Turbo header design

[Greg Hermann]

>I don't know the in's and out's of this 180 degree situation but as a frame
>of reference, the Saturns use a 180 degree crank, 2 coils, fire 2 injectors
>at a time, etc.  Runs dead smooth.
>
>Rick
>
>> -----Original Message-----
>> From:	Clarence L.Snyder [SMTP:clare.snyder.on.ca at ibm.net]
>> Sent:	Friday, January 08, 1999 1:56 AM
>> To:	diy_efi at efi332.eng.ohio-state.edu
>> Subject:	Re: Turbo header design
>>
>> Greg Hermann wrote:
>> >
>> > >
>> > >    Care to elaborate on this a little? Are we talking about crank
>> vibration
>> > >(hamonic balancer/flywheel) or something else over my head? Also, a
>> Chevy
>> > >V-8 fires every 90 degrees of crank rotation. How does a flat crank V-8
>> > >fire? Every 180 degrees would make sense, but then it would take 4
>> turns of
>> > >the crank to hit all 8?! I am so confused......
>> >
>> > Secondary vibration, due to the fact that piston accelerations are
>> > different at the top and bottom of the stroke due to con rod angularity.
>> A
>> > four cylinder has an up and down shafing force at twice crank speed
>> (which
>> > is sometimes countered fairly well with two "balance shafts" counter
>> > rotating at twice crank speed.) A flat crank V-8 is like two fours.  Too
>> > late at night to try to describe the shaking which results.
>>
>> The well known "big four buzz" common to modified Ford "B"s, Vauxhaul
>> 2300s, and ford 2300s, as well as the Vegas (ouch!!) My '28 Chevy
>> National and Vauxhaul HC 2300 twin-carb both buzzed pretty good. Hard to
>> immagine two of them out of phase!!

The Vega was so bad cuz its block was so #@$% light! (that lightness turned
into bigger amplitude shake) A pancake 8 is fine with a flat crank, cuz the
two fours cancel each others shake perfectly (except for a twisting moment
about the yaw axis through the center of mass if the bores are offset from
side to side). Had that morning coffee now!

Regards, Greg