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Chipper Chapman · 02-07-2012, 10:51 PM

Todd, what A56 is talking about for the exhaust is that it's not the back pressure the system gives to the engine, but the velocity at which the exhaust gases have to travel in a smaller primary tube. The higher velocity (or rate of speed) will help to draw (or scavenge) the air/fuel into the cylinder during that minimal overlap period, effectively cheating the engine into thinking it has more cam duration. On the monte we ran small primary street headers (cheapo flowtechs) that achevied this, but with a 3" system and mufflers to not create excess back pressure. It went .4 under with a 100k mile engine.

02-07-2012, 10:51 PM	#11
Chipper Chapman Member Join Date: Jan 2004 Location: Belmont N.S. Canada Posts: 473 Likes: 246 Liked 166 Times in 71 Posts	Re: Pure stock 340 Mopar Todd, what A56 is talking about for the exhaust is that it's not the back pressure the system gives to the engine, but the velocity at which the exhaust gases have to travel in a smaller primary tube. The higher velocity (or rate of speed) will help to draw (or scavenge) the air/fuel into the cylinder during that minimal overlap period, effectively cheating the engine into thinking it has more cam duration. On the monte we ran small primary street headers (cheapo flowtechs) that achevied this, but with a 3" system and mufflers to not create excess back pressure. It went .4 under with a 100k mile engine.