Hey Everyone, I did a search on exhaust that i was interested in getting but I had a quick question on back pressure. I know if you get a true dual exhaust you back pressure decreases which in some cases decreases your low end torq and HP. My question is if you have for instance Intake,and a upgraded Plenum or intake Manifold would that increase you back pressure hence increasing HP. Im i thinking of this in the right way or am I a dumb@$$?

Thanks

 

the backpressure will give you more low end but decrease the top end hp. most race engines are high reving free flowing engines. my goal is to make mine as free flowing as i can stand and try to stay in the higher rpms as much as possible.. my two cents

 

What happens is you redistribute the airflow to be more even through all 6 of the cylinders. You also help to equalize the pressure drop (which is freeing up the flow some, not decreasing it).

There is a reason Nissan used a y-pipe version of an exhaust. If a true dual design would have netted more hp/tq, you better believe something as cheap as steel tubes would have made their way into the design. IMO, with FI, more air flow is better. For NA there is a limit and Nissan, Honda and the other auto manufacturers all seem to agree on this. Ever see a V-6 Accord? It has a y-pipe. Most production V-6's come with y-pipes for that matter.

 

Thanks for the input.

 

The purpose of a cast iron exhaust manifold is to route the exhaust gases out the tailpipe.

The purpose of a tuned exhaust header is to route the exhaust pulses into a collector precisely timed so that the previous pulse creates a vaccume that sucks out the following pulse... and so on. That's why it's critical to keep all the pipes the same length and to have them in the correct location in the collector.

When you go to a FI car, these rules become obsolete. There's no need to finesse the exhaust out of a cylinder, you just increase the compression as required with the supercharger or whatever. That's why most blown dragsters don't have headers as we know them... they just have four pipes that vent to the atmosphere.