Subject: Re: [TR] TR3 Crank

From: "TeriAnn J. Wakeman" <[email-masked]>
Date: Wed, 25 Sep 2013 07:38:10 -0700

On 9/25/13 6:39 AM, [email-masked] wrote:
>
> I don't know what caused it but I've heard that even the factory cars had
> problems over 5,000.
>
>
The TR3/4 crank has a major harmonic around 5200 RPM that tends to break 
the crank at the base of the flywheel mounting flange.  There is a 
second major harmonic a little above 6200 RPM that tends to break the 
stock crank in the middle.  This is why the TR engine is factory 
redlined at 5000 RPM.  The harmonics can shift a little along the RPM 
spectrum if the crank, rods, pistons & flywheel are not balanced.

The aftermarket harmonic balancer sold the the TR engines tames the 5200 
RPM harmonic.  It requires going to a narrow fan belt & an electric fan.

My engine is balanced, has a nitrided stock crank and a harmonic 
balancer. It sees 6000 RPM under full acceleration.

TeriAnn

** [email-masked] **

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From: Don Hiscock <[email-masked]>
Date: Wed, 25 Sep 2013 09:53:38 -0500

...and a guy *seriously* rallying a well-known TR4 in the UK with a
*very* tuned engine uses an 8100 rpm redline, IIRC.

These aren't normal production engines anymore, though!

On 9/25/13, TeriAnn J. Wakeman <[email-masked]> wrote:
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From: "TeriAnn J. Wakeman" <[email-masked]>
Date: Wed, 25 Sep 2013 08:10:36 -0700

> These aren't normal production engines anymore, though!
And almost certainly with a very expensive crank and rods.  8100 RPM in 
the TR 4 cyl engine is really pushing it with cubic money.  I could only 
afford about 6000 RPM.  Costs start getting really expensive to get past 
that second harmonic.

TeriAnn