Exhaust Length?

Other then noise and weight, what effects does the length of the exhaust have on a naturally aspirated engine?

You mean on a Yugo?

I am assuming you mean long tube headers, not longer exhaust.

It affects the power band to some extent. Generality says, short pipe- high end power,less at low rpm. Long pipe- the opposite.

Had a good example of that with an MG 1100. Pipe broke of just below the manifold/header. The loss of low end power was very noticeable when you don't have a lot to start with.

If you are talking about a Yugo header, you will gain low end torque, which is very valuable on a low weight momentum car.

Longer or shorter exhaust piping (after the header) will not do anything.

It has to do with the pulse/ volume/ scavenging at the point where they gather in the collector.

Once you get past the collector, there's really no benefit to an exhaust as SVreX said. That's just to get the stinky stuff away from the driver. There is the need for just a bit of restriction post-collector to make sure the scavenging works, but very little.

There are some freeware programs that help and can get you on the right track. Check here: http://www.bgsoflex.com/auto.html

SVreX wrote: If you are talking about a Yugo header, you will gain low end torque, which is very valuable on a low weight momentum car. Longer or shorter exhaust piping (after the header) will not do anything. It has to do with the pulse/ volume/ scavenging at the point where they gather in the collector.

No. I was talking post header.

Argo1 wrote: There are some freeware programs that help and can get you on the right track. Check here: http://www.bgsoflex.com/auto.html

I am guessing that maximum RPM is asking when you want to make your maximum power.

caveat: please, not only corroborate what i type but also for all information you encounter. this will help determine future credible sources.

the way the exhaust is comprised most certainly will have a impact on the way power is developed. length and size of pipe, shape of the bends, number of mufflers and style, etc. effect the flow of exhaust; velocity reduced. pending where you want the "powerband" it may work out okay for your specific setup. but, understand that these variables should all try and coincide as closely as possible with one another to support your goals. to have huge primary headers and not have the rest of the supporting mods to move air efficiently at the higher rpms would be counter product to one's goals.

there is a velocity node for exhaust flow that people chasing efficiency's try to achieve; look into it but something about high 3xx fps is coming to mind. the idea is, to slow and scavenging suffers and to high becomes turbulent -> chocking; iirc.

i have experimented with having to open of an exhaust for the rest of the engine variables that dictate where power is intended to be made. by open, i mean open cutout within a 2 feet after the collector and it was a straight shot. the other section of the y pipe for cutout was full length. after i cut that back that section with zero mufflers/res/cat the car was a noticeable sluggish till ~4700; both cutout and other section of tail piper were wide open. i then added a very restrictive (few discs) supertrapp muffler to the very short tail pipe section( 2 feet past cutout). this made a huge difference and dropped the band down 400 or so rpms and did not appear to have any issues up top either.

these are just my anecdotal experiences but they contradict what others have typed. i ask those with an open mind to investigate both sides further.

93EXCivic wrote: No. I was talking post header.

Then it really won't matter at all.

Run it short and dump it out the side. It will save you a couple of bends and restrictions trying to get around the rear suspension.

I've got a complete exhaust you can have if you want it.