Torque Converter Stall Speed

[DaveFikel]

Hi guys-

I'm going to rebuild my 10R60 with a SunCoast Category 3 kit. I figure I might as well replace the torque converter since the trans will be removed and it makes sense to replace it then. I have no clue about choosing the torque converter stall speed & am hopeful to get a bit of advice.

My goal is the quickest quarter mile as I will never, ever get near the top end speed of my ST. Going that fast will probably just scare the crap put of me. I plan on replacing the spark plugs and beefing up the turbos, fuel pump, & injectors this summer. I'm also running on E-50 on a ZFG tune.

So, what stall speed would you choose for a category 3 rebuild kit? Keeping in mind I'm interested in being quick off the line and don't care much about top end speed.

Thanks in advance!

 

[2020FordRaptor]

Curious also to see what the optimal stall speed is. @ZFGracing would know, and RSA would be able to tell you also.

 

[Cruising68]

Good advice!

Depends totally on the hp/torque curve. You want the stall speed to be close to where the engine starts making good power after the turbo lag. Having said that, if you’ve never driven a vehicle with a high stall converter there are disadvantages. Higher stall means more heat and daily driving is not a lot of fun.

Don’t know what the spec for the ST converter is but my guess is it’s higher than a NA engine. I can hit almost 3k standing still.


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[2020FordRaptor]

Good advice!

Depends totally on the hp/torque curve. You want the stall speed to be close to where the engine starts making good power after the turbo lag. Having said that, if you’ve never driven a vehicle with a high stall converter there are disadvantages. Higher stall means more heat and daily driving is not a lot of fun.

Don’t know what the spec for the ST converter is but my guess is it’s higher than a NA engine. I can hit almost 3k standing still.


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See that’s what I’m curious about. The stall seems pretty good for the stock unit, wondering if it’s just right.

 

[BrooseDaMoose]

I can't remember where I saw it but it was 2,300 for the stock converter. ZFG sells the Suncoast Pro-Loc converter and recommends a stall speed of 2,800.

Edit: I just found it and it's actually on the ZFG site: Torque Converter

 

[Cruising68]

I can't remember where I saw it but it was 2,300 for the stock converter. ZFG sells the Suncoast Pro-Loc converter and recommends a stall speed of 2,800.

Edit: I just found it and it's actually on the ZFG site: Torque Converter

That sounds about right for a turbo car. IIRC most of my cars and trucks were all under 2k rpm stock. I bet if you look back at his dyno charts, good things are happening at 2800rpm

I had a couple of high stall converters (3k+) in faster vehicles. They were great at the track but they sucked hard daily driving! With a loud exhaust they sounded like I was red light dragging even though I was barely feathering the throttle.


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[BrooseDaMoose]

Yeah, my mustang had a 3,500 TCI and sucked on the street. My 302 Ranger had a 2,800 Hughes and it was definately better.

 

[DaveFikel]

Why do they suck so much on the street? I do have a complete 3" exhaust from engine to tail pipes.

Thanks for all the responses!

 

[DaHuntah]

Read this: How stuff works

 

[Cruising68]

Why do they suck so much on the street? I do have a complete 3" exhaust from engine to tail pipes.

Thanks for all the responses!

Cause they rev like crazy every time you are accelerating from a light even with light throttle. If it’s really loose the car won’t move until it hits its stall speed.


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[DaveFikel]

I watched a couple videos & I see why it'd be a pain. Thanks for all the input!

 

[pgk1]

Years ago I had a 1972 Gran Torino 429 cu in. with a C6 and ended up finding a 1970 429 SCJ block for it and had a 514 cu in stroker motor built for it with a NOS Pro fogger kit along with all the necessary internals so it would survive, roller rocker, cam lifters, topped off with a 1050cfm carb. I ended up blowing up the C6 and had transmission shop build up another trans with SVO clutch plates, maunal valve body and some other mods, they also sold me a modded B&M super holeshot converter that had a higher stall in it. I don't remember noticing that it revved up much higher than the stock one did unless I loaded it up. Actually now that I think about it with all the HP and torque that motor made a stock converter would have been fine. Like someone else had mentioned I would contact ZFG and see what they would recommend.