convertors and dyno numbers
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convertors and dyno numbers Do all high stall convertors show extremely poor dyno numbers? It seems like the more I look into this the more it seems that a dyno doesn't accurately represent the true hp/tq of combinations that use non stock stall convertors..
From personal experience I watched a turbo car dyno 430rwhp with a stock torque convertor with a 3500 stall a few months later the same combination dynoed 340rwhp. Same dyno similiar weather.
From personal experience I watched a turbo car dyno 430rwhp with a stock torque convertor with a 3500 stall a few months later the same combination dynoed 340rwhp. Same dyno similiar weather.
The converter in a high stall unlocked will show lower numbers, For and auto the real test is not on the dyno but at the track as many have said before "autos do not make good dyno queens" But they do rule at the the track
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Numbers that low is that a concern? With my micro knowledge it seems that the design behind a dyno works against the design and engineering of a high stall convertor. Isn't a convertor designed to take into account that the load your accelerating will decrease not stay constant?
Actually no the lower numbers are not a concern. A stall the best I can explain arranges torque and hp in a different way so that its used over a broader range.
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This converter stuff is amazing, so you can have a car that dyno's like a stock car but runs like a 400+ hp car? Are dyno numbers on a stalled auto that far off for a indicator of true horsepower?
I agree that A4s will dyno lower...but 90hp in this case is pretty drastic of course there are many different variables going from day to day.
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What he said the tracks the true test
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Let's throw this out there, what if the car made a few less hp with 1.7lbs more boost, temps, a/f where all good. I'm wondering if the converter is so efficient at doing what it's designed to do that when you put a constant load like the dyno does it just flat isn't efficient. Just throwing that out there. Similiar to two boats both making the same power, same propeller one boat is light more efficient takes less power once on plane. A larger heavier boat pushing more water no matter how fast you spin the prop it doesn't convert to forward energy? Isn't a dyno similiar to a heavy boat? Launching a car similiar to accelerating a boat from a stop? Just a theory.
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OK I think I'm onto something. When researching dynometers it seems that one of the reasons you run into such wide ranges of dyno numbers is the dyno software. I'll give 2 examples.
Some dyno's have you put in vehicle weight, trans type and other data to make as accurate as possible accelerating YOUR vehicle. That's why a auto will dyno close to a manual.
Some dyno's use a basic software program especially the smaller Japanese tuner shops because they don't see many automatics, or diesels, trucks, etc. That software doesn't take into account vehicle weight, trans type and is geared toward a manual trans 3rd gear pull. It puts a constant non changing load on the dyno so as the stalled auto makes more power and torque the converter becomes much less efficient. A couple of dyno operators said with the constant load what can happen with a stalled out is the torque and power curve will climb and than just go flat as the converter looses it's efficiency. If you increase boost power will not change much.
Some dyno's have you put in vehicle weight, trans type and other data to make as accurate as possible accelerating YOUR vehicle. That's why a auto will dyno close to a manual.
Some dyno's use a basic software program especially the smaller Japanese tuner shops because they don't see many automatics, or diesels, trucks, etc. That software doesn't take into account vehicle weight, trans type and is geared toward a manual trans 3rd gear pull. It puts a constant non changing load on the dyno so as the stalled auto makes more power and torque the converter becomes much less efficient. A couple of dyno operators said with the constant load what can happen with a stalled out is the torque and power curve will climb and than just go flat as the converter looses it's efficiency. If you increase boost power will not change much.
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converters will not shine on the dyno. For example we have customers making 550 to the tire in 3400 lb car but runs mid 8's on Drag radials.
Greg
Greg
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im confused doesnt the high stall eventually lock up? other than some minor slippage why would dyno #'s be greatly reduced. so your saying my 350rwhp would drop if i added a 3k stall? thx
I have a stalled auto and 446 to the wheels with a 4k stall "LOCKED". If your stall is UNLOCKED it will put down a lot less. The tuner will program the transmission usually through it's torque management, etc to tell the stall when to lock or what not. I think when mine was unlocked it put down like 356 or something I don't remember.
Like has been mentioned dyno numbers with a stall are only usefull for tuning purposes and a manual trans or even and auto with a stock converter will show way higher numbers on the dyno all things else being equal. But at the track NOW THATS ANOTHER STORY!
I know one of our customers ordered a 3800 stall with a 2.5 str last year I was speaking with him and on the dyno unlocked he was only making like 360 rwhp but was turning well into the tens at the track.
So those numbers are virtulally meaningless for anything other than tuning.
I know one of our customers ordered a 3800 stall with a 2.5 str last year I was speaking with him and on the dyno unlocked he was only making like 360 rwhp but was turning well into the tens at the track.
So those numbers are virtulally meaningless for anything other than tuning.
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