I am building a Jeep primarily for offroad. Lots of slow technical rock crawling and some fast hill climbs. While 0-60 launches will be fun to show off, I really don't care how fast it is and would rather have good control offroad without lighting up the tires every time I touch the gas peddle.

Vehicle weight: 4800lbs
Engine: LS3 480 crate engine (this is the "hot cam" version)
Transmission: 6L80e (comes with 3000k stall)
Transfer case ratio: 3:1
Gear ratio: 5.38
Tire size: 37"

I'm still in the planning phase so I haven't tried the 3000k converter that comes with the transmission, but it seems pretty high for my application? Should I plan on switching it out?

 

I am in NO way, shape, or form an expert in NON-Racing related Off-Road Motor-Sports...

But I would assume that the use of a "High Stall-Speed" torque-converter for rock-climbing and/ or other crawling/ slow moving off-road contests would be the wrong direction to go in.
I would think that a "Low Stall-Speed" converter would provide much better control over torque application and help prevent spinning the tires when you don't want to (meaning light throttle use).
The 3,000 RPM converter probably would break the tires lose when you do not want, under light throttle.
It will probably also make the truck roll backwards under light throttle instead of starting to crawl forwards.

I am aware that there are times when heavy throttle is applied to rock-climb... but that also light throttle crawling is necessary.
The 3,000 RPM converter is really intended for full-time heavy-throttle use, like in drag racing.

Hopefully someone with actual experience in this field will chime in, as I am just speculating.

 

I'm in mid swap-parts collection on a Jeep Yj as well,
One suggestion a couple different transmission guys pointed
out is that if the converter isn't locked its making heat.
If your stall is too high,, you won't be able to get lockup soon enough at highway speed and the heat "can" supposedly get out of control.
Also want some balance on the torque transfer with the stall I've been told by a few that a 2200 is about right for 33-35 tires and 4.** ish rear axle range.

Universal recommendation,, use a BIG trans cooler...

I've been mulling over the complexity and side effects if the trans is set up to act normal in "D" and be aggressive in M or Tapshift mode.. I'd like more control in the bottom couple gears when doing something more technical.. Rather not always have the 1-2 shift happen at the wrong moment. And the stall has to play in ...

 

The only time you would want the torque-converter to lock is when at a steady cruising speed under light throttle.

I do not see this scenario occurring while rock-climbing.

However a good operating cooler is always a good idea; as is a temp gauge with sending unit in the pan.
Ideally keeping temps between 160*F and 180*F.

 

This is my concern with the higher stall.

Chevy doesn't sell this transmission in the connect and cruise with a lower stall so I am curious if there's a reason why... If not I'll replace it with a lower stall before even installing and get it tuned for the change.

One thing I came across is the due to the hot cam the higher stall converter is needed to prevent the vehicle from being jumpy and lurch at slow speeds. Is there truth to that?

 

I have a large cooler already in place. If it isn't enough I'll place a second CBR cooler with a fan in line.

 

Okay, I'll be the one to say it: A big cam in a rock-crawling rig isn't a good idea.
You will be needing a lot of low-end power in that situation, and that isn't what you will get with a "hot" cam.

You need a low-stall converter for a low-speed rock crawler, and you will just be crutching a larger issue with your choice.

 

Hmm...

Would the LS3 430 with the 2400k stall 6L80e be the smarter choice? Top it off with a supercharger to get more out of it for fast stuff?

Or the LSX 454 with the 2400k stall 6L80e?

I want power for go fast stuff and hill climbs without sacrificing handling for technical low speed stuff.

 

a 9.5" 3000 stall wouldn't be to far off for a rock crawler if built correctly. I would probably a recommend something slightly tighter for a new build like a 2800. If the converter is this stall speed with a positive fin angle it will still give great control over applied torque and wheel speed. The 28-3000 stall option is a pretty popular choice for most of our rock bouncer type converters if that helps you make your choice.

Anything chance you can post the cams specs?
One thing to consider as well is cam size and duration, with a big enough cam you may have no choice but to go with something looser unless you plan to change the cam.

 

The nice thing about a higher stall converter in your setup is that the increased slippage allows for a very gradual torque apply curve, enabling you to gently modulate the throttle when needed in low speed/low gear situations, and providing a big torque hit when you want it.

 

A rock bouncer converter is going to be way too hot for my needs. Ultra4 would be closer but even those tend to rely on double footing to keep wheel spin under control.

TECH SPECS
Part Number: 19370411 / 19301358 / 19301358
Engine Type: LS-Series Gen IV Small-Block V-8
Displacement (cu in): 376 cu in (6.2L)
Bore x Stroke (in): 4.065 x 3.622 (103.25 x 92mm)
Block (P/N 12623967): Cast-aluminum with 6-bolt, cross-bolted main caps
Crankshaft (P/N 12597569): Nodular iron
Connecting Rods (P/N 12649190): Powdered metal
Pistons (P/N 19207287): Hypereutectic aluminum
Camshaft Type (P/N 88958753): Hydraulic roller
Valve Lift (in): .525 intake / .525 exhaust
Camshaft Duration (@.050 in): 219° intake / 228° exhaust
Cylinder Heads (P/N 12629063): Aluminum L92-style port; as cast with 68cc chambers
Valve Size (in): 2.165 intake/ 1.590 exhaust
Compression Ratio: 10.7:1
Rocker Arms (P/N 12669995 int): Investment-cast, roller trunnion
Rocker Arms (P/N 12669993 exh): Investment-cast, roller trunnion
Rocker Arm Ratio: 1.7:1
Recommended Fuel: Premium pump
Maximum Recommended rpm: 6,600
Reluctor Wheel: 58x
Balanced: Internal

 

Dalton, Thank you for adding your input.

I was really hoping someone with knowledge or experience would contribute to the thread.

Do you feel a 3,000 RPM unit could be tight enough to prevent roll-back at low throttle input?
...I am sure the truck isn't light and will probably be nearly standing completely up near 90 degrees.
Not the best scenario for traction.

 

As Dixiebandit said... I feel a different camshaft would be far better than what the engine comes with.

Something that is more intended to produce increased lower RPM and Mid-range torque/ Mid-range horse power.
Obviously then a torque-converter that pairs well with that camshaft, would be ideal.

Even with my limited knowledge of your sport... I can confidently say that a camshaft change would be a massive benefit.
I would recommend that you give "Brian Tooley Racing" a call for a camshaft recommendation without having purchased a torque-converter yet.
He will most likely choose something with more intake lift, and less duration for both intake and exhaust... based on the engine specs you listed.

After a new camshaft is chosen, then I would call FTI/ Dalton and have a torque-converter spec'd as the last thing you do.
Having everything else done; you can give Dalton all the information on the truck... and he can give you the best torque-converter recommendation for the entire package/ build/ truck.

 

Really good question.

 

Is it that crazy of a cam?

Here's the specs of the stock crate cam to compare it to the hot cam I listed above:

TECH SPECS
Part Number: 19370416
Engine Type: LS-Series Gen IV Small-Block V-8
Displacement (cu in): 376 cu in (6.2L)
Bore x Stroke (in): 4.065 x 3.622 (103.25 x 92mm)
Block (P/N 12623967): Cast-aluminum with 6-bolt, cross-bolted main caps
Crankshaft (P/N 12597569): Nodular iron
Connecting Rods (P/N 12649190): Powdered metal
Pistons (P/N 19207287): Hypereutectic aluminum
Camshaft Type (P/N 12623063): Hydraulic roller
Valve Lift (in): .551 intake / .522 exhaust
Camshaft Duration (@.050 in): 204° intake / 211° exhaust
Cylinder Heads (P/N 12629063): Aluminum L92-style port; as cast with 68cc chambers
Valve Size (in): 2.165 intake / 1.590 exhaust
Compression Ratio: 10.7:1
Rocker Arms (P/N 12669995 int): Investment-cast, roller trunnion
Rocker Arms (P/N 12669993 exh): Investment-cast, roller trunnion
Rocker Arm Ratio: 1.7:1
Recommended Fuel: Premium pump
Maximum Recommended rpm: 6,600
Reluctor Wheel: 58x
Balanced: Internal

 

I talked to Chris at Circle D and he recommended their 278mm torque converter in 2600-2800 rpm stall: https://www.circledspecialties.com/6...p-series-278mm

He mentioned this converter would work well for the stock cam LS3 430 and the hot cam 480 (the one I'm planning on going with) and if I supercharge in the future. It will smooth out the chop from the hot cam so it'll still idle and crawl well at low speeds/rpms. The 278mm converter is 11 inches in diameter making it about an inch smaller in diameter than factory which is where most of the higher stall rpm comes from. The smaller diameter will help to transfer less fluid at idle. This will give less pushing at the brakes, because of the cam. The 2600-2800 stall will allow the pedal to feel connected while not being too tight for the cam.

​​​​​When I asked if I should go with the 430 cam instead of the 480 cam he said he'd use the 480 cam.

 

No, it's not.

But it is also not meant for a heavy vehicle/ truck that needs low rpm torque instead of really high rpm HP.

That cam/ engine combination is good for a street cruiser/ car that works well as a street/ strip vehicle... like the majority of car enthusiast would want.

Circle D is perfectly fine... they gave you a recommendation for the engine as it currently is.
I have seen torque converters (inside and out) from most all of the companies that market to us here and converters that cost between $5,000 to $30,000 (lenco-drive torque-converter for engines in the 3,500 to 5,000 HP range)...

I would go with FTI over any of the other companies in our market.
I prefer FTI for their:

-available selection.
-materials used.
-method of construction.
-technology used.
-design choices.
-quality control.
-performance.
-reliability.
-cost.
-availability of service and repair.
-customer service.

The bottom line is that I like the products... I like the people behind the products... and I like to cost to performance ratio.

FTI Performance Torque-Converters offers great products; they are also a very active and supportive sponsor here.

The man to talk to is Dalton.

Please visit: FTIPerformance.com -OR- Please call: 866-726-8358 and ask for Dalton.
They will take good care of you.

 

Built the way i would build a "3000 or 2800 stall" converter, yes it would be tight enough. Keep in mind Tox also has a BUNCH of ratio in the drivetrain as well(which is totally fine btw) so that will give the converter plenty of mechanical advantage over the tire.
If it helps at all for comparison... my 7k lb truck idles at 7-800rpm with my 3200RPM converter and sits perfectly still at about a 30-35* angle at idle(steep driveway). 37" tire and 4.56 gear. Tox has much more gear, less weight, tighter converter, and probably more low end torque as well(mine is a mod motor)

Sorry "rock bouncer" was a poor choice of words on my part. I know those are normally the tube chassis low center of gravity of trucks that do hill climbs or ultra4 type runs. I was thinking rock crawler/trail crawl/ride type setup that could even be street driven. Looking at these cam specs I'm going to stick with my original 2800RPM recommendation. Should still idle just fine and offer plenty of control over the tire as i mentioned before.

Vortec: As always thanks for the shoutouts!

 

Thanks for the input guys. I'm starting to think that the LS3 430 (stock cam) will be a better fit for my uses and it'll probably idle lower which is nice. I worry that I'm fighting too hard to get rid of the chop characteristics of the hot cam by covering it up with a torque converter and will be unsatisfied with the results. It does feel like a waste leaving 65hp on the table, but not being able to enjoy how it crawls at slow speeds isn't great either. Maybe I should use it as an excuse to put a supercharger on top so I can preserve the slow speed crawl quality the stock engine would provide and still be able to let it eat at high speeds.

 

Thank you for posting replies on this thread!