Lean or Rich

[cruzerz545]

Does it reall matter if your lean? I thought the oil is what lubes everything?

How will running a little lean hurt the car? Its just less fuel....


-jim

[chameleon]

Yes, running lean really matters. You are right cruzerz545, oil is what lubricates the car. But running lean is not a lubrication issue, it is a heat issue, and the heat that running lean causes is not caused by friction.

Believe it or not, in addition to being the source of energy in an internal combustion engine, fuel actually also acts as a coolant for your cylinders. As you probably already know, you can only burn fuel when there is the presence of oxygen. A properly tuned engine will inject more gas into the cylinder than the volume of the present oxygen will allow to burn. The remaining gas will absorb and dissipate some of the heat that resulted from the combustion process and exit out the exhaust pipe.

When you lean out your air/fuel ratio to the point that there is no fuel left in the cylinders to dissipate any of the heat resulting from combustion, you begin to run into serious problems. The heat will build to such an intensity that you will litterally melt the inside of your engine. Especially in an engine like ours that uses lots of aluminum parts, after all, aluminum melts at 660 degrees Celsius. A typical normal crown temperature is around 550 degrees Celsius and typical exhaust temperatures will be around 850 degrees Celsius.

Typical damage that results from running your engine lean is damage to the tops of the pistons, damaged seals/rings, and melted valves. I've actually seen many cases of a lean running engine burning holes clear through a piston.

[oldster]

Right on chameleon. For a living example go to a NHRA national event on the last day of qualifying. They will normally run the fuel cars last in the evening. Everyone pulls out all the stops to make the show which means leaning the motors to the point of detonation. As they go through the traps you will see shooting stars flying out past the header flames, those are the tops of the pistons. Very, very exciting but not recommended to try at home.

[cruzerz545]

So, if I run a little lean with my nitrous( fuel wise), I shoud be ok because the nitrogen will cool the culinder down much more then fuel will.

Now, do you know if we can use fuel pressure regulators on our car? Also, do you know what aftermarket injectors we can use?

thanks for the info!
-jim-



Originally posted by chameleon
Yes, running lean really matters. You are right cruzerz545, oil is what lubricates the car. But running lean is not a lubrication issue, it is a heat issue, and the heat that running lean causes is not caused by friction.

Believe it or not, in addition to being the source of energy in an internal combustion engine, fuel actually also acts as a coolant for your cylinders. As you probably already know, you can only burn fuel when there is the presence of oxygen. A properly tuned engine will inject more gas into the cylinder than the volume of the present oxygen will allow to burn. The remaining gas will absorb and dissipate some of the heat that resulted from the combustion process and exit out the exhaust pipe.

When you lean out your air/fuel ratio to the point that there is no fuel left in the cylinders to dissipate any of the heat resulting from combustion, you begin to run into serious problems. The heat will build to such an intensity that you will litterally melt the inside of your engine. Especially in an engine like ours that uses lots of aluminum parts, after all, aluminum melts at 660 degrees Celsius. A typical normal crown temperature is around 550 degrees Celsius and typical exhaust temperatures will be around 850 degrees Celsius.

Typical damage that results from running your engine lean is damage to the tops of the pistons, damaged seals/rings, and melted valves. I've actually seen many cases of a lean running engine burning holes clear through a piston.

[MaasNeotek]

No, just becuase you are runnin N2O doesn't mean you run cooler - the N2O cools the air charge prior to ignition - making it more dense. When the cyl. fires - you are burning more material, faster, and therefore hotter. In fact, running lean on N2O is far more dangerous.

[cruzerz545]

I get it. Cool.
OK answer me this.

How does nitrous effect cylinder pressure? Its not compressed air, but its not forced induction either. Howm much of an increase in cylinder pressure will I notice compared to a turbo?


-jim

[MaasNeotek]

Good question - and I don't know if I have 'the' answer - but I may be able to shed a little light.

Cylinder pressure - at what point?

In reality - at the bottom of the intake stroke, 14.7psi - just like ANY NA engine. Theres no 'boost' per se. What you DO get from the nitrous is a combo benefit.

1. The nitrous decompression during the shot decreases the temperature of the intake charge. While not increasing it's pressure - it does increase the density of the intake charge, and therefore it's oxygen holding capacity (much like driving at -40c).

2. The Additional oxygen released during combustion (greater than 30% more) obviously allows you to burn more fuel, and therefore make more power. (The nitrous doesn't actually release the oxygen until the cyl. pressure hits 575°f - which generally is during the power stroke - unless you are running hot and detonating -- bad...)

During the power stroke the maximum force exerted on the piston, is increased - like a turbo... (or like a CAI vs. Non-CAI) The power produced is not as much as a Turbo, or more than a turbo... so at this point all comparisons are mute. Theres no way to compare NA/Turbo/N2O unless you are talking about specifics - so I'll just run away...

Hope something in there helped.

Cheers!

[cruzerz545]

So, because N2O is not compressing the air, there shouldnt be much more compression. Were as if you were pushing 12PSI with a turbo, there should be my cylnider pressure.
.


So Basically you get O2 from the compressed air from the turbo, were Nitrous you have the O2 already, therefor less cylinder pressure?


-jim

[MaasNeotek]

Theres a gray term floating around here...

Cylinder Pressure... It means nothing - and everything.

The motor compresses anything in the Cyl. to a given ratio... (11.5:1) on the celi GTS. The pressure? Who the heck knows. 11.5 times the pressure in the cyl at the bottom of the intake stroke.

Now - the density of the intake charge at atmospheric pressure is a variable (which is why your NA car runs better in Cold air - more dense - more O₂) and it is the pressure of the intake charge that is 'Boosted' in a Turbo/SC vehicle. This has NO BEARING on the DENSITY of the charge however - which is why an intercooled turbo works better - the intercooler doesn't increase pressure - rather, it makes the intake charge more DENSE.

Atmospheric pressure is approximately (~)14.7psi in an NA car or ~14.7psi + Boost in a Turbo/SC...

Generally without accepting the leakdown and inefficiencies in an NA engine you are looking at (~14.7x11.5)psi at top of the compression stroke, just prior to ignition... Around 170psi. (this is not scientific fact - just number crunching - any engine expert can correct me or back me up here... - I'm happy to learn either way) - Which in some respects is validated by the pressures seen in a compression tester. (Right Larry?)

With nitrous, the power comes from the point of ignition when the gasses expand and burn, pushing the cyl down. With nitrous, there is more O₂ available to burn in a higher concentration... More power per volume of intake charge, but no modification to the pressure of the intake charge. However, more power is created during the power stroke, and the power has to go somewhere - the piston/conn-rod/crank are the next in line to take the force.

In a turbo, you get the power from boosting the pre-ignition cyl. pressure and forcing more O₂ into the cylinder prior to the compression stroke. (at 6psi of boost - 14.7+6*11.5 = 238.05psi) You have the same issues with handling the power during the power stroke, with the added issue of the increased pressure on the head / cylinder walls / Piston rings / Conn-rod during the compression stroke.

Hmmm waitaminit - that sounds like it makes a 50hp N₂O shot less dangerous for a NA motor than adding a 50hp turbo.... woah.... somebody with a degree in auto mechanics double check my brainfart please... I think that's right.. but just wanna make sure...

Of course - there are other issues with Nitrous to think about - but that's a quickrundown.... ish. :)

[cruzerz545]

That all makes sense to me. Good thinking. I talked to my mad scientists father and he told me pretty much what you told me here.,with on additional thing, he said the nitrogen is cold when released in the air, but is even colder when burned, so if I am not mistaken, the engine will get cooled from the nitrogen, as well as the intake manifold.


-jim


Originally posted by MaasNeotek
Theres a gray term floating around here...

Cylinder Pressure... It means nothing - and everything.

The motor compresses anything in the Cyl. to a given ratio... (11.5:1) on the celi GTS. The pressure? Who the heck knows. 11.5 times the pressure in the cyl at the bottom of the intake stroke.

Now - the density of the intake charge at atmospheric pressure is a variable (which is why your NA car runs better in Cold air - more dense - more O₂) and it is the pressure of the intake charge that is 'Boosted' in a Turbo/SC vehicle. This has NO BEARING on the DENSITY of the charge however - which is why an intercooled turbo works better - the intercooler doesn't increase pressure - rather, it makes the intake charge more DENSE.

Atmospheric pressure is approximately (~)14.7psi in an NA car or ~14.7psi + Boost in a Turbo/SC...

Generally without accepting the leakdown and inefficiencies in an NA engine you are looking at (~14.7x11.5)psi at top of the compression stroke, just prior to ignition... Around 170psi. (this is not scientific fact - just number crunching - any engine expert can correct me or back me up here... - I'm happy to learn either way) - Which in some respects is validated by the pressures seen in a compression tester. (Right Larry?)

With nitrous, the power comes from the point of ignition when the gasses expand and burn, pushing the cyl down. With nitrous, there is more O₂ available to burn in a higher concentration... More power per volume of intake charge, but no modification to the pressure of the intake charge. However, more power is created during the power stroke, and the power has to go somewhere - the piston/conn-rod/crank are the next in line to take the force.

In a turbo, you get the power from boosting the pre-ignition cyl. pressure and forcing more O₂ into the cylinder prior to the compression stroke. (at 6psi of boost - 14.7+6*11.5 = 238.05psi) You have the same issues with handling the power during the power stroke, with the added issue of the increased pressure on the head / cylinder walls / Piston rings / Conn-rod during the compression stroke.

Hmmm waitaminit - that sounds like it makes a 50hp N₂O shot less dangerous for a NA motor than adding a 50hp turbo.... woah.... somebody with a degree in auto mechanics double check my brainfart please... I think that's right.. but just wanna make sure...

Of course - there are other issues with Nitrous to think about - but that's a quickrundown.... ish. :)

[MaasNeotek]

Nitrogen providing cooling? Doubtful. Gasses are insulators, not heat transfer agents. That's why we are driving liquid cooled engines. The volume of gas we are talking about (55mmx60mm) isn't enough volume to cool anything when compared to the temperature of fuel burn in the cyl. EGT's WILL increase in either application (adding N20 or Turbo to NA designed engine.)

:)

[cruzerz545]

I looked in my chemistry book and it said it does cool, A LOT when burned at high temps. Oh well.
Anyway thanks for the info!


Originally posted by MaasNeotek
Nitrogen providing cooling? Doubtful. Gasses are insulators, not heat transfer agents. That's why we are driving liquid cooled engines. The volume of gas we are talking about (55mmx60mm) isn't enough volume to cool anything when compared to the temperature of fuel burn in the cyl. EGT's WILL increase in either application (adding N20 or Turbo to NA designed engine.)

:)

[MaasNeotek]

Too bad you got out the chemistry book, and not the math book.

The Earths Atmosphere is 79% nitrogen, 20% oxygen, and 1% "other gases". Since nitrous oxide is higher in oxygen, and when injected into the cylinder for combustion, there is as much as a 30% increase in the available oxygen there is LESS nitrogen in the cylinder at the time of combustion - so, even there is less nitrogen available for exothermic 'cooling' in the cylinder. (Thats what you are thinking of - when Nitrogen expands as with MOST gasses - it absorbs heat as a part of that process)

What you need to think about is: What is the cooling capacity of a given volume of Nitrous Oxide in an exothermic reaction vs. the heating capacity of the same volume of Nitrous Oxide and Atmospheric air when used as an accelerant when burning atomized gasoline.

==============For Reference....

From: http://www.idavette.net/hib/nitrous.htm

"A property of nitrous oxide is that at about 565 degrees F., it breaks down into nitrogen and oxygen. When it is introduced into the intake tract of an internal combustion engine, it is sucked into the combustion chamber and, on the compression stroke, when the charge air temperature reachs 565 deg., a very oxygen-rich mixture results. If we add extra fuel during nitrous oxide injection, the effect is like a super charger or increasing the compression ratio of the engine. Automotive nitrous systems work like the automotive eqivalent of a jet's "afterburner" and is used for short duration extra bursts of power.

Nitrous oxide has this effect because it has a higher percentage of oxygen content than does the air in the atmosphere. Nitrous has 36% oxygen by weight and the atmosphere has 23%. Additionally, nitrous oxide is 50% more dense than air at the same pressure. Thus, a cubic foot of nitrous oxide contains 2.3 times as much oxygen as a cubic foot of air. Just do a bit of math in your head and you can see if we substitute some nitrous oxide for some of the air going into an engine than add the appropriate amount of additional fuel, the engine is going to put out more power.

Simply stated, nitrous oxide injection is very much like a supercharger or a compression ratio increase in that, during combustion, it can dramatically increase the dynamic cylinder pressure in the engine.

Of course, when we significantly increase the cylinder pressure in the engine, we also increase the engine's tendancy to detonate. This is why almost all nitrous motors require retarded spark timing during nitrous oxide operation. The cylinder pressure increase is also why, when misused or improperly installed, operation with nitrous causes problems with head gasket seal and failures of the rings or pistons. I should point out that any number of things that put an engine into severe detonation, such as too much boost from a supercharger, low octane fuel, excessive compression ratio or overly lean air-fuel ratio will also cause the same kinds of damage."


From "http://www.chm.bris.ac.uk/motm/n2o/n2oc.htm" - Molecule of the month...

"At room temperature, N2O is quite unreactive with most substances, including alkali metals, halogens, and even ozone. It is therefore widely used as a propellant in aerosol cans in place of the CFCs which can damage the ozone layer. When heated sufficiently, however, N2O decomposes exothermically to N2 and O2.

If this reaction occurs in the combustion chamber of an automobile, 3 moles of gas would be produced from 2 moles, providing an extra boost to the piston, as well as liberating more heat. It also has a number of other benefits. The increased oxygen provides more efficient combustion of fuel, the nitrogen buffers the increased cylinder pressure controlling the combustion, and the latent heat of vaporisation of the N2O reduces the intake temperature. Therefore N2O is occasionally injected into the fuel lines of racing cars to give more power to the engine and to give the car exceptional acceleration."

[cruzerz545]

sorry i ruffled a feather.


Originally posted by MaasNeotek
Too bad you got out the chemistry book, and not the math book.

The Earths Atmosphere is 79% nitrogen, 20% oxygen, and 1% "other gases". Since nitrous oxide is higher in oxygen, and when injected into the cylinder for combustion, there is as much as a 30% increase in the available oxygen there is LESS nitrogen in the cylinder at the time of combustion - so, even there is less nitrogen available for exothermic 'cooling' in the cylinder. (Thats what you are thinking of - when Nitrogen expands as with MOST gasses - it absorbs heat as a part of that process)

What you need to think about is: What is the cooling capacity of a given volume of Nitrous Oxide in an exothermic reaction vs. the heating capacity of the same volume of Nitrous Oxide and Atmospheric air when used as an accelerant when burning atomized gasoline.

==============For Reference....

From: http://www.idavette.net/hib/nitrous.htm

"A property of nitrous oxide is that at about 565 degrees F., it breaks down into nitrogen and oxygen. When it is introduced into the intake tract of an internal combustion engine, it is sucked into the combustion chamber and, on the compression stroke, when the charge air temperature reachs 565 deg., a very oxygen-rich mixture results. If we add extra fuel during nitrous oxide injection, the effect is like a super charger or increasing the compression ratio of the engine. Automotive nitrous systems work like the automotive eqivalent of a jet's "afterburner" and is used for short duration extra bursts of power.

Nitrous oxide has this effect because it has a higher percentage of oxygen content than does the air in the atmosphere. Nitrous has 36% oxygen by weight and the atmosphere has 23%. Additionally, nitrous oxide is 50% more dense than air at the same pressure. Thus, a cubic foot of nitrous oxide contains 2.3 times as much oxygen as a cubic foot of air. Just do a bit of math in your head and you can see if we substitute some nitrous oxide for some of the air going into an engine than add the appropriate amount of additional fuel, the engine is going to put out more power.

Simply stated, nitrous oxide injection is very much like a supercharger or a compression ratio increase in that, during combustion, it can dramatically increase the dynamic cylinder pressure in the engine.

Of course, when we significantly increase the cylinder pressure in the engine, we also increase the engine's tendancy to detonate. This is why almost all nitrous motors require retarded spark timing during nitrous oxide operation. The cylinder pressure increase is also why, when misused or improperly installed, operation with nitrous causes problems with head gasket seal and failures of the rings or pistons. I should point out that any number of things that put an engine into severe detonation, such as too much boost from a supercharger, low octane fuel, excessive compression ratio or overly lean air-fuel ratio will also cause the same kinds of damage."


From "http://www.chm.bris.ac.uk/motm/n2o/n2oc.htm" - Molecule of the month...

"At room temperature, N2O is quite unreactive with most substances, including alkali metals, halogens, and even ozone. It is therefore widely used as a propellant in aerosol cans in place of the CFCs which can damage the ozone layer. When heated sufficiently, however, N2O decomposes exothermically to N2 and O2.

If this reaction occurs in the combustion chamber of an automobile, 3 moles of gas would be produced from 2 moles, providing an extra boost to the piston, as well as liberating more heat. It also has a number of other benefits. The increased oxygen provides more efficient combustion of fuel, the nitrogen buffers the increased cylinder pressure controlling the combustion, and the latent heat of vaporisation of the N2O reduces the intake temperature. Therefore N2O is occasionally injected into the fuel lines of racing cars to give more power to the engine and to give the car exceptional acceleration."

[MaasNeotek]

No ruffling! :) IssCool!

Just want to make sure people are informed. I sell Nitrous systems in Canada, and want people to understand what they do, and how they work.

Informed individuals make informed buyers, and informed individuals don't tend to talk out their ass - so, you know a little more now than you did 2 days ago! ;)

I appreciate the conversation, and don't have anything but respect for your desire to learn a little more about your engine!

Cheers!

[GTS LAID]

wow why cant we have one of these hearty fireside chats about every other component in the car... we should stick this in technical... anyone??

[Kit99bar]

thanks for the explanation!


Originally posted by chameleon
Yes, running lean really matters. You are right cruzerz545, oil is what lubricates the car. But running lean is not a lubrication issue, it is a heat issue, and the heat that running lean causes is not caused by friction.

Believe it or not, in addition to being the source of energy in an internal combustion engine, fuel actually also acts as a coolant for your cylinders. As you probably already know, you can only burn fuel when there is the presence of oxygen. A properly tuned engine will inject more gas into the cylinder than the volume of the present oxygen will allow to burn. The remaining gas will absorb and dissipate some of the heat that resulted from the combustion process and exit out the exhaust pipe.

When you lean out your air/fuel ratio to the point that there is no fuel left in the cylinders to dissipate any of the heat resulting from combustion, you begin to run into serious problems. The heat will build to such an intensity that you will litterally melt the inside of your engine. Especially in an engine like ours that uses lots of aluminum parts, after all, aluminum melts at 660 degrees Celsius. A typical normal crown temperature is around 550 degrees Celsius and typical exhaust temperatures will be around 850 degrees Celsius.

Typical damage that results from running your engine lean is damage to the tops of the pistons, damaged seals/rings, and melted valves. I've actually seen many cases of a lean running engine burning holes clear through a piston.

[cruzerz545]

sweeetness.

Well, I am going to try to up my fuel jets to the next jet. See if I can run just a tad richer.

[z6joker9]

VERY good reading!

move this to where more people will read it

[MaasNeotek]

Sorry it's so long winded, but I'm glad some of you found it valuable!

Larry - feel free to move as you see appropriate. :)