Which is faster carb or Fuel injection?

jmarkaudio · 07-29-2013, 05:28 PM

There a more things going on then have been touched on here. A carb will meter fuel and make changes almost instantly as the signal changes. A carb will also meter fuel in a continuous flow, constantly mixing fuel with the incoming air. Atomization is only part of the picture, how well the fuel is HOMOGENIZED or evenly mixed with incoming air plays a big part in a couple areas. A well homogenized mix early in the induction tract will more evenly distribute to the cylinders, when the mix is more equal you don't have to run the good cylinders rich to make up for the lean cylinders. Also a well homogenized mix will burn more consistently and evenly in the combustion chamber and without as much ignition lead. This make more power. A FI system send fuel in pulses, and unless you set it up with the injectors above the throttle blade like a formula one engine you will not mix it close as well into the chamber as a carb. And anyone that believes a FI will distribute more evenly even though the injector is placed right above the valve is dreaming. With a batch fire setup forget it, even with sequential you get fuel flying around in the plenum making distribution less than ideal. Sure you can tune each one, but what if it isn't consistent in where the fuel goes to all the time? And then there is the processing delay, it takes a very fast processing system to work best and still it will never respond as fast as a carb.

All considered, it is still a case by case deal as to what works best. If the carb is restricted by blade size and the FI is not as some of the Engine Masters have been, FI may win out. If cylinder to cylinder distribution is hampered by the intake design, like a dual plane, then FI may have an advantage. If g-forces change to extremes like a road race engine then FI may have and advantage. If fuel consumption is a key factor, number of pit stops, then FI usually will have the advantage. In a drag car with an optimized intake and no limit to throttle blade size, I'll take a carb.

07-29-2013, 05:28 PM	#14
jmarkaudio Junior Member Join Date: Apr 2008 Posts: 83 Likes: 0 Liked 0 Times in 0 Posts	Re: Which is faster carb or Fuel injection? There a more things going on then have been touched on here. A carb will meter fuel and make changes almost instantly as the signal changes. A carb will also meter fuel in a continuous flow, constantly mixing fuel with the incoming air. Atomization is only part of the picture, how well the fuel is HOMOGENIZED or evenly mixed with incoming air plays a big part in a couple areas. A well homogenized mix early in the induction tract will more evenly distribute to the cylinders, when the mix is more equal you don't have to run the good cylinders rich to make up for the lean cylinders. Also a well homogenized mix will burn more consistently and evenly in the combustion chamber and without as much ignition lead. This make more power. A FI system send fuel in pulses, and unless you set it up with the injectors above the throttle blade like a formula one engine you will not mix it close as well into the chamber as a carb. And anyone that believes a FI will distribute more evenly even though the injector is placed right above the valve is dreaming. With a batch fire setup forget it, even with sequential you get fuel flying around in the plenum making distribution less than ideal. Sure you can tune each one, but what if it isn't consistent in where the fuel goes to all the time? And then there is the processing delay, it takes a very fast processing system to work best and still it will never respond as fast as a carb. All considered, it is still a case by case deal as to what works best. If the carb is restricted by blade size and the FI is not as some of the Engine Masters have been, FI may win out. If cylinder to cylinder distribution is hampered by the intake design, like a dual plane, then FI may have an advantage. If g-forces change to extremes like a road race engine then FI may have and advantage. If fuel consumption is a key factor, number of pit stops, then FI usually will have the advantage. In a drag car with an optimized intake and no limit to throttle blade size, I'll take a carb.