Adding oil to gas tank

What about premixing oil in gas on a pro turbo with secondary injectors in intake manifold? That should be good, as it would lube piston skirts and crank also, right?

Peppa said:

What about premixing oil in gas on a pro turbo with secondary injectors in intake manifold? That should be good, as it would lube piston skirts and crank also, right?

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In this case the premix going through the secondary injectors would provide extra lubrication to the piston skirts and crank. :bc:

4Z said:

Outside if warranty, could one "T" in a fitting to two of the existing line going to crankcase and install old school brass nozzles int the T-bodies?

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I'm not following you exactly. All the oil being put out by the pump is already going into the crankcase. If you installed two check valves into the throttle bodies the oil you put into those check valves would still go directly into the case with the air flow.

Essentially, you would be robbing Peter to pay Peter.

Maybe i don't understand what you are asking.

what would then be best on a turbo, turning up the oilpump or run premixed oil in gas? or a mix of both?

Peppa said:

what would then be best on a turbo, turning up the oilpump or run premixed oil in gas? or a mix of both?

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Both!

Would the oil mix with incoming air, lube reeds and give more coverage of lube than just what boost port offers ?

AK IQ Pilot said:

I'm not following you exactly. All the oil being put out by the pump is already going into the crankcase. If you installed two check valves into the throttle bodies the oil you put into those check valves would still go directly into the case with the air flow.

Essentially, you would be robbing Peter to pay Peter.

Maybe i don't understand what you are asking.

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My feelings are that adding oil to the fuel tank is a hold over from the good old piston/port, pre/mix engine designs from the past where 20:1 mixtures ruled and there were no EPA issues. I added the required break-in oil to my cfi engines, only because the dealer insisted. Whether it did any good is debatable. If you own an etec engine, adding oil to the fuel tank is taboo as it may clog the injectors - which shoot directly into the combustion chamber. And then there is the new 600 Arctic Cat engine that uses a slotted piston, special oil and a computer to dole out the oil. And then there are the boosted engines and the trickery ramps up.

I also believe neglected, mal-maintained drive trains cause more engine failures that the oiling issues being discussed.
550iq

4Z said:

Would the oil mix with incoming air, lube reeds and give more coverage of lube than just what boost port offers ?

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Ok, just to be clear. Unless you're premixing oil into the fuel, no oil gets injected in the boost port. Oil that is mixed with the fuel, ONLY goes into the boost port.


I see no benefit in injecting oil upstream of the reeds. As long as the oil pump is pumping enough oil there is already adequate oil being injected just downstream of the reeds in the center of the case adjacent to the lower rod bearing on both cylinders. As soon as the incoming air from the throttle body passes through the reeds it picks up this oil and delivers it to the rotating assembly and then up to the transfer ports. Moving this check valve up in the air stream by an inch offers no additional benefit. The reeds do not need lubrication.

A CFI oil pump has 6 outlet ports for oil delivery. 3 ports on the top and 3 ports on the bottom. These 6 ports do not pump an equal amount of oil. The center port on the top and the center port on the bottom pump more oil than either of the two ports to the side of center. It is critical that these oil lines be evenly distributed between the PTO and Mag side of the motor.

Oil pumped into the center check valve lubricates the center crank bearings and the water pump shaft and gears. This oil drains back to the Mag side cylinder once it has completed it's job in the center cavity.

The Mag side of the motor gets oil from three check valves. Mag bearing check valve, Center bearing check valve, and "Rod bearing" check valve. The PTO side of the motor gets oil from two check valves. The "Rod bearing" check valve and the PTO bearing check valve. From the oil pump, two of the low flow ports are "T'd" together and routed to the PTO bearing check valve. This oil line routing provides an equal distribution of oil to each side of the motor.

I'm sure that was more than anyone cared to know but it is good for discussion.

RETRO ASSAULT said:

The oil pump has a barrel valve in it and if you turn it too far you'll start closing off the oil port. So you will supply your engine with more oil at 1/2 and 3/4 throttle but at full throttle you will have less If you turn up the oil pump too far.
Not my .02, facts.
One last thing, the oil pumps that are found on at least Polaris and Arctic Cat snowmobiles do not supply a constant flow of oil. they pump like a pneumatic fuel pump. gulps of oil, not a constant flow like you'd see in a car engine. So adding oil to the gas tank bridges the gap between gulps.
I don't always hold my snowmobile throttle wide open but when I do, I would like the oil pump port to be wide open, Not closed off because I adjusted it too far.

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This is exactly what I was told by the guys at Carl's as well as in my discussion with Curt at FTX yet I was scoffed at when I posted that you should mix some oil in the tank to overcome the fact that turning up the oil pump does nothing for WOT. I'll go with their advice, thank you very much!

Have FUN!

G MAN

AK IQ Pilot said:

Thats kind of my take too.



On a CFI-2 motor, Premix enters the cylinder from the boost ports when the piston is headed to BDC. A small amount of premix hits the piston at the boost ports but nowhere else on the piston. Once the piston has reached BDC the premix is in the combustion chamber area above the piston and rings. At this point the cylinders above the rings are being lubricated by the premix. As the piston travels back up on the compression cycle the premix is wiped from the cylinder walls by the rings. At no time does premix lubricate the cylinder below the transfer ports. A very small amount of premix will lubricate the piston in the area of the boost port but this is relatively insignificant.

.

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Curious.... Where did you get this information?? Is this direct from Polaris?

Thanks

RKT said:

Curious.... Where did you get this information?? Is this direct from Polaris?

Thanks

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Not from Polaris, it's from taking enough of them apart.

How do you think it works?

I will be mixing my gas and oil 100:1 on my 2013 Polaris.
Good day.

So lets take a look at this in a little more detail. Watch the gif below.

Imagine the green gasses as the air/fuel/oil mixture. If you increase your oil pump output you lubricate the entire engine. Everything: the crank, the bearings, the wrist pin bearings, the piston skirts, the cylinder skirts, the cylinder above the piston, etc. Every part of the rotating assembly sees the benefits of the increase of the oil pump output. Also notice that the air/fuel/oil that contacts the piston skirts and cylinder skirts is not burned off and it's not wiped off by the rings. If you add extra oil to the beginning of the flow path the entire engine benefits from the extra oil.

Now imagine injecting extra oil only into the combustion chamber. While the transfer port is still open the extra oil in the premix enters the combustion chamber through the transfer port. The rings wipe some of the oil off the cylinders as the piston heads up to TDC. Then combustion happens any remaining oil on the cylinder is burned by the 1000 degree explosion as the piston heads back to BDC. The extra oil in the fuel may offer some lubricating benefit to the upper part of the cylinder but how much is really debatable.

Keep in mind that all oil that enters the flow path of the motor eventually goes right out the exhaust either completely burned or partially burned. There is never a time where any appreciable amount of oil accumulates in the motor. It doesn't matter whether you put it in at the beginning of the flow path or half way through the flow path, it all goes out the exhaust eventually.

If your desire is to provide more lubrication to the motor why wouldn't you want to lubricate the entire motor instead of just the part of the motor above the piston rings.

One thing here isn't debatable. Increasing the oil pump output increases oil delivery to the entire motor both above the piston rings and below. Adding oil to your fuel only increases oil delivery to the combustion chamber above the piston rings.

The choice seem so simple.

Hope the gif works.





http://upload.wikimedia.org/wikipedia/commons/3/31/2-Stroke_Engine_ani.gif

Rev Kev said:

The fuel ~vs~ oil and lean debate is basically this, lets say the injector flows 5mm of fuel pre firing stroke, now displace some of that fuel with oil, lets say for sake of arguement, 1mm, now you are only flowing 4mm of fuel, and 1mm of oil, basically you are now introducing less fuel with the same amount of air, this equates a lean condition, enough to make a real world difference? I doubt it. As far as adding extra lubrication to the bottom end, it will not, as fuel is injected into the transfer port, as it enters the combustion chamber, so no added benefit to the bottom end, but yes to the piston and upper rings. Turning up the oil pump is the only real way to add lube to the bottom end. My $0.2

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It's an empirical fact that oil displaces gas for any given volume of mixed fuel but I can't grasp how the presence of oil in the fuel (I'm not an engineer) would cause a lean condition. Doesn't the oil/gas ratio affect the flashpoint of the fuel? From my own, limited, non-scientific observation too much oil in the gas produces lots of smoke and fouled plugs. My assumption is more oil raises the specific gravity of the fuel and flashpoint resulting in incomplete combustion of which the smoke and fouling are common symptoms.

If you keep adding oil to the gas you will eventually get a mixture that won't ignite. I don't know what that point is chemically but that seems to be the exact opposite of a lean condition.

I defer to the fuel system experts but that's my anecdotal observation.

Wait, what was all that "not my .02, facts" talk? I've discussed this with guys who have been riding and turbo-ing and working around snowmobile motors for 40 years and they told me you can lean the fuel:air ratio too far with too much oil in the tank and risk burning up the motor. If you say "it just can't happen" then let's hear why, because it makes sense that it can happen.

Oregonsledder said:

I know this has been discussed a bit, but I think the fact that there seems to be two very different views on this is interesting. Let me start the debate by raising a few questions.
First many say adding oil to the gas leans out the burn, why do you think that? Why would sled manufactures add oil to new sleds gas tanks for the initial break in period. If the oil causes a lean condition, would it be smart for a manufacturer to suggest this on a new tight engine?

Second, most two stroke engines from the very beginning have had oil in the gas, why has that worked so well for so many years? The desired gas to oil ratio is approximately the same whether the engine is injected with oil or if it’s mixed in the gas. And yes I understand that the oil injection is not direct injection, but for the sake of this discussion it shouldn’t matter.

There is also the issue of oiling the bottom end with injection systems, but that’s not what I want this thread to discuss.

What are your thoughts on whether oil added to gas leans out the burn, and if so why is that?

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IMO if you are going to add "extra oil" to a tank of gas, you might as well delete the oil injection system and go to straight up premix

The Fourth Wolf said:

It's an empirical fact that oil displaces gas for any given volume of mixed fuel but I can't grasp how the presence of oil in the fuel (I'm not an engineer) would cause a lean condition. Doesn't the oil/gas ratio affect the flashpoint of the fuel? From my own, limited, non-scientific observation too much oil in the gas produces lots of smoke and fouled plugs. My assumption is more oil raises the specific gravity of the fuel and flashpoint resulting in incomplete combustion of which the smoke and fouling are common symptoms.

If you keep adding oil to the gas you will eventually get a mixture that won't ignite. I don't know what that point is chemically but that seems to be the exact opposite of a lean condition.

I defer to the fuel system experts but that's my anecdotal observation.

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I made a similar observation, but Im no expert either. I think its lean strictly in terms of fuel and air, but Im with you. This can't be the same type of lean that you get on a 4 stroke motor with the same catastrophic effects right?

Running 20 to 1 oil mix in the tank will decrease the amount of fuel in that mix by 5% because the injector allows only a pre-programmed amount of fluid through at that point just as a jet would (because of diameter) depending on velocity in the venturi. This may be enough to be an issue if you are set perfect for the conditions.
100 to 1 is 1% less fuel. I don't think many are that close to the edge. IMO the added oil to the fuel in the Poo motor helps (maybe in my own mind lol) reduce the possibility of scuffing on the intake side ( seen some pics). The direct spray on the back of the piston MAY wash the thin film of oil off for the short duration of injector opening.
Believe what you want.

The idea of oil in the fuel clogging injector screens or filters is something I have never seen. Other brands inject into the crankcase or upstream of the reeds and can and do run premix only.
I have run inexpensive semi-syn (pretty dirty oil lol) oil for decades in both carb and injector systems at up to 20 to 1 ratios and, like I said, never had an issue with either fuel system.
Believe what you want.

The crankcase of a two stroke is a bit of a collection vessel and there is always a bit of oil sloshing around to give you extra for say 30, 40 secs (picture your start up in a closed garage lol) of lots of oil at WFO.
Lots of oil is good for everything (especially HP) in a two stroke except passing EPA tests and cost of ownership tests. Oil dripping of your crank and staining the cylinder walls is what a builder likes to see when he pulls one apart.
Non pressure fed roller and ball bearings like oil sloshing around. Rings seal better with lots of oil (dynos show more HP with 20 to 1 than 50 to 1 because of ring seal). Piston to cylinder wall contact benefits (less of) from more oil.
Believe what you want.

Some motors today are finally getting the most of your two stroke oil Like the new Cat 600 and the Etec or Ptec or whatever). This is good for those motors because everyone is needing to lower emissions today and oil out the exhaust is bad for the world so they take it away hoping to get through the warranty period before the extra wear shows up lol.
Fingers crossed lol.
Unfortunately the CFI is not one of them. It is still old school let-the-oil-slosh-around and get to where it needs to get to with only crankcase turbulence giving it any direction. The additional lack of fuel in the crankcase (fuel is a lubricant and a cooling agent down there) makes me want more oil.
IMO if there is a new motor from Poo it will address this issue first and power second.
Believe what you want.


History has shown that two-strokes like oil and pay you back with power and life.

So,,, lol, believe what you want.

Will oil in the gas lean the mixture? Absolutely. Enough to cause engine failure? Probably not. The evaporation of pure gasoline has a tremendous cooling effect on its environment (piston top, cylinder, head). When oil is mixed into the gasoline, the oil displaces an equal volume of gasoline (meaning there is now less gasoline=less cooling). There is less gasoline in a gas/oil mixture, less cooling when the mixture evaporates, and a leaner condition.