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gearing

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deepindebt:
Question for you dirt guys, what type of gear change do you make from Bonneville to Elmo if any? We run a 2.79 on the salt, have a 3.0 that i was thinking would be good for the dirt, then i got to thinking that due to the lack of traction on the dirt that we may just blow the tires off with the lower gear? Thoughts?(4 speed manual)
Thanks

SPDRACR:
El Mirage gearing should be done for the record attempt. Tire slippage is controlled by your right foot.
Is your roadster with your Bonneville gear capable of pulling that gear in a 1 3/10 miles.
Our roadster is currently a 2.91 for El mirage and a was going to be a 2.47 for Bonneville but we know how that went.   

Stan Back:
Here's a longer echo from the above . . .

This is from our team's 8 years of setting C and D Street Roadster records with a 4-speed at both events.

First was Bonneville.  What's the record?  Our motor tops out at 7500(?) RPM.  We want to be almost near that at the 4 so we can maintain that for a full mile.  Do the math and select a gear that might do that and find out if that works. After a few years, make a little more horsepower and add in some gear.  After a few years, we went from (as I may remember) a 3.10 to a 3.00 and it took a lot of work to finally max that one out.  Keep good records of what exactly you're doing each run.

Now we're at El Mirage.  What's the record?  We want to be at our peak horsepower at 1.3 miles for a very short time.  From experience, the lower gear may spin the tires at launch and more.  Give it a higher gear, and it may never get into 4th but the driver doesn't have to do anything but change gears.  Whoops, missed again.  Maybe the driver has to "drive".  Taking off in 2nd takes the oneness off his responsibility and slows down the whole process.  Maybe never get in 4th, never get the record.

Figure out what RPM you need and either drive better or add horsepower.  Or just keep rear gear changing to get your best speed with what you got.  Enjoy the circus.

Stan Back   

Attached your file... maybe... :cheers:

deepindebt:
Great info and killer record keeping Stan, i think for our first trip we will keep the Bonneville gear in and feel it out since I'm sure due to rookie passes we wont be allowed to drop the hammer anyways.
Thanks for the info from you both.

Stan Back:
Thanx to Stainless for posting our chart.  A few explanations are as follows . . .

Pill -- Size of Hilborn bypass return line jet, adjusts lean or rich.
Temp. -- Temperature at time of run.
Alt. -- Relative altitude air pressure.
Meter -- Mysterious Black Box handed down from engine builder -- probably taking Alt. and Temp. numbers giving a relative rating.
Pyro -- Pyrometer high temperature average of each bank -- only one sensor on each V-8 bank.
Speeds -- As noted.  El Mirage at speed trap.   

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