The Dodge Challenger Message Board

It does not sound the same as a single pipe. Everthing else about them has already been said except that I think when this thread started I was using two separate pipes and later I fitted a H-Pipe.

With the H-Pipe the exhaust noise level did indeed drop slightly and the car sounded more tame at idle than it had before.

It was still what you would call very loud and meaty sounding though. The only difference is you get a "Blap" out of both pipes at the same time rather than alternative pipes.

Dave is right. It sounds 'different' not single exhaust sounding at all, just higher pitched, throaty, but different than seperate duals. I have met some that didnt like it at all. It's worth 15-25 H.P. at higher rpms. Thats all I needed to utilize it.

whats the theory behind the increased hp, pardon my ignorance

The exhaust gasses travel as pulses of pressure. Each pulse of pressure is followed by an equal amount of negative pressure.

If you can tune an exhaust pipe so that you have low pressure at the end of it when the exhaust valve opens it draws the exhaust gas out faster and you get more out. Air and gas have mass so therefore inertia. So you can end up with low pressure in the cylinder. That means you get more air and fuel in on the intake stroke.

Now tuning the exhaust is not an easy science. There are various ways of trying to get it right. Some systems will only work at one ideal rpm.

You need equal length headers for a start. The collector at the end of the headers does the same thing which is why headers produce more power.

Most of us can't fit equal length headers in our street cars though but you still get a little benefit from them.

The x-pipe and H-pipe however will work quite well in any system. But it works best when used with equal length headers.

Because low rpm cylinder scavenging is improved by these low pressure pulses you generally get better low rpm torque. High rpm torque and HP is usually not affected much if at all.

thanx dave that makes perfect sense , ill have to check out how a few different cars sound with the x pipe before i use 1 though its always been the norm to have seperate pipes here in aus "its all about the note " if the gain is mainly low end torque & making less difference as the revs increase then it probably wont be to much of an issue & itll be a cheaper system to as what ever i use will need to be custom made or the expense would be rediculous thanks again for the info im sure itll come in handy 1 day
cheers ian

yes, thanks Dave. Bugger it, i'll get an X pipe mailed over, and see how it goes

dave-r wrote:The exhaust gasses travel as pulses of pressure. Each pulse of pressure is followed by an equal amount of negative pressure.

If you can tune an exhaust pipe so that you have low pressure at the end of it when the exhaust valve opens it draws the exhaust gas out faster and you get more out. Air and gas have mass so therefore inertia. So you can end up with low pressure in the cylinder. That means you get more air and fuel in on the intake stroke.

Now tuning the exhaust is not an easy science. There are various ways of trying to get it right. Some systems will only work at one ideal rpm.

You need equal length headers for a start. The collector at the end of the headers does the same thing which is why headers produce more power.

Most of us can't fit equal length headers in our street cars though but you still get a little benefit from them.

The x-pipe and H-pipe however will work quite well in any system. But it works best when used with equal length headers.

Because low rpm cylinder scavenging is improved by these low pressure pulses you generally get better low rpm torque. High rpm torque and HP is usually not affected much if at all.

I read it , is for that I use this system