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underdrive pulley made me slower?

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Old 06-15-2009, 01:00 PM
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Default underdrive pulley made me slower?

So I just put on my Asp unsersrive pulley and tested my quartermile time with my phone (iPhone tests using gps and g forces) and I actually can't get it to run the same time as before and I got to thinking a heavier flywheel would make you go faster y would a lighterweight harmonic balancer make u go faster? I do understand the principal but maybe they counteracted eachother
Old 06-15-2009, 01:15 PM
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I wouldn't put much faith in the accuracy of the iPhone software. Go get some real numbers at the track
Old 06-15-2009, 01:17 PM
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x1000...i used one of those apps WHILE i was at the track and it said my truck ran 14.2 @ 100 mph when I actually ran 15.0 @ 91 mph.
Old 06-15-2009, 01:20 PM
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dont think a balancer can make you slower.
Old 06-15-2009, 02:21 PM
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Sometimes an underdrive pulley can cause false KR. If it trips several degrees, I could see you going slower however I do not feel this is your case. Please don't measure performance gains with an I-phone app.
Old 06-15-2009, 09:34 PM
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Originally Posted by krambo
Sometimes an underdrive pulley can cause false KR.
I've heard this before too...what exactly happens to cause the false knock?
Old 06-15-2009, 09:37 PM
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Yaw I k ow the numbers wouldn't be accurate but I figured sence my before st was 13.3 with the phone then after it was 13.4 with my phone I was just curious if anyone ever herd of it slowing me down when I get the thing dynoed I'm taking it to the track
Old 06-16-2009, 02:47 PM
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too many other variables that will affect your times..ie: ambient air temp. air density, barometric pressure, etc..
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