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Author Topic: Flywheels  (Read 12379 times)
roy4matra
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« Reply #15 on: July 27, 2011, 08:55:22 pm »

I have been told that the "s" flywheel is lighter then the standard 2.2..
Do anybody have any experience as to how much this effects performance?..

Yes the 'S' flywheel was lighter.  You have to understand that the standard 2.2 had the engine from the Tagora with no modifications except where necessary top fit transversely in the Murena.  Consequently it was designed for a heavy relatively slow saloon car not a lighter sports car.  This was done purely on cost grounds.

The Murena should have had a lighter flywheel and uprated engine to suit its sports profile, if they had really had any thought to its pedigree. :-)

After demand for more power, the Prep 142 kit was offered to uprate cars in service.  Since this was a dealer fit after market kit it was only the minimum necessaary to keep work down, so whilst the head was removed to fit a new cam, the powertain was not removed so nothing was done to the flywheel.  When they did the work at the factory for the 'S' they also lightened the flywheel as well as a few smaller tweeks that the Prep 142 did not have.  This does not produce any more power - but the reduced mass makes the acceleration quicker.  A lightened and balanced flywheel will benefit the Murena since it is too heavy as standard and will allow the car to accelerate noticeably quicker without being so light (like a race prepared enngine) that the power pulses will create any concern.

The genuine 'S' cam has a shorter duration but higher lift than the Holbay 58C fast road cam profile.  This produces faster valve accelerations and decelerations, but a genuine 'S' is still a smooth car, so we know that the lighter flywheel is eminently suitable.  The Holbay cam gives a better performance than the 'S' with its wider duration and high lift as I can testify having driven both in excellent condition.  So a lighter flywheel will suit the Holbay cam as easily as the 'S' and should give no cause for concerns at all if done properly.  No need to buy a new one, simply have the one you have machined, and the crank/flywheel/pulley balanced.

The late 2.2 engines are supposed to have a seven bolt crank/flywheel but I have only stripped one genuine 'S' and that still had the five bolt crank.  My guess is that only late Tagora were actually fitted with the late cranks, since Matra had already been supplied with their engines before the change took place.

Roy
« Last Edit: August 27, 2018, 04:32:58 pm by roy4matra » Logged

suffolkpete
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« Reply #16 on: July 28, 2011, 11:16:08 am »

The Murena should have had a lighter flywheel and uprated engine to suit its sports profile, if they had really had any thought to its pedigree. :-)

It does, 7.3kg as standard on the 1.6  Smiley  It's what Coltec call a "light factory" flywheel.

By the way Roy, since you changed your ISP, your avatar no longer appears on your posts.  Can you update the link so that we can see your smiling face again  Wink
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krede
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« Reply #17 on: August 02, 2011, 10:44:52 am »

Thanks Roy... think I'll have my spare flywheel lightened then Smiley
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