Date: Thu, 21 Jun 2007 02:42:19 -0500
Reply-To: Matt Roberds <mattroberds@COX.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Matt Roberds <mattroberds@COX.NET>
Subject: Re: Higher elevation -- anything to watch out for?
In-Reply-To: <20070621031333.QGBM3928.eastrmmtai114.cox.net@eastrmimpi03.cox.net>
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> From: Jeff Oxroad <Oxroad@AOL.COM>
> Date: Wed, 20 Jun 2007 22:21:49 EDT
>
> Both times it was as I had just arrived [in Denver]. I shut down the
> [1.9] bus to go into a store lets say for 10 minutes and it wouldn't
> start again. Kind of a flooded situation in that I had to pull the
> plugs, let it all dry out for a while, and then it fired up.
If it was a carb instead of fool injection, I'd say that sounds like
a classic case of vapor lock. I think FI is not nearly as susceptible
to that as carbs are, but I guess it could happen.
> I was told that at elevation the gasoline is configured differently than
> lower elevation gasoline.
Maybe. It might be a little more volatile to improve its ability to
burn in the thinner air. I do know that you can "get away" with lower
octane at elevation - in Missouri, Kansas, Oklahoma, Arkansas your
typical choices at the pump are 87, 89, and 91; in Denver you get
something like 85, 87, and 89. (All (R+M)/2 numbers.)
> I was also told that the condition I suffered those few times was
> due to not stopping as I gained elevation and fill (top off for lack
> of a better term) the tank with the "properly" configured gasoline
> as I got higher.
I somewhat suspect that what this actually does is give you a couple of
gallons of gasoline that haven't been sitting around heating up in your
van, which reduces the evaporation rate in the tank.
> I was told that at every 1000 feet of gain or so you should fill what
> space you have in the tank with the elevation configured gasoline. This
> because as you go higher it's a difference configuration for the
> ascending elevation.
I know gasoline blends are kind of micro-managed in some parts of the
country, but I don't think they're that micro-managed. If you have
A/C, an interesting experiment might be to fill up the van's tank down
in the valley, then fill up a couple of fuel jugs as well at the same
station. Stash the jugs securely inside the van (now would be an
excellent time to stop smoking), run the A/C, and drive up the mountain.
When you burn a couple of gallons out of the van's tank, stop and dump
a jug into the van's tank. See if filling up with cooler "valley"
gasoline has the same beneficial effects as filling up with "elevation"
gasoline periodically.
Matt Roberds
