[Tom Vaught]

Back in August of 2009, I made a post about Overbalancing the parts of the engine on the forum I moderate on another website.

Because some of the info directly related to Boosted Engines I will start a thread here and welcome any new info on the subject.

Here is the post from August of 2009.

This is the Advanced Tech Section but sometimes it helps people if they understand the basics of how things work and then can apply that info to other "Advanced Tech" Racing Projects. I found this web site while looking for an answer to a "Dishing" Pistons vs Balance question on another forum.

Here is the website:

Parts 1,2, & 3 are covered in this link

http://www.eatonbalancing.com/blog/2007/11/

Parts 4 & 5 are covered in this link:

http://www.eatonbalancing.com/blog/2007/11/page/2/

This info caught my eye:

"The use of nitrous oxide, superchargers, or turbo chargers typically also requires a certain amount of overbalance. Using nitro methane in conjunction with a blower is likely the worse case scenario as cylinder pressures are extremely high under detonation which artificially increases the piston weight by a more than a normal amount. Any form of blown engine will benefit from a given amount of overbalance simply due to the weight of the piston averaging artificially heavier not only from the increase in cylinder pressure at ignition, but the increase in cylinder pressure taking place while the cylinder is also filling during the intake stroke. In this instance, the piston is averaging an overall heavier weight when running at speed. A normally aspirated engine has a given amount of pressure counterbalance in that the piston is subjected to negative pressure when the cylinder is filling but is under increased pressure during compression and ignition. If an aspirated engine is working with an extremely well designed induction system and is benefiting from a ramming effect to fill the cylinders at the upper rpm ranges, then overbalancing also helps here. And then there's the rpm factor. Balancing is linear up to a point throughout the rpm range but depending upon the masses at work within your particular assembly, there is a point in which the crankshaft rpm starts to out run the dynamics of the existing state of balance. Overbalance allows these dynamics to stay in tune or 'caught up' to the rpm's of the crankshaft. There are proprietary formulas that calculate these amounts of overbalance for all the different variables and will vary somewhat from shop to shop. Again, talk with your balance shop regarding overbalancing and determine if this would be best applied to your application."

Tom Vaught

So Mike and Eric, & Jack, any new info out there?

Have a great day and be safe out there.

TV.