Another Stall Question

[justinsain1026]

Why would you need a bigger stall for? I still dont understand exactly what they do. Im a newb.

[mzoomora]

If you have an upgraded cam that doesnt make real good power below 2000 rpm. Also, even most stock motors will be faster with a small stall, it allows the engine to get into its power band sooner.

[Scotty_S-15]

On 2005-03-04 13:39, justinsain1026 wrote:

Why would you need a bigger stall for? I still dont understand exactly what they do. Im a newb.



to go into a little more detail of what Mzoomora said:

.................. Basically, when you stomp on it, the engine speed jumps up to a point limited by the stall speed of the converter. So let\'s say you\'ve got a basically stock 350, rated at 300 HP at 5000 RPms, and a stock converter rated at 1500 RPM stall speed. You stomp on it from a standing start, the engine jumps up to 1500 RPMs, and as you accelerate, the engine speed increases as your speed increases. Problem is, your 300 HP engine is only making 100 HP at 1500 RPMs.

....... So if you had a 2200RPM rated converter with the same engine, when you stomped on it, it would jump to about 2200 RPMs. Your 300 HP engine can make 150 HP at 2200 RPMs. So, it\'s like getting a free 50 HP shot off the line. (arbitrary figures)

........ And it becomes even more critical with a modified engine, because most things that increase power at higher RPMs, cause you to lose power at lower RPMs. So to overcome this, it\'s best to get the engine into the higher RPM ranges immediately to accelerate well.

.......... A hypothetical example: A naturally aspirated 350 engine making 600 HP @ 7500 RPM, hooked to a stock 1600 RPM converter. You\'re at the track, the light turns green, you stomp on it, the RPMs go to only 1400, and your 600 HP engine is only making 70 HP at 1400 RPMs. You accelerate slowly. We need that engine to get into the RPM range where it can make power. Of course lower gear ratios help.... We can try to get the tires to spin so the RPMs can climb, but that is counter-productive. So? A converter with a 5000 RPM stall speed! Yeah, that\'s the ticket!

......... Lets say you want and can drive this 600 HP monster on the steet now and then. When driving under normal part throttle conditions, the truck will accellerate somewhat normally, not needing to get to 5000 RPMs to move your truck. This is where good converter technology comes into play. A good converter will lock up fairly well under light light throttle loads, but jump up to it\'s stall speed under full throttle conditions.

[justinsain1026]

Thank you, thats helps me out a lot. Thanks for taking the time to type all of that. http://www.s10v8.com/images/smilies/icon_biggrin.gif

[wild85]

That 600hp engine would not run with a 1500rpm converter for the record. Every time you would put it in gear, it would stall. Mine did this with a stock converter with the cam i have now.I imagine a 600hp engine would have one hell of a cam. But Scotty I know what you mean anyways.

[Scotty_S-15]

On 2005-03-04 21:58, wild85 wrote:

That 600hp engine would not run with a 1500rpm converter for the record. Every time you would put it in gear, it would stall. Mine did this with a stock converter with the cam i have now.I imagine a 600hp engine would have one hell of a cam. But Scotty I know what you mean anyways.



Good point Wild. and that\'s why I used the 600 HP figure, knowing that it WOULD have one hell of a cam, hence making zippo power at low speed. And that sort of affirms what a lot of guys don\'t realize.... That a highly modified (mainly cam) engine makes less power at idle & low RPMs than a stock engine. Which is why the \"hot\" engine wants to stall when you put it in gear, yet a stock engine won\'t.