Are longtubes "free" torque or is the torque a result of better flow?

[crazypete]

Hi guys. The title says it all. I am running mac 1 5/8 longtubes and I am wondering if the extra torque is due to wonderous exhaust pulse effects and reduced backpressure or am I now flowing extra air through the engine?

I am thinking of this entierely from a mileage perspective.

 

[BK_CAULEY]

there both about the same arent they? reduced back pressure= better flow

 

[85_SS_302_Coupe]

Better equalizing of exhaust pulses promotes freer flowing exhaust which allows for a freer intake of air. It's a domino effect.

 

[crazypete]

So is it a net decrease of a fraction of a MPG or a net increase of a fraction of a MPG?

I'm trying to get it back to it's 25 mpg glory and I liked the underhood space offered by my unequal shorties. So if the longtubes are hurting me, I would love to go back to my shorties.

Thats all.

 

[Foxfan88]

increasing the exhaust flow allows your engine to take in more air. which in turn means more fuel can be dumped in and that means worse mileage.

 

[tmoss]

if you see an increase in power after putting long tubes on, it may mean the restriction in the exxhaust system has been reduced, as a result the "blow down" cycle is not leaving as much burned exhaust charge in the cyclinder, so the next intake cycle has more combustible A/F which increases power output. If there is overlap in the cam, it can also mean that therre is the right balancce of exhaust port flow so that as the intake valve starts to open, the "vacuum" pulled in the chamber can help pull that fresh A/F charge into the cylinder. What you don't want to happen is the exhaust pull it right out the exhaust valve, loosing charge and power.

 

[stykthyn]

so do longtubes hurt or help mileage. I am wanting to get a set, but if they significantly kill mpg I'll have to pass

 

[tmoss]

Have you kept before and after mileage figures? If not, there is no way to tell for sure........

 

[HaynStang]

Doesn't adding a higher flowing exhaust usually help MPG a little bit? I don't know if longtubes would have the same effect, just thinking out loud.

Maybe with gas prices the way they are we should start a list of mods known to help MPG... underdrives, e-fan, what else???