Brad,
You are making GREAT progress! Keep up the good work!
First off, my advice is nothing more then what I have read and understood form this board and a few other boards. A few experts also set me straight a while back.
Running on the edge of knock is where max engine output occurs. It is also a "Tango with the knock devil", a VERY fine balancing act on the music between the "instruments" of Octane, Timing, Intake Charge air temperature, Heat , Air Flow, Pressure drop, Air Velocity, and Fuel delivery. Without a scan tool, the dance may be short lived as one instrument may be playing the wrong music for this "tango". A scan tool will indicate what instrument is off.
Don't get discouraged, there a few things you can do and stay a few steps away from the dance floor.
As you stated previously, the Xylene (although effective to a point) is cost prohibitive and not the most productive way to stay out of the knock.
There are a few simplified options to reduce your knock with some suggestions listed below for resolution. This is NOT a concrete listing but should be a good start. Hopefully, the experts on this board will add to this, or provide better insight.
Reduce the boost - Adjust the WG rod. The lower the boost, the less combustion heat (lower compression), and the less chance of knock for a given octane rating and timing (All other factors being equal)
Reduce the timing - Review the Ultra chip documentation and run a setting with the lowest timing. I belief this to be setting #4. Ultimately, a custom chip, but not needed! You have all the programs you need for now. (It will be hard to find a programmer for the Hot Air ECM.) As I was told by "Turbo Riviera" and "Slow_85" - "You are giving yourself a steep hill to climb".
Increase octane - Xylene, or race gas are great for testing and/or racing but this is a cost prohibitive option for the daily driver. The higher the octane, the more heat (Boost) and timing you can run without knock. You also know that the "Stuff" (Insert your choice words) in the little bottles do not work.
Cool the intake charge in the manifold - Methanol / Alky / Water injection, or, intercool. I realize you are staying "Hot Air", so the intercooler is out. The cooler the charge before igniting it, the more timing you can run. Most run Methanol and there are a few kits available on the market.
Get the turbo in it's efficiency range - I belief the stock Hot Air turbo max pressure/efficiency is around 15 PSI (?). I belief intake temps can reach 350 - 450F around the 20 PSI range! Clearly an issue!
Increase the turbo size - A bigger turbo will also reduce the intake temps as there will be much less heat for the same boost pressure due to increased flow at a given demand. You need boost AND flow. (Then is are spool issues and larger injectors, etc).
Increase fuel delivery - Increase your fuel pressure 1 PSI at a time and check for knock. Be careful as there is such a thing as rich knock! Keep track of outside temps and humidity. One can get REAL scientific with this but not needed. (O2 readings and/or EGT should give a good idea where you are at)
There are also other ways to reduce heat and increase flow through intake porting and exhaust system mods. As stated in the beginning, this is not a concrete list but is intended as a good starting point.
Again, hope this gives some insight. Keep up the good work!!
PS;
If your engine is burning any oil, you will have issues. Oil GREATLY REDUCES the net octane of your fuel and you are aware by now how BIG the effect of 3 octane points is in a given range.
Do a search on here Brad for E85 in the subject title and you will find guys talking about how corrosive the stuff is. All the cars that are meant to run on this stuff have plastic or stainless steal fuel systems......just something to think about
Nick
