Buying a converter?

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busboy

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Got a line on a Dynamic 9.5 / 3800 stall, guy says it was behind a 400, not sure what car or engine build but he said it was "too much for his setup". I'd like to put this behind my 1969 340/727 in the Dart. My motor is pretty much a stock rebuild, XE268 cam, LD340, 750 Holley, car has 3:23's. Sounds like a high stall but this converter is getting great reviews, very civilized driving around town but really delivers when you lean on the loud pedal. My 340 is internally balanced, not sure about a 400? Any thoughts on running this converter?
 
More stall is not always better. Think of stall in the lines of when you release a clutch the full way. It also makes more heat, and if you cruise at all it will always be slipping. Creating heat and more problems my friend, stay within your recommended stall range, 2-2500.

This may help:

http://www.badasscars.com/index.cfm/page/ptype=product/product_id=78/prd78.htm 'What does a high stall converter do?'

Last paragraph:

Most street performance cars running your typical "performance" cam should be running a stall converter in the 2,800 RPM area. For hotter cars (street / strip) with bigger cams, etc. then a converter in the 3,000 - 3,200 RPM is more suited. For mild performance cars with something like a 350 HP engine, a 2,400 stall is about right. The basic rule of thumb is; if your engine "comes alive" at say, 3,500 RPM, then you want a stall converter with about 3,500 of stall to it. Most people tend to over cam and over carburete their cars... and those same people tend to under stall converter their cars too, which REALLY makes it a complete turd. if they need a 3,000 RPM stall, they'll usually get something like a 2,000 RPM, which just doesn't get it off the line. You have to remember... 80% of the race is the first 100 feet. If you can't get off the line, you are going to lose the race.
 
Yes that converter gets good reviews. But that is because they are built to your specific combo and intended use.

Yes a 9 1/2" converter will work with 3.23 gears. But maybe not that one. What was the combo it came out of. The guy should have a reciept or part number that you can use to call dynamic and see what exactly it is


Your best bet is to call dynamis, ultimate and ptc and get the one you feel most comfortable with to build one to your combo and intended use. Main thing to remember is to be 100% honest about your combo and intended use.
 
PoisonDart74 said:
More stall is not always better. Think of stall in the lines of when you release a clutch the full way. It also makes more heat, and if you cruise at all it will always be slipping. Creating heat and more problems my friend, stay within your recommended stall range, 2-2500.

This may help:

http://www.badasscars.com/index.cfm/page/ptype=product/product_id=78/prd78.htm 'What does a high stall converter do?'

Last paragraph:

Most street performance cars running your typical "performance" cam should be running a stall converter in the 2,800 RPM area. For hotter cars (street / strip) with bigger cams, etc. then a converter in the 3,000 - 3,200 RPM is more suited. For mild performance cars with something like a 350 HP engine, a 2,400 stall is about right. The basic rule of thumb is; if your engine "comes alive" at say, 3,500 RPM, then you want a stall converter with about 3,500 of stall to it. Most people tend to over cam and over carburete their cars... and those same people tend to under stall converter their cars too, which REALLY makes it a complete turd. if they need a 3,000 RPM stall, they'll usually get something like a 2,000 RPM, which just doesn't get it off the line. You have to remember... 80% of the race is the first 100 feet. If you can't get off the line, you are going to lose the race.
Click to expand...


That is way old school advice. Converter science has come a long way. These newer efficient converters can flash at 3800 rpm and drive like a stock one on the street. Best of all worlds.
 
A higher stall converter isn't "slipping" to create the higher stall speed. It's just multiplying the torque at a different ratio. It will however contribute to more heat because it takes more fluid to pass through it to create the same amount of work. Think of it as like how different prop pitches affect the acceleration or top speed on a boat.
 
I just bought a used 8 1/2 dynamic to replace my 9 1/2 tci super street converter. Boy was I disappointed after install.Way less stall than the 9 1/2 tci. Was probably for a big horse power motor.Well my loss.Live and learn.Buy for your specific needs,Kevin.
 
A converter built to stall 3800 behind a big block 400 might not even stall 2800 behind a 340. Reason being the big block most likely makes quite a bit more low end torque and torque has a great effect on what a converter will stall too. My car is a perfect example. I had a converter built for my old 360 to stall 3000. It was a PTC and they nailed it cause it stalled right exactly 3000. I installed a mild (as in lots of low end torque) 408 last year but kept the same converter cause I knew it'd do all I needed it too as maximum performance wasn't the main goal. That very same converter stalls 3500 behind my mild 408. Why, more torque.

Oh yeah, it drives like it's a nearly stock converter until you nail it. New technology is great.
 

I read some where a quote I like very much(forget who said it) but it goes like this.... "you can lie about the horse power your car is putting out to EVERYONE you meet... but when it comes to the guy building you converter tell him the truth." A mismatched torque converter is not going to give you the results your hoping for.
 
Learn from others on this subject!
I'm dealing with a somewhat mismatched set of components with my car. I have a 70 Charger with a sloppy feeling converter. I have a 440/493 with a '509 cam. I run a 727 with a 9 3/4" converter spec'd to stall at 3000 rpms. It will blow off the tires through 2nd gear from a standing start, but part throttle operation leaves me disappointed. It does move from idle, but nothing like a car with a stock converter. It slips like I'm on wet grass and although the car IS speeding up, the car speed isn't directly proportional to the engine speed. It IS like launching a car slowly with a stiff clutch... slipping but getting MORE efficient as RPMs climb. If I mash it, the car will respond. I just don't like the spongy feeling at part throttle.
At freeway speeds, it isn't any better. I run a Gear Vendors overdrive with a .78 ratio. This reduces my 3.91 axle ratio down to a 3.05. The loose converter feels even worse with a taller ratio. I'm leaning toward switching to a larger converter with at least 800 rpms LESS stall. My engine makes plenty of power from idle on up. I don't think that I need all the stall that this converter has.

EDIT:
If I were only interested in drag racing the car, my setup would be fine. The car responds great for that sort of thing.
 
Frankenduster said:
Learn from others on this subject!
I'm dealing with a somewhat mismatched set of components with my car. I have a 70 Charger with a sloppy feeling converter. I have a 440/493 with a '509 cam. I run a 727 with a 9 3/4" converter spec'd to stall at 3000 rpms. It will blow off the tires through 2nd gear from a standing start, but part throttle operation leaves me disappointed. It does move from idle, but nothing like a car with a stock converter. It slips like I'm on wet grass and although the car IS speeding up, the car speed isn't directly proportional to the engine speed. It IS like launching a car slowly with a stiff clutch... slipping but getting MORE efficient as RPMs climb. If I mash it, the car will respond. I just don't like the spongy feeling at part throttle.
At freeway speeds, it isn't any better. I run a Gear Vendors overdrive with a .78 ratio. This reduces my 3.91 axle ratio down to a 3.05. The loose converter feels even worse with a taller ratio. I'm leaning toward switching to a larger converter with at least 800 rpms LESS stall. My engine makes plenty of power from idle on up. I don't think that I need all the stall that this converter has.

EDIT:
If I were only interested in drag racing the car, my setup would be fine. The car responds great for that sort of thing.
Click to expand...

It not the stall speed that's the problem, it's the design of the converter. There are basically 2 designs, what's known as a "loose" design converter, which is all that there used to be until the last 15-20 yrs. It slips like a bad clutch on light throttle takeoff but is more efficient for a race car. There then is what's known as a "tight" design converter. It'll drive pretty much like a stock converter with just a little bit of slippage at light to moderate throttle but when you mash the loud pedal it comes alive and flashes to what ever stall it's designed for. That's what you need for street driving. I bet your loose converter is building a ton of heat in overdrive. There are a lot of good converter companies out there. I've had great service from John Cope at Cope Tracing trans, he's a member here and very knowledgeable. He set me up with my converter and I love it. Works just like he said it would. Price was good too.
 
Be careful on buying a used converter. They're a sealed unit, and until it's cut open you have no way of knowing the condition of it. It might be good, it might be just about trashed. I've seen lots of converters cut open that looked good on the outside, the oil was pink, and once cut open things like, the sprag in need of replacement, the vanes in the pump were coming loose, the bearings (if any) needed to be replaced etc. etc.
Also, buying a used high stall(10" and smaller) can also be risky if your application isn't identical to the vehicle it came out of. Just because a converter stalled at a specific rate in one car, doesn't mean it will stall the same in your car. High stall converters improperly applied are the biggest waste of your performance dollar.
Our company typically custom built most 10" converters and ALL 9", 8" AND 7" converters to the customers specs and dyno sheet.
 
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