Alky vs Race Fuel ?

[Nasty Wendy]

Plus, spark plugs, piston tops and combustion chambers are spotless. No carbon buildup. Less thermal loading of the engine components, lower exhaust temps, more products of combustion. No worries of the fuel quickly going stale. Milder flame speed.

And did I mention the famous wide tuning range of methanol? Reach your hands into the sky my fellow racers and give a shout out of thanks!

This ain't a which fuel is better for every reason except power thread, all he was asking is which fuel can make more power or rather go faster. I told him this shiggidity was going to get complicated....I TOLD HIM.

Sorry to have to tell you, but your reasoning is flawed.

I'm used to that LOL. If you think my reasoning is flawed now wait until you see what I'm about to post next.

True, it takes about twice as much methanol to a given amount of air to come up with a stoich mixture compared to a stoich ratio with gasoline given a same amount of air, but take a closer look at the btu values for gasoline and methanol for the same quantity of each... Now take that btu value for methanol and times it by 2 because that's how much more fuel you're going to need to come up with for a stoich ratio with methanol. What do you come up with?
Given equal amounts of air and the proper amounts of gasoline and methanol to burn at stoich ratios, the methanol wins out, hands down.

Not enough room in the combustion chamber when burning methanol is more flawed reasoning. Sorry.
A stoich methanol/air charge is 6.45 lbs of air to 1 lb of methanol. Air will compress. Vaporized and for the most part dissociated methanol will compress. So why would there not be enough room?

I'm going to try not to type up a novel here.
A gallon of Methanol has ~ 62,800 BTUs.
A gallon of Gasoline has ~ 125,000 BTUs.

This shows why you have to burn twice as much methanol to make the same power as a given volume of gasoline. It takes 2 GALLONS of methanol to exceed 1GALLON of gasoline by 600 BTUs. Air/Fuel ratios aren't measured in volume however, they are measured in weight.

The specific gravity of Methanol is .791.
The specific gravity of Gasoline is .739.
Methanol is ~ 6% heavier than gasoline.

Comparing two equal weights of the fuels will show that methanol produces LESS THAN HALF of the BTUs of gasoline by weight. Take the weight of that gallon of methanol (62,800 BTUs) and take that same weight in gasoline and it will produce 132,500 BTUs. This shows that even though the stoich mixture for methanol calls for twice as much methanol (by weight) it won't produce as many BTUs as a stoich mixture of gasoline. In a situation where you are comparing using gasoline vs. methanol to a constant weight of air the gasoline wins hands down.

I had to go to the cliffnote version because this post was going to become a novel.

 

[Nasty Wendy]

Dang I didn't defend my logic on 'room in the combustion chamber'. Simply put because fuel doesn't compress, the room it takes in the combustion chamber doesn't change. So with methanol occuping twice as much room in the combustion chamber its clear why room in the chamber can be a limiting factor of how much power an engine can make with methanol before it becomes a factor with gasoline. Why are you spraying NAAAAAWWWZZZZZSSSSTHHH? Is it to get twice as much O2 in the cylinder as the air its replacing? Could you burn the amount of methanol you are injecting at the ratio that you want without using NO2? If you wouldn't be able to then one would think that you are already experiencing the limitations of what you can get into the cylinder.

 

[Alky V6]

BUT.......

Methanol isnt as readily available as say........ denatured Alky.....

so would the type of alky have as much of an effect?

A.j.

Every alcohol does have different properties and chemical makeups. Some make a good fuel, some don't.
I've never heard of a Top Alcohol Funny car burning denatured alcohol.

 

[Alky V6]

This ain't a which fuel is better for every reason except power thread, all he was asking is which fuel can make more power or rather go faster. I told him this shiggidity was going to get complicated....I TOLD HIM.


I'm used to that LOL. If you think my reasoning is flawed now wait until you see what I'm about to post next.


I'm going to try not to type up a novel here.
A gallon of Methanol has ~ 62,800 BTUs.
A gallon of Gasoline has ~ 125,000 BTUs.

This shows why you have to burn twice as much methanol to make the same power as a given volume of gasoline. It takes 2 GALLONS of methanol to exceed 1GALLON of gasoline by 600 BTUs. Air/Fuel ratios aren't measured in volume however, they are measured in weight.

The specific gravity of Methanol is .791.
The specific gravity of Gasoline is .739.
Methanol is ~ 6% heavier than gasoline.

Comparing two equal weights of the fuels will show that methanol produces LESS THAN HALF of the BTUs of gasoline by weight. Take the weight of that gallon of methanol (62,800 BTUs) and take that same weight in gasoline and it will produce 132,500 BTUs. This shows that even though the stoich mixture for methanol calls for twice as much methanol (by weight) it won't produce as many BTUs as a stoich mixture of gasoline. In a situation where you are comparing using gasoline vs. methanol to a constant weight of air the gasoline wins hands down.

I had to go to the cliffnote version because this post was going to become a novel.

Yes, you're right. We're talking about weight when it comes to a/f ratios. So how does that work out with my 2.279 multiplier?

 

[dr_frankenstein]

Every alcohol does have different properties and chemical makeups. Some make a good fuel, some don't.
I've never heard of a Top Alcohol Funny car burning denatured alcohol.

exactly..... so would the race gas make for a better choice then to inject large amounts of denatured Alky?

thats where im in a bind... meth not so easy to get..... denatured can be bought at any hardware store...

I understand the advantages of meth... I have followed your work closely Don, But I wonder about the Denatured alky... whats the advantages disadvantages of that?

Hmm......

A.j.

 

[Nasty Wendy]

Let's look at the btu question in a different way.

The stoich a/f ratio for gasoline is 14.7:1.
That's 14.7 lbs of air and 1 lb of fuel.

Now let's setup a stoich ratio for methanol using the same 14.7 lbs of air in our figure.
You only need 6.45 lbs of air to one lb of methanol to come up with a stoich a/f ratio. Now we're given 14.7 lbs of air to play with. How much more methanol will we need with 14.7 lbs of air to come up with a proper stoich a/f ratio with methanol?
14.7 lbs of air is 2.279 times the amount of air compared to 6.45 lbs. So we will need 2.279 times more methanol to be used with the 14.7 lbs of air to come up with a stoich a/f ratio.

Maybe someone can help us with the btu values of gasoline and methanol. Take the btu value for the methanol and times that value by 2.279. Compare the answer to the btu value of gasoline. What do you come up with?

For what we are talking about a 14.7:1 a/f would net a thermal melt down of epic proportions. When we make power with gasoline we usually tune for between 11.5-11.8:1 a/f. So at 11.5:1 gasoline requires 1.783 times the air as methanol.....at 11.8:1 it requires 1.829 times the air. On a STOCK engine the air is compressed 800% and on race engines significantly more. The volume taken up by air in the combustion chamber is no where near as significant as the volume taken up by the fuel. The difference is having to choose to need a higher volume of air ,something that can compress (a lot), vs. having a higher volume of fuel, something that cannot be compressed.

 

[Alky V6]

Dang I didn't defend my logic on 'room in the combustion chamber'. Simply put because fuel doesn't compress, the room it takes in the combustion chamber doesn't change. So with methanol occuping twice as much room in the combustion chamber its clear why room in the chamber can be a limiting factor of how much power an engine can make with methanol before it becomes a factor with gasoline. Why are you spraying NAAAAAWWWZZZZZSSSSTHHH? Is it to get twice as much O2 in the cylinder as the air its replacing? Could you burn the amount of methanol you are injecting at the ratio that you want without using NO2? If you wouldn't be able to then one would think that you are already experiencing the limitations of what you can get into the cylinder.

Interesting. I'm reading this over a few times to try to figure out what your viewpoint is here.
For one thing, you are correct. Fuel in LIQUID form does not compress. What you have to realize is that by the time the piston reaches TDC, much of the fuel has dissociated into a form that is combustible. For methanol to be combustible, it must first dissociate. That means, the methanol molecule breaks down into its more basic molecular components. What do you have when the methanol molecule, due to preheating from surrounding surfaces and the heat of compression, and combustion, dissociates? Do you have liquids or gases? What are the gases? Are the gases compressible?

 

[Alky V6]

exactly..... so would the race gas make for a better choice then to inject large amounts of denatured Alky?

thats where im in a bind... meth not so easy to get..... denatured can be bought at any hardware store...

I understand the advantages of meth... I have followed your work closely Don, But I wonder about the Denatured alky... whats the advantages disadvantages of that?

Hmm......

A.j.

Well first, speaking from an auxiliary injection point of view, the main reason for injecting alky is for the cooling affect alcohol has on combustion temps. Does denatured cool as well as methanol? You would have to check out the physical properties of each to tell.
Injecting racing gasoline in place of alcohol from a detonation control stand point doesn't make sense to me. First, gasoline doesn't cool anywhere near the way alcohol does, and second, why inject the gasoline separate from your primary fuel supply? Or are you talking about running pump gasoline as the primary fuel and then injecting racing fuel as the auxiliary? I don't like that at all.

 

[Alky V6]

For what we are talking about a 14.7:1 a/f would net a thermal melt down of epic proportions. When we make power with gasoline we usually tune for between 11.5-11.8:1 a/f. So at 11.5:1 gasoline requires 1.783 times the air as methanol.....at 11.8:1 it requires 1.829 times the air. On a STOCK engine the air is compressed 800% and on race engines significantly more. The volume taken up by air in the combustion chamber is no where near as significant as the volume taken up by the fuel. The difference is having to choose to need a higher volume of air ,something that can compress (a lot), vs. having a higher volume of fuel, something that cannot be compressed.

I think the following post to this one answered your question.

 

[Alky V6]

Dang I didn't defend my logic on 'room in the combustion chamber'. Simply put because fuel doesn't compress, the room it takes in the combustion chamber doesn't change. So with methanol occuping twice as much room in the combustion chamber its clear why room in the chamber can be a limiting factor of how much power an engine can make with methanol before it becomes a factor with gasoline. Why are you spraying NAAAAAWWWZZZZZSSSSTHHH? Is it to get twice as much O2 in the cylinder as the air its replacing? Could you burn the amount of methanol you are injecting at the ratio that you want without using NO2? If you wouldn't be able to then one would think that you are already experiencing the limitations of what you can get into the cylinder.

The second part of this is confusing the heck out of me.

Yes. I'm injecting nitrous to pack more oxygen into the cylinder so that more fuel can be burned. More fuel burned equals more power. Space constraints of the combustion chamber is no concern because most of the fuel has dissociated by the start of the ignition event.

How do you think Top Fuel is able to pack in so much nitro into a 62.5 cid cylinder? They're running around 1:1 a/f ratio boosted! Believe me, I'm no where near that.

 

[Alky V6]

For what we are talking about a 14.7:1 a/f would net a thermal melt down of epic proportions. When we make power with gasoline we usually tune for between 11.5-11.8:1 a/f. So at 11.5:1 gasoline requires 1.783 times the air as methanol.....at 11.8:1 it requires 1.829 times the air. On a STOCK engine the air is compressed 800% and on race engines significantly more. The volume taken up by air in the combustion chamber is no where near as significant as the volume taken up by the fuel. The difference is having to choose to need a higher volume of air ,something that can compress (a lot), vs. having a higher volume of fuel, something that cannot be compressed.

An interesting thing to note here is that methanol can be burned at much richer mixtures than gasoline can. As you go richer, you gain further charge cooling. Further cooling results in a denser charge which allows more fuel to be burned. What kind of btu comparison are you looking at now under those circumstances?

 

[Nasty Wendy]

Well first, speaking from an auxiliary injection point of view, the main reason for injecting alky is for the cooling affect alcohol has on combustion temps. Does denatured cool as well as methanol? You would have to check out the physical properties of each to tell.
Injecting racing gasoline in place of alcohol from a detonation control stand point doesn't make sense to me. First, gasoline doesn't cool anywhere near the way alcohol does, and second, why inject the gasoline separate from your primary fuel supply? Or are you talking about running pump gasoline as the primary fuel and then injecting racing fuel as the auxiliary? I don't like that at all.

I agree 100%. Denatured vs straight methanol goes, the methanol burns as a fuel much better than denatured so that the main advantage of spraying methanol vs. denatured. Denatured works great when methanol isn't available as does water.

Interesting. I'm reading this over a few times to try to figure out what your angle is here.

I guess I didn't really have an angle so to speak. I was trying to keep the discussion simple by just giving the 'room in the CC' comparison with the fuel as we see it in its liquid form. Yes I know I dumbed it WAAAAY down but thats all I was trying to do.

For one thing, you are correct. Fuel in LIQUID form does not compress. What you have to realize is that by the time the piston reaches TDC, much of the fuel has dissociated into a form that is combustible. For methanol to be combustible, it must first dissociate. That means, the methanol molecule breaks down into its more basic molecular components. What do you have when the methanol molecule, due to preheating from surrounding surfaces and the heat of compression, and combustion, dissociates? Do you have liquids or gases? What are the gases? Are the gases compressible?

Whatever we use as fuel has to vaporize. So again we are talking about same thing only on a molecular level. The BTUs come from the hydrogen present in the fuels. Methanol's atomic structure is CH3OH. For every molecule of methanol that vaporizes we get 4 hydrogen atoms for BTUs one Carbon atom (useful for carbon build up) and one oxygen atom (which is another necessary ingredient in combustion). Gasoline's atomic structure is C8H18 which gives us 18 hydrogen atoms for BTUs and of course 8 carbon atoms which can be compressed into diamonds:biggrin:. Molecule for molecule its really no comparison at 18 vs. 4......yeah I know I dumbed it down again.

We are starting to get really complicated now. The next step will be to break down the mass of one mole of each molecule and correlate that to how many BTUs get produced by the amount of fuel that actually vaporizes and then take into account the CC volume that is occupied by non vaporized fuel.........all to come down to the FACT that you have to burn twice as much methanol to make roughly the same power as a given volume of gasoline. And when in two similar engines you have to fit twice as much FUEL into a cylinder to make the same power as the next guy you will be limited by CC volume long before he is.

 

[Nasty Wendy]

An interesting thing to note here is that methanol can be burned at much richer mixtures than gasoline can. As you go richer, you gain further charge cooling. Further cooling results in a denser charge which allows more fuel to be burned. What kind of btu comparison are you looking at now under those circumstances?

I would think that is taken into account when you are figuring out the target a/f ratio in the first place.....otherwise you could shut that NO2 off and make a lot more power couldn't you?

And Top Fuelers run the combustion chambers damn near liquid full at ignition. They are a whole different monster.

 

[Alky V6]

Could you burn the amount of methanol you are injecting at the ratio that you want without using NO2? If you wouldn't be able to then one would think that you are already experiencing the limitations of what you can get into the cylinder.

The answer to this question is yes. If I had boost (better air density) instead of nitrous, I could burn the amount of methanol I want.
Due to the size of my turbo and the kind of spool up I have without the use of nitrous, it's awfully hard for me to see more boost for the launch. Hence, the use of the nitrous to get the oxygen level in the cylinders that I need to burn enough fuel to end up with more power and a faster spool up for the launch.
The ceiling of the power level that I've reached with the primary nitrous system has nothing to do with the amount of space I have in the combustion chamber. That is not limiting me. It is the fact that nitrous and methanol both cool the charge. The more you inject, the cooler the charge. If you cool the charge too much, it will amount to less dissociation of the nitrous/fuel charge, resulting in less power in the cylinder and more fuel just being pushed out the exhaust unburned.

It's pretty cool having a fuel that will tell you when you've reached the hp limit of the system by giving you less power, instead of the alternative with gasoline where you keep increasing the system hp level until something blows up.

 

[Alky V6]

I would think that is taken into account when you are figuring out the target a/f ratio in the first place.....otherwise you could shut that NO2 off and make a lot more power couldn't you?

And Top Fuelers run the combustion chambers damn near liquid full at ignition. They are a whole different monster.

Top Fuel is a different monster, but it goes to show how much fuel can actually be stuffed into a combustion chamber.

I don't undertand your first sentence. Why would shutting off the nitrous make more power?

 

[Alky V6]

I agree 100%. Denatured vs straight methanol goes, the methanol burns as a fuel much better than denatured so that the main advantage of spraying methanol vs. denatured. Denatured works great when methanol isn't available as does water.



I guess I didn't really have an angle so to speak. I was trying to keep the discussion simple by just giving the 'room in the CC' comparison with the fuel as we see it in its liquid form. Yes I know I dumbed it WAAAAY down but thats all I was trying to do.



Whatever we use as fuel has to vaporize. So again we are talking about same thing only on a molecular level. The BTUs come from the hydrogen present in the fuels. Methanol's atomic structure is CH3OH. For every molecule of methanol that vaporizes we get 4 hydrogen atoms for BTUs one Carbon atom (useful for carbon build up) and one oxygen atom (which is another necessary ingredient in combustion). Gasoline's atomic structure is C8H18 which gives us 18 hydrogen atoms for BTUs and of course 8 carbon atoms which can be compressed into diamonds:biggrin:. Molecule for molecule its really no comparison at 18 vs. 4......yeah I know I dumbed it down again.

We are starting to get really complicated now. The next step will be to break down the mass of one mole of each molecule and correlate that to how many BTUs get produced by the amount of fuel that actually vaporizes and then take into account the CC volume that is occupied by non vaporized fuel.........all to come down to the FACT that you have to burn twice as much methanol to make roughly the same power as a given volume of gasoline. And when in two similar engines you have to fit twice as much FUEL into a cylinder to make the same power as the next guy you will be limited by CC volume long before he is.

I have to agree that if you're talking about trying to burn methanol at the same a/f ratio as gasoline, methanol doesn't have a chance. But, that's not really very practical is it?
When you compare best power a/f ratios of gasoline to best power a/f ratios of methanol and take into account the VE value of the cooling affect methanol has, there's just no comparison.

 

[Alky V6]

We are starting to get really complicated now. The next step will be to break down the mass of one mole of each molecule and correlate that to how many BTUs get produced by the amount of fuel that actually vaporizes and then take into account the CC volume that is occupied by non vaporized fuel.........all to come down to the FACT that you have to burn twice as much methanol to make roughly the same power as a given volume of gasoline. And when in two similar engines you have to fit twice as much FUEL into a cylinder to make the same power as the next guy you will be limited by CC volume long before he is.

The VE of the engine will come into play long before the lack of combustion chamber volume to stuff in more air and fuel does.

 

[Nasty Wendy]

I don't undertand your first sentence. Why would shutting off the nitrous make more power?

I was poking fun at your statement I quoted below.

An interesting thing to note here is that methanol can be burned at much richer mixtures than gasoline can. As you go richer, you gain further charge cooling. Further cooling results in a denser charge which allows more fuel to be burned. What kind of btu comparison are you looking at now under those circumstances?

I would think that is taken into account when you are figuring out the target a/f ratio in the first place.....otherwise you could shut that NO2 off and make a lot more power couldn't you?

See my point? Your target a/f ratio already takes that into account, otherwise all you would ever have to do is add more methanol to make more power.


There was also something I had forgotten about your set up when I asked my earlier question about YOU personally running out of room in your cc. You are limited by those cute little valves in your cylinder heads:smile: rather than cc volume.

 

[Alky V6]

I was poking fun at your statement I quoted below.





See my point? Your target a/f ratio already takes that into account, otherwise all you would ever have to do is add more methanol to make more power.


There was also something I had forgotten about your set up when I asked my earlier question about YOU personally running out of room in your cc. You are limited by those cute little valves in your cylinder heads:smile: rather than cc volume.

Within the constraints of how rich you can actually run methanol compared to gasoline, I guess if you could also supply the air to burn it, and have the right temperature range to process it, then yes, I could turn off the nitrous. But getting the air in there is the primary problem isn't it?

As I've already stated, VE becomes a problem long before combustion chamber space does. And a fuel that helps VE (charge density) helps to make power.

Yes, those cute valves are a testiment to the VE effectiveness of methanol. Try to get away with valves that size with gasoline.

 

[Nasty Wendy]

I have to agree that if you're talking about trying to burn methanol at the same a/f ratio as gasoline, methanol doesn't have a chance. But, that's not really very practical is it?
When you compare best power a/f ratios of gasoline to best power a/f ratios of methanol and take into account the VE value of the cooling affect methanol has, there's just no comparison.

I'm talking about burning them at their individual optimum a/f ratios.
For you there is no comparison. Methanol wins hands down because of the limitation you built the motor around. You couldn't flow what you would need through those heads to make the power you are making with gas. You intentionally put those limitations on your engine. As your ability to make that car faster grew you chose not to change the heads. You decided to work around the limitations they presented and challenged yourself to make the car haul ass DESPITE of the heads. I tip my hat to a job well done. I was thoroughly impressed with you and your car. You certainly know that if someone with your skill set and resources had a budget that was the sum of what you have invested in your car were to build a Turbo Regal from scratch with the goal of 1/8th or 1/4 mile performance in mind that they would not face the same hurdles that you do. (I wonder if thats the longest sentence ever typed on a messageboard?)

The VE of the engine will come into play long before the lack of combustion chamber volume to stuff in more air and fuel does.

The VE of an engine can exceed 100%. You chose to limit your engines ability to ingest and exhale fuel and gasses by using the M&A heads. I understand that and think that it adds a very unique aspect to your car that I can appreciate. That doesn't mean that every car is limited by those restrictions though.