Dyno'd KJR Performance Lightweight pulley
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Dyno'd KJR Performance Lightweight pulley
The car revs quicker and defiantly pulls harder from 40 to 120 The factory pulley is said to weight 6.24lbs and KJR 2.08lbs.
The dyno result are disappointing and show no real gain. The HP and TQ curve are basically the same.
This is the second mod to show no definitive HP and/or TQ gain
2003 5AT G35C
Before
Z-tube+Stillen Hi-Flow Airbox, 1/2" MD spacer w/ISO Kit, Invidia G200
250.36 HP _ 229.12 FT-LB
After
Z-tube+Stillen Hi-Flow Airbox, 1/2" MD spacer w/ISO Kit, Invidia G200, KJR LW Pulley
250.49 HP _ 229.73 FT-LB
The dyno result are disappointing and show no real gain. The HP and TQ curve are basically the same.
This is the second mod to show no definitive HP and/or TQ gain
2003 5AT G35C
Before
Z-tube+Stillen Hi-Flow Airbox, 1/2" MD spacer w/ISO Kit, Invidia G200
250.36 HP _ 229.12 FT-LB
After
Z-tube+Stillen Hi-Flow Airbox, 1/2" MD spacer w/ISO Kit, Invidia G200, KJR LW Pulley
250.49 HP _ 229.73 FT-LB
Last edited by G35StrongMan; 11-19-2005 at 02:52 PM.
#3
#6
Finally the truth is out. I'm glad someone FINALLY dynoed the UDP to prove what I've been saying all along.....no gains. I had an UDP on a prior VQ and the motor did rev quicker, but on the track and dyno, absolutely no difference.
Nope. If you reduce rotational inertia (light rims), it will show up on the dyno. Since the pulley is already a lightweight device mounted directly to the crank and it's VERY SMALL in diameter, it's not going to make any measureable difference on the dyno or the track. Period.
Originally Posted by obender66
Some of the mods will not show on dyno. Pulleys and flywheels are the example. They give "equivalent weight saving " gain-same kind you would get from striping your interior for example. Car will be lighter and pull harder, but you will see zero gain on dyno.
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#10
Originally Posted by itsbo1313
The KJR is not a UDP. It's OEM sized, just lighter.
#11
Remember... when you dyno you're in 4th or 5th gear going 3000 rpms to redline. That's not where a flywheel or UDP is supposed to shine. You SHOULD NOT see gains from these mods on a dyno, it just doesn't make sense.
Gains from these mods are initial gains. Getting the object in motion easier is the task. Keeping it going is basically no extra work and it's the "keeping it going" that you're measuring on the dyno.
my 2 cents.
Gains from these mods are initial gains. Getting the object in motion easier is the task. Keeping it going is basically no extra work and it's the "keeping it going" that you're measuring on the dyno.
my 2 cents.
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http://www.kjrperformance.com/
$170 shipped to my front door.
I haven’t had any CELs with my current setup.
$170 shipped to my front door.
I haven’t had any CELs with my current setup.
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Originally Posted by G35StrongMan
The car revs quicker and defiantly pulls harder from 40 to 120 The factory pulley is said to weight 6.24lbs and KJR 2.08lbs.
The dyno result are disappointing and show no real gain. The HP and TQ curve are basically the same.
This is the second mod to show no definitive HP and/or TQ gain
2003 5AT G35C
Before
Z-tube+Stillen Hi-Flow Airbox, 1/2" MD spacer w/ISO Kit, Invidia G200
250.36 HP _ 229.12 FT-LB
After
Z-tube+Stillen Hi-Flow Airbox, 1/2" MD spacer w/ISO Kit, Invidia G200, KJR LW Pulley
250.49 HP _ 229.73 FT-LB
The dyno result are disappointing and show no real gain. The HP and TQ curve are basically the same.
This is the second mod to show no definitive HP and/or TQ gain
2003 5AT G35C
Before
Z-tube+Stillen Hi-Flow Airbox, 1/2" MD spacer w/ISO Kit, Invidia G200
250.36 HP _ 229.12 FT-LB
After
Z-tube+Stillen Hi-Flow Airbox, 1/2" MD spacer w/ISO Kit, Invidia G200, KJR LW Pulley
250.49 HP _ 229.73 FT-LB
If the pulley is just lightened (and not underdrive), it will do virtually nothing in-gear. No surprise here, I've been trying to tell people this for years on forums for my last car. Here's a link I wrote if you're interested in why this is exactly: http://www.stanford.edu/~mpg/lighten...omponents.html
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What's the stock crank pulley diameter? Assuming 8", I ran the numbers for the KJR crank pulley (scale them by (D/8)^2 if it's not 8"), and the gains are the following percentages in each gear for the 5AT (and the equivalent peak power "gain" assuming 250 whp):
1st: 0.810% (2.02 whp)
2nd: 0.331% (0.830 whp)
3rd: 0.140% (0.350 whp)
4th: 0.0646% (0.161 whp)
5th: 0.0449% (0.112 whp)
Yeah, FEEL THE POWER baby! Screw the possible minuses of excess engine wear or bearing failure, it's worth it for the 2 whp in 1st alone.
Note that these numbers assume the crank pulley's mass distribution is equivalent to that of a flat disc (most accurate of the simple inertial assumptions). However if you assume all of the mass is concentrated in an infinitesimal ring at the outer crank radius, you will get twice these numbers, and a real crank pulley lies somewhere in between. But two times nothing is still nothing. :P
1st: 0.810% (2.02 whp)
2nd: 0.331% (0.830 whp)
3rd: 0.140% (0.350 whp)
4th: 0.0646% (0.161 whp)
5th: 0.0449% (0.112 whp)
Yeah, FEEL THE POWER baby! Screw the possible minuses of excess engine wear or bearing failure, it's worth it for the 2 whp in 1st alone.
Note that these numbers assume the crank pulley's mass distribution is equivalent to that of a flat disc (most accurate of the simple inertial assumptions). However if you assume all of the mass is concentrated in an infinitesimal ring at the outer crank radius, you will get twice these numbers, and a real crank pulley lies somewhere in between. But two times nothing is still nothing. :P
Last edited by MechEE; 01-03-2006 at 11:53 AM.