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Author Topic: LR Free Wheel and RPMs  (Read 1308 times)
sfreitas20
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« on: December 21, 2009, 10:57:47 AM »

So recently I had a local setup guy tell me that my son's engine should turn way more RPMs than it does because we are running 4.59 gear ratio and running free on the left rear and he is comparing that to cars in the same class running a one-way and around 4.3 gear ratios.  It didn't really make sense to me because of other contributing factors (primarily tire diameter difference), but he kept saying that my car must not be getting around the track well because if it was the RPMs with that ratio would be way higher especially with the free wheel on the left rear.

My son was running lap times pretty much even with the other cars that day and has always been competitive.  Is there something to his claim, or is he full of shiz?
« Last Edit: December 21, 2009, 12:39:24 PM by sfreitas20 » Logged

Scott Freitas
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« Reply #1 on: December 21, 2009, 12:52:50 PM »

Not enough info. The one thing I can tell you is that every once in a while you get an engine that is just odd. We had a 160 that would win never breaking 5000 rpm. I would set the gear to turn 4880 on the low end. Beyond that, what rpm are you running, what class, what tire size, what tire temps, checked front alignment etc.?
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sfreitas20
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« Reply #2 on: December 21, 2009, 03:03:10 PM »

Don't have my notes here in front of me at work, but I will post other information later.  We run Junior Honda and in that practice session were turning around 5300.  I don't remember the number off the top of my head, but we are running recommended lead-in by Nervo for the car.  It is a 35" Grizz.  Will post tire diameter later on.

It is funny you say that about the engines because the fastest laps we ever run have been when we turn 5500 RPMs even though the builder has said to stay as close to 5300 as possible.
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Scott Freitas
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« Reply #3 on: December 21, 2009, 06:13:37 PM »

At our track the fast guys in Jr. Honda never turn more than 5100 with the restrictor and the new timing.  The old timing did like more RPMS.  While testing take alot of gear out of it and see what happens. Try going below 4.00 just to see what happens. 
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