CMB Engines are using a special Intelligent Piston in their 2001 specs engines from now on but what does this mean? Just an other useless invention? Just read and get convinced about the principal of working.
Long Taper Piston and Sleeve Design in CMB and MAC Engines
Also known (thanks to Dieter Suchan from CMB Germany ) as LSi and SSi : "i"
standing for "Intelligent Piston" which describes the Key Issue about
this New and Revolutionary Design.
Credit for its Inception goes to Andy Brown of Competition Marine Designs and
Mauro Braghieri of CMB Italy. Andy is the Designer of MAC Marine Racing Engines
which are manufactured by CMB in Italy.
Andy is also assisting us in developing the CMB LSi OnRoad and Off Road Program
here in
the US.
I recently asked him to explain the Long Taper Design in Detail. The
Conversation lasted a little more than one Hour but I will try to explain the
Key Design Features .
A ringless ABC Sleeve must have a certain amount of Taper
(Tighter on Top/ Larger on Bottom) in Order for the Piston to achieve a perfect
Seal as it moves upwards towards TDC. Some Taper is also needed in the Piston
itself.
The Goal is to have a perfect sealing/fitting Assembly when the Engine is at
Operating Temperature without too much frictional Loss.
Conventional Sleeve Design uses a high Taper Angle and the appropriate Piston to
fit. This Assembly will feel very tight when not at operating Temperature. The
Premise of this Design is , that when the Sleeve reaches a certain Temperature
the desired Fit is achieved. This works very well.
With ever increasing Power Levels it was observed that Piston
Wear and Liner Wear were increasing dramatically and maximum Output of the
Assembly was only possible for relatively short Periods of Time. Why?
Temperature of the Engine while running on the Track or in a Racing Boat have
been found not to
be constant. They vary with Engine Speed and Throttle Position. Most importantly
the Piston was determined to be expanding faster than the Sleeve with Increase
in Throttle and Power Output. A Solution was found after many Months of Testing
and Material Selection.
Long Taper Sleeve Design uses a lower Taper Angle Sleeve and a Piston with two separate Taper Angles distributed between the Piston Crown and a Point just below the Wrist Pin Area. This Assembly will feel almost no Tightness when not at operating Temperature. The Premise of this Design is, that the Piston will fit to the Liner rather than the Liner having to expand to fit to the Piston. And since the Piston is the Part which expands the fastest of all Components involved, by having the Material and the Design proper Fit can be achieved over a wider Temperature Range.
The Results were cooler operating Temps, wider Power Band , less Frictional
Losses, longer Life of the Assembly while maintaining high Power Output, very
short Break In Times.
And since this type of design is Patented it truly is only available on CMB and
MAC Engines.
CMB......coming to a Race Track near you. Count on it !
Best Regards
Rich Reid.........REID R/C PERFORMANCE
Hope this helps, we are currently testing some cool Stuff
