Balance a Burtz

[johnneilson]

Spinning bob weights on the crank do nothing you cannot simulate the offset acceleration of the mass between tdc and bdc

The best you can do is make the rods equal weight and end to end
Pistons even weight and as light as you think you can get away with

Just an observation over the years is that hopped up motors will shake and those not familiar with them think it is out of balance

If your motor is only making 45 hp it should be smooth when you get to 200 hp it will shake

J

[Dan McEachern]

Putting the bob weight issue aside for the time being, a trip to the balance shop will set you back $200-$300 depending on what needs to be corrected. Given the overall cost of a Burtz engine why would a person even consider not checking the balance? It's common knowledge that the rods need correction (the total weight garbage is just that- the crank will see any big end weight difference, and you will feel it) so just spend the $$ so you are confident that you have a good motor when you drop it in your car! pretty simple.......

[johnneilson]

Agree Dan when making changes such as lightning a flywheel or drilling crank for oil

The Burtz should be good out of the box
The crank and flywheel should be done to ISO standards
Rods and pistons easy on a gram scale

John

[nkaminar]

There are two sides to this coin. To be 100% accurate the all parts should be equal in weight, big end and small end of rods included, and the crankshaft dynamically balanced using correct bob weights. On the other side of the coin, I put my Burtz engine together without doing any balancing and it does not have any vibration problems.

[Terry Burtz, Calif]

Originally Posted by nkaminar

There are two sides to this coin. To be 100% accurate the all parts should be equal in weight, big end and small end of rods included, and the crankshaft dynamically balanced using correct bob weights. On the other side of the coin, I put my Burtz engine together without doing any balancing and it does not have any vibration problems.

nkaminar,

Thanks for your comment.

The moving parts are manufactured and balanced in factories that make parts for domestic and foreign engines.

The factories are not making engines for Ferrari, Lamborghini, Bentley, Indianapolis, Bonneville, or circle track racing.

The "Builders Guide" for the new engine mentions balance. Pasted below is from the "Builders Guide":
The connecting rods are balanced in sets to modern engine standards. Each of the 4 connecting rod weights are within a few grams of each other, but the center of gravity is slightly different for each connecting rod. If you are building a race engine or are a perfectionist, please see the YouTube video https://www.youtube.com/watch?v=QLpiF0E0EJU

It would be very unfair to 99% of our customers if we increased the price to accommodate the 1% that want closer tolerances and balance.

[Dan McEachern]

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from above: "should be equal in weight". If you all are good with that, then what can I say? I don't think that anyone in this thread advocated for Terry or John to be unfair to their customers, or change anything about their product.