Date: Thu, 17 Sep 2009 21:21:36 -0400
Reply-To: Dennis Haynes <d23haynes57@HOTMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Dennis Haynes <d23haynes57@HOTMAIL.COM>
Subject: Re: waterboxer pinging
In-Reply-To: <26337668.45766.1253196235651.JavaMail.mcneely4@127.0.0.1>
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The waterboxer running properly and adjusted properly does not need or benefit from higher octane fuel. The pathetic performance and piston design makes this engine extremely knock resistant. It when things are not right and tweaks are made such as advancing the ignition timing is when things can go wrong under the wrong conditions. The combination of the "wet liner" engine and the far away from the driver placement hide the pinging sound when the audible ping does occur.
It is a common OEM practice to detune engines to compensate or plan for operation under heavy loads. Especially in the days when engine management was limited. For example I had a '99 motor home with the Ford Triton V-10. It was rated at 275 HP. The same exact engine in a Ford van was rated at 325 HP. Why. Because they knew that at 20,500 pounds plus towing a car the engine would often be operated at full throttle. You won’t be flooring it to get a 6,000 pound van up a hill that long so go ahead and give it a good 0-60 run. Your gonna lift your foot or run out of road.
As for alcohol, it actually helps raise the octane. It also reduces performance and peak flame temps, (les BTUs/gallon). It is used as an oxygenate in addition to replacing some quantity or gasoline. In colder weather it also reduces CO emissions due to the dissolved O2 and helps to reduce NOx.
Dennis
-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of Dave Mcneely
Sent: Thursday, September 17, 2009 10:04 AM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: waterboxer pinging
On Wed, Sep 16, 2009 at 11:34 PM , Dennis Haynes wrote:
> Remember that with the water boxer pinging occurs long before you'll
> hear it
> in the front seat.
>
> Dennis
So, GoWesty has an article about this phenomenon, and in it recommends
premium gasoline for all waterboxers, whether the bigger bore ones they
sell, or original. When in the west, where regular octane gasoline is
85 rather than the 87 minimum that VW recommends, I use a higher grade,
which often turns out to be 88 or even 89. I know the reason for the
lower octane at higher altitudes (lower oxygen partial pressure, so
lower combustion rates, so less likelihood of pre-ignition), but being
ignorant about all the effects, just go with the higher octane. With
other cars, I just go with the regular gasoline, and have never had a
problem. VW also recommends using regular gasoline without alcohol
(with the caveat, "if available"). When that was written, it WAS
generally available. Nowadays, in some areas, ONLY gasoline with 10%
alcohol is sold, though here in Oklahoma it is available in some parts
of the state at a higher price than the gasoline with alcohol. In much
of Texas, NO companies sell the "straight stuff."
I do try to pay attention to rpms, and not let them fall too much (avoid
lugging).
So, how does the addition of alcohol interact with the octane
recommendation and pinging or knocking? And, am I just wasting my
money, as most auto manufacturers state, when I pay extra for the higher
octane stuff when out west?
Thanks, Dave McNeely
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