Allroads_Lead_Somewhere

I forgot to respond to that question.
There are many advantages from running W/M injection in the 2.7T. The more obvious would be; A cooler and more dense fuel dump into the combustion chamber. Aside from the power increase, you have the added benefit of an incredible cleaning of the intake and valves. I've seen comparisons of cyl. heads that have been run with W/M injection, vs. those that have not. The lack of any carbon deposits in the W/M heads was amazing! Also, you will get the benefit of a slightly higher increase in octane and an incredible benefit of lower AIT's and the subsequent advance in timing. This benefits an otherwise stock Allroad as it would any forced induction engine. If you have Ross Tech's VCDS (lite), you can measure the difference in AIT and the timing advance. You can definitely feel the difference.
I run the Coolingmist Varicool-2 with the variable-progressive controller with the injection based on boost (you can also inject based on any 0-5v input, such as MAF, or MAP). I start injection at 8 psi with max input at 18 psi. On an otherwise stock 2.7T, I would suggest that start injection at around 3 psi and max out at 7 psi (based on the stock boost being between 7-11 psi). Yes, the stock boost in the AR does vary by 2-3 psi, based on the N75 setting at the factory. In the "Old days", I used to adjust the N75 a few degrees CCW to increase max boost by about 3 psi. (I don't suggest that you do this unless you are willing to fork out the funds for a new N75 valve. They are a bit sensitive and can't handle continued adjustment) At one point, early on, I swapped in an N75 from ECS Tuning that is designed to add around 3 psi of boost. I believe this is the same N75 valve that is used in the Audi TT.
To sum it up, yes, It has been demonstrated that W/M injection gives the stock 2.7T a decent amount of increased power, but I would doubt that it adds the advertised claim of 20 to 30 HP. That is highly unlikely on a stock Allroad.

kermac

Having run w/m injection on my 1.8T (GTRS turbo and all the supporting gear) for over a year, can I say I think there are a few misconceptions floating around on this thread?

Straight methanol does NOT increase your octane rating, neither does it of itself increase the output of the engine. What it does is to cool (by giving off latent heat if I remember my elementary physics) the charge air coming in from the turbocharger, helping to prevent pre-ignition (or detonation) of the charge in the cylinder. Without some form of fluid injection (straight water works as well, but is not as efficient), the ecu detects detonation and cuts back the degree of ignition advance, which causes the engine to lose power in a major way.

What w/m injection does is to lower the temperature of the intake charge, thus preventing the loss of power, and maintaining the power output at the level it would have been at if the intake air had not been so overheated. If you have the capacity to tune your engine, you can then take advantage of this by tuning for more power without risking detonation damage. It is this that gives you the extra power, not the injection per se.

It's an old technique which goes back to the early years of the 20th Century, but was highly developed during WWII for high-performance fighter aircraft engines (by both sides). There's a whole lot of stuff about it on the web. It works just as brilliantly in the 2.7T as in any other turbocharged engine. Some car makers even fitted it as standard equipment around the early 60s, but dropped it as the average Joe couldn't remember to keep the reservoir topped up and engines would detonate and blow themselves up.

It's great stuff - it has a few drawbacks, but generally speaking is far more efficient at lowering the temperature of the incoming air than even the best intercooler. And it's a whole lot cheaper!

Kristopher

Methanol is a fuel and so it does have an octane rating. Top Fuel dragsters and rally cars are the among those that run it due to this novelty.

Water does a nice job at cooling the intake charge but so does methanol due to pulling the latent heat out of the charge as mentioned.

Since water isn't a 'fuel' in this sense, it doesn't have an octane rating. However they help both in the charge air and also by reducing the heat generated in the compression stroke. This is also why both can benefit a naturally aspirated car to some degree (high ignition advance, high static compression = heat and detonation).

kermac

I don't diagree Kristopher, although I believe I'm right in saying straight methanol has a lower octane rating than gasoline? Obviously when mixed with water it's very considerably lower.

The reason it works in a force-fed engine, inasfar as I remember my elementary physics (it WAS 50 years ago...), is that it cools the charge and thus the engine, not because it changes the octane rating

09mehashaw

Not trying to be mean, but you are wrong.
Methanol has an Octane rating of almost 109 (108.7) to be exact according to Wikipedia.
However, according to this government document on page 52, Methanol is said to have an Octane rating of 115 (significantly higher than simply 93)