nah.. this guy did it based on displacement of the engine.. one group was like 1.4L to 1.9L, then the next was 2.0L to something else, and so on and so forth.. maybe he's full of crap.. maybe not.. lol..

but, your point with the turbos is correct.. they do need a bigger piping, regardless of displacement.

 

I don't have turbo. I haven't won the lottery yet either, that's my story and I'm sticking to it.
No one has really told me 'WHY' it will poorly effect performance.
Lets say I had the optimal diameter of pipe that would carry the exhaust of only two of the four exhaust ports, to create the best low end power.... ahhhhhhhh sh!t, I give up. I'm beating a dead horse here.

 

What about those silly Civic SI's that I see running dual exhaust with an engine .1L larger than an accent? Is it a "Y" pipe to the other exhaust with a less than 2" dia?
The Cuda kit is "rice" then?

[ September 08, 2002, 12:21 PM: Message edited by: aktivkontrol ]

 

most civic owners don't know crap about tuning and are completely rice

but theres about 10-15% that know what they are doing and those are the ones running really fast hondas

 

The ones who know what they are doing also stick to a SINGLE pipe on an inline motor. Don't make me come back in here and slap you all....

As we've already covered: if you're putting a dual exhaust on an inline engine, you're doing it because you want the LOOK, not performance.

 

But what about the Cuda kit then?
Rice?
Don't get me wrong, I like the kit, personally.

 

The reason you need backpressure is this:

When exhaust gas leaves through the valves after the explosion, there is pressure inside the cylinder that forces the exhaust out due to the expansion of the now hot gasses. Duh. Next, as the hot gas moves down into the manifold, it reaches the point where the one pipe, meets the other four. When the gas nmoves past the other four, it creates an area of lower pressure behind it in the other cylinders. This serves to help suck out more of the exhaust gas from the next explosion in order to allow more oxygenated air to enter the cylinder. There is always going to be some exhaust gas left over from the explosion in the cylinder because the valve closes before it all escapes. The effect where the gas rushing past helps to suck out the air from antoher cylinder is called scavenging. This is also why different cams can help increase horsepower, by allowing more gas to enter/exit. Extend the duration too long however and you get the cylinder coming up before the valves are shut all the way. Also higher lift cams do not idle as well because the are looking for air that is not comming in fast enough so the engine is rougher until higher RPM's when more exhaust allows more gas to enter and the lower intake pressure sucks in more air. Also the intake and exhaust cams are open at the same time for an instant to aid in the process of forceing old air out and new air in. So, to answer you question, if there is not enough pressure in the pipe, the exhaust doesn't move fast enough to suck out enough gas from the next fired cylinder and each cylinder is on it's own. Forecd induction cars have an air pump that forces more air into the cylinder thereby making it so that a larger pipe can be used with out the negative effects.

 

Not to get blasted but why do some motorcycles have a seperate exhaust pipe for each cylinder?

 

Not all motorcycles are inline engines... There are a very large number that are V-twins, or a pair of cylinders in a V configuration.

If your motor is in a V setup, dual exhaust is much easier and worthwhile.

 

i put dual exhaust on my 2001 tiburon and gained alot of pick up, along with some top end. i would say to try it bc even if it doesnt help it will look good and sound good. so what to lose. but hey its ur car do what u want.