Have just heard from a local workshop that they'll be trying to inject fuel into the pipe before the I/C to give the charged air a cooler intake. Will this be better than water injection? Or probably injecting nitrogen? These guys are builders for 4cyl cars like Evo's and V-tec turbos. Any advises?

 

Injecting fuel *before* the IC sounds like a disaster waiting to happen. Risk of fuel puddling in the end tanks and all... I'm sure someone will go and pull up examples where fuel introduced before intercooling worked, but... raw fuel sitting there doesn't sound good.

IIRC the problem with injecting nitrogen or other cyrogenic gasses is that they don't absorb enough heat per mass of gas... so in order to equal the absorbtion of water injection, you're filling the cylinders with too high a proportion of inert gas to burn well. I'd have to go back and look up numbers but...