Originally posted by flubyux2
its a band-aid for an inadequate fuel system or poor octane levels... its not a cure-all. its a finite source; when youre out of alky, youre out of boost... sort of. youll be limited to low boost. plus... it creates a possibility of burning a piston, like if your doing a run and your tank goes emtpy but you dont know it. its just creating a situation where stuff can go wrong. i wouldnt rely on it to make power. i would rely on adequate fuel system sizing, race gas or a bad ass intercooler setup.
you know when youre out of high octane gas, and with a datalogger, youll know when your fuel system is at its limits.
the octane-increasing benefit gained by using alcohol is marginal at best. in a 10% concentration, ethanol will raise octane by 2.5-3.0 units. 10% concentration is typically referred to as E-10 fuel, a reformulated gasoline which contains ethanol or MTBE as a oxygenate. it helps the gas burn cleaner to meet the Clean Air Act. the only problem is that the alcohol (Ethanol or MTBE) reacts w/ the water vapor in the air and will cause the fuel to separate into a gasoline layer and an alcohol/water layer. My mom was telling me about this and how it sucks for the Californians because the shelf-life is reduced w/ RFG's. when it separates out, the octane is reduced. the MTBE is Methanol (wood liquor) reacted with Ether and produces Methyl Tertiary Butyl Ether which is allowed in a 15% concentration over Ethanol (corn liquor).
the Main benefit of alky injection is the latent heat absorbed by the evaporation of the alky liquid. it reduces the intake charges substantially and will help control knock as 4drwhore already stated. but a properly sized and tuned fuel system will control knock quite welll on pump gas. running Toluene/Xylene additives will only reduce the knock tendancy more and allow more boost or cylinder pressures, thus a higher tolerance for heat.
tune a rich curve for street duty on pump gas and then tune a "lean" curve for track/weekend duty on xylene/race gas.
alky/water injection is just a crutch, to me. i would personally never put myself in a situation to rely on an item which has the possibilty of running out on me when i most need it, like nitrous on a slow car.
I don't agree with this fully. People who say it is a band aid just don't know all the facts. You say "what happens when you run out of alky" well.. what happens when you run out of race gas? You just turn down the boost. If you run out of alki during the middle of a pull you'll get knock and the car will retard timing and you will notice it and stop the pull. The same as if your car ran out of race gas. Alcohol injection is not a band aid it is more of a replacement for running race gas. How much does race gas(c16) cost a gallon these days? Alcohol is 3 dollars a gallon and that will actually last you a long time. You get the same benifits of running race gas when you need it without the cost. With the use of a hob switch it only injects the methonal at a set psi. So if you aren't in boost then you never really use it except for when needed. I don't see how you can call alki injection a band aid when it is allowing 50trim daily drivers cars to run 127mph(the fastest mph ANY 50 trim has seen no nitrous).