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Re: Subject: [Spit] Ideal PRM for cruise

To: Stuart Greenwood <sagreenwood@earthlink.net>,
Subject: Re: Subject: [Spit] Ideal PRM for cruise
From: Doug Braun <doug@dougbraun.com>
Date: Sat, 26 May 2007 06:05:51 -0700 (PDT)
When my hardtop is on, my engine and/or exhaust 
has an annoying booming resonance around 2750 RPM.
It gets pretty tiring driving at that RPM for extended
periods.  I have made sure all the rubber mounts
are good, I have put matting under the carpets
and Dynamat on the inside of the firewall, but the
entire car body simply becomes a resonating chamber at
that RPM.  Higher or lower RPMs are a lot smoother.
The exhaust is stock, BTW.

With the top off, it is much quieter at that RPM.

Doug

--- Stuart Greenwood <sagreenwood@earthlink.net>
wrote:

> Each engine might have a different sweet spot
> dependant on how well the rotating bits are
> balanced. and/or how it is wearing. When I bought my
> car the engine had never been out of the car. It ran
> best at 4000 rpm.  which was about 70 mph with the 3
> rail non overdrive gearbox. My brother in law had a
> English Ford Granada with a V4 engine. It was
> horrible as it came up to 3000 rpm but above that it
> smoothed out nicely and ran like a top.


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