Tight vs Loose Torque Converters

[dvw]

More than one way to loosen a converter. Bend the fins, add excessive clearance between the drive side and turbine, different diameter. Most modern converters have tight clearance. The most common way of swapping stall speed now is a stator change. Different angle or number of blades/fins. PTC will build a very nice street converter for a reasonable price. I have one of theirs , 5300 flash street driven. I've driven it from Detroit to Columbus.
Doug

 

[33 IMP]

This is one of my old ones. It's a little on the loose side now.

 

[RPMagoo]

While on the topic. -- The Guy at My trans shop wants to have a convertor made, (for My 306 - 370 HP Ford -- AOD transmission), with the damper removed. -- He says that "it will still be a lock-up convertor. -- Comments on this ? -- Thanks

 

[66Satellite47]

While on the topic. -- The Guy at My trans shop wants to have a convertor made, (for My 306 - 370 HP Ford -- AOD transmission), with the damper removed. -- He says that "it will still be a lock-up convertor. -- Comments on this ? -- Thanks

Lock up converters are a whole different deal.

 

[Curiousyellow71]

My understanding the converter damper absorbs the shock as the converter locks up. Its similar to the springs in a clutch. High hp the springs give up and they usually are replaced and are solid and then the drivetrain has to absorb the shock. Maybe a aod had issues with that...? Dont know? Small engine 370hp not sure getting rid of the springs is necessary, but I suppose it's going to be able to take more abuse. Its suppose to make the converter engagement harder but harder on tranny parts. There is a upside and a downside to removing them...if the converter can handle the hp I'd run them, if it can't then go with solid. The hp your talking doesnt sound extreme...but I've only been through a overhaul on one ford aod...made me appreciate mopar autos.
https://www.sonnax.com/tech_resources/235-dampered-damperless-converters-what-s-the-story

 

[wyrmrider]

AOD has a unique mechanical lock up
I'd do some serious research

AOD I ave the big transgo kit and pickup parts in my 88
Transgo developed the kit for the AODE on my 92 Mercury
have not touched either trans since kitting them

 

[MiradaMegaCab]

In my experience I’d use a loose converter on a ProCharger equipped engine. This lets the RPMs flash quickly helping the ProCharger to build boost quicker.

On my Roots blown applications, I use a tight converter to utilize the engines low RPM torque.

 

[Moparfiend]

I still have yet to contact Lenny and others to discuss my application because its not solidified at this point (mainly camshaft). But this discussion and research is helpful along the way and its a whole bunch better than thinking of the **** we are all dealing with...... So if my 340 power band is say steep 3000-6000 would a stall 2800 stall be better off the line than a 2400 all (other things being equal)?

 

[33 IMP]

If I had a three-grand-up power band, i wouldn't consider anything less than a quality 3500rpm flash stall.

Edit: but I've got a 4500 behind a big block with a .557 purple shaft and 3.91s, and a 5500 in my opel. Take my opinion with a grain of salt.

 

[33 IMP]

Be aware that a "three grand stall" might stall 3200 or more behind a stout street big block, but maybe only 2300-2500 behind a small (and nowadays a 340 is small) block with a big camshaft (not a whole lot of low end torque).

 

[Curiousyellow71]

http://www.ptcrace.com/
https://www.dynamicconverters.com/aboutus.htm

Ptc is a couple hundred bucks cheaper then dynamic, I noticed coan has a decent priced 9 1/2 ptc....but we went with dynamic... Our dynamic 9 1/2 flashs 4200 , goes down the highway pretty good at 2000 rpm. Have not drove a lot yet, behind a 510, shifting at 6k.
In all honesty for a small block that doesnt have the big block torque I would probably try a PTC. I talked with them and was impressed, just seemed like the Lupo's are mopar guys and were more confident in setting the converter up how I wanted.
For stalls below 3k that work decent in a car low geared that 55mph is towards 3k we were happy so far with these converters...pretty good bang for the buck, summit sells them.
http://www.hughesperformance.com/

When I say low geared you don't want to put in a converter that slips 2 much at cruising speed. You can go to wallace racing and plug in your tire size and gear and figure out what rpm. Loose converters (the hughes we've run) will not be much fun to go to big, need to take some time figuring cruising speed say at your 55 mph rpm and choose a stall less then that rpm...or try the two links above and spend some money on a tight converter.
http://www.wallaceracing.com/calc-gear-tire-rpm-mph.php
and yes 2800 leaves harder the 2600, 4200 will require some traction.

 

[66Satellite47]

Thinking back, my converter selections depended a lot on which manufacturer was really close to Mopar. My early days mid '70's B&M was still tight with Mopar, later Turbo Action (Paul Forte), now Frank Lupo Dynamic is still very Mopar focused. I hear that PTC is also. My only outrider experience was the Coan. One of my Chev buddy's picked up so much from his Coan, I had to try one, worked great. Again talking to the real tech guy before buying is the key. The phone salesperson is not likely to produce the best results. Stall speed has so many variables, cover size & design, fin and stator design, engine torque & torque curve, HP. The real experts can combine the options to get a good "stall speed".

 

[dvw]

My street car has had both the $450 9" PTC and a Turbo Action full race 8". They are about .05 apart in ET.
Doug

 

[33 IMP]

Last time I talked personally with the owner of a local well-respected converter builder, the converter he built me picked up two tenths and two mph in the eighth. He was a one man shop, and is retired now.

 

[66Satellite47]

Last time I talked personally with the owner of a local well-respected converter builder, the converter he built me picked up two tenths and two mph in the eighth. He was a one man shop, and is retired now.

If the person really knows the internal dynamics, that's what you get.

 

[CoronetDarter]

Ultimate Converter concepts built an 11" converter that allows the car to drive like a new car. At cruise and light throttle, the car responds nicely. Hammer down from a stop, the tires spin.
It is a win-win.

Got my 3000 stall from Ultimate. As Greg said, you get the best of both worlds. Don't understand the engineering behind it but it works.

 

[andyf]

I told Paul at Turbo Action what I was building and he built a converter for me. I don't know if it is loose or tight but it seems to work really well. My engine makes more than 600 ft-lbs of torque so Paul said that any converter he could build for me would end up a little looser than a factory type converter. The one he sent me is a 10 inch. The car idles fine without creeping but it moves as soon as I take my foot off the brake. On the freeway the driveshaft speed is within a couple percent of engine speed.

 

[Moparfiend]

I told Paul at Turbo Action what I was building and he built a converter for me. I don't know if it is loose or tight but it seems to work really well. My engine makes more than 600 ft-lbs of torque so Paul said that any converter he could build for me would end up a little looser than a factory type converter. The one he sent me is a 10 inch. The car idles fine without creeping but it moves as soon as I take my foot off the brake. On the freeway the driveshaft speed is within a couple percent of engine speed.

I gotta chew on that for a bit......On the freeway the driveshaft speed is within a couple percent of engine speed

 

[Moparfiend]

I gotta chew on that for a bit......On the freeway the driveshaft speed is within a couple percent of engine speed

I chewed it and tried to swallow but it came up. How do you know your driveshaft rotational RPM?

 

[RJRENTON]

With all the discussions and comments about "tight" and "loose" torque converter operation, wouldn't it be better to further define exactly what tight and loose represent in numerical terms rather than the subjective or opinionated trem. Its extremely difficult to achieve repeatability based on undefined terms.
I thought that the term was Stall RPM, or stall speed, defined as: where the engine rpm was increased (converters pump or impeller rpm) to the point where the converter's turbine section begins to rotate, with the stator locked to provide maximum torque multiplication. The stall speed or rpm was determined by the angles of the impeller and turbine blades and the number and angles of the stator blades and when the stator clutch begins to freewheel. The higher the stall speed allowed the engine to get to its highest torque peak and higher up on the horsepower curve to produce its best power. The disadvantage of a high stall speed converter was poor low rpm operation and significantly higher transmission oil temperatures due to higher oil shear during low rpm operation. I guess that this pertains to the basic 3 element converter not the converters with the lock up clutch. At this point in time, perhaps someone can better define the torque converter's operation to make the operation more understandable to the uneducated like me.
BOB RENTON