Date: Tue, 22 Jan 2002 19:59:26 -0500
Reply-To: "G. Matthew Bulley" <gmbulley@BULLEY-HEWLETT.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: "G. Matthew Bulley" <gmbulley@BULLEY-HEWLETT.COM>
Organization: Bulley-Hewlett
Subject: Re: '80 Westfalia-- best way to drive over passes
In-Reply-To: <012301c1a39f$b9463c40$99890fce@vern>
Content-Type: text/plain; charset="US-ASCII"
There is one assertion that Bob makes that didn't sit right with me, and
those of you not interested in theoretical discussions are welcome to
depart before you doze off on this one...
The primary assertion is that climbing a hill = increasing the load on
the motor (which in turn) = increase in waste heat. My experience
doesn't bear this out at all. Follow me...
Using our current Vanagon Westfalia (4speed manual on a 2.0 l stock box)
as an example... on encountering a hill, if you reduce your speed to
about 45-48 mph, and put it in 3rd, you have used the transmission and a
reduction in speed to reduce the load on the motor. You've made a
mechanical exchange, sacrificing time, and distance to essentially
reduce the pressure required at the crown of the piston. The motor spins
faster, under much lighter load to move you more slowly. That's the idea
behind a transmission.
Again, in my experience, by reducing my speed, and keeping the van in
the "sweet spot" of 4,400-4800 rpm, even if that means downshifting to
second, or driving only at 1/4 throttle for flatter stretches, I see no
heat gain. None. The fan is blowing at its peak, the oil cooler is
working at its peak, and thanks to lower gears, and some patience, my
motor is not straining or gaining new heat. I've actually seen the oil
temp in my 914 (a different car) drop on long climbs.
My experience biking bears this out as well. Most riders have a "sweet
spot" between 60 and 72 pedal strokes per minute (30-36 rpm at the
crank). As long as you aren't racing (going for speed) you can climb
mountains all day long, and never tire more than on the flats, if you
change gears appropriately to keep pedaling in your sweet spot.
Thoughts on this appreciated.
From historic, walkable Mount Olive, NC,
G. Matthew Bulley
Bulley-Hewlett
Corporate Communications
Business: www.bulley-hewlett.com
Alliance: www.ntara.com
Home: www.MountOliveNC.info
-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@GERRY.VANAGON.COM] On Behalf
Of Robert Donalds
Sent: Tuesday, January 22, 2002 6:51 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: '80 Westfalia-- best way to drive over passes
fellow vanagon types
air-cooled engines collect heat over time lets say you are driving down
the highway for an hour or two
in the heat of the summer and you then find that the road is in fact
going to have a long incline. The engine that you have been driving for
an hour or so is completely saturated with heat that means the oil is at
around 225 f ( and that all the heat the oil will willingly absorb) the
heads are at least at 300 350 f ( I don't believe most gauges ) and now
you want to add more load to the engine. so the head temp will continue
to climb as will the oil temp. The air cooled engine can and does have
limits as to the load you can place upon it and those limits drop as the
ambient air temp and road heat goes up because the air the fan pulls in
is hotter can not absorb the heat off of the heads was fast as is needed
when you push a fully warmed engine up a long grade in the heat of the
day you might not blow the engine up but the engine will degrade (make
less power) every time you do this So why would VW make an engine that
cant take a licking and keep on ticking like it did last summer?. they
did!!! the difference is the fuel. the new fuels are very fancy they
make better power and are what I like to call designer fuels they are
blended to run a water cooled engine with head temps that are much lower
and consistent. the air cooled engine has head temps that hit 450 500 F
at the spark plug on a climb up a pass I DON'T CARE WHAT YOUR GAUGE SAYS
it a toy not an instrument and is nice to look at but that's all.The
fuel can let you down in a big way under these conditions. when the fuel
has what I will call abnormal combustion it burns slower and hotter and
none of this is good for the air-cooled engine
The thing to do is to stop at the bottom of the pass for an hour and
have lunch, make the van rock for a while, have a nap and let the engine
cool down. The engine will never get anywhere as hot in the 10 or 15
mile of climb as it would if you hit the hills fully warmed up in the
heat of the day doing 60 mph
BECAUSE THE ENGINE ACCUMULATES HEAT OVER TIME and the amount of time
depends on the air temp, load and we could also say fan intake air temp,
air fuel ratio and some other stuff that I am afraid to go into
Im not kidding so pack a lunch
all right reserved
Bob Donalds
http://www.bostonengine.com
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