Fiat 500L 650cc Engine - Bottom End & Cylinders

by Geo3


Crankcase and Crankshaft
Without spending a fortune on the engine, the DIY tuning options are limited

•    First strip the engine down to make sure it's healthy.
•    The standard engine is limited to maximum power at 4700 rpm, by its inlet breathing and cam duration.
•    While increasing rpm, the most fundamental problems are, the crank strength and support, but should be fine up to 45 bhp, as long as it is balanced properly
•    The standard crank will take 6000rpm, but is prone to blowing out the staked in oil blanking plugs (when rebuilding make sure to add a couple of spot welds).
•    The crank can also whip, due to the lack of reinforcement in the crankcase and with standard sump
•    But this can be reduced, by fitting a cast alloy Abarth sump, which also has the added benefit of holding more oil with greater cooling.
•    The original Fiat 2-cylinder balancing is actually pretty good, although, a parallel twin can never be fully balanced.


To safely raise revs above 6,000 rpm, you require to consider the following

•    If you want to rev above 6,000 rpm, you need a steel crank and a reinforced steel-encased main bearing (the standard crank flexes above 6,000 rpm and wears out the bearings and cracks the big cast iron main bearing carrier).
    If you fit Ferrari Dino con rods, you get a beautiful rod and cheaper than many of the alternatives, and you will now have an engine which will rev to 6,500 rpm, all day long.
   

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