Vapor fuel continued desscussion!!

[oil pan 4]

Using that flawed logic you shouldn't be even considering propane or gasoline engines.
Diesels typically get 10% to 20% better fuel economy per gallon than their gasoline counter parts.

No ignore the "36% more energy" nonsense.
This was a comparison of BTUs per mile.

1 BTU of propane = 1 BTU of gasoline

When comparing BTUs per mile there is no deceptive energy per volume advantage. BTU per mile levels the playing field when comparing different fuels when trying to accomplish the same work.

[stovie]

Originally Posted by oil pan 4

Using that flawed logic you shouldn't be even considering propane or gasoline engines.
Diesels typically get 10% to 20% better fuel economy per gallon than their gasoline counter parts.

No ignore the "36% more energy" nonsense.
This was a comparison of BTUs per mile.

1 BTU of propane = 1 BTU of gasoline

When comparing BTUs per mile there is no deceptive energy per volume advantage. BTU per mile levels the playing field when comparing different fuels when trying to accomplish the same work.

Being the op of this thread I was taking the discussion back to what I was talking about. I really don't care about BTU's and all that. I just know that having to richen a engine to drop temperature and leaning it out raises temperature sounds completely backwards to me and the excuses I hear about why that is make absolutely no sense at all.

If you were to take a container and put a 16 ft flue on it, then put a line in for fuel and a line for air you can have the fuel turned all the way up and control the burn in the container by controlling the air input alone. That's pretty much how a car is in the end, an enclosed container.

[RedDevil]

Originally Posted by stovie

I just know that having to richen a engine to drop temperature and leaning it out raises temperature sounds completely backwards to me and the excuses I hear about why that is make absolutely no sense at all.

At the danger of sounding like another excuse, I'll try explain the way I see it:

When you increase the amount of fuel for the same amount of air, you do increase the total volume of the exhaust gas (as the fuel will vaporize, whether completely burnt or not).
In a rich mixture you get more volume but as all the oxygen is used up, you won't produce more heat than is possible for that amount of oxygen.

In a perfect mixture most of the fuel gets burned and most of the oxygen is used up - but not all. The heat production is nearly the same as with the rich mixture, but as that heat is concentrated on a lesser volume of exhaust gas that gets hotter.

in a slightly lean mixture pretty much all the fuel gets burned, so the (even smaller volume of) exhaust gas gets as hot as it can be.

In an overly lean mixture the amount of heat produced drops faster than the total exhaust volume, I'd expect the temperature to finally drop again then.

[IamIan]

Originally Posted by stovie

I really don't care about BTU's and all that.

I think that might possibly be the underlining disconnect / breakdown in communication .. I don't see the benefit in trying to avoid the energy (BTUs) part of the topic.

BTU's , Joules, Wh , etc .. are units of energy.

Energy is the capacity to do work .. any kind of work.

Heat the air = a type of work
Heat the engine = a type of work.
Move the piston = a type of work.
Move air in the piston = a type of work.
Turn the shaft = a type of work.
Move the car = a type of work.
Make sound = a type of work.
etc... etc.

If you are talking about or thinking about .. the ability to do work .. any type of work .. you are talking about energy .. weather you intended to be or not... weather you like thinking about energy or not .. that is what is being described.

[user removed]

I think I'll just tell gravity to leave me alone, been fighting it for 64 years.

regards
mech

[2000mc]

On fuel to air ratios and temperatures-
I've known for a long time that an engine running lean runs hotter, but I wasn't ever very satisfied with the fuel cooling type answers. Today I found an answer that makes more sense to me.

Lean ratios burn slower, and expose the engine to combustion temperatures for longer durations.

While I prefer this explanation, I'm still looking for more supporting info. Using this idea, I would think that leaning out mixtures wouldn't have a direct corellation to fuel savings in part to more energy being wasted as heat.
Does anyone know how the ignition timing differs in cars w/ lean burn at a given rpm and map?

[oil pan 4]

Originally Posted by IamIan

Heat the air = a type of work
Heat the engine = a type of work.
Move the piston = a type of work.
Move air in the piston = a type of work.
Turn the shaft = a type of work.
Move the car = a type of work.
Make sound = a type of work.
etc... etc.

Exactly why we should use units of volume to compare work being done. Makes perfect sense.

[pgfpro]

Originally Posted by Old Mechanic

I think I'll just tell gravity to leave me alone, been fighting it for 64 years.

regards
mech

LMAO Awesome mech!!!!

[IamIan]

Originally Posted by 2000mc

Lean ratios burn slower, and expose the engine to combustion temperatures for longer durations.

Does anyone know how the ignition timing differs in cars w/ lean burn at a given rpm and map?

When my Gen1 enters LB the ignition timing advances .. thus tiny bit more time .. I have not logged the exact map of it .. but yes .. at the same 2,000 RPMs LB or non-LB .. the LB has slightly advanced ignition timing for each combustion event portion.

Ignition timing is retarded when my Gen1 enter rich AFR... thus slightly less time.

- - - - -

Caution however in this line of thinking .. the combustion event might be a fraction of a second longer in LB and shorter in Rich... but the total time of that power stroke per ICE cycle (for the same RPM) is not changed.

- - - - - -

I find it also useful to think of more 'complete' combustion .. closer to stoich and in Rich there are enough unburned hydrocarbons (un-used fuel energy) in the exhaust ... to be used as fuel energy for the NOx Cat .. in LB there are not enough unburned hydrocarbons (unused fuel energy) in the exhaust to be used as fuel energy for the NOx Cat.

2nd thing I find useful .. is ICE efficiency .. the Gen1 Insight ICE was tested and shown that the LB operation improved the BSFC (efficiency) by ~20% .. soo more of the fuel energy was being efficiently converted to shaft work by the ICE while in LB.

[user removed]

Would you attribute the 20% improvement to more efficient combustion, or greater throttle opening, or a combination of both in what Percentage?

regards
mech