Wiseacre Dave
Well-Known Member
Here is some information that may help people understand the VW cylinder firing order.
I've received a very nice 1835 cc motor from Scott Cassler of Hummel Engines, and I'm trying to learn more about how it works. I've studied the threads here, including this one: https://www.homebuiltairplanes.com/...et-this-great-plains-vw-to-start.19703/page-2
I understand how the firing order works for the motor with the Slick magneto and electronic ignition (both of which I have). I understand that the cylinder numbering is arbitrary as long as the magneto "knows" which cylinder is on the combustion stroke. So, how can there be different published firing orders?
I've learned that the reason you see different published firing orders for the VW motor is that there are different systems for numbering the cylinders. The VW factory firing order (1 4 3 2) is just a permutation of the firing order (1 2 3 4) based on my choice of cylinder numbering for the aircraft (see the diagram). In other words, the cylinders ARE fired in the same relative order in different cylinder numbering systems. It's like cutting a deck of cards: after the cut, the cards still have the same RELATIVE order with respect to each other; but they occur in a different COUNTING order. Conclusion: different firing orders are the result of different cylinder numbering systems and they represent the same actual cylinder firing sequence in the motor.
I've received a very nice 1835 cc motor from Scott Cassler of Hummel Engines, and I'm trying to learn more about how it works. I've studied the threads here, including this one: https://www.homebuiltairplanes.com/...et-this-great-plains-vw-to-start.19703/page-2
I understand how the firing order works for the motor with the Slick magneto and electronic ignition (both of which I have). I understand that the cylinder numbering is arbitrary as long as the magneto "knows" which cylinder is on the combustion stroke. So, how can there be different published firing orders?
I've learned that the reason you see different published firing orders for the VW motor is that there are different systems for numbering the cylinders. The VW factory firing order (1 4 3 2) is just a permutation of the firing order (1 2 3 4) based on my choice of cylinder numbering for the aircraft (see the diagram). In other words, the cylinders ARE fired in the same relative order in different cylinder numbering systems. It's like cutting a deck of cards: after the cut, the cards still have the same RELATIVE order with respect to each other; but they occur in a different COUNTING order. Conclusion: different firing orders are the result of different cylinder numbering systems and they represent the same actual cylinder firing sequence in the motor.
