Date: Wed, 11 Jan 2012 12:18:31 -0800
Reply-To: Angus Gordon <birdworks@GMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Angus Gordon <birdworks@GMAIL.COM>
Subject: Re: Was:Re: Oil in Coolant Morphed to "Power at Altitude" or
something like that.
In-Reply-To: <8B88BAD7-C5C6-4418-9E91-16722F44762D@gmail.com>
Content-Type: text/plain; charset=us-ascii
After sending the last comment regarding fuel mileage I realized my Syncro was doing 23 mph and burning no fuel at all! Talk about efficient!
Angus
On Jan 11, 2012, at 10:56 AM, Angus Gordon <birdworks@gmail.com> wrote:
>
> I believe the increase in mileage can be attributed to decreased aerodynamic drag due to the thinner air, for any given speed (ground speed so to speak).
>
> Angus
>
> Angus Gordon
> Bainbridge Island WA
>
> On Jan 11, 2012, at 9:53 AM, Don Hanson <dhanson928@GMAIL.COM> wrote:
>
>> On Tue, Jan 10, 2012 at 6:22 PM, Larry Plotkin <zeplotkin@gmail.com> wrote:
>>
>>> Finn wrote:
>>>
>>> Klip, klip ...
>>> ... I moved from NJ to Taos, NM ... At 7000 feet here in Taos, I believe
>>> that the hp loss is around 21% ... Is there anyone listening that is at a
>>> similar altitude... I
>>> would have no problem getting to say 75 mph at sea level in the 87...
>>>
>>> Well, I have no tech help for you but ... I ran my 87 Wolfy hardtop 4sp
>>> (stock everything except 27x8.5 14 tires) in the northwest near sea level
>>> for 11 years and then moved to the AZ mountains where I've been for nine
>>> years, at 7000 feet. I changed nothing, adjusted nothing, and noticed no
>>> change in performance. 75 is easy as ever. Coming up here from the desert
>>> ain't fun, a crawl in 3rd gear often, but climbing near 6000 feet in two
>>> hours, that just goes with the vehicle. So I guess I'd be looking for
>>> something to fix, not an inherent limitation of elevation.
>>>
>>> (And I guess I'd have to add that Taos must be way better than anything in
>>> NJ, at any speed.)
>>> lp
>>>
>> There is a significant loss in power from any internal combustion engine
>> as altitude increases.. Someone will probably know the numbers exactly but
>> I'd guess about 20% power loss at 7000' above sea level as compared to sea
>> level on a normally aspirated motor is about right. Forced induction
>> motors are less affected by elevation gains, and of course, engines with
>> carbs...they are more affected than fuel injected motors.
>>
>>
>> Combustion in the motor is very dependent on oxygen and simply, there
>> is less oxygen as you gain elevation...A turbo or supercharged motor can
>> adjust and pack in more combustable mix...maintaining better power as you
>> gain altitude. A fuel injected motor can adjust it's mixture to
>> compensate for less oxygen, keeping the air fuel ratio correct as you
>> climb up...but it must just diminish the amount of fuel to compensate for
>> the diminished oxygen in the atmosphere. A carbed motor loses power two
>> ways in that there is less air to burn stuff AND since it doesn't adjust to
>> this...the air fuel ratio gets 'out of spec' and it runs rich, further
>> losing power that way.
>>
>> If you doubt this...check it with a watch or something next time you go
>> from ocean to mountains...do a simple 0>75mph timed run both places and you
>> will certainly find it takes significantly longer at elevation to reach
>> your target speed.
>>
>> On a side note: I have noticed a significant increase in miles per
>> gallon at higher elevations in my inline Jetta gas motored vanagon....I get
>> around 23mpg as my normal fuel consumption overall, but when I venture into
>> the high mountains I have seen fuel economy jump to(max) 26 miles per
>> gallon on several occasions... Wonder what causes that, exactly?
>>
>> Don Hanson