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demosh
 
Quote:
Originally Posted by why_ask_why
I don't think top fuel dragsters even have 2600+lb ft

Engine torque, not "wtq"
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Old 08-30-2004, 03:31 PM demosh is offline  
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demosh
 
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Originally Posted by SFC
please, call up dynojet and discuss it with their engineers since we're clearly below your massive intellectual prowess.

800-992-4993 / Toll Free

I have a better idea. How about you read through the mechanics chapters of this book:


And then show where my calculations went wrong
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Old 08-30-2004, 03:33 PM demosh is offline  
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Tex Arcana
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Quote:
Originally Posted by LagPenguin
It's not a joke? Dyno runs are taken through direct drive, 1:1, not first.

Chassis dynos take the accelleration of a set of rollers of known mass and take the acceleration of said rollers and converts that to torque, and from that calculates horsepower. The problem is, how does that calculation (and even the torque "measurement" is a calculation, based on the acceleration of the rollers) come up with the number?

For instance: my truck. By the book, it's putting out 450 ft-lbs torque at the crank. Ignoring the other drivtrain losses, then it should be putting out 757ft-lbs at each wheels, for a total of 1514 ft-lbs, this assuming it's going thru the transmission at 1:1 (3rd gear) during the dyno run, and thru the rear end at 1:3.73 gear ratio. And since it's well-known that gear ratios multiply torque, the question remains: where is the discrepancy??
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Old 08-30-2004, 03:33 PM Tex Arcana is offline  
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Quote:
Originally Posted by demosh
Engine torque, not "wtq"

2600+ and any street car=gnoes
are you using the metric system or something like that??
this is some funny shit
Old 08-30-2004, 03:34 PM Why_Ask_Why is offline  
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Tex Arcana
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Quote:
Originally Posted by SFC
and you're obviously a fucking moron, car's torque is measured at a 1:1 gear ratio so you're "in final drive" is fucking retarded, as are you.

But you're still ignoring the final drive ratios, and how they multiply torque.
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Last edited by Tex Arcana; 08-30-2004 at 03:42 PM..
Old 08-30-2004, 03:34 PM Tex Arcana is offline  
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LagPenguin
 
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Quote:
Originally Posted by demosh
194 lbs-ft * 1.00 * 3.82 = 741 lbs-ft torque on the wheels.

I think im going to start a "Demosh's elementary mechanics" thread. Highschool seems to have failed, maybe I'll do better

pinion shaft turns 3.82, ring gear turns 1. Thats a gear reduction, not multiplication.
Old 08-30-2004, 03:35 PM LagPenguin is offline  
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demosh
 
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Originally Posted by why_ask_why
2600+ and any street car=gnoes
are you using the metric system or something like that??
this is some funny shit

Do you understand mechanics?
Ever heard about leverage?
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Old 08-30-2004, 03:36 PM demosh is offline  
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Quote:
Originally Posted by prak
If I didn't know better I'd think this wasn't Automotive [M]ayhem but Genmay
Don't bitch, this is what the majority of the people here decided they wanted.
Old 08-30-2004, 03:41 PM SemperFly is offline  
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Quote:
Originally Posted by demosh
Do you understand mechanics?
Ever heard about leverage?

do you realize how astronomically high your numbers are?? and if you aren't talking about wheel ft lbs then why did you make a direct comparison to a car that was quoting wheel ft lbs?
Old 08-30-2004, 03:43 PM Why_Ask_Why is offline  
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SFC
 
Quote:
Originally Posted by Tex Arcana
But you're still ignoring the final drive ratios.


dont' worry, posted on another forum which has several tuners, one of them will "solve it" so we can end this "my dad's volvo has 2000lb/ft".
Old 08-30-2004, 03:43 PM SFC is offline  
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Tex Arcana
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Quote:
Originally Posted by FlyNavy
Don't bitch, this is what the majority of the people here decided they wanted.

Yeah, you cumhound.
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Old 08-30-2004, 03:43 PM Tex Arcana is offline  
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Tex Arcana
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Quote:
Originally Posted by SFC
dont' worry, posted on another forum which has several tuners, one of them will "solve it" so we can end this "my dad's volvo has 2000lb/ft".

Yeah, so did I, becasue ti bugs me too. So far, tho, the "tuners" are scratching their heads.
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Old 08-30-2004, 03:44 PM Tex Arcana is offline  
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demosh
 
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Originally Posted by why_ask_why
do you realize how astronomically high your numbers are?? and if you aren't talking about wheel ft lbs then why did you make a direct comparison to a car that was quoting wheel ft lbs?

But I am talking about wheel torque. And those are the numbers at the wheels in first gear in Saab 900s when the engine is at its torque peak. I fail to see any mistakes in my calculations.
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Old 08-30-2004, 03:44 PM demosh is offline  
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Quote:
Originally Posted by demosh
Im assuming by wtq, he means wheel torque. Thats what I meant.

Engine produces 194 lbs-ft at its best. 1st gear = 3.58:1, final drive = 3.82:1

194 lbs-ft * 3.58 * 3.82 = 2653 lbs-ft at the wheels
what the fuck

torque numbers are in the same gear as horsepower numbers, dinker horsepower isn't even measured on a dyno; it's calculated from the torque
Old 08-30-2004, 03:46 PM SemperFly is offline  
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Quote:
Originally Posted by demosh
But I am talking about wheel torque. And those are the numbers at the wheels in first gear in Saab 900s when the engine is at its torque peak. I fail to see any mistakes in my calculations.

Because you're multiplying the final drive.
Old 08-30-2004, 03:47 PM LagPenguin is offline  
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