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BMW 3-Series (E90 E92) Forum > BMW E90/E92/E93 3-series General Forums > Regional Forums > UK > UK Technical Forum > Add methanol into petrol tank?



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      09-15-2017, 09:52 AM   #1
johnscales
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Add methanol into petrol tank?

Hi all.

Read on another forum that a chap has been adding 10% meth to his tank successfully for years (I gather he also drags a lot too and knows his stuff as he was directly asked to chime in on the thread about the topic).
I've only found one other thread with google (actually on this forum) where someone stated that it's not a good idea for DI cars :

"The N54 and N55 are direct injection motors which means that the fuel is injected DIRECTLY into the combustion chamber. In comparison, the conventional port injection engines inject their fuel usually in the intake manifold ports.

The whole purpose of methanol injection is that it has time to mix with the hot air charge. When methanol is mixed with air, it evaporates and during this process it absorbs heat. This in turn makes the air charge colder and denser. Ultimately, colder air allows for better suppression of detonation.

Now, think about what you are asking for a minute... You want to add meth/water mix to your gas tank presumably because you want to enjoy the benefits of the suppressed detonation. Well, that ain't gonna happen since methanol will not be mixing with air and cooling the air charge."

I've no idea either way and it sounds valid on every point accept the last sentence doesn't ring true since the directly injected petrol still mixes with air in the combustion chamber. I'm guessing that there isn't the time required for the meth to combust successfully?
Since I see very little on the subject my guess is that it isn't done for good reason.

I became side tracked whilst looking into getting a meth injection kit and getting a full and complete answer has eluded the forums.
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      09-16-2017, 06:11 PM   #2
ChawenHalo
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Can't help unfortunately but well, these are complicated engines and fairly sensitive to changes due to the myriad of sensors. Lastly there are simpler ways of getting more BHP out of these cars and I've never really met or talked about these things with people in Europe especially with BMW's .From memory its something the Scooby and Mitsui guys do more often on heavy builds.

From what I know it just helps with tolerances on high tunes.
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      09-22-2017, 07:17 AM   #3
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Yes you can add meth directly to your tank. It's the best usable fuel there is bar maybe Nitromethane but it has a 4.5:1 AFR vs the 12.5:1 AFR for petrol (max power AFR ratio), meaning (12.5/4.5 = 2.7) you need to pump nearly 2 to 3 times as much fuel to hit the same air to fuel ratio. The oxygen sensors just work off the lamba values so it doesn't matter what the fuel is. It tries to hit say 0.85 lambda. (14.7*0.85 = 12.5, That will actually result in 6.5*0.85 = 5.5:1) So that will require 2.3 times the amount of fuel.

However if you add only enough to make your fuel 10% methanol then the added fuel requirement will be fairly low and the benefits are quite high. Methanol directly injected has an effective octane rating of 180 due to all the evaporation cooling.

The down side is that injectors will be pumping more fuel and can fail faster. Non compatible materials can swell and weaken. i.e. Orings and seals. But if your fuel is still 90% petrol then the contact between methanol and these components can be quite low. If used it many times and had no ill effects.

However water methanol injection is the way to go.

Don't add water and methanol to your fuel tank. Just methanol. Methanol easily separates from petrol when water is present to form a layer of water and methanol. The biggest problem with methanol petrol blends is how quickly they absorb water. However M50 (a 50% blend of petrol and methanol) has the same performance as E85. 85% ethanol, 15% petrol.

It's the fuel of the future. It can tolerate higher compression ratios to run more efficiently than diesel. It can be made from CO2 in the air, as a waste product from other processes or from fermentation. Its nowhere near as toxic as petrol to the environment. Bacteria naturally break it down if it leaks into the environment. If it gets into water it slowly breaks down and dilutes.
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