Methanol Injection, Octane, etc, etc

[4sfed4]

I have been doing some digging into methanol, its use as in the alky injection kits and how it will affect power and "effective octane".

It appears that methanol is roughly 99 octane on the (RON+MON/2) scale which is the typical pump gas rating scheme. (The RON = research octane and MON = motor octane.) Motor octane is far more important than research octane when it comes to a performance application. The info Ive been able to find out about methanol (from the Sunoco fuels website) indicates that methanol only has a MON of about 89 (and a RON of 109). Typical 110 race gas (like Union 76 110) is 106 MON.

So, it appears that methanol is a little short on MON when compared to race gas. So, I am expecting that one cant run anywhere near as much timing with methanol injection as one could on pure race gas?

The next thing about methanol......

Methanol has an energy content of about 9800 BTU/lbm, while gasoline is a much higher 19,000 BTU/lbm. So, at first it would seem, since engines are just heat pumps, as though methanol is down on power potential compared to gasoline.

But, it appears the best A/F for power with methanol is about 5.5:1, whereas gasoline is, lets say, roughly 12:1. So, it takes about 12.5 / 5.5, or 2.2 times as much methanol by mass as gasoline to give the same ideal A/F ratio.

So, if one were to run straight methanol, youd have 2.2 times as much enetering the engine as gasoline to maintain the same ideal A/F. So, the actual amount of potential fule energy present would be 9800 BTU/lbm x 2.2, or 21560 BTU/lbm. This is about 13% more energy than gasoline. So, there should be a power gain potential with straight methanol (which I think there is in real world practice).

But, if methanol is mixed with gasoline in the intake ports (as it is in the typical alky injection system), one ends up with a "hybrid" type of fuel. If the mix ratio were, say 20% by mass methanol to 80% gasoline, is it safe to say that the "effective octane" is going to be about (93 x 0.80)+(99 x .20), or only 94.2?

But, the heat energy present (i.e. power potential) in that "hybrid" fuel is going to be (19000 x 0.8)+ (9800 x 0.2) or 17,160 BTU/lbm?

Sorry for the long post, but this topic has been of interest to me for some time. What am I missing here? Are the lion's share of the gains from methanol injection due to charge air cooling alone?

 

[Razor]

No way I can run 11.2's on 94 octane with my setup.

So the cooling negates a lot of the need for octane, obviously as the boost goes up so does the heat.. methanol keeps things in check. And it has been noted on a lot of applications where more boost can be run on methanol than race gas. Timing is another thing, and probably has to do with the octane present. Hence why lower timing levels are run.

Same token you could look at water as having infinite octane.. the higher the octane the harder it is to burn rite??? So adding water to fuel would give you unlimited octane rite?

Keep the research going.. I'll fire up some more popcorn

 

[4sfed4]

Originally posted by Razor
No way I can run 11.2's on 94 octane with my setup.

Thats what is throwing me for a loop!

The "real" octane benefits seem to be higher than the "actual" octane increases are. I agree....it seems impossible that guys can do what they do with methanol injection if there was only a slight effect on "effecctive" fuel octane. There is something else going on and Id like to figure out what it is.....if for no other reason than Ive never seen anyone else out there post what the heck "it" is

So the cooling negates a lot of the need for octane, obviously as the boost goes up so does the heat.. methanol keeps things in check. And it has been noted on a lot of applications where more boost can be run on methanol than race gas. Timing is another thing, and probably has to do with the octane present. Hence why lower timing levels are run.

I have a feeling this is getting to the root of the matter......The IAT reduction (or more appropriately the resulting density increase) is probably the lions share of the power gain. Again...from purely a theoretical standpoint, each 48 F or so reduction in IAT can result in a 10% power gain. So, taking IATs from 150 to 100 on a 500 hp car could mean 50 hp. That seems to ring true as I know my car sure feels a whole helluva lot quicker on a 45 degree night than on 95 degree day. It doesnt even feel like the same car.

Same token you could look at water as having infinite octane.. the higher the octane the harder it is to burn rite??? So adding water to fuel would give you unlimited octane rite?

I have thought about that too. Only problem is....there is only so much room in the intake port. The water displaces air and provides no heat energy for the combustion process So, you still need the larger volume of gasoline as the fuel for combustion. Otherwise, for knock control and intake cooling, I think water would work the best....from a purely theoretical standpoint of course

So, the fact that methanol doesnt cool quite as well as water (per unit mass) is negated by the fact that methanol also acts as fuel (and water doesnt). So, the total volume taken up in the intake port for fueling with a methanol/gasoline mixture is less than that for a gasoline/water mixture. Thats good as you also need the maximum amount of air in there as well.

Keep the research going.. I'll fire up some more popcorn

All in the interests of learning about this stuff

 

[4sfed4]

From the one star rating of this thread, I guess not everyone finds this topic as interesting as me! LOL.

I am excited to try this methanol injection (got 5 gallons of methanol from Holeshot Engineering earlier this week ) and am just curious as to how its actually "doing what its doing".

 

[4sfed4]

Wow.....somebody doesnt like this thread! Two "1" votes already. I had to give it a 5 just to bring it up from the cellar!

LOL.

Apparently, I have offended some folks here and wasted bandwidth. That was not intended as I have a serious interest in how all this works.

 

[turbosam6]

I once read that methanol had an octane rating of 120+, can't remember where I saw that.

 

[4sfed4]

A serious rookie mistake was made in my calculations above. Its pianfully obvious after I thought about it for a few minutes.

If 20% of your gasoline is being replaced with methanol, you cant add back in only that same 20% by mass of methanol. You have to add in 2.2 times as much by mass.

So, the correct calculation for "effective octane" per unit mass is probably more like--

=(93 x 0.56) + (99 x 0.44)

=95.64 "effective octane"

The same idea would follow for the energy present in the "hybrid" fuel, so the actual energy of the mix would be 20,152 Btu/lbm.

 

[d0n_3d]

I have heard alot of good things about methanol...but it's too corrosive for my pump setup thus I run 100% denatured alcohol...otherwise I would run the methanol...I guess you can run higher boost with it and not detonate? Good thread Larry...very technical

 

[bruce]

You also need to look at the Stoich AFRs. Most alcohols take 2x as much fuel to reach stoich.

There are two parts of the combustion reactions, disassociation, and then reassociation. The first reguires energy, the second releases it. Breaking water down gives you, Hydrogen, and oxygen, both fuel, and oxidant.

Googling for NACA, and then In Cylinder Cooling, and/or reading Sir Harry Ricardos, books, will give alot on insight into what is going on from the point of view of the original reseachers rather then some of the current opinions of what's going on.

 

[Razor]

Monkey wrench..

Companies like VP dont rate theyre Methanol in octane numbers, but purity.

The octane is a rule of thumb based on its detonation effectiveness.

I know of a test done yesterday to an SC C5 Vette that made 507 RWHP at 12.2 AFR, then just shooting a little methanol and not making any change, the next pull the RWHP went to 539. And picked up 14 ft lbs of TQ. While not overly impressive, the system barely sprayed the motor and it picked up. So the cooling and oxygenating effects work.

Back under my rock

 

[4sfed4]

Originally posted by Razor
Monkey wrench..

Companies like VP dont rate theyre Methanol in octane numbers, but purity.

The octane is a rule of thumb based on its detonation effectiveness.

I know of a test done yesterday to an SC C5 Vette that made 507 RWHP at 12.2 AFR, then just shooting a little methanol and not making any change, the next pull the RWHP went to 539. And picked up 14 ft lbs of TQ. While not overly impressive, the system barely sprayed the motor and it picked up. So the cooling and oxygenating effects work.

Back under my rock

I just looked up Sunoco's methanol online and it said RON = 109 and MON=89 and R+M/2 = 99. So, Im not sure how other companies rate it.

There is no doubt methanol works! I am not trying to contradict that! But, it seems thats the message that has somehow come across. Why...I have no idea. I am CHEAP....so I would not spend $400+ on a kit that I thought wasnt going to do anything for me

My only idea here has been.....lets figure out HOW it works. I just dont think I have been able to figure that out yet from a technical perspective. Its kinda like gravity......we know its there...we know it works......

 

[4sfed4]

Originally posted by 4sfed4
A serious rookie mistake was made in my calculations above. Its pianfully obvious after I thought about it for a few minutes.

If 20% of your gasoline is being replaced with methanol, you cant add back in only that same 20% by mass of methanol. You have to add in 2.2 times as much by mass.

So, the correct calculation for "effective octane" per unit mass is probably more like--

=(93 x 0.56) + (99 x 0.44)

=95.64 "effective octane"

The same idea would follow for the energy present in the "hybrid" fuel, so the actual energy of the mix would be 20,152 Btu/lbm.

Boy...I am really dumb. The above is wrong too

When you work out the fueling stuff correctly--

Effective octane = (0.645 x 93) + (0.355 x 99) = 95.14