[NA] See-through engine combustion

In the late 70's my dad ran the auto shop at a high school and had a similar engine. He called it 'acrylic' but I am not sure what it was made of. It was very finicky and you could not run it more than about 20 seconds for fear of it melting. No high speed camera, couldn't see the flame front but it was very neat at that age to have the internal mysteries of an otto engine revealed.
 
Kind of odd his plug fires on the exhaust stroke. But I guess that's not uncommon in smaller engines. Makes the timing a lot easier.
 
flyingron said:
Kind of odd his plug fires on the exhaust stroke. But I guess that's not uncommon in smaller engines. Makes the timing a lot easier.
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It's not uncommon at all on all sizes of engines. These days, it's the oddball that doesn't have waste spark ignition. Basically, those that still have distributors, and some coil-on-plug designs driven by a cam sensor. Most cars don't even have cam sensors anymore, as you can reuse the crank sensor for timing in a waste spark system.
 
MAKG1 said:
It's not uncommon at all on all sizes of engines. These days, it's the oddball that doesn't have waste spark ignition. Basically, those that still have distributors, and some coil-on-plug designs driven by a cam sensor. Most cars don't even have cam sensors anymore, as you can reuse the crank sensor for timing in a waste spark system.
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With variable timing engines cam sensors are required, just about every new car has a cam sensor
 
Criitter7 said:
With variable timing engines cam sensors are required, just about every new car has a cam sensor
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With variable VALVE timing, yes, you need the cam sensor (or something very much like it) to time the spark relative to valve events. Not so necessary for fixed valve timing.

Many a neophyte mechanic has gone looking for Saturn "cam sensors," as they have a P-code, but no actual sensor.
 
Cam sensor also syc's the fuel injection to the intake events on engines that have sequential fuel injection or direct fuel injection.
 
Capt. Geoffrey Thorpe said:
Cam sensor also syc's the fuel injection to the intake events on engines that have sequential fuel injection or direct fuel injection.
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Not necessarily. The Saturn I referenced fires its SEFI off the #1 coil (which fires #1 and #4 plugs at opposite polarity). That's why it has the P-code. It gets set off by poor grounding of the coil to the engine block, or an arcing #1 or #4 spark plug wire.
 
deonb said:
What I find most interesting is that both of you independently described it as "nifty".
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It's a careful word without much meaning. LOL

Neat-o sounds too old.

Cool is overused.

Groovy... too Austin Powers.

Wicked... too 80's.

Amazing... save that one for something that really is.

Heh.
 
denverpilot said:
It's a careful word without much meaning. LOL

Neat-o sounds too old.

Cool is overused.

Groovy... too Austin Powers.

Wicked... too 80's.

Amazing... save that one for something that really is.

Heh.
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Nifty .. too Leave It To Beaver

How about "tubular" or "gnarly?" Too surfer?
 
Let'sgoflying! said:
How about a video showing variable valve timing in action?
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Not a video, but this is what you get with late intake valve timing - bottom axis is cylinder volume (logarithmic scale), left axis is cylinder pressure (logarithmic scale). Video doesn't look much different...

A-B is compression, you see that the pressure doesn't rise right away starting at A because the intake valve is late to close. B-C is most of the combustion, C-D expansion, D-E blowdown as the exhaust opens, E-F exhaust stroke, F-A intake stroke - again the retarded intake timing causes the slope from F towards the right since the valve is still closed, then it opens and the pressure equalizes near the intake manifold pressure until it gets to A

PV_Diagram.JPG
 
I didn't have the "visible V8" but I did have a visible Wankel engine when I was a kid.
 
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