a tight torque converter
 

Just what does tight mean? Is a tight TC one that is opposed to loose? There is alot of chatter out there in other searches but seems like there are some contradictions I think. These terms are used here too but is talked about at a level of hands on experience and I'm just trying to get my head around it, get a feel for it so to speak.

Just slang….

Tight = lower stall
Loose = higher stall

Stan

You can have a tight low stall, a tight high stall, a loose low stall, and a loose high stall, and pretty much anything in between.

The stall, high or low is more where the engine couples up with the transmission, or flash’s too. The engine goes up against the load and can’t gain any more RPMs until the load moves, and the transmission turns.

Tight or loose is how much tq can be transmitted while the engine is below the flash RPM/stall speed. Tight the car tries to move as soon as you put the transmission in gear. Loose the car doesn’t really try to move until the engine is nearly up against the stall or flash speed.

That’s not how we described them when I worked at a transmission shop that rebuilt and built new converters. If you make it loose by increasing clearance between the stator and pump, that will increase stall and also create heat. It’s a “cheap” way for a crappy converter company to make a higher stall. If you change the pitch of the stator and or change the diameter of the pump and or stator you effectively change the stall while maintaining efficiency and reducing heat. If you have a lot of clearance you have extra slip under and over stall.
My experience, The converters we built were for up to super pro type cars. Nothing super high horsepower. So it may be different when you get into the 1000’s of HP.

Stan65, I agree with how you are describing tight al loose converters.

What I described is more street jargon for how the stall acts on the street, versus actually describing the stator, pitch, and pump, and how they are working together to make up the stalls attributes.

What made things kind of confusing is when companies started to use “tight stators setup” to build “loose” converters, i.e., high stalls speeds that pull the car around like a stock converter at low speeds. FTI call’s their 9.5” street stall a “tight 4000”. Lol, so it is both tight and loose. Dynamic uses the same language. Different companies use different terms, PTC from what I recall refers to zero stator, or the slippage for stator design, I think tight and loose for them only refers to the stall speed.

In my world I know it as such. You can have 2 different 3000 stall convertors but how they feel when they start locking up is the difference.

The tight convertor will go from stall to lock immediately and solidly like a switch was thrown.

The loose convertor will go from stall to lock softly something more like a properly released clutch.

These feelings relate directly to how the convertor was manufactured and to some extent it's diameter.

A loose convertor not only will have a higher stall speed, it will "couple" less efficiently than a "tight" convertor, causing more slippage friction and heat. Additionally, a loose convertor may even affect your stop speed and cruise RPM as the convertor is just "slippy" even at high RPM.

I swapped my 3500 stall TCI with forumite Lee Atkins (who was trying to squeeze a bit more out of his 11 second Firebird) for his tight 2800 stall Hughes Convertor. He tried mine and it actually slowed his car down and lost some mph through the traps due to the slippage.

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The response rate of a converter as RPMs increase varies a lot on different converters, the diameter of the stall makes some difference also. Some converters start to move the car at pretty low RPMs, but you can almost hold the converter to the flash speed by applying only the brakes. They tend to slip quite a bit if the cruising RPM is below the flash RPM to far. Usually describes the bigger diameter converters that are a bit loose, with a 10”, 11” or 12” converters. The bigger the converter, generally the sooner the car try’s to move.

I have a stock 11” (like what you would find behind a TH350), a 11” 2800 and a 11” 4000 stall in three different cars. The stock 11” converter I can take it to 2200 RPM by hold the brakes, but moves the car around fine like any other stock converter. The 2800 stall 11” was tight enough that it it work ok on a car with 2.73 gears. It starts to move the car a bit later than the stock 11”, but can only hold it with the brakes to about 2200, not much different than the stock 11” until the engine goes full throttle. I had several different gear sets behind the 11” 4000, 3.23s was the highest, 4.88 was the lowest. You had to drive 75 or faster to keep it from slipping with 3.23s. Pretty much could hit the flash RPM by just holding the brakes, but it hit the flash RPM hard and couples up really well. I would guess that one is set up fairly loose inside, and probably the main reason it works as well as it does holding power past the flash is because of it’s fairly big 11” diameter. Most converters you find like it with that high of a flash RPM are 10” or smaller. The old Continental’s converters people like on this forum are often bigger in diameter and couple up really well, but they get loose similar to the 11” I have when they are set up to stall much above 3500.

I had a mushy 3000 10” Dayco that was like connecting the engine to the rear end with a rubber band.

My favorite street stalls have been 9.5” stalls. I have one the flashes to 4400 (Built by Dynamic) but I can only hold it to 2000 RPM with the brakes. It is pretty soft below 2000. I have a 3400 (FTI) and a 3800 (Sinister) in the same diameter. The lower flash helps how the converter coupled up quite a bit below 2000. But IMHO, I like the 4400 flash, it works well enough in town below 2000, and it is extra fun when it hits the 4400 flash and tries to twist the car in two. :)

Thanks Jay S, your descriptions are helping me relate to my new TC realizing it is working correctly. I have a TSP 9.5 inch where I basically made a mistake in order. I currently have a 216° 0.050 cam in a 428 with 245 cfm 6X-4 and said I'd be going to a 228° or so in the future and I might not get there too soon now. I have 3.23's. The brakes hold to around 2,500 and the TC is ranged at 2,600- 2,800. It is what I'd call loose below 2,700 but feels linked up above. I'm pretty used to it now I just don't like that it sounds like it is "straining" to get moving at low rpm but this is a totally different story when you get on it, wow! It is like a very noticable amount of horsepower has been added. That is eye opening. I'm working on getting a new rear right now and will go with a bit shorter gear which I understand reduces flash somewhat. That may help a little. Once I replace my fuel pump and get driving it I'm going to test the calculation that I should be turning around 2,700 at 45mph in 2nd.

I have a friend with almost the same TSP converter that you have. Suppose to stall in the 2600 to 2800 range. He has 3.90s though in a 461 CID RA4 in a 70 GTO, in paint and body jail right now, hasn’t ran it yet. JLMounce on here has had the same 2800 TSP converter with highway gears, he went to a 4L80E a while ago. If you want to compare notes, send him a PM, he will tell you if yours is operating the way his did. To me yours sound a little on the loose side of how it should perform, they vary some combo to combo though. With that TSP you should not need to drop to a lower gear though if you have 3.23s now. A couple series lower gears won’t change it that much.

Tight feels like a crisp pull-away, as if a dry clutch, regardless of gearing.
loose, feels like a mushy revy pull-away when you want tight, as if slipping, regardlesss of gearing.

Now gearing matters; tight will feel tight with racier gears. Loose SHOULD feel tight with racier gears.

The real value is a hi-stall converter feeling tight with highway gears.

IMO there is no such thing as a tight converter or a loose converter. There is a right converter and a wrong converter.

Folks use the term loose if they feel it slips to much or tight if they want to boast about their track performance. "Tight" gives an extra wow factor because most folks figure a car would be faster with a looser converter, that's what race cars use.

Example ; over the years the Jim Hand tight 10 converter has went from initially flash stalling from 3200 to as much as 4200 as of late. Same tight converter, big difference in stall.

You can take a loose 10" converter in a car with a 3:42 gear and make it a tight 10" converter by installing 3:90 gears.... Same converter, two different definitions.

JMHO

The terminology is skewed a bit these days as it means different things to different people. The real question is whether it's the right converter for the car.

One interesting way of determining whether a converter was right or wrong that Steve at Hughes wanted to know was how much rpm drop at WOT upshifts was occuring. They use that method a lot on some big HP applications. Steve told me they like to shoot for about 700 rpm drop on upshifts with a 400 turbo, in my case 4L80E with same gear ratios, and an NA engine.

So when testing one of his converters I was datalogging at the track. When I datalogged 850-ish rpm drops, he wanted the converter back to loosen it just a pinch. Was an interesting approach that I had never had a converter company ask for before.

Anyway, Hughes was the first that actually built a converter that was on the tight side, the car drove really nice. I told Steve I was afraid if we loosened it that I might lose some of the really nice drivability it had. Even though it was a lockup converter, unlocked it was fantastic. He assured me he wouldn't affect how it drove. He was right, still drives the same around town but WOT rpm drop on shifts are now more in line with what he was looking for. This converter picked the car up 6 mph at the track (unlocked) over the best of the other mushy converters I was putting in the car, and 8 mph over the worst mushy converter.

You trying locking it at the track? If so how did that work out?

Unfortunately I have not yet. For the testing to be accurate I have to start out not locking it to compare to other converters that were in the car.

The other unfortunate part of that is I typically only get 2 runs in and I'm parked because both cars run under the roll bar rule and I have no interest in putting roll bars in them. They are street cars first, fun track cars second. So it takes quite a few trips to the track to experiment with different things before I get told to slow it down or park it.

The good news is that the new converter working as it should allows me to finally start tuning on the car as it now responds to changes. The mushy converters the best MPH was 122, the worst converter was 120. The new converter now went 127mph first pass right off the street. Was rich so I pulled a little fuel and very next pass was 128 mph.

Next trip to the track will be experimenting with converter locking and what ever else I can squeeze in before I'm told I'm done for the day, lol.

What I really need is a track rental where they are a little more lenient on the rules, and get a few more passes in.

Seems like most of the backlash I get on street cars when someone tries a higher stall converter is from the feel of the converter below the flash point. The terminally is all over the place for describing how the converters act. As long as the converter holds the power, most of the street guys that never take their car to the track don’t seem to care that much about whether or not the converters slips a few percent at the top end of the track, but they do seem care about the cars feel at the lower RPMs.

Many of us (including me) that are drag racers care more about how it couple on the top end than what the converter doesn’t do below 2000.