While all engines (other than those with rammed air) will suffer from a loss
of power at elevation, I believe the original poster was asking about an
"abnormal" loss of power.

While it's nice to discuss theory, it most likely didn't do him any good
with his problem.

I'd suggest that he look at his oxygen sensor for a possible fix.  If it is
disconnected or fouled (running open loop), his van will take a dump big
time above a mile high or so.

Karl Wolz

----- Original Message -----
From: "Frank Grunthaner" <FrankGRUN@AOL.COM>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Monday, March 11, 2002 3:51 PM
Subject: Re: Loss of power at altitude

> The poser loss issue is directly the reduction in atmospheric pressure.
The
> EFI computer keeps the proper air/fuel ratio and the developed power drops
> proportionately.
>
> Only one device eliminates this problem - a turbocharger. With the turbo
you
> can control the manifold pressure and there is adequate compression
capacity
> to overcome the atmospheric pressure reduction.
>
> The reason that you so strongly notice the reduction in power as compared
to
> other vehicles is explained in my posts on gearing and engine power
issues.
> The key problem is the amount of additional thrust available from the
> engine/powertrain combination above and beyond the thrust needed to move
the
> vanagon under the conditions required. Hint: Professional hill-climber
racers
> run very high numerical ratio final drives compared to flattrackers. Your
> vanagon probably has 5% reserve thrust capacity after paying the altitude
> penalty.
>
> Frank Grunthaner