View Single Post
  #4 (permalink)  
Old 07-11-2021, 06:14 AM
Luce Luce is offline
CC Member
Visit my Photo Gallery

Join Date: Aug 2010
Cobra Make, Engine: Lone Star with IRS, 427W with megasquirt, T56 magnum
Posts: 292
Not Ranked     

Actually, OEMs open the injector shortly after closing the intake valve so the fuel boils to a vapor on the back side of a closed valve. THIS gives 100% atomization and minimum emissions at low speed.

Also, near max HP high rpm, the injector if not grossly oversized is open 75% duty cycle. the intake valve is only open ~30% of the time.

Port will give a much better idle quality and drivability, but a TBI actually can produce a tiny bit more top end power because the wet fuel in the manifold evaporating gives a cooling effect to the intake charge, like in a carb. Carbed engines can make a few more horsest han port injected, all other things equal.
Reply With Quote