LOMY
02-08-2003, 03:34 PM
I've managed to pull together some info about Methanol as a fuel additive. Could come in useful before
SantaPod !!
Warning : I am not suggesting that you use Methanol in your car, that is down to personal choice (and risk). I am just explaining some of the pros and cons so that you can make your own choice. As far as the law is concerned: i think that up to 5% is probably OK on the road, higher mixes are only officially for off road use in the UK. Need checking really.....i suppose.:)
Methanol Charcteristics
METHANOL (Methyl Alcohol) CH30H is a volatile, highly inflammable, water-clear
liquid with a mild odour. Like all alcohol based fuel it will mix with water
or nitromethane in all proportions and almost all proportions with petrol.
Methanol is an oxygenate, that is, each molecule contains a single oxygen atom which serves
to aid general combustion when released (from the Methanol by burning) thus increasing the net energy
release per cylinder per cycle. This raises the compression in the cylinder and hence power! Nitrous Oxide has the same effect.
Methanol itself (as opposed to petrol) also has a relatively large energy release
from combustion per molecule (see below). However, it also has a high 'latent heat of
vapourisation'. Which means that the fine liquid particles in the fuel/air mix from the injectors
take considerable energy (i.e. heat) from within the combustion chamber before vapourising.
The net result is a cooling (or dampening as Ailsa put it) of the surroundings before ignition
takes place.
One result of this is that it enables higher compression ratios to be used without
causing pre-ignition (or detonation) of the fuel (i.e. the excess energy of compression goes towards vapourising
the liquid before ignition). There is an alcohol fuel called OCTANE, not really used now but the
pressure allowed before pre-ignition (i.e. without a spark, like diesel) was denoted as 100 (% ?)
for Octane and all other fuels were then given an 'Octane' value relative to this figure. That is to say a fuel that can
reach a higher compression before pre-ignition was said to have and octane number greater than 100 and so on.
The definition of Octane number has altered slightly since then but still relates to the ability to take
pressure before pre-ignition.
here are some basic characteristics of Methanol
Flash Point ............................................16C
Boiling Point ..........................................64C
Freezing Point ........................................-97C
Specific Gravity ......................................0.796
Lbs/Gall approx 8
Conservative Maxium Compression Ratio ................. 17:1
Air/Fuel Ratio for Max Power lbs/lbs ...................4.5:1
Energy from Combustion B.T.U/lb ........................9770
Cooling Effect (Latent heat of Vaporisation) B.T.U./lb .472
Other materials are suitable oxygenate fuel additives too such as
NITROMETHANE(CH3NO2) :devil2: , ACETONE (Dimethyl Ketone, CH3COCH3) and ETHER based compounds.
Of these, Nitromethane is particularly effective because of its high oxygen content. Nitromethane enables considerable power
increases to be obtained if used alone (70 percent minimum with proper use).Most often used blended with methanol, in various
mixtures to provide higher octane rating (reducing tendency to detonate)and reduce power (i.e. less oxygen in methanol).
There are also the Benzines (hydrates) such as BENZINE (CH6H5) and NITROBENZENE(C6H5NO2) but these should be avoided since
there are a serious risks (common to all the oxygenates and hydrates to a greater or lesser degree). Principally, it is important not to allow
excessive contamination of skin, inhalation of vapour since Benzol(Benzine) is known to be a human carcinogen.
Methanol however is amongst the least toxic of the lot. On a par with petrol itself so treat it as you would petrol (i.e. wash it off straight away
if you get it on your hands, dont inhale fumes) and all should be fine. It does corrode Magnesium most plasics and paints,
so dont splash any on your VR4!
Naturally any change in fuelling needs to be accounted for in the fuel injection system and in the case of Methanol,
the full power advantage can only be attained by re-jetting the engine. If your engine has a 10.1 compression ratio,
then the use of 10% methanol in the fuel will raise compression to 11.5:1 and require re-jetting to 1.125 times the diameter of the original
jet size to obtain full benefit (around 20% power increase has been quoted). However, even without rejetting, compression will be still be
raised to some degree and so it is possible to get power increase in our cars using Methanol without engine modification.
The important part is that we must not allow compression to exceed the VR4 engines upper limit compression ratio.
There is always some flexibility in compression ratio in performance engines like ours so i was happy to use a 5% Methanol mix
which is estimated to raise compression by less than 10%. But it would be good to know the limit for safe use.
Does anyone in the club know what the existing compression ratio and upper limits are for the VR4 engine (280 bhp model).
Also if anyone knows anything else relevant to fuelling, or can correct me in any of the things i have said, please do so.
Cheers
SantaPod !!
Warning : I am not suggesting that you use Methanol in your car, that is down to personal choice (and risk). I am just explaining some of the pros and cons so that you can make your own choice. As far as the law is concerned: i think that up to 5% is probably OK on the road, higher mixes are only officially for off road use in the UK. Need checking really.....i suppose.:)
Methanol Charcteristics
METHANOL (Methyl Alcohol) CH30H is a volatile, highly inflammable, water-clear
liquid with a mild odour. Like all alcohol based fuel it will mix with water
or nitromethane in all proportions and almost all proportions with petrol.
Methanol is an oxygenate, that is, each molecule contains a single oxygen atom which serves
to aid general combustion when released (from the Methanol by burning) thus increasing the net energy
release per cylinder per cycle. This raises the compression in the cylinder and hence power! Nitrous Oxide has the same effect.
Methanol itself (as opposed to petrol) also has a relatively large energy release
from combustion per molecule (see below). However, it also has a high 'latent heat of
vapourisation'. Which means that the fine liquid particles in the fuel/air mix from the injectors
take considerable energy (i.e. heat) from within the combustion chamber before vapourising.
The net result is a cooling (or dampening as Ailsa put it) of the surroundings before ignition
takes place.
One result of this is that it enables higher compression ratios to be used without
causing pre-ignition (or detonation) of the fuel (i.e. the excess energy of compression goes towards vapourising
the liquid before ignition). There is an alcohol fuel called OCTANE, not really used now but the
pressure allowed before pre-ignition (i.e. without a spark, like diesel) was denoted as 100 (% ?)
for Octane and all other fuels were then given an 'Octane' value relative to this figure. That is to say a fuel that can
reach a higher compression before pre-ignition was said to have and octane number greater than 100 and so on.
The definition of Octane number has altered slightly since then but still relates to the ability to take
pressure before pre-ignition.
here are some basic characteristics of Methanol
Flash Point ............................................16C
Boiling Point ..........................................64C
Freezing Point ........................................-97C
Specific Gravity ......................................0.796
Lbs/Gall approx 8
Conservative Maxium Compression Ratio ................. 17:1
Air/Fuel Ratio for Max Power lbs/lbs ...................4.5:1
Energy from Combustion B.T.U/lb ........................9770
Cooling Effect (Latent heat of Vaporisation) B.T.U./lb .472
Other materials are suitable oxygenate fuel additives too such as
NITROMETHANE(CH3NO2) :devil2: , ACETONE (Dimethyl Ketone, CH3COCH3) and ETHER based compounds.
Of these, Nitromethane is particularly effective because of its high oxygen content. Nitromethane enables considerable power
increases to be obtained if used alone (70 percent minimum with proper use).Most often used blended with methanol, in various
mixtures to provide higher octane rating (reducing tendency to detonate)and reduce power (i.e. less oxygen in methanol).
There are also the Benzines (hydrates) such as BENZINE (CH6H5) and NITROBENZENE(C6H5NO2) but these should be avoided since
there are a serious risks (common to all the oxygenates and hydrates to a greater or lesser degree). Principally, it is important not to allow
excessive contamination of skin, inhalation of vapour since Benzol(Benzine) is known to be a human carcinogen.
Methanol however is amongst the least toxic of the lot. On a par with petrol itself so treat it as you would petrol (i.e. wash it off straight away
if you get it on your hands, dont inhale fumes) and all should be fine. It does corrode Magnesium most plasics and paints,
so dont splash any on your VR4!
Naturally any change in fuelling needs to be accounted for in the fuel injection system and in the case of Methanol,
the full power advantage can only be attained by re-jetting the engine. If your engine has a 10.1 compression ratio,
then the use of 10% methanol in the fuel will raise compression to 11.5:1 and require re-jetting to 1.125 times the diameter of the original
jet size to obtain full benefit (around 20% power increase has been quoted). However, even without rejetting, compression will be still be
raised to some degree and so it is possible to get power increase in our cars using Methanol without engine modification.
The important part is that we must not allow compression to exceed the VR4 engines upper limit compression ratio.
There is always some flexibility in compression ratio in performance engines like ours so i was happy to use a 5% Methanol mix
which is estimated to raise compression by less than 10%. But it would be good to know the limit for safe use.
Does anyone in the club know what the existing compression ratio and upper limits are for the VR4 engine (280 bhp model).
Also if anyone knows anything else relevant to fuelling, or can correct me in any of the things i have said, please do so.
Cheers