Gary, It goes 1point richer because the stoichmetric ratio of methanol is less than half that of fuel,,, your wide band is set to see 14.7 as stoich not 6+/- .... What you aim for AFR wise is purely dependent on modification, timing, cam size, air flow ectr, some motors will run happy at 12.8 at 300wkw, some will only run clean at 10.5,,, all in knowing how to tune not just what to aim figures at.
Thanks for clearing that up, that is the way I thought of it but the more you read on the net the contradictory this topic is.
You have PM.
DriftZ: "I swear if a CA18 beats my SR im getting a RB!"
After some in-depth research (10 minutes tops) comparing dyno sheets and compressor maps for the gt2871r .64 and the gt3071r .64 it would appear that you are in fact right, so much for that idea
Diesel power, hmm, yes, I think I'll have some of that.
Detonation
Detonation is said to occur when the air and fuel mixture in your engines cylinders explodes, or detonates, rather than burning smoothly. This
exploding mixture can cause serious engine damage e.g. damaged spark plugs, melted pistons and melted valves. So it's definitely something
that must be stopped. Below is a brief explanation of detonation - it's not meant to be a full in depth article, just a guide.
Detonation can be caused by a large number of things, but they can be put into 2 classes:
l Pre-ignition of the air+fuel mixture
l Excessive peak cylinder pressure for the fuel used
Pre-ignition can be caused by hot spots in the combustion chamber - this can be the spark plug tip, glowing carbon deposits or other hot spots.
This cause of detonation isn't very common in modern engine as they run fairly clean, with minimal deposits. Spark plugs are often changed to a
lower heat grade - this helps conduct heat away from the plug tip which reduces the chance of pre-ignition.
Excessive cylinder pressure for a given fuel can cause detonation. Excessive peak cylinder pressure can be caused by:
l Ignition timing too advanced - peak cylinder pressure occurs too early in the engine cycle and causes detonation
l Air + fuel mixture too lean - a lean mixture burns faster than a richer mixture, this can also cause peak cylinder pressure to occur too
early
l Effective compression ratio (CR) too high - if the static CR is too high, or you are running too much boost, detonation can occur.
Fuel plays a big part in detonation. Different fuels have different resistance to detonation. This resistance to detonation is measured and a fuel is
given a RON or MON rating. A fuel with a higher RON or MON rating will be more resistant to detonation. Normal unleaded has a rating of 95
RON (Research octane number), super unleaded is 97 RON and Optimax is about 98 RON. Tesco Have just started to sell 99 RON fuel - I've used
this and it seems to be more resistant to detonation than Optimax, and usually cheaper.
I have highlited the reason I think he burnt a piston, my car was mapped according to the water/meth, the timing was increased as far as it could without detonating, I drove with the car like that for a long time with no probs, I then sold it to him, he drove straight to Capetown with no probs, he drove around in capetown for a while with no probs, then the water/meth was stopped and the timing pulled back, not enough though....a few days later....oops....
Took my car to dynotech and they sorted the detonation problem.They ran the car for about 4 runs on the dyno, and a new sound occurred.Sounds like its coming from the lifters :(so they stopped and know if got to fix the sound first and take it back again. The car is still running lean (10.5),but atleast I can drive without detonation.
