Rotary Car Club - View Single Post - auxiliary injection-who here has it?

dudemaaan · 09-11-2009, 01:51 AM

I'll chime in and correct/add a few things.

Water if atomized correctly, and if running a proper ignition system won't cause a loss in power. Many people see an increase in power.

Water CAN be tuned up on, either by running more timing, leaner mixtures, or higher boost. I'm currently running 23 psi on water alone with no knock. I run tap water, which is not being brave just smart. There is nothing in it that is any more contaminated then gasoline from the gas station. I run a filter and regularly check my nozzle.

Other points to consider, meth/alcohol you need to run 2-3 times more for the same knock suppressing effects as water. But alcohol does cool the intake charge better.

Another drawback to alcohol AI systems is they require removing fuel from the maps. If the injection system fails, the motor is toast. This means you need a very reliable setup, which if you plan on pushing the limits with any aux system it should be reliable. I've had my system not functioning at least once at 23 psi, but due to my fairly conservative tune and only using water my motor was fine.

Another good option is to run 50/50, it has the best of both worlds and is more of a compromise between water or alcohol. Benefits include less usage over alcohol (smaller nozzle), better intake cooling over water, good knock suppressing effects, cost per volume is less then meth/alcohol, and less fuel pulled from the maps. I' plan to experiment with it sometime but I prefer free right now.

I'm guessing the "denatured alcohol" would be Ethanol, as thats the other popular choice for AI.

Points:
Ethanol has a flash point of 55.4* F
Methanol has flash point of 51.8*F

A gallon of ethanol = .........84,400 Btu..............(gasoline =125,000 Btu)
Gallon of methanol = .........62,800 Btu.............. (E85 =90,500 Btu)

Octane rating of ethanol is..129 RON..........(gasoline = 91-95 RON)
Octane of methanol is........123 RON................. (E85 = 105 RON)

What this means is it takes more methanol then ethanol to reach the same heat value (btu), and to raise the octane level of the mixture to a certain point (injecting more). It also means that the air temperatures will be reduced more, both due to the lower flash point, and the requirement for more of the fuel to be used.

Hope that helps add some more info on the subject.

09-11-2009, 01:51 AM	#13
dudemaaan Rotary Fanatic Join Date: Mar 2008 Location: Brenham, TX Posts: 335 Rep Power: 18	I'll chime in and correct/add a few things. Water if atomized correctly, and if running a proper ignition system won't cause a loss in power. Many people see an increase in power. Water CAN be tuned up on, either by running more timing, leaner mixtures, or higher boost. I'm currently running 23 psi on water alone with no knock. I run tap water, which is not being brave just smart. There is nothing in it that is any more contaminated then gasoline from the gas station. I run a filter and regularly check my nozzle. Other points to consider, meth/alcohol you need to run 2-3 times more for the same knock suppressing effects as water. But alcohol does cool the intake charge better. Another drawback to alcohol AI systems is they require removing fuel from the maps. If the injection system fails, the motor is toast. This means you need a very reliable setup, which if you plan on pushing the limits with any aux system it should be reliable. I've had my system not functioning at least once at 23 psi, but due to my fairly conservative tune and only using water my motor was fine. Another good option is to run 50/50, it has the best of both worlds and is more of a compromise between water or alcohol. Benefits include less usage over alcohol (smaller nozzle), better intake cooling over water, good knock suppressing effects, cost per volume is less then meth/alcohol, and less fuel pulled from the maps. I' plan to experiment with it sometime but I prefer free right now. I'm guessing the "denatured alcohol" would be Ethanol, as thats the other popular choice for AI. Points: Ethanol has a flash point of 55.4* F Methanol has flash point of 51.8F A gallon of ethanol = .........84,400 Btu..............(gasoline =125,000 Btu) Gallon of methanol = .........62,800 Btu.............. (E85 =90,500 Btu) Octane rating of ethanol is..129 RON..........(gasoline = 91-95 RON) Octane of methanol is........123 RON................. (E85 = 105 RON) What this means is it takes more methanol then ethanol to reach the same heat value (btu), and to raise the octane level of the mixture to a certain point (injecting more). It also means that the air temperatures will be reduced more, both due to the lower flash point, and the requirement for more of the fuel to be used. Hope that helps add some more info on the subject. __________________ 500+ HP thanks to:* Fast reacting IAT sensor thread! Mechanical Pre-turbo Water Injection Thread Dual Stock fuel pumps Thread T2 differential swap! Last edited by dudemaaan; 09-11-2009 at 01:53 AM.