I had a B+M Holeshot 2400 converter, very good around town. I didnt have to use a lot of pedal to get the car rolling. I installed an external cooler just to be on the safe side. I had no heat issues.
I run a custom built 10 in. 3k stall in my Camaro and it will flash around 34-3500 but around town driving it is fine. It holds the car at a stop light and will start to move under 1500 rpm with light gas pedal.Originally posted by GRN69CHV:
I run a tight 10" converter behind a big block. It is actually a bit lazy until you get into it. Mine is set up for a 2800 - 3000 stall, but you can punch it and get it to about 3200. You have to be particular when talking converters. My car will basically not move until about 2400. So when you say 2400, do you mean lock up at 2400 or start to move at 2400?
Basically "stall" means when the torque converter "locks-up" under a load. With that, if you take a car with a 2,500RPM stall converter and you hold your foot on the brake hard, and hit the gas at the same time, (as if you were going to power brake), the "general" RPM in which the tires will break loose is at "about" 2,500RPM. If the converter was a 3,500RPM stall, then it would be at approximately that RPM in which it forces the tires to break loose. Keep in mind, if you put that same converter behind a nasty big block, in a car that has serious traction or is quite heavy, the torque of the engine will drive the stall speed up to a higher RPM, and an engine with less power will have the opposite effect and won't be able to stall the converter out as high. It's all relative to torque, vehicle weight and rear gearing. It isn't an exact science as far as an exact stall RPM goes.
Stock cars have anywhere from 1,000 to 1,400 RPM stalls from the factory. The reason a stall converter works is simple; an engine at 1,200 RPM is only making about 80 or so horsepower (on average), but at 2,500 RPM it could be making 150 to 200HP, and obviously trying to get a car moving using 150-200HP is going to be much better than one trying to launch at 80HP or so. Most performance engines don't make power until 3,000 or so RPM, hence why when you have a higher horsepower engine with a big cam, you need a higher stall speed so the engine is in it's "power band" when taking-off from the line, other wise it will fall on its face and be a turd off the line.
Some people believe that "stall" means the car won't start moving until the engine reaches that particular RPM, and that isn't even close to being true. We build race cars with 6,000+ RPM stall converters and when you put the car in gear and let it idle, it WILL roll along at 5 - 10 MPH, just like any other car will when put in gear and with the brake off. In fact, we usually cruise through the pits with the car simply in gear and idling, so if a 6,000RPM converter means that the car won't start moving UNTIL that RPM, then we'd have to have the engine wound-out to that RPM to put along through the pits at 10-15 MPH, and that simply isn't the case. Stall means that when the car is on the starting line, (with say a 4,500RPM stall converter), and the trans brake is on, (which locks the transmission in first and reverse at the same time), and you hit full throttle, the engine will wind-up to 4,500RPM with the car just sitting there, so when you slip your finger off the trans brake button and the tranny engages out of reverse, the car instantly launches at 4,500 RPM, and a race motor at 4,500RPM is pretty much at it's peak torque curve when leaving the line, hence the big wheelies you see on some drag cars or the incredibly low 60 Ft. times when traction is good. Race engines make no power at low RPM's, and are usually shy on torque, so the nastier the engine, the higher the stall speed needs to be (in general anyway). Again, cubic inches, torque, vehicle weight and gear ratio have a big factor in this.
A 6,000RPM converter behind a stock engine might not even get to 6,000RPM because the engine can't make enough torque (or power) to spool-up to that RPM because of the load of the converter. The car will start rolling at a much lower RPM and may never be able to reach 6,000RPM. This is also true for any converter from about 3,000RPM on up. Most mild race cars (9-10 second quarter mile times) use anywhere from 3,000 stalls to 4,500 stall speeds on average. Faster cars usually use even higher stall speeds, especially in smaller cubic inch engines that don't make the torque if big displacement engines. Also, the higher the stall speed, the more heat the converter will make, from hydraulic (fluid) friction inside the converter. A high stall converter can easily make enough heat to fry a transmission if you hold it on the line long enough at full RPM if the stall speed is above 3,500RPM or so, so a good tranny cooler is essential when running ANY type of high stall converter.
One common misconception about stall speed is that it's when the converter locks up - it doesn't ever lock up unless it's a lock-up converter. If the converter locked up at the stall speed, your tranny input shaft would go directly to the crankshaft speed. It's not called 'lock-up' speed, it's called 'stall' speed. It's when the engine stalls, or fails to gain rpm when pushed against the converter. The same converter will stall the engine at different speeds when used in different situations.Originally posted by BowtieAaron:
what do you mean by stall? thats when the engine will stall? or the tranny acts like it is slipping until that RPM (or thereabout), and then grab and go? i always get confused when people talk about converters.