Date:         Thu, 20 Sep 2001 09:21:58 +0000
Reply-To:     Alistair Bell <albell@UVIC.CA>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Alistair Bell <albell@UVIC.CA>
Subject:      Re: Digifant II 'Diesel' Conversion Pics
Comments: To: vanagon@volkswagen.org
In-Reply-To:  <AIEFIGCNNANNIHLNFBPEAELFDPAA.vanagon@volkswagen.org>
Content-type: text/plain; charset="US-ASCII"

on 20/9/01 3:48 AM, David Marshall at vanagon@volkswagen.org wrote:

>>>> I made some remarks on air intake noise....<<<<
>
> #### This is addressing noise and not the vibration problem.
>

David,

the noise and the vibration problem are somewhat linked. A lot of the
vibrations at certain rpms come from ,IMO, resonances in the exhaust system
as well as inherent resonant frequencies in the engine itself. To a much,
much lesser extent, noise in the intake system will contribute to the
"perceived" vibration problem (if not contributing much in actual
vibration).

Don't get me wrong, I like the roar (and the other advantages) of the
unshrouded K&N filter, but it does add to the overall noise and may well
resonate at frequencies that coincide with that particular engines "buzz
point".

Its an interesting idea to change the characteristics of the rubber engine
mounting blocks to reduce or eliminate the vibrations (don't forget the
trans. mount), but as the I4 install exhaust system is suspended from the
engine, not the body, for its entire length, any vibrations/resonances
produced there will be tranferred to the engine. Reducing the noise of the
exhaust, will reduce the amount of buzzing experienced by the driver.

Some have compalined of buzzing at around 4K rpm, others at around 3200. I
think the difference is due to the type of exhaust each is using.

Alistair



albell@uvic.ca
'82 Westy, diesel=>I4 gas


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