Fooling Chassis Dynos
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Melting Slicks
Joined: Oct 2002
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Fooling Chassis Dynos
I was wondering if you can actually change your horsepower by putting in a different gear ratio? i have 3.73 so if i go to 2.8? then wont the dyno think i have more horsepower? or if i put it into overdrive?
Race Director
Joined: Aug 1999
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From: WI
Re: Fooling Chassis Dynos (battsup)
batts, If a chassis dyno is anything like an engine dyno they calculate with a "correction factor" adjusted to a barometer. A turn of the **** and you instantly gain (or lose) hp. ...redvetracr
Race Director
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From: Who says "Nothing is impossible" ? I've been doing nothing for years.
Re: Fooling Chassis Dynos (redvetracr)
All it needs is the actuall engine RPM and RPM of the drum and it caculates the rear end ratio or more than likely dosen't need it to calculate the torque, that being said I wonder if you run the same car on the dyno with a say 3:1 (3.08) and a 4:1 ( 4:10) would it give you the same torque and HP numbers ?
I don't see how it could since the rear end ratio is a torque multiplier. And you are calculating HP at the rear wheels here not the flywheel so you could theoretically have the same HP at the flywheel but different at the rear wheels depending on the rear end ?
Just rambling :D
I don't see how it could since the rear end ratio is a torque multiplier. And you are calculating HP at the rear wheels here not the flywheel so you could theoretically have the same HP at the flywheel but different at the rear wheels depending on the rear end ?
Just rambling :D
Racer
Joined: Jun 2001
Posts: 305
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From: Fort Collins CO
Re: Fooling Chassis Dynos (MotorHead)
I don't see how it could since the rear end ratio is a torque multiplier. And you are calculating HP at the rear wheels here not the flywheel so you could theoretically have the same HP at the flywheel but different at the rear wheels depending on the rear end ?
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From: central FL, near the beach.
Re: Fooling Chassis Dynos (battsup)
YES
you can change the RWHP!
Steep gears suck HP.(small pinion with more teeth)
if it is a 1/4 mile car run steep gears.
BUT for top speed the 2.8 is better.
Source: c5 tech section(they have verified this over and over)
But OD will suck power, that is why OD trans sometimes overheat at high speed.
.
Sometimes the dyno fools the owner;
the test is so short, vacuum secondaries may not open fully or soon enough.
[Modified by Matt Gruber, 10:15 AM 8/17/2003]
you can change the RWHP!
Steep gears suck HP.(small pinion with more teeth)
if it is a 1/4 mile car run steep gears.
BUT for top speed the 2.8 is better.
Source: c5 tech section(they have verified this over and over)
But OD will suck power, that is why OD trans sometimes overheat at high speed.
.
Sometimes the dyno fools the owner;
the test is so short, vacuum secondaries may not open fully or soon enough.
[Modified by Matt Gruber, 10:15 AM 8/17/2003]
