Re: [Amc-list] AMC V8 Diesel - Did AMC ever create one?

[adh@xxxxxxxxxxxxxxxxx (Sandwich Maker)]

" From: Arvon Griffiths <arfonrg@xxxxxxxxxxxx>
" 
" 
" >Squirting the diesel in behind the valve should even be okay, then 
" >use the sparker hole for a glow plug for cold starts. Wonder if that 
" >would work? If not, you'd have to use the sparker hole for an 
" >injector or do some major machine work.

this is ignoring the very high compression diesels need, 16:1
-at-least-, and commonly 20:1 or more.  really big diesels can get
away with less, but they have surface/volume scale effects on their
side.

i don't think it could be done without a purpose-designed diesel
cylinder head.

" I may be wrong but, I was to understand that diesels inject fuel 
" directly into the cylinder and it burns as it is being injected.

that's one form, direct injection.  older and less efficient but
easier to scale down is indirect injection, where the cylinder has
very little clearance volume but squishes nearly all of the air into a
small 'prechamber' where the fuel is injected.

you can imagine prechamber shape is critical.  since '48 the leading
design has been the ricardo comet 5, developed for a then radically
small 160 cube perkins.  now diesels of only a few cubic inches and 3
hp are routine.  even gm used it for the 5.7 and 6.2/6.5, after
failing to make anything even as good on their own.

and btw the famous diesel rattle occurs when injection gets ahead of
combustion and the fuel suddenly detonates.  this is why they have to
be heavy, and in corrollary why they don't spin very fast.

" IF you can inject fuel from behind a valve, how do you keep it from 
" igniting while the intake valve is open? And/or how do you get it to 
" ignite once the valves are closed?

exactly why imho it's not possible.
________________________________________________________________________
Andrew Hay                                  the genius nature
internet rambler                            is to see what all have seen
adh@xxxxxxxxxxxxxxxxx                       and think what none thought
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