Passionre

[Oilsmoke]

Can the rotating crank Mass be balanced as a whole unit?

Pistons, rods, crank, flywheel. For a superior Balanced & blueprinted Engine.

[raggedraider]

yes and no

hows that for an answer?

 

in a perfect world:

pistons,connecting rods, ect would weigh exactly the same ( not rotating mass )

 

the crank/ flywheel can be " balanced" as a unit (rotating mass)

 

the ratio of reciprocating mass is controled by the counterweights/piston weight,connecting rod weight ( the whipping around parts)

 

these weights ( reciprocating )are " chosen" to produce frequencys ( engine vibration ) more or less at ( less at useful rpms) , ( more at un useful rpms ( more " shake " at idle ) )

 

good crank harmonics ( i think) is when the velocity of the reciprocating mass matches the energy of the " countering " energy ( perfect harmony) ( no shaky, shaky)

this will only occur at a specific rpm

 

so if you balance a crank/piston assmbly to operate with no vibration at low rpms it might shake badly at the high rpm range

and if you balance for high, it might shake at low ( more shake a idel)

 

in a two cyl

the engine can create " sympathetic " frequencys

where a crank can create vibrations at low and high

 

i.e 1000 rpms no vibe,4000 bad shake, 7000 rpms no shake,12000 smooth

 

this would be due to " phase cancelation"

 

at this point i have to tell you that im not an engineer and all of the above could be wrong.( so somebody correct me if im wrong)

 

hope i helped

what was the question?

i need a job

[MotulMonsta]

It isn't worth the money or the headace. Your talking about a whole new can of worms if you want to shave the crank down to try to better ballance the motor.

[DUNEDEMON]

MotulMonsta do you do a lot of crank work at your shop?

[PassionRE]

yes and no

hows that for an answer?

 

in a perfect world:

pistons,connecting rods, ect would weigh exactly the same ( not rotating mass )

 

the crank/ flywheel can be " balanced" as a unit (rotating mass)

 

the ratio of reciprocating mass is controled by the counterweights/piston weight,connecting rod weight ( the whipping around parts)

 

these weights ( reciprocating )are " chosen"  to produce frequencys ( engine vibration ) more or less at ( less at useful rpms) , ( more at un useful rpms ( more " shake " at idle ) )

 

good crank harmonics ( i think) is when the velocity of the reciprocating mass matches the energy of the " countering " energy  ( perfect harmony) ( no shaky, shaky)

this will only occur at a specific rpm

 

so if you balance a crank/piston assmbly to operate with no vibration at low rpms it might shake badly at the high rpm range

and if you balance for high, it might shake at low  ( more shake a idel)

 

in a two cyl

the engine can  create " sympathetic "  frequencys

where a crank can create vibrations at low and high

 

i.e  1000 rpms no vibe,4000 bad shake, 7000 rpms no shake,12000 smooth

 

this would be due to " phase cancelation"

 

at this point i have to tell you that im not an engineer and all of the above could be wrong.( so somebody correct me if im wrong)

 

hope i helped

what was the question?

i need a job

What he said................Banshee cranks are designed with harmonic averaging in mind just as most any internal combustion engine. The only truely effective crank balancing design over a broad rpm range is internal compensating counter-balancers simular to what is used in Lycoming Aircraft engines...Jim

[MotulMonsta]

Nope, that I don't do seeing as my shop at the present time does not have the means to support the work.

[brugal]

MotulMonsta do you do a lot of crank work at your shop?

DUNEDEMON ,YOUR KILLING ME.

[raggedraider]

so i was right ?