Just thinking out loud is all??

[pdq67]

I have wondered what would happen if fuel used in our engines actually detonated like a bomb instead of burned very fast like it does?

Could a real detonating fuel be used if it's setting off point was done after the piston was down a bit from TDC so that it didn't blow the piston up.

In other words start the detonation such that it is used to push on the piston some AFTER TDC.... Not BTDC or at TDC like is done with gasoline and alcohols... But ATDC..

My reasoning for thinking about this is that a detonation would produce more AND much quicker energy than liquid/gaseous fuels burning quickly over time do now is all. IF doing so wouldn't blow the engine up??

pdq67

[F-BIRD'88]

Take a hammer to a piston. Same effect.

[modok]

if a diesel sounds like a diesel, that's ok, if your gas engine sounds like a diesel that's bad.
but, it is possible to get a MUCH faster burn without actual knock. Fast enough that it's basically the same as instant.
Part load and lean running looking for fuel economy is where the OE's have never been able to get fast enough.

Squish, swirl, tumble, more compact chamber shapes, and better wet flow can SPEED the burn.
In actuality there is a point of diminishing returns.
Meaning if you are already running a LOW amount of ignition advance for the type of engine ....barely anything to gain from speeding up the burn further.
IMO the amount of advance the engine NEEDS, that tells you where your at.

[peejay]

Someone posted a ways back some cylinder pressure charts for a high compression naturally aspirated engine vs. a lower compression engine with boost. I think it was in response to the idea that an 8:1 engine with 15psi makes the same cylinder pressure as a 16:1 engine?

The boost and lower compression made for a lower peak pressure and a longer average pressure, which is good for keeping the engine alive.

Super high RPM engines run under a kind of "controlled detonation" because that is the only way to get it all to burn. Rich people problems!

[mag2555]

Jez, why not just apply for a permit from the NRC to allow you to detonate a Nono Nuke in each cylinder and you will achieve the same blown up motor result in far less time!

[pdq67]

^^^^^^^^^^^^^^^

Ya, right mag255!!

GEEZ!!

Thanks guys for the information. I see some here got what I was talking about.

Exploding on the swing down, just past TDC so the crank can start spinning...

pdq67

[F-BIRD'88]

its a internal COMBUSTION engine.
Not a explosion engine.

[GARY C]

I have wondered what would happen if fuel used in our engines actually detonated like a bomb instead of burned very fast like it does?

Could a real detonating fuel be used if it's setting off point was done after the piston was down a bit from TDC so that it didn't blow the piston up.

In other words start the detonation such that it is used to push on the piston some AFTER TDC.... Not BTDC or at TDC like is done with gasoline and alcohols... But ATDC..

My reasoning for thinking about this is that a detonation would produce more AND much quicker energy than liquid/gaseous fuels burning quickly over time do now is all. IF doing so wouldn't blow the engine up??

pdq67

One of the biggest issue I see would be try to keep a fuel like that from lighting when you didn't want it to.

Mazda has a very hightech high compression supercharged lean burn engine that runs near compression ignition, it is pretty interesting what all they have do do to control cylinder pressure.

[GerryP]

Homogeneous and stratified combustion are the primary considerations, I believe. The difference between a log burning and a block of C4 blowing up is how fast the combustion reaction occurs. It's really a matter of semantics whether we say gasoline is a controlled burn or dynamite is an explosion. You get into low energy detonation and high energy detonation but even that is somewhat subjective. There are no "everything all at once" combustion events, not even nuclear. Diesels can run on gasoline and gasoline engines can burn diesel. Stoic is the same...well, within a tenth, for either. Again, it's the homogeneous or stratified combustion that matters and how the engine is throttled. Yes, I know diesel fuel pumps need lube so it won't run long without lube for the pump. And, yes, a gas engine on diesel will be real sooty. Multi-fuel engines were somewhat common in military vehicles. Interesting reading on how they handled various fuels.