OK OK..........
I got a low down on this stuff.
I called a couple friends of mine and got opinions, thoughts and past experiances from them, and came up with my corrections. Charlie was right........ I thought wrong. However I have my new plan for alky injection.... I will share what I learned and you can make decisions towards yours.
:biggrin:
OK, round one winner due to knock out ....... pre turbo.
and boiled down here is my conclusion.
A turbocharger only knows 2 important properties of the gas it is compressing. The density of the gas at the compressor inlet and the pressure ratio it is operating at, which is determined by the rotor rpm and the gas density. If you increase the pressure or reduce the temperature at the inlet you will modify both of those parameters. In both cases (increased inlet pressure, or lower inlet temperature) you increase the apparent density of the gas passing through the compressor. At a given rotor rpm with a given gas density you will flow a very specific volume of gas and it will be compressed to a specific pressure ratio on exit. That is what the compressor map is based on. If you change the inlet conditions (gas density) you in effect slide the compressor map left and right. This is the "corrected flow" of the turbocharger!!!! Ah HA!!! now with alky, we can make an exsisting turbo fit the reqirements of higher horsepower....
By injecting Alky ahead of the compressor two things happen. You cool the inlet air substantially, this in effect moves your true operating point to the left on the compressor map. (in most cases for max performance this is a good thing, although on some turbocharger conditions it can cause compressor surge.) Which we can get into later if you truly want to go that way.
You also change the pressure temperature profile inside the compressor wheel itself. And theroetically we actually change the shape of the compressor map. As the gas moves outward and is compressed, heat that would have normally gone into heat and increased pressure is absorbed by the Alky mist and so the compressor has less work to do since it is no longer fighting this temperature driven pressure increase, it can achieve more mass flow at that pressure ratio.
your end F'n result is, you increase the mass flow through the compressor --- in effect you make it act like the turbo is bigger than under normal conditions.
However................................ theres a catch,
nozzle location and placement pre turbocharger,
Quoting Vernon Tomlinson, Hilborn Fuel Injection:
Improper location of alcohol nozzles at the inlet of the turbocharger in some applications reduced power. The alcohol spray blocked some of the air that would otherwise be drawn into the inlet. Moving the nozzle location away from the air inlet opening produced 25 HP more than a close location in those cases.
Suggesting that 12 to 18 for sfi cars, and as far as the longest straight shot possible directly from turbo. And for situations in carb use, where distance is limited, he suggested aiming the nozzle directly at the nut in the center of the compressor wheel... as the edges of the fins are where erosion tends to occur. Erosion is usually caused by cheep/poor nozzles due to lack of inital atomization - this needs to be carefully observed during nozzle selection.
So there you have it. The data I hope can solve some questions for us.
A.j.
