To carb or not to carb

Sterling · 03-20-2008, 07:14 AM

Lots of variables to consider.
Blow through carb set-ups typically delete the emulsion system in favor of a modified fuel bowl vent system in order to avoid siphoning at high flow. The emulsion system is there to bleed off main fuel draw signal at high velocity (thus preventing siphoning) and as a great side benefit, provides aeration of fuel prior to mixing in the carb. This helps with very fine tuning and fuel efficiency.
Lack of pre-aerating is not such a problem at extremely high velocity, but low to mid range can theoretically suffer, but how would you know?
Carbs utilizing annular boosters and other goodies can better disperse the fuel, coming close to mimicking aeration that an NA carb does.
Negating the emulsion system is a compromise, but blow through setups handle the charge much better than draw though, and they also have the even greater advantage of being able to cool the intake charge using an intercooler.
Even though the carb's emulsion system can be retained on a draw through system to produce an aerated, fine mist, it's basically taking a lace-delicate charge and throwing it in a Cuisinart. Drawing through the carb also doesn't allow for an intercooler, either. BUT, it's a lot easier to set up all around, and the "kick-ass" factor over NA far outweighs the increase from stepping up to a blow through setup using identical components and an intercooler. In other words, going from draw though to blow through setup using the same parts and an intercooler is definitely going to be better, but it's not going to "wow" you anything like when you went from NA to draw through. (Edit: -"On the street" is how I mean to end this. Well known in drag applications, using an intercooler and dry ice, the performance increase is all the difference in the world. However, it's obviously a different application, and not practical for the street applications in the context of this discussion.)

03-20-2008, 07:14 AM	#14
Sterling Premium Vendor Join Date: Feb 2008 Posts: 74 Rep Power: 18	Lots of variables to consider. Blow through carb set-ups typically delete the emulsion system in favor of a modified fuel bowl vent system in order to avoid siphoning at high flow. The emulsion system is there to bleed off main fuel draw signal at high velocity (thus preventing siphoning) and as a great side benefit, provides aeration of fuel prior to mixing in the carb. This helps with very fine tuning and fuel efficiency. Lack of pre-aerating is not such a problem at extremely high velocity, but low to mid range can theoretically suffer, but how would you know? Carbs utilizing annular boosters and other goodies can better disperse the fuel, coming close to mimicking aeration that an NA carb does. Negating the emulsion system is a compromise, but blow through setups handle the charge much better than draw though, and they also have the even greater advantage of being able to cool the intake charge using an intercooler. Even though the carb's emulsion system can be retained on a draw through system to produce an aerated, fine mist, it's basically taking a lace-delicate charge and throwing it in a Cuisinart. Drawing through the carb also doesn't allow for an intercooler, either. BUT, it's a lot easier to set up all around, and the "kick-ass" factor over NA far outweighs the increase from stepping up to a blow through setup using identical components and an intercooler. In other words, going from draw though to blow through setup using the same parts and an intercooler is definitely going to be better, but it's not going to "wow" you anything like when you went from NA to draw through. (Edit: -"On the street" is how I mean to end this. Well known in drag applications, using an intercooler and dry ice, the performance increase is all the difference in the world. However, it's obviously a different application, and not practical for the street applications in the context of this discussion.) Last edited by Sterling; 03-20-2008 at 07:22 AM.