Re: Odd Firing

["content22207" <brobertson@xxxx>]

PRV in final version was also converted to 60 degrees. I believe this
is engine Chrysler Eagles used.

Bill Robertson
#5939

>--- In dmcnews@xxxxxxxxxxxxxxx, "B Benson" <delornut@xxxx> wrote:
> This has been on the list a couple of times but again, the reason an
engine
> is odd or even firing is because of the crankshaft design as related
to the
> number of cylinders and their degree of opposed separation. In the
case of
> the DeLorean engine it is six cylinders with two groups of three
cylinders
> opposed at 90 degrees. The most economical design for crankshafts in
a 'V'
> configured engine is to have a pair of opposed cylinders sharing the
same
> journal of the crankshaft. When you oppose six cylinders at 90
degrees and
> have each opposing cylinder share a common crankcase journal the
math works
> out to the fact that one of these cylinders rotates the crankshaft more
> degrees than the other. The firing order is configured accordingly.
A more expensive
> approach is to utilize a crankshaft with individual journals for each
> cylinder which equalizes crankshaft rotation throughout all cylinders.
> Unfortunately that creates more expense for the manufacturer and
many have
> adopted a less expensive approach with a counter rotating balance shaft
> designed into the engines total configuration to counter the odd firing
> scenario . This works out very well and results in a smooth running odd
> firing engine. Since many V-6's were derived from 90 degree V-8's
> (8 cylinders at 90 degrees do result in an even firing scenario)
they ended up as odd firing. Newer V-6's have been been designed in 60
degree configurations
> to allow the math to work out to even firing.
> 
> Bruce Benson