that very insightful. thank u very much
and i have equal length shorties by the way lol

 

Google "Velocity"

 

If you don't tune a car after adding a set of headers, I could see how there might be a power difference between a more free flowing vs more restrictive.

Just my .02

 

me tooooooooooooooooooo

 

What?!? That made no sense.

There will always be a difference between a free flowing exhaust and a restrictive exhaust regardless of the state of tune. Hense,.. why else would it be 'restrictive' ?

And to be honest (And I could be off track here) but I have never heard of tuning an engine to the exhaust. I have always seen an exhaust tuned for the engine. At least thats how the big money cars do it. People like you and I just buy an exhaust and hope for the best.

I usually tailor my exhaust for a specific sound I am looking for. On the street I dont see where it would really make a difference one way or the other where performance is concerned.

Forced induction motors have almost no need for scavenging. Its why a FI motor rarely sees the same gains from long tubes vs an NA motor that strives on efficiency and scavenging to get the most out of it. Two completely different animals.

Hurst

 

Hurst,

My generalizations were about overall backpressure, not header diameter and length. A more descriptive test for that would be to install a 1" muffler, a 1.5", etc to see what makes the most power.

Brian
EFI-Unlimited

 

Yes but whether its in the mufflers, the mid pipe (O/R vs Catted) or in the headers, some form of back pressure is created. From everything I have read and understand,.. a relatively stock NA motor will make more power with a small amount of back pressure vs something like open 2" headers. An all out race motor designed to spin 9k wouldnt be as effected by the lack of back pressure. Where, why and how,.. I honestly dont understand.

You made the generalization,.. I knew that you knew the answers. I just wanted to debate it so I could get you or Shawn to elaborate on it.

Hurst

 

Superwes.. If it were me I would go with a nice set of long tubes of equal length. Diameter depends on the insides of the motor, if your stock go with cheap bolt ons, I personally don't have a problem with some BBK headers, seem to work well on eveything I've put them on..

Another question I might ask is; could the "missing torque" be a timing/tune issue to begin with?


Hurst... People like you and me don't have big money motors that are already tweaked to the max. In those cases a dialed in exhaust to the engine I could see.

When I'm working with a car that only has one manifold choice like a Ford Escort or Focus I definitely have to tune for the manifold. Especially on a SULEV vehicle or even a late model OBDII.

If we were talking old school carb with the room to move runner lengths and diameters that's also a different story

In the case of this 5.0 with the old school computer you can get away without a tune but I bet money you get more with one.

Man every post I make seems to get anally probed lately

Oh well one day someone will understand that I do actually know what I'm talking about for the most part....Years of training, EFI classes, dealership experience and tech support to other dealers mean something somewhere I'm sure...

 

This is the core of this debate. Most everything I have tested says that a relatively stock motor will make best power with an open exhaust past the collector. However, the perception that back pressure would improve it, is fairly strong among performance enthusiasts. Honestly, I would like to see a real test of this exact scenario to either bust or confirm this 'gear head myth'

Brian
EFI-Unlimited

 

If I still had my Dyno I would have no problem participating in this study