Torque Converters

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sirhk100

Racer
Feb 24, 2003
16,317
183
63
Las Vegas
I know what they do but all the options of them honestly confuses me...

My motor is going to be roughly a 640hp/540tq setup and it's being built with cruising at 4500rpm in mind. It'll be okay to punch it up to the 6500rpm range for real fun when needed. I've got a built 4L80 behind it. 5.0 gears in the rear. I'm on 35s.
<<<<<<<<< The truck is right there in my avatar...

My motor builder (engine is currently in his possession with a 5-6 week lead time right now on it) recommended a 10" tight converter with a 2800-3000 stall.

This truck is not going to be raced, it's going to be cruised and played. Yeah, I know that sounds absurd with the specs above but hey... It snowballed a bit!!! LOL

My concern though is heat from that torque converter. I have dual coolers both with fans. Me personally I'm thinking something like a 2400-2600 stall in a 11" or 12". I "think" that's going to be better for temp concerns? Am I wrong? What about lockup vs not lockup?


I emailed TCS and got this reply but honestly, it's mostly jibberish as I don't understand the details...

Thank you for your inquiry. Our 4x4 converters usually are built in the 24/2600 stall speed range. With the power estimate of your engine @ 640 / 5500 TQ @ 540 / 5000. We suggest our 4L8SB converter (custom build) w/single disc lock up. Features of this converter are custom single disc clutch assembly w/billet cover, low stall stator, ballooning plates, vanes are furnaced brazed, converter uses Torrington bearings rather than washers, hardened hub. Please note single disc converter is for cruising and if the truck is to be chassis dyno’d the converter would not be locked up during testing (multi disc converter option is available will take full power w/converter locked up). Single disc converter your cost would be $1020.80 multi disc $1350.00. Lead time for build would be 2 – 3 days, shipping ground would be @ $70/80 and would take @ four days. Note will need to see the dyno sheet for this converter build, need to see lower rpm @3500 – 4000 rpm starting points, want to see how the engine builds torque

In our use and our world, what's the difference in a single disc vs. multi disc for a difference of $330?

Any transmission guru's out there? Everytime I think I'm about done with the money... Bam, here's another grand+! LOL
 

marcytech

Mega Member
Mar 16, 2011
6,228
626
113
limited knowledge but ill chime in with what i learned with my recent converter purchase and trans build. not sure if you already know some or all this info but here it is!
converter stall speed does not make the converter 100% lock up. theres always slipping happening. "lock up" converters get you closer to 100% lock up than regular converters. i was told you want your stall speed close to the rpm range where your motor makes the most power.
torrington bearings and hd hardened input hub is a MUST.
im runnin about a 3000 ish stall converter in my 4.0 ranger and heat isnt an issue at all compared to the old 1800 stall i ran for the past two years (2 12" cbr coolers for the trans)
 

sirhk100

Racer
Feb 24, 2003
16,317
183
63
Las Vegas
Are you actually seeing lower temps now with the 3000 vs the old 1800? If you don't mind, what brand or who'd you source yours from?

And yeah, didn't know it's always slipping. I did assume locked up meant locked up. LOL
 

marcytech

Mega Member
Mar 16, 2011
6,228
626
113
not seeing lower temps, but not seeing higher temps either. its exactly the same so far!
i got mine from edge racing converters in simi valley.
i should note this is all info from my c4 trans. the new style gm converters with clutches in em may actually be true lock up. mine doesnt have a clutch inside of it.
side note; lock up converters will bring crusing rpm down meaning temps too. so theres something to think about. i opted out of a lock up converter due to budget.
 
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sirhk100

Racer
Feb 24, 2003
16,317
183
63
Las Vegas
Yeah, I'm getting close to where I'm going to have to start thinking budget which sucks cause I'm so close to literally being done without skimping on anything... Stupid money tree is coming up like $3K short for where I want to be with this truck when it hits the dirt this fall... Granted, there's other trees to rob from but I REALLY don't want to thin them... LOL
 

partybarge_pilot

Uno mas Cervesa!
May 14, 2004
10,309
1,042
113
Easton, KS
Make sure you have a lockout switch for the lock up converter. If you run it locked off road you will kill parts.

Size won't make much difference on heat production, stall will. Go with the recommended stall, it will be way more fun to beat on. Flip the lock up switch when you hit the pavement for good cruising manners.
 

sirhk100

Racer
Feb 24, 2003
16,317
183
63
Las Vegas
I guess stupid question would be how is a switch wired up to the converter for lockout? My transmission has no harness of any sort going to it...
 

partybarge_pilot

Uno mas Cervesa!
May 14, 2004
10,309
1,042
113
Easton, KS
Stock ones have a wire that goes to the brake light switch. I forget if it gets ground or power. When you hit the brakes it unlocks. Make it think the brakes are on. Put a doide inline so it doesn't back feed and turn on the brake lights.
 

sirhk100

Racer
Feb 24, 2003
16,317
183
63
Las Vegas
Does the wire go directly to the converter itself or just into the transmission harness?

My converter that I pulled out had nothing electronic and Culhane removed everything electronic from the transmission as well.
 

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