-lrb- paris l'usine nouvelle 2 dec 93 -rrb- * alexis m. 733-6345 -lrb- france -rrb- working with french automakers , the french petroleum institute -lrb- ifp -rrb- has developed two experimental fuel -injection techniques aimed at making the two-stroke automobile engine a viable alternative to the conventional four-stroke engine by eliminating its chief disadvantage : emissions of unburned hydrocarbons that are 10 to 20 percent higher than those of a conventional engine .