Simviation Forums

How balanced is a 5 cylinder straight engine?

A 4 cylinder engine, whether straight or flat, is inherently imbalanced because there are 4 dead centres in a 4 stroke cycle. When 1 cylinder is in dead center, all 4 are. So all 4 must accelerate together.

A 3 cylinder engine has 2 cylinders moving when 1 is in dead centre. But if a middle cylinder is in top dead centre then end cylinders are moving one up the other down. When the middle cylinder is in bottom dead centre, the end cylinders are moving in opposite direction, and therefore the whole engine suffers a rocking momentum.

How about a straight 5 - what are the relevant imbalances here?

Have a look at the original Audi Quattro and Quattro S1. Then look through the rally records for the mid-1980s
'Nuff said

Types of Piston Engine Configurations:

http://en.wikipedia.org/wiki/Category:P ... igurations

So many!... ...!

...and balance:
http://en.wikipedia.org/wiki/Engine_balance

Paul... ...!

One of my Bikes, in the centre, has a Twin Cylinder, water-cooled engine, with Pistons displaced by 180 degrees, nicely balanced... ...!

Types of Piston Engine Configurations:

http://en.wikipedia.org/wiki/Category:P ... igurations

So many!... ...!

...and balance:
http://en.wikipedia.org/wiki/Engine_balance

Paul... ...!

One of my Bikes, in the centre, has a Twin Cylinder, water-cooled engine, with Pistons displaced by 180 degrees, nicely balanced... ...!

Honda RC116 is a twin engine, 50 ccm (25 ccm per cylinder). Naturally aspirated, 16 horsepower.

As for an inline 5, Honda RC149 is 125 ccm. However, it is poorly balanced, with weird crankshaft structure.