Don;
Back when JW/Gulf Racing was running the Ford GT40 Le Mans program, they
used a Cosworth V8 with a 180 degree crank. The first few laps at a test
track were run and the driver brought the car into the pit. In answer to the
question "How many RPM were you turning?", the driver simply pointed to the
tach-- the needle has shaken loose and was lying at the bottom of the glass.
All the other instruments were in the same sorry state. The vibration was so
severe that something broke almost every time the car was run.
An in-line 6 is inherently in balance but an in-line 4 is not. You have your
work cut out for you.
Regards, Neil Tucson, AZ
--------------------------------------------------
From: "Don McMeekin" <landspeed@columbus.rr.com>
Sent: Monday, May 30, 2011 8:03 PM
To: "LSR LSR" <land-speed@autox.team.net>
Subject: [Land-speed] Bad vibes
> Anyone silly enough to cut an engine in half should probably expect to
> encounter some "unusual" problems along the way. During a recent dyno
> pull, our half Windsor (3 liter inline four) sheared off all six Locktite
> secured 7/16" ARP flywheel bolts, and almost welded the flywheel to the
> crank. Seems that we have a harmonic vibration problem that has created
> more force than our system can tolerate. So.......... we probably need to
> strengthen the parts and reduce the "bad vibes".
>
> The most obvious action would be to strengthen the parts by increasing
> the bolt diameter, adding some dowels, and making sure that everything
> fits. Reducing the the force could be a little more difficult. The
> balancer (cheapo fluid type) is clearly not up to the task and should to
> be upgraded to something more in tune with this engine's harmonic
> characteristics. I really don't have any experience in this area and
> would greatly appreciate any thoughts that list members would care to
> share.
>
> Thanks, Don
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