[s-cars] Engine completey hosed

[Bill Mahoney]

Calvin Fired ~

"Since all cylinders fire every 720 degrees of crank rotation the separation

between consecutive firing events, which #4 and #5 happen to be, should

nominally be 144 degrees of crank rotation.  This means that the piston in

number 5 is approximately 36 degrees after bottom dead center and therefore

a good way into its compression stroke at the time #4 fires.  Now, what we

know about a compression stroke is that it doesn't build much compression if

the valves are open.  Ok, I'm being a smartass :)  Depending upon cam

timing, which I don't have readily at my fingertips for any Audi cam at the

moment, the intake valve will have probably closed some 30 to 40 degrees

prior to tyhis firing event.  Also, there is some time necessary for the

flame front to travel through the headgasket leak and into cylinder #5.

 

The point I am trying to make is that both valves in the #5 cylinder are

most likely closed, or damn closed to completely closed when #4 is firing,

which could create something akin to detonation in the #5 cylinder.

Although it is a bit different because the piston in #5 is most likely

further down in the hole than when normal detonation would occur.  I don't

know how this would make it worse or better on the piston, but I can tell

you it probably doesn't do anything good for the piston's longevity."

 

Woah!  Calvin!  Awesome hypothesis!  And explanation too.  Gheeash, so well
written even I almost comprende.

Misplaced detonation being one of the banes of a high boost urS, maybe a
Detonation AudiOmeter DetectOmeter (DAD)tm

should be a must have item?  http://autospeed.com/cms/article.html?
<http://autospeed.com/cms/article.html?&A=0353> &A=0353

Connect it to your stereo to erase all doubts of your sanity.

Bill~no knock / when running I hope~m