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To refresh everyone first on the history, I ran some very meticulously controlled fuel mileage experiments before and after changing from 3.73 to 4.56 gearing.

You can search under "gas mileage" or "fuel mileage", around February - March timeframe, if you really want the blow by blow details.

To summarize, with the stock 3.73 gearing, with cruisse control on, rolling hills limited access highway, at 60 mph, no wind (i.e. 1 to 3 mph max and running BOTH with and against it) 22.8 mpg.

After the regearing to 4.56, I got 21.1 mpg, or only a 7.4% reduction. (Along with a full 1 second reduction in 0 to 60 time!)

Tonight, after Reese at MTI Racing did another finer computer tuning on my SSR, I managed to run a full 20 miles under the above conditions, except with an 8 mph CROSSwind, and, incredibly, I got 22.6 mpg!

So, Reese's tuning got me back almost exactly to where I was before the gearing change, BUT I also have a lot more POWER on tap.

I am writing about this so that folks do NOT assume that modifying their SSR is necessarily going to hurt their fuel mileage, IF they restrain themselves in how often they USE that extra power. Of course, that's hard to do . . .

Jim G
 

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Hey JimG, a question. Here in the St. Louis Metro area we have the ethanol added gas. 10% ethanol, I think. I have been using the 89 octane in mine. If I drive the SSr really nice I might see on an overall average tank of gas 17.1 mpg and about 295 miles from full to a 1/4 tank.

I can tell that the ethanol is useless because I've ran straight gas in it with better results.

What is the octane you are using and is there any ethonal in it? On your gauges what is your average from a full tank of gas to about a 1/4 of tank and mileage?
 

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HD-Fatboy: I am running 92 octane Chevron withOUT ethanol.

I have had very bad expereicnes with ethaneol in Minnesota and elsewhere. It hurst both power output and fuel mileage. It is a garbage idea popular in states with lots of corn growers (like Minnesota). In those states, the growers get higher prices for their crops because of the MANDATED ethanol usage, and we all pay the price for their greed.

You cannot expect anyone to quote accurate "miles to 1/4 mark" as mileage varies WILDLY based on traffic conditions and use or non-use of air conditioning.

On my commutes into work here in downtown Atlanta on this contract assignment (I mean DOWNMTOWN too - exact center of the city!!), I have logged my mileage using the onboard computer several times. It ranges from a high of 16.0 to a low of 10.0. The 16 is early morning with traffic lights but light traffic, and the 10 is stop and go rush hour when the weather is wet and hot.

Jim G
 

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Thanks JimG,
Unfortunately we only have the corn gas around here. It's not often I get the chance to fill the tank with straight gas.
 

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Discussion Starter #5
Just so you know too: Using that crap ethanol gas causes your PCM to alter its tables to adapt to it, and then even when you fill up with REAL fuel, it takes a while for the PCM to rewrite its tables to the better fuel.

Jim G
 
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