Here's a good short article on water injection:

http://autospeed.drive.com.au/cms/A_107970/article.html

I still like this topic.

 

Someone needs to change the title why its alky injection

 

Some how i don't think Rich is up for that

 

I thought methanol is 116 octang?

 

Thanks for the link at the bottom of your post!

MarkinKC69Z - I still like this topic, too.

 

Methanol is ~100 octane when tested by the standard method. However, due to the cooling effect of the high heat of vaporization when used as the primary fuel it has detonation resistance of a much higher octane gasoline. When used as an injection fuel, the effect on detonation resistance has not been well quantified. IOW, I doubt if any of us hobbyists ever defined an appropriate test procedure and then ran the tests with differing mixtures of water/methanol. Most of what we know is rule of thumb stuff.

But technnically speaking, the octane rating of methanol is ~100 with the MON and RON as stated.

Rich

 

HOW DO YOU DETERMINE OCTANE?
Ok, then, how is octane rating determined? First, you go out and get a suitable supply of the fuel which you wish to test. Then, you get yourself some heptane (made from pine sap) and some iso-octane (a petroleum derivative). Finally, you and your buddies arbitrarily, agree that iso-octane has an octane rating of 100 while heptane has an octane rating of 0.

Next, you call up Waukesha Motors and order yourself an ASTM-CFR test engine. Make sure you have about $250,000 available on your VISA before you order it. This single-cylinder wonder has a four bowl carburetor and a movable cylinder head that can vary the compression ratio between 4:1 to 18:1 while the engine is running.

You fill the ASTM-CFR full of your mystery fuel and, for automotive fuels, you run two test protocols using the ASTM. One protocol is called the motor protocol and the other the research protocol. You vary the compression ratio until the onset of knock and write down all kinds of various scientific parameters.

Next, you run your reference fuel, made up of various proportions of heptane and iso-octane through the ASTM-CFR. You keep varying the proportion of heptane to iso-octane until you get a fuel that behaves just like (knock-wise) your mystery fuel. Once you get that, you say to yourself "How much heptane did I have to add to the iso-octane to get the mixture to knock in the ASTM-CFR just like my mystery fuel?" If the answer is, say, 10% heptane to 90% iso-octane, your mystery fuel has an octane number of 90.

How do the motor and research protocol differ? Mostly in input parameters. In the motor protocol (ASTM D2700-92), the input air temp is maintained at 38C, the ignition timing varies with compression ratio between 14 and 26 degrees BTDC, and the motor is run at 900 RPM. In the research protocol (ASTM D2699-92) the input air temperature varies between 20C and 52C (depending on barometric pressure), timing is fixed at 13 degrees BTDC, and the motor is run at 600RPM.

The motor method, developed in the 1920s, was the first octane rating method devised. After its introduction, many more methods were introduced. During the 1940s through the 1960s one of those methods, the research method, was found to more closely correlate with the fuels and vehicles then available. However, in the early 1970s automobiles running on high-speed roads, such as the German Autobahn, started destroying themselves from high-speed knock. It was found that the difference in ratings between the research and motor method, known as the fuel's sensitivity was important as well. The greater the fuel's sensitivity, the worse it performed from a knock point of view in demanding, real-world, applications.

Remember, at the pumps, the results of the motor and research numbers are averaged together to get the value you see. The fuel's sensitivity is not published. Highly cracked fuels have high sensitivity while paraffinic fuels often show near zero difference between the two. While the fuel's sensitivity is not published at the pump it can be a valuable indicator as to the fuel's real world octane performance. Remember, the octane tests are conducted in a lab using a special test engine; the lower the fuel's sensitivity, the more likely it is that the fuel will, indeed, behave as expected. Generally, the closer the fuel's research rating to the published rating the more reliable the published rating. Because the motor and research methods primarily differ in terms of input parameters (the test engine is the same for both), the greater difference that a fuel exhibits between its motor and research test will be due to differences in input parameters (intake temp, timing, etc.). A fuel that has an octane rating that varies with intake parameters is said to be more "sensitive."

Lifted from http://www.prime-mover.org/Engines/G...es/octane.html

Rich

 

Now if only we could get people to agree on the octane rating of methanol instead of inflating it to 116 or whatever.

Thanks for the cut and paste, it was an informative refresher. Luckily there are companies out there that will do the testing for a fee.

 

BTW, there is a whole different test procedure for determining octane over 100.

FWIW, as a practical matter, with a high VE NA engine max hp is seen in the range of 14:1 CR, IF detonation can be avoided by using a fuel of sufficient octane. Both high octane race gas and M100 can be used sucessfully in such an engine. 116 octane is not needed for that CR, many people use fuels in the 112 octane range. "Restricted" applications run as high as 17:1 and also do not need extremely high octane - however, forced induction motors do.

Rich

 

Yes, anything over 100 octane is acutally inferred and not directly measured.

 

Very good advice. You should get out sometime though...it'll help you out a lot.

"your heart is free...have the courage to follow her!!" Uncle Argile-Braveheart

 

Water is unlimited octane

And refer to the Honda Formula One program where they ran engines at 60 PSI boost making in excess of 1300 HP on a 4cyl.. Top Alcohol Dragsters.. etc.. running insane cylinder pressures.. on methanol.

Who cares what the octane is.

 

I just read this whole thing and have to ask a question: If you cool the air temperature in the intake by some means on a supercharged car, will there actually be more moles of oxygen in the intake at this lower temperature than there were at the previous higher temperature? (If you don't change anything, nothing, except the temperature of the air in the intake.) I would think that maybe with the pressure on the high side of the supercharger reduced due to the lower temperature, it might be able to push more moles of gas in there .
I have some other ideas but I'll keep this short.

 

Blowers "blow" better than they "suck". So that's one reason to put the heat exchanger on the outlet side of the blower rather than the intake side. The flow restriction is less important there. The main one though is that it's much easier to cool hot air (on the pressure side) than to cool already cool air on the intake side. If I knew any thermodynamics, I could explain it better.

Rich

 

You're thinking correctly, but not for meth or water injection.

With an intercooler, you cool the air at the discharge of the compressor. This makes it contract and the pressure drops. The lower pressure means the compressor has to overcome less dP so the flow increases and so does the power.

With water or Meth injection, you cool the air by injecting a liquid. The air contracts, but the extra space available is filled in with flashed liquid, so the pressure does not change. No change in pressure means no change in flow and no change in power. Now, increase the boost or timing, and you get the extra power.

Mike