Methenol Injection question

[blk00gtvert]

I am in the racing industry and i have learned to use this site for advice. The use of methenol an/or water injection into a turbocharged gasoline engine to both cool the combustion chambers and raise the octane of the fuel has been around for quite some time. in my experince i have been able to use 100% methenol injected as a fine mist into the air intake after the turbo has worked the best. i have been able to use timing and boost pressures for c-16 (116) octane fuels on 100 octane and methenol injection. somone however brought up an intreaging question to me. what is one were to use the same setup but inject RC car fuel which is chemicly 80% methenol and 20% nitromethane. assuming we are taling about an engine that is machanicly able to hadle extream power. would i see any benifits from adding nitromethane to the mixture? tuning WOULD be done and figure a 500ML delivery rate as an average.

 

[kenre]

RC car fuel will also have from 15 to 20% oil, usually abot 5% castor with the remaining a synthetic oil. Unless you mix your own nitro/methanol mix, the oil will be a disadvantage.

Nitromethane is also very difficuilt to atomize. The Nitro will add more oxygen as it burns, leading to a lean mixture, meaning you will need more fuel to couteract this.

Experiement at your own risk!

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Was told it couldnt be done, so
i went and did it!

 

[blk00gtvert]

i was aware about the oil and i was also aware of the nitro having oxygen. i was however wondering if i could use this to my advantage... right now all meth systems require you to lean out the preexisting tune after installing meth kits because the meth being injected is the same as injecting more fuel and actually causes the car to go rich i was wondering if the nirto would counteract this thus minumizing the need to lean out the mixture. what do you think?

 

[patprimmer]

Nitro methane is not high octane. Once you start adding it to an engine originally optimised to 100% methanol, you need to reduce compression or boost. You also need to increase fuel supply. The amount of fuel needed can be so high that it cannot evaporate and a lot of liquid fuel is carried over to the cylinder.

As 100% nitro methane likes a fuel to air ratio of about (from memory) 1.8:1, if you use a lot of it in a high compression engine, the evaporated fuel in the cylinder can approach or even exceed the compressed volume of the cylinder, leading to extremely high compression ratio or even hydraulic lock which causes extreme engine damage.

Nitro methane is also quite toxic and it's products of combustion are quite corrosive to many metals typically used in engines.

For boost enrichment of a petrol engine, I would recommend 100% methanol as a safe and most effective fuel.

Additives to make the flame visible would considerably improve safety in case of a methanol leak or spill and a fire. There is a greatly increased burn risk from the fact that methanol fires are invisible.

Regards

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[blk00gtvert]

so are you saying that the nitro will over ride the octane boost of adding the meth to the combustion?

 

[patprimmer]

It can, depending on amount used. It will also be very expensive to use because of both its cost and the amounts required.

Nitro methane also has a very slow burn rate, so it changes ignition timing requirements.

Nitro methane also has a different co-efficient of expansion to methanol, so the percentage changes with temperature changes. Also as a lot more is required, a much larger tank is required. Unless this is a very short course race car, the extra fuel load will outweigh any power gains.

Regards

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[blk00gtvert]

well to clear up things. it would be used on 1/4 mile vehicles. and the amount of mixure used per pass would probably be around 3-4 OZ to give you an idea of the amount being injected into the engine. not sure if this helps

 

[patprimmer]

Well it could be used for 1/4 mile, and at low add rates, hydraulic lock won't be a problem.

It will still decrease the octane of the methanol.

Regards

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[blk00gtvert]

ok so we have established that it COULD be used. now i have to figure out if it is worth usging. it will lower the octane of the alcohol. that is a fact. but by how much? if i have to lower boost from the decreased ocatane than to make this all worth while the nitro would have to increas the power above what i loss from becresed boost

 

[arlin1]

Some water/meth injection companies actualy sell a nitro to mix in with your water/methanol. You do not need to jet richer than you were with out any injection at all. Just think of it this way if you got your mixture right than adding more flamable fuel to your mix makes it richer. The a:f ratio is very rich for nitro but you will be very unlikely to hydrolock you engine with it lol. Just think of how small of a container you use for meth injection and think your engine is runing at how many thousand rpm for how many mitutes and how much methanol do you actualy burn up? I have turbo gas burning car I am going to implement this on in order to run more boost and make more power (maybe my n/a car as well). The oil contant is generaly from the 2-5% range in hobby fuels so thats not to big of a deal pluss its castor it smells good I do recomend waching you mixture as always to make sure your a:f does not get out of control. You can buy pure nitro it is not cheep but make 2.4x the power in comparison to pump gas If you mix it down it should not cost you to much. On other thing is you want to store it in a proper container in a cool dark place. Good luck.

 

[blk00gtvert]

AWSOME!! thank you very much i did not know that. so if i were to purchase some nitro and mix myself and i do get the mixture down right. is there going to be a measurable gain over using strait alcohol? thank you very much

 

[Majik]

In regards to us physically coming over and mixing nitro for you and putting it in your car and trying it out. My magic 8 ball says "try again later"

If you'll reread pat's post. It lays out the benefit vs cost pretty clearly. You'll need more fuel, less dynamic compression and the nitro might eat parts in your engine. 3oz a pass tells me that you've got room for improvement in that meth setup. Since there's no parameters for your "race car"; it's hard to say what it's going to do but since you're in the race industry and your going to tune it the answers are there if you roll it up on the dyno. You might be able to "tune" an advantage over just straight meth but just dumping it into the tank probably won't yield any gains.

 

[arlin1]

Majik have you looked up speck for the top mitro funney cars the run as much as 65psi boost they are very different engines.

 

[arlin1]

I belive the a:f ratio of pure nitro is more around 4-5:1 for max hp Even it it was 1.8:1 it is a mesurement of the weight of the fuel so you would still be very very unlikely to hydrolock your engine. For instance if you are runing a v8 your heads will be around 80cc so you would need right around 80cc to hydrolock you engine per cylinder per 2 revolutions. So if you sprayed that much that would equil 80x4 (v8 has four ignition events per revolution)= 320cc per revolution that would mean each injector would have to spray 80cc per rev and that would meen they are each capable of spraying more then 240,000 cc per minute @6000 rpm (you need injectors to be beolow the 80% duty cycle) I have never herd of injectors over 160 cc/min and so that would also meen that you engine would require thats 240 litres per injector per minute so thats 960 litres a minute of total fluid your engine would require to hydrolock! I think you will be ok.

 

[patprimmer]

arlin1

Are you saying that with a puny little nitro methane fuel enrichment system over a petrol main fuel system you cannot get hydraulic lock, or are you saying that a high percentage nitro methane main fuel system cannot hydraulic lock.

What is your source of the a:f ratio for nitro methane.

My source is the "Harvey Racing Engines Fuel Injection Basics" 3rd Edition.

Re optimum a:f ratio for various fuel it states:-

Gasoline 13:1
Methanol 5.9:1
100% Nitro 1.6:1
90% Nitro 1.8:1

Top fuel cars run mechanical injection because electronic injection cannot supply anywhere near enough fuel for the reasons you state.

A blown alcohol V8 can run as many as 32 high flow special racing methanol injectors. So far as I know, no one has tried to fit and fire the 80 to 100 injectors that a blown 100% nitro V8 would require.

Regards

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[arlin1]

No I am saying what he is wondering is if you can mix some nitro into the methanol injection tank and pray it in to the intake The injection systems dont typicaly spray that much so I realy dont see hydrolock being a posibility being as a typical injection system is usaly just activated at higher loads and only sprays a mist to cool into the intake. My A:f #'s could be off it was from the top of my head.