Discovered why my engine was blown up.

[Skrilex]

Well I Glad I found this out now before hooking up my Cummins conversion, but while draining the fuel tank I discovered that it was fully full of gas. SO, I’m guessing that’s why my pushrods were all bent and con rod was ejected through the pan. So now I have 25 gal free gas! Mystery finally solved.

 

[Retiredwarhorses]

Usually just won’t run when gassed up...but anything is possible.
this is why we drain all our fuel tanks on GP trucks, more due to very very old fuel.

 

[Skrilex]

Why don’t they run when on gas? I’ve been trying to resolve in my mind why a diesel won’t run happily fine on gas actually. I’d guess the timing would be a tad advanced and the injectors might complain after a while but otherwise why wouldn’t they just run? But a google search does indicate that bent parts and broken con rods can result from gassing a diesel. I dunno?

 

[jasonjc]

Throw Diesel on a fire. Then throw gas on a fire.

 

[Action]

There are no spark plugs in a diesel motor to keep it running.

 

[ken]

Knowing this, do you feel any better about the GM diesel?

 

[orgnal]

Why don’t they run when on gas? I’ve been trying to resolve in my mind why a diesel won’t run happily fine on gas actually. I’d guess the timing would be a tad advanced and the injectors might complain after a while but otherwise why wouldn’t they just run? But a google search does indicate that bent parts and broken con rods can result from gassing a diesel. I dunno?

Compression ratio is much higher in diesel engines. There is no spark plug to appropriately time the ignition of the gasoline. Ignition of gasoline happens a good bit before the Piston reaches top dead center. The ignition of gasoline under pressure (in the absence of spark plug) is much more explosive than ignition of diesel. Now that the gasoline has ignited in an explosive manner much before the Piston has reached top dead center and the Piston is still getting pushed towards top dead center, the connecting rod(s) break.

McReddy

 

[Skrilex]

Knowing this, do you feel any better about the GM diesel?

Not in the slightest.

 

[ken]

understood

 

[Karl kostman]

So what I am getting out of all this gasoline talk is that I can NOW run gasoline in my 920, and I am again guessing from this conversation that my 8V92 should just love gasoline right??? OK I could not help myself, I just had to say something!!! Sorry!
Karl

 

[Skrilex]

But the fuel is injected at the right time for ignition either way right? So how can it ping?

 

[1 Patriot-of-many]

But the fuel is injected at the right time for ignition either way right? So how can it ping?

As noted previously Gasoline is much more volatile and ignites faster than diesel.
Gasoline burns really fast. If you consistently ignite the fuel a little too early which the high compression of a diesel does, you'll blow holes in your pistons, break piston rings, break connecting rods, shatter crankshafts, blow head gaskets, etc.

 

[ken]

Since gas burns faster than diesel, it is injected later and fired with a timed spark plug. This gives the piston time to clear TDC before the expolosion although it was injected before TDC. Since it takes diesel longer to ignite it is injected sooner in the compression stroke. Because the gas was burning too early it casued the piston to be shoved down while it was still traveling up. This will break pistons/rods/cranks etc. Fuels are different in many ways not just in name.

 

[Skrilex]

That makes sense. So how do multi fuel engines deal with this?

 

[ken]

The multi fuel piston has a bowl shape in the top. Thinner fuel like gas or solvents when injected into the cylinder will "puddle" in this bowl. Since they are thinner they will squirt and not vaporize. The fuel density compensator on the back of the IP will increase the fuel rate so the driver never notices a power loss. As the piston travels down on the powerstroke, the fuel will then vaporize and burn. This makes for a long burn so the gas will not "flash burn". The guy who figured this out 50 years ago must be a genius! No electronics and no BS. Just reliability.

 

[Skrilex]

Very cool thanks for the lesson!

 

[911joeblow]

Of course modern flex-fuel and multi-fuel engines have fuel quality sensors which determine the octane of the fuel as it is pumped and electronically adjust on the fly.

 

[Skrilex]

Oh wow I didn’t know that either. Cars these days lol.