Date:         Sat, 23 Nov 96 17:31:03 EST
Sender:       Vanagon Mailing List <vanagon@vanagon.com>
From:         jag@cs.rochester.edu
Subject:      Re: Good AND inexpensive tire pump, where to find?

>From: Austin <austins@ix.netcom.com>
> This is going to be really stoopid, but hey it's Friday:  how 'bout using
> the engine as a pump???  I'm imagining removing all plugs, ground the coil
> wire, disconnect the fuel pump, then screw in a long hose with a compression
> test fitting at one end & a tire filling valve at the other.  It shouldn't
> take but a couple of seconds of cranking to fill up a tire  ( & it's at
> least 130 psi - could do road bike tires too!!!)  ???.   Comments  (be kind
> - it's been a long week).

Ok, I missed Fri, but anyway here is a variation, also not to be 
taken too seriously:

Why tap the air at the spark plug hole? The engine is essentially set up
as a gigantic pump already in "stock" operation. Just "dam" (partially 
plug) the exhaust and tap pressurized gases there. Question is of
course how much back pressure can the engine take without stalling.

In big diesels "exhaust braking" is done by partially closing the
exhaust, but I have no idea how much back pressure they operate
under. Any car with a turbo also must have some back pressure.
Seems to me that generating 10 psi boost requires on the order of
10 psi back pressure. (could be less, because the flow (volume)
of the exhaust is greater than the flow of intake air.)

So plug that exhaust, attach a hose and pump your tires!
(But don't fill your scuba tanks! (unless you disable fuel delivery!)

/m