this is appreciated. Do you guys think I have this 78 vette motor/trans/rear gear set up good for a street cruiser
Neil in Tenn


[Modified by Nomad78SA, 8:09 PM 9/25/2002]

page62

I can tell you this much. When you lockup in 4th, stall doesn't matter. There's literally a clutch inside the converter that grabs and gives you 100% torque transfer.

But I did hit a stall condition the other day. I made a left turn onto a steep driveway. I think the car had already shifted into 2nd. I had to rev the engine to get up the ramp. Once on top, I was fine again...but it sure did frighten me!

69stingray

Lets really simplify this. If I am sitting on level ground with a 2,200 RPM stall converter, with the transmission in drive and step on the gas, what happens? I assume the car sits there until the engine RMP hits 2,200 RPM? :crazy:

gerry72

The things that affect what the ultimate stall speed is of any converter are engine torque and where it makes its torque (the fat part of the torque curve), vehicle weight, transmission and rear gearing, final gearing (tire diameter affects things beyond pucking up your speedo reading).

Essentially, everything about how the converter behaves is based upon load. And to answer a later question, just because your converter is rated at 3,000 rpm stall speed doesn't either mean you will see that stall speed or that the car won't move until you hit that rpm. Remember, it's all based upon load.

Lets use a 2k rpm converter as an example in the same car. An engine that makes a lot of torque down low (lets say a stock LS5) may see a higher than rated stall speed. An engine that doesn't see the fat part of the torque curve until over 4k rpm (like say a tarted-up 350) may not get even close to the converter's rated speed. Of course the other components have something to do with this. Let's take the LS5 car with a stock 3.08 rear and then we swap to 4.11s without changing anything else. The stall speed will, by all historical examples, be lower since you've reduced load.

That's why in my earlier reply I wrote that stall speeds allow you to compare one converter to another but aren't very precise when it comes to a specific application. What you want to do is get a converter that takes everything about your car into consideration and then similtaniously fits what you're trying to accomplish.

Now, even with a high-stall converter that doesn't mean that if you've got everything exactly right and consulted the converter manufacturer for their recommendation and followed it that you will actually achieve the stall speed of the converter. This is because torque converters multiply torque by a factor of around two. Most brakes will not be able to hold the drivetrain to achieve rated stall. This is particularly true with rear disc brakes since discs have a lower static clamping force than drum brakes. This is how you do burnouts without a linelock. The only way to absolutely stall up the converter is with a transbrake(not a good thing for a street car). You can also flash-stall a converter but in reality all you want is for the converter to do what you want it to do and it doesn't matter if you hit some arbitrary magic number.

So remember, it's all based upon load; consult a professional when it comes to selecting the right converter, your car will move well before the stall rating, and make double-damn sure you get an auxillary trans cooler.

Hope all that helps a little more.

page62

Gerry provided a beautiful technical answer. I'll provide a simple, seat-of-the-pants response:

With a 2200 stall converter, the car moves away from a stoplight just like it would normally do -- however, it may be slipping more than a normal converter. At low rpms in non-lockup, it feels a little "slushier" than a stock converter -- no big deal.

The key to the higher stall converters is if you drag race. You can put the tranny in gear, press the brake and rev the engine up to the stall speed. Then you release the brake, and WHEE-HAA! you take off...