NAC: how to test gas ?

[Roy Wendell]

On Thursday, August 02, 2007, at 07:11PM, Louis-Alain Richard <laraa at sympatico.ca> wrote:

>Hi everyone,
>
> 
>
>Since I am testing press car these days, I always wonder if the guy before
>me put Premium gas in the car (when needed) or just said "regular, since I
>won't drive it again".
>
> 
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>Is there a way to easily test fuel grade ? Color, odor, taste ? It might
>seems trivial, but fuel grade do have an incidence on performance,
>obviously, but also on fuel economy and driveability. My actual loaner, a
>Subaru Legacy Spec B, gave me only 282 km with 45 liters, (that's 16
>l/100km, or 15 MPG) and the engine is always "stumbling" a bit under hard
>acceleration. The car has 2000 km. Brady and I did put it on his dyno and
>specs were within the expected figures, so I am confused.
>
> 
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>Thanks in advance,
>
> 
>
>Louis-Alain in hot, hot Montreal tonight (32C at 10:00PM, that's 90F folks.)

I'm sure that other's have more authority (I'm thinking of the guy at the lab in Bolder) but off the top of my head no. That's why they use those test motors to arrive at the octane ratings.

As for some first hand info, if I recall correctly doesn't the Spec B have essentially an STI motor? I ask because my friend's '06 STI used to do the exact same thing when new but it eventually went away. It's almost like it was running some sort of learning routine that took a while to optimize. I remember being incredulous when I first rode in it that Subaru could have stuffed up the tuning so badly on their highest performance model. The hesitation was obvious from the passenger seat. When I drove it a month or so later and every time since including in a couple of autocross competitions it's been smooth as glass.

I can't say as the mileage is all that surprising either. Big sticky tires, awd, and power add up and my friend has to work very hard to get his milage into the 20s with a smaller car. I'm also not sure at your current milage (or would that be kilometerage?) that the engine is completely broken in.

As a side note, the temperatures that you are currently enduring can't be helping the performance much. There are very good reasons why Subaru mounts the intercooler up on top of the engine where they do but heat soak in traffic on a hot day causes a noticable performance drop.

Roy