Date:         Sun, 23 Feb 2003 19:48:00 EST
Reply-To:     FrankGRUN@AOL.COM
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Frank Grunthaner <FrankGRUN@AOL.COM>
Subject:      I4 engine/vibrations - A few quick comments
Comments: To: McNock@EASYSTREET.COM
Content-Type: text/plain; charset="US-ASCII"

In a message dated 2/23/03 4:12:07 PM, McNock@EASYSTREET.COM writes:

<< beat to death yes, but definitively figured out - no! (at least for this

van!)


I have been to your website may times (fabulous and thanks) and searched the

achives many times. Below  I have a list of all that has been done.


It is mostly everything every discussed.  That is why I am so frustated.

Better, Absolutely. Fixed - well no. >>

You'e definitely correct on your website observations, but fall a bit short
on the summary. I have indicated in the past and at some length a number of
technical issues that come to the solution including the mounting of the
exhaust, the coupling of the exhaust and the details of the engine mount.

Of all of these, resonance plays a powerful role. After eliminating the basic
engine issues (bent pulleys, H/A mounting brackets and exhaust coupling) you
will return to the engine mount and its active or passive isolation
technology. All manufacturers of large displacement 4 cylinder in line
engines must confront this problem. The problem is minor at 1.6L, more
significant at 1.8L, a real discomfort at 2.0L and a major pain in the tush
at 2.3 and above. All manufacturers (VW. Porsche, Audi, Mercedes, SAAB, Volvo
to name a few Euro's) adopt one of two solutions: Addition of a balance shaft
to the engine or the use of hydraulic (actively damped) engine mounts. I have
adapted the SAAB hydraulic mount to the VW Vanagon diesel mounting system
(refers to the '82 design only since this is what I play with). On my test
stand, the Audi 3A 2.0L engine (inline 4) with turbo is vibration free. But I
have more work to do for better clearance. I have not yet been able to mount
the new engine in the Vanagon, so I haven't conducted any vibration
measurements yet. I will!

In the meantime feel free to experiment with the hydraulics. BTW your
description of differences betwixt the 82 and later varients also misses a
few key points.

Frank Grunthaner