In a message dated 7/24/03 8:19:10 PM, gull@GULL.US writes:

<< My suspicion is that what's going on here isn't a chemical effect, but a

mechanical one -- the SeaFoam doesn't burn well and instead forms little

droplets that bang around in there and scour away the carbon.  Some people

use diesel fuel or water (!) to get the same effect.

 >>

While I have no comment on the mechanistic details of the organic additives
(seafoam and diesel fuel) but the ability of water to remove heavy carbon
deposits is a well understood oxidation mechanism. Under combustion temperatures,
injected water droplets lead to small water clusters which in turn lead to
significant levels of the highly reactive molecule OH. This is probably the most
reactive oxidizing agent for carbon compounds from aliphatics through graphite,
kerrogens and diamond. The reactivity of the OH molecule together with
thermal and stress profiles leads to rapid oxidative attack at the metal/carbon
deposit interface. This delaminates the coating and chunks are released. For thick
coatings, the equivalent of grain boundaries are attacked in the carbon film
also leading to substantial material release. The point is that the carbon is
not just simply oxidized layer by layer (although this does happen on high
humidity ambients) but rather its taken apart releasing bulk material. Of course,
carbon is a protectant in this situation in that OH will rapidly oxidize
aluminum (especially aluminum/silicon alloys).

Chemistry (and especially internal combustion chamber chemical dynamics) is
both fun and interesting!

Frank Grunthaner