Basic Engine Questions, Firing Order and Water Out the Tailpipe Options

[Highland]

Wondering what the firing order isn't 1-4-2-3 instead of the actual 1-4-3-2. Wouldn't it make more sense to go back and forth between opposing sides? Would the engine sound smoother with 1-4-2-3?

I happen to be by my tailpipe when my engine transitioned from cold idle (~1800 rpm) to warm idle (~1000 rpm). When the rpm dropped water sputtered out the tail pipe and continued compared to dry exhaust while cold idle. I know water is a product of combustion, but does this tell me anything about running to rich or lean at these idle conditions?

[Ron914]

Wondering what the firing order isn't 1-4-2-3 instead of the actual 1-4-3-2. Wouldn't it make more sense to go back and forth between opposing sides? Would the engine sound smoother with 1-4-2-3?

I happen to be by my tailpipe when my engine transitioned from cold idle (~1800 rpm) to warm idle (~1000 rpm). When the rpm dropped water sputtered out the tail pipe and continued compared to dry exhaust while cold idle. I know water is a product of combustion, but does this tell me anything about running to rich or lean at these idle conditions?

I don't have the answer but I am interested in other members responses as I also noticed the water out of the tailpipe after starting up my motor after a motor rebuild .

[914werke]

ever wonder why the fire order on a Suby (4) is 1324

[technicalninja]

When you burn a gallon of gasoline you produce ALMOST a gallon of water.

It's why all exhaust systems have drain holes in the mufflers.

It's mostly superheated steam and you don't see it.

When the exhaust system is above 212 degrees it boils it off.

Your exhaust is saturated after a drive and after it cools below 212 condensation forms internally.

Hence, you tend to see it during warm up the next time you run it.

[Superhawk996]

Wouldn't it make more sense to go back and forth between opposing sides? Would the engine sound smoother with 1-4-2-3?

Disregard my answer I don’t think I’m understanding the question.


Look at a T4 crank and the answer will become obvious.


You would end up with two crank pins adjacent to each other and/or one large shared crank pin / rod journal. Having only two large crank pins that are 180 degrees opposite each other would create strength issues and problematic harmonics that would bend & fatigue the crank. This would place more stress on a crank that is only supported by three bearings.

This would also have an effect on cylinder back offset between 1/2 and 3/4 sides. I suspect the cylinders would end up too close together though I admit I’m not going to look into the dimensions to prove or disprove this.

As the firing order is currently, or as proposed, it is alternating across cylinder banks.

[914_teener]

Wondering what the firing order isn't 1-4-2-3 instead of the actual 1-4-3-2. Wouldn't it make more sense to go back and forth between opposing sides? Would the engine sound smoother with 1-4-2-3?

I happen to be by my tailpipe when my engine transitioned from cold idle (~1800 rpm) to warm idle (~1000 rpm). When the rpm dropped water sputtered out the tail pipe and continued compared to dry exhaust while cold idle. I know water is a product of combustion, but does this tell me anything about running to rich or lean at these idle conditions?

Last question no it does not tell you about idle mixture. A CO meter will.

[Superhawk996]

ever wonder why the fire order on a Suby (4) is 1324

(IMG:style_emoticons/default/laugh.gif) now I'm totally confused (IMG:style_emoticons/default/av-943.gif) since Subaru cylinder number scheme is different.

Regardless both are flat plane cranks, have to have 180 degrees between cylinder firing which at the end of the day, that sort of establishes the sound. Meaning, you'll never end up with a syncopated sound like you get off a V8 or a Harley.

[Dave_Darling]

I can only speculate about the firing order--but I think that it was chosen to give the best balance to the running motor. They had a fairly long time to work that out, since the layout and firing order of the 914 motor is shared with the VW Type I. Depending on how you break up the cycle, the motor either fires each diagonal in turn, or each side in turn. (1 and 4 are diagonal from each other; 3 and 2 are diagonal from each other. But if you start counting the cycle at 4 instead of 1, you'll see that 4 and 3 are on one side of the motor and 2 and 1 are on the other side of the motor.)

Inline-4 engines have a different firing order to keep them relatively balanced, as their layout is pretty different from a boxer-4.

The water is normal, and probably not indicative of anything specific.

--DD

[Highland]

Last question no it does not tell you about idle mixture. A CO meter will.
[/quote]

What is ideal CO for stock 2L Type 4? If the product of combustion is CO2 and H2O, is a CO a result of not enough O2 or a rich mixture?

[930cabman]

Maybe the boys in the fatherland did an eeny miny mo and came up with the firing order (IMG:style_emoticons/default/driving.gif)

[Superhawk996]

Maybe the boys in the fatherland did an eeny miny mo and came up with the firing order (IMG:style_emoticons/default/driving.gif)

I believe 1432 is dictated by the camshaft which shares 4 lobes for 8 lifters. To do 1423 the lobes would have to be split into 8 separate lobes and would take up more space.

The down side of this compact cam arrangement is that the tappet wear patterns overlap on lobes creating an area that basically sees twice the wear. This overlap area ends up becoming a notch area when the cam is worn.

The other possibility is that firing order helps minimize 2nd order harmonics that are always present for a flat plane crank.

Seriously doubt there was any guessing involved.

[73-914]

How many lobes on camshaft? Only 4 , 2 intake 2 exhaust. Therefore firing order has to be 1 4 3 2. (IMG:style_emoticons/default/poke.gif)

[Superhawk996]

ever wonder why the fire order on a Suby (4) is 1324

(IMG:style_emoticons/default/laugh.gif) now I'm totally confused (IMG:style_emoticons/default/av-943.gif) since Subaru cylinder number scheme is different.

This was bugging me. Looked up Subi cylinder numbering and renumbered to 914 numbering convention.

Subi 1324 = 914 4321 which = 1432 (IMG:style_emoticons/default/av-943.gif) now I get it. I’m slow and not intimately familiar with Subi’s. (IMG:style_emoticons/default/happy11.gif)

[930cabman]

How many lobes on camshaft? Only 4 , 2 intake 2 exhaust. Therefore firing order has to be 1 4 3 2. (IMG:style_emoticons/default/poke.gif)

I knew someone had the answer (IMG:style_emoticons/default/screwy.gif)

[technicalninja]

Between the difference in 4-cylinder numbering sequence and the different firing orders the engines USUALLY ran 1-4-3-2.

This is ALMOST all 4 cylinders.

Honda was an exception.

OLD Honda's ran 1-3-4-2.

New Hondas run 1-4-3-2.

Trying to alter firing order is "fully designing" the engine.

Not worth doing in my book...