Fooling Chassis Dynos
08-17-2003, 12:37 AM
#1
Melting Slicks
Thread Starter
Member Since: Oct 2002
Posts: 2,106
Likes: 0
Received 0 Likes
on
0 Posts
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?
08-17-2003, 12:43 AM
#2
Safety Car
Re: Fooling Chassis Dynos (battsup)
No, the dyno computes rpms and mph, so it knows your rear end ratio.
08-17-2003, 01:17 AM
#3
Race Director
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
08-17-2003, 01:45 AM
#4
Race Director
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
08-17-2003, 03:21 AM
#5
Racer
Member Since: Jun 2001
Location: Fort Collins CO
Posts: 305
Likes: 0
Received 0 Likes
on
0 Posts
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 ?
08-17-2003, 07:40 AM
#6
Race Director
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]