Which Stall Converter

[skerry]

I'm reaching out here because if I read one more article on what a Torque Converter does that doesn't tell me how to at least get a ball park on which stall converter to go with I'm going to pull my hair out.

 

I'm just looking for advice, here is what I'm working with:

 

I have a SBC 350 with stock heads, rpm performer intake, Lunati voodoo cam, and everything else stock(About 350HP). I have a built 700R4. I have the R180 with the 370 gears(I know, it's the odd one) diff. Lunati says the cam "likes 2800 stall" but I think I'm bit underpowered based on what I've read for that high. I'm thinking 2500 but would love to hear some ones opinion who knows what they are talking about(because I don't). Any other questions or details you might need, feel free to ask.

 

Thanks

Stephen

 

 

[NewZed]

Race only or street only?  Or in-between?  

 

If you don't trust the cam designer, who will you trust?  If you're not getting the power from the cam, maybe you have the wrong cam for the blend of parts.

[skerry]

Street Only and I trust the cam designer but I know a lot more goes into Stall than what Cam you have. They have nothing about it in their spec, it's just on the sales page as a side note "likes 2800 stall". It doesn't specify at what HP or Peak Torque or gearing or car weight.  I've researched the cam and it's about as far as I can go with my stock setup. I chose the cam because it has a smooth power range with a little bit of punch up top but like I said before after reading everything it really seems like the 2800 is going to make my car sluggish in the bottom end. And it also seems like if I get too low then it will make it idle rough. I was just kind of hoping that maybe someone had a similar setup or close enough that they could say, this is what I have and this is what I would do. You know what I mean?

[NewZed]

I'm definitely no expert on converter stall speeds but I think that you have your understanding backward.  The 2500 will be more sluggish than the 2800.  The number is where the converter starts to "grab".  So 2800 would be like revving the engine to 2800 RPM with a clutch and a manual transmission to get moving versus revving to 2500.  Basically the high stall speed converter cars sound like somebody slipping the hell out of their clutch to get going.  So high stall, you'll be the guy making a lot of noise to get going from a stop, low stall, you'll be quieter but not as quick.

 

The converter should, generally, match the torque curve of the engine.  So Lunati's advice is based on what their cam should produce.You probably don't want to go higher than that because it would be a waste of energy, but you could probably go lower to make the engine more streetable.  Then tune the driving experience by adjusting the gear change points of the transmission.

 

I'm just talking from what little I know about automatics.

[skerry]

Cool, I appreciate the explanation. I guess all of that reading didn't do me much good as I thought lol I would like to find the happy medium in there. I think that the 2400 might be the key. I think I'm going to take the plunge and make adjustments as you suggested. Thanks for your input.

[skirkland1980]

A torque converter will stall more with a heavy car an less with a lighter car. Also since the 700r4 has a very low first gear coupled with your 3.70 and low flowing heads I'd go with a 2500.

[RebekahsZ]

NewZed-that was a great explanation. We all want to have "fast cars" but most of us don't get it, that most racing parts are designed around wide open throttle. Then when we get them, we complain that they drive like crap. Problem is, they weren't designed to drive, they were meant to race, which means foot either hard on the gas, or hard on the brake. Case in point: the relatively mild soup-up cam in my truck helped it make about 70 hp over stock (along with some other parts too). But, it really hurt parking lot driveability and the idle has to be set higher, and the tailpipe fumes from un-burned fuel at idle make the truck so stinky my wife won't ride with me. Everything is a trade off. That's why there is no "best" on hybridz. It's a good rule.

[rsicard]

Kudos to New-Zed.  That was a VERY CLEAR explanation concerning converter stall speeds!

[skerry]

Wish I would have seen the response(doh!), I went with the 2800 though it does say(2500-2800). The motor has gotten a little more beefy than I first anticipated. To go with the Lunati Cam, I have Comp Cam 981-16 Valve Springs, roller rocker arms and I found that the heads were a little better than stock. Now I need to make sure that the diff is the one that I think it is. I'm scared I've created a monster when I wanted a daily driver.

[skirkland1980]

You shouldn't notice much difference under normal driving conditions. In my car I've used 2000, 3000, and 4000. Only time I noticed Difference was when I loaded the converter for launching.