Torque Converter Advancement

[RevTheory]

How much do you guys think torque converter tech has advanced over the last 15 years? Probably a little broad, I know. I've got a 2,500 lock-up (700r4) I bought back in '04 but, if things have improved quite a bit, I may be willing to pony up for a new, possibly custom if this engine/truck project ever comes together.

Mine's the 15 year-old version of this one https://transmissioncenter.net/shop/mr- ... araptor-2/. If I can get this engine on the dyno before Christ returns, I can forward the results and relevant truck info to someone for a custom. Anyone stand out as a leader in custom converters for high-torque SBCs in 4x4s with O/D?

One of the problems I had with this one is my snotty, little 383 idled ~1,000 rpm and this converter loaded it pretty hard when dropped into gear and then still reminded me of driving around with an old B&M Holeshot.

[F-BIRD'88]

Your current converter is just a GM factory lock up converter with the fins bent over a bit more to raise the stall speed a bit over stock.
The stall torque ratio is low compared to a th350-th400 high stall 10" converter.

The best high stall lock up converters for your trans are
the ones made from the GM 245MM (9") lock up converter core.
EG: yank,. or Precision industries Vigilanty.
They are not cheap..
Various options stator, lock up clitch etc etc.
You get what you pay for. Custom Stall from 3000 to over 4500 matched to your engine output.
All high stall converters feel a bit soggy at part throttle on initial acceleration..
These converters have a tuned stall torque ratio that you can choose from.(how hard the converter hits and multiplies torque output right at inital WOT launch)
from mild to wild. Not cheap.
These are not the only 2 companies that build custom high stall lock up converters on a 245MM core.

[rebelrouser]

Do a free experiment, simply send your specs to several converter companies, IF selecting and building a converter is a science, then by my opinion you should get similar combinations from all those companies. My bet is you will get a wide range of suggestions. Which means they guess more than calculate. I am on my 6th converter configuration for my new engine, hope to try it out soon. They are getting a little better each time. My issue is either they are pigs in the 60 foot, blowing off the tires, or the shift light never goes off during a run, blowing right through.

[RevTheory]

They mention being able to order them in 2, 2.5 and 3x torque multiplication and I don't know how any of that behaves when driving. I'll probably call them later but sales people always tell you what you want to hear so I usually find it helpful to ask opinions here first. I know squat about converters and would be easy prey, lol

[F-BIRD'88]

Blowing off the tires....
If you don't have traction its not the torque converters fault.
STR is how much engine torque is multiplied by the stator shape/angle /fin count and fin contour 's effect
as you first launch the car. A high STR hits hard
A low STR hits less hard initially but the torque multiply effect is extended out a bit further down track when the car is launching and the converter is in "stall mode"
This is independent from converter stall speed rpm on launch.
If yiu need the car to get up on the back wheels on launch try a high STR. (and lots of gear)
If the rear axle over reacts try a lower STR.
Big nitrous may want a lower STR.
It is a fine tuning converter performance element. like say a tone control on a guitar.

This is a tuning element more for drag strip launch than "driving" around town.
A converter that it dialed in for that car fir the track
is going to be agressive on the street.
Any time the car lacks rear gear the converter driving impression "dyno effect" is going to be more pronounced at low speed street driving.

[RevTheory]

I would think a higher STR with a heavy 4x4, 35x14.5 Super Swampers and 4.56 gears with a relatively low stall speed, say 2,500 max, right?

This engine combo will likely be all done by ~5,500; it's gonna be gobs of torque. If I've got it right, it should start the pull at 450 ft/lbs and hopefully pushing 550 ft/lbs by 4,200 ish.

I appreciate the help. This gives me something to go with when I call them.

[F-BIRD'88]

I find the gm Th700r4 a uninspiring trans.
I was glad to ditch mine and go back to my old trusty Th350. with a off the shelf B&M SuperHoleshot 10" converter.. Car picked up 4 tenths et and 1 mph.
Every thing about the car was BETTER.
1.6 sec 60 ft wheels up drag launches even on the street.
Much better in every way that matters.
IMHO the Th700 r4 is a dog.
The new GM OD transmissions based off the TH400 design are soooo much better in every way including the torque converters design and performance.
No cheap...

[F-BIRD'88]

For a heavy 4x4 with big tires and a hot 383 I'd get a TH400 transmission.

You are under geared.. Any high stall will have a more pronounced "dyno effect" driving impression feel to it at low speed in a big heavy vehicle with big tires.
I'd look at a Th400 with a stock GM 12" converter from a Th-350 trans.. It will max stall about 2400 rpm behind a high torque (at low mid rpm) hot 383. With good coupling efficientcy..
Dial down the camshaft if needed.
Dial up the low rpm torque if needed (dual plane with full divided plenum/spacer VS open spacer or single plane.
The "driving impression" will be much better.
You cannot measure this stuff on a dyno.

[GARY C]

How much do you guys think torque converter tech has advanced over the last 15 years? Probably a little broad, I know. I've got a 2,500 lock-up (700r4) I bought back in '04 but, if things have improved quite a bit, I may be willing to pony up for a new, possibly custom if this engine/truck project ever comes together.

Mine's the 15 year-old version of this one https://transmissioncenter.net/shop/mr- ... araptor-2/. If I can get this engine on the dyno before Christ returns, I can forward the results and relevant truck info to someone for a custom. Anyone stand out as a leader in custom converters for high-torque SBCs in 4x4s with O/D?

One of the problems I had with this one is my snotty, little 383 idled ~1,000 rpm and this converter loaded it pretty hard when dropped into gear and then still reminded me of driving around with an old B&M Holeshot.

If it is anywhere near what they advertise I wouldn't change it, you could spend money changing something before you know how it works.

[rebelrouser]

Blowing off the tires....
If you don't have traction its not the torque converters fault.
STR is how much engine torque is multiplied by the stator shape/angle /fin count and fin contour 's effect
as you first launch the car. A high STR hits hard
A low STR hits less hard initially but the torque multiply effect is extended out a bit further down track when the car is launching and the converter is in "stall mode"
This is independent from converter stall speed rpm on launch.
If yiu need the car to get up on the back wheels on launch try a high STR. (and lots of gear)
If the rear axle over reacts try a lower STR.
Big nitrous may want a lower STR.
It is a fine tuning converter performance element. like say a tone control on a guitar.

This is a tuning element more for drag strip launch than "driving" around town.
A converter that it dialed in for that car fir the track
is going to be agressive on the street.
Any time the car lacks rear gear the converter driving impression "dyno effect" is going to be more pronounced at low speed street driving.

BUT if the class is limited to a 10.5 tire, and you have a 4-link and set it to 150% anti squat and it is still slipping the tires, the converter is not spec'd to the application. Buy a different converter and set the anti squat to 105% like it was and it leaves perfect. low 1.30 60 foot times and carries the wheels about 6 inches almost to the 60 foot. If converters were a science then an experienced builder should be able to get close on the first try, and not have the racer spend thousands, in trial and error changes. I have sent in engine specs and asked for cam recommendations and the companies are almost always very close to each other on what the engine needs. I had one converter builder admit to me that many times it is simply what the builder has on the shelf to use at the time.

[F-BIRD'88]

Before it was a 4x4 truck with 35" mudders.
Now its a 10.5" tire rule drag car.
Make up your mind.
Garbage in= garbage out.

[HQM383]

I had one converter builder admit to me that many times it is simply what the builder has on the shelf to use at the time.

I’ve also had a converter guy tell me that some will often gravitate toward using what core gives greatest profit margin.

[RevTheory]

Before it was a 4x4 truck with 35" mudders.
Now its a 10.5" tire rule drag car.
Make up your mind.
Garbage in= garbage out.

I'm the OP and it's always been a 4x4 with 35x14.5 tires. You're the one that brought up drag racing and someone responded to it.