Engine balancing

[spetz]

I was wondering what is the best type of engine balancing?

How do the following two methods compare to each other:

Balancing of engine with crank, flywheel, rods and pistons all as one recorporating mass (pistons always stay connected to rods)

Or

Balancing everything individually, neutral balancing of rods and so on?


Also, if the engine has been balanced already, and the rods are shotpeened after the balance, does it need to be balanced again?




More info,
THe engine is a 6A12 Mitsubishi MIVEC from an FTO. It has been balanced with other work done by Milton from Harris Engineering in Sydney, the engine will be assembled by Charlie from Good Performance Centre.

Milton balanced the engine without taking the rods off from the pistons, and when I asked to get the rods shotpeened he told me taking them off the pistons may break them, which made me think how the engine was balanced if they had never been taken off.

[J_Mech]

Shot penning the connecting rods should not effect the balance of the engine from what it was before. That is the process would not remove material (mass) or change the geometry of the connecting rods excessively, therefore the mass and mass distribution of the connecting rod would not change.

In engine balancing I would see the flywheel being treated independantly of the other components. Classically the role of the flywheel is to smooth out the output speed/vibrations of the engine (simply by adding inertia). It should be balanced on its own.

Not sure how they balance engines outside of OEM but in engine design you take into account reciprocating mass and add a portion of that mass to the counter balances on the crank (explained simply), maybe someone here can explain how the engine is balanced in workshops. Any way I would expect that the engine balancing takes into account piston, rings, pins, clips, conrods, bearings, crank.

J_Mech

[Menzy]

[quote=spetz]More info,
THe engine is a 6A12 Mitsubishi MIVEC from an FTO.quote]


hmm ... "Ozhonda" :confused:

[Slow96GSR]

Mitsu motors are close to Hondas so it's ok!!

There is a machine that basically spins the crank and stops it where it needs a "hole" put for balancing, like a CNC lathe. There are weights that are on the crank that act as the rods. This tells the machine where the off spot is on the balancing. With the pistons we weight them and get them equal to each other with in .0001oz of each other. Same with the rods. This also includes the bolts and bearings. As for the flywheel, we balance with it on and the pressure plate, but not the clutch disc, as it is not a connected mass on the rotating mass. If you have an aftermarket pulley we balance with it too. Anything bolted/connected to the crank is on it when we balance. It is a must!

The beast!
http://www.strathlan.com/CMS/images/balancer.jpg

[spetz]

Mitsu motors are close to Hondas so it's ok!!

How so?
I thought they were quite different especially in the head design?

Anyway, yeah it is Ozhonda but I initially became a member because a friend had a B16A civic and MIVEC/VTEC is quite similar.

Has anyone heard of Harris Engines (engineering maybe?)
That is who did the balancing


Also, just to fire things up, there will be a K20A Vs. 6A12 test soon.
I am having a DC5R gearbox fitted into my Lancer and a friend is having a K20A into his EG civic fitted. Both engines will have near identical mods, and both cars will be weighed and the difference will be covered by putting more people into the lighter car (EG Civic) to get the weights the same.
Then see how they compare to each other seeing as weight, gearing, and mods will be pretty much identical