Date: Sun, 1 Jul 2001 09:58:00 -0500
Reply-To: John Rodgers <jhrodgers@CHARTER.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: John Rodgers <jhrodgers@CHARTER.NET>
Subject: Re: Tough driving(thin air)
Content-Type: text/plain; charset=us-ascii
In the aviation world engine power is usually expressed based on
standard sea-level atmospheric pressure (29.92 inches) and a standard
day ( as I recall that is is 69 degrees F - memory may be failing me
here).
Two types of supercharges exist for the aircraft world. They are
designed to address air density for combustion related to altitude and
temperature.
One is a simple turbocharger that allows sea-level pressure to be
maintained to higher flight altitudes. They are usually gated to avoid
an over-boost on take-off. At some altitude the turbo looses it
abilities because the air has become so thin that even it cannot
compress the thin air sufficiently to provide a combustible mixture so
there is power loss. But at that altitude there is very little
resistance to the airframe so speed increases dramatically ---to a
point.
The second type is a two-stage blower. With these, a pilot had to be
very careful not to boost the manifold pressure to the point of blowing
up a cylinder. Typically these engines would pull more than sea-level
pressure on take-off. Power was important and the engines were designed
to use much higher manifold pressures on take-off and climb-out. The
superchargers made it possible to pull 60 inches of pressure or maybe
more, and that is WAY above the best sea-level pressure even on a very
cold day. That power was needed to get large heavy machines off the
ground.
On the vanagon perhaps some type of small gated turbocharger might be
available. I have seen somewhere a picture of a turbo'd WBX, but I don't
remember where. I have also seen turbo's available that a good
automotive craftsman could adapt.
If a gated turbo could be installed to keep the atmospheric pressure at
sea-level where-ever you are ... be it at the beach or Leadville, CO on
a hot day, you would really have something.
John Rodgers
88 GL Driver
Bob Nugent wrote:
>
> Speaking of Santa Fe, that's where I live. I've always referred to the
> altitude here as a "reverse turbo". I suspect that if I could get the engine
> power clear up to zero, (sea-level performance, that is) I'd be able to live
> with the 2.1 WBX . I think 4 or 5 lbs. of boost would probably accomplish
> that. Anybody know of a small supercharger system that would work in that
> range -- and integrate with the fuel injection system? I can't see how that
> would put more strain on the engine than running it at sea level without a
> blower. Any ideas?
>
> Bob
