I was thinking of edge as the falling off point where we are operating safely, and then suddenly, being in detonation and throwing parts thru the block
Maybe, I should have said we go from the "Green" safe zone immediately into the "Red" danger zone.
When we add alky to the equation, we seem to insert a greenish yellow zone which still allows us to make safe power and this zone is fairly wide before we get into the red? My mind and mouth/fingers seem to have a transition zone in between them, these days.
I used to have a page on my site with a bunch of cooling calculations which has disappeared with time. Of the three primary alcohols, methanol seems to provide the most cooling by a small margin. In the Sixties when Holley/Spearco sold some water injection kits that sprayed into the carburetor, they were on non boosted applications and they used straight water. They allowed us to run more timing and we made a little more power. Water always creates more cooling, but, it also "waters down" the fuel content of the mixture.
When GM had the turbo'd Old's and the turbo'd Corvair, they ran a mix. I am not sure the alky did much other than keep it from freezing easily and they kept it low to eliminate fire potential. They considered the same for the 84/85 GN's but went to the IC on the 86/87's. I think they were covering their rears on blown engines on dry tanks??
I think when you run 100% alky, you add a fuel content benefit with regard to octane addition and this fuel content also broadens this transition zone between the "green and red" zones due to the lower sensitivity to A/F as we add more and more methanol to the mix. This is my conjecture, anyway.
I have seen some cars that were spraying alky make runs with the A/F down around 10.3-1 and then a run at 10.8 with virtually no change in miles per hour.
Running straight methanol and no gas might give you the same results over two full numbers of A/F. When we run a mix of the two, or E85, perhaps, it's really difficult to discuss what's the best A/F. Lambda is probably the better term to use but, you have to learn something else, there. I am too old to learn new tricks.
Anyway, I think spraying a lot of methanol takes us away from pure charge cooling to a blended it fuel which provides lower heat, but, can greatly increase the boost that can safely be applied without being in danger of suddenly falling off the the cliff into the detonation abyss.
