Using a E85 mix let me get my home made car through its UK certification (the Single Vehicle Approval - SVA as it was)
You have to meet both a noise limit and emissions limits .The car has Supertrapp silencers with 12 discs and removing one disc cuts noise by about one decibel but builds up back pressure I got down to two discs to meet the noise limit but the back pressure enriched the mixture a lot.
I could have played with jets etc but I'm no Holley expert and that takes time.. So instead I blended E85 with unleaded BP race fuel.
Fortunately a neighbour worked for BP and had access to an expert in their fuels research centre who kindly advised on the correct blend.
The lower calorific value of the mix flowing through the existing jets got the CO/HC etc down below the required levels all on its own.
As the tests are done at 3,000 rpm and no load their wasn't much detonation risk and the engine actually ran much smoother - I think because the race fuel is highly oxygenated on its own.
Edited by mariner, 11 December 2020 - 12:01.