I read that 70% of the exhaust goes through the right muffler and 30% goes to the left muffler in a stock dual exhaust system. Can anyone explain to me why this is? Is there an advantage to this type of system or is it set-up this way because of the gas emissions? I read a thread where people said that you lose HP and torque with a true dual exhaust, this just doesn't make sense to me, someone school me on this!

[IMG]local://upfiles/49242/AE2BAB69CBC74C1E92CA8D4909CD6DBA.jpg[/IMG]

 

It is the shape and design of the stock exhaust.....It's like a 2 in 1 with a big leak out the left side.

On the tru duals, because of the softail frame, the rear cylinder loop has to have such a bend in it that the exhaust won't free flow as easily as the design on a bagger..There's more room on the frame of a bagger to have a more gradual bend in the loop.

A tru dual system doesn't exactly lose HP...You will gain HP going from the stock system to the tru dual....You just won't gain all the HP you possibly could with a quality 2 in 1 or good 2 in 2.

This was a long struggle for me with my Heritage Springer...I had the tru duals with fishtails and it is the look that meant for the bike...I put so much into the engine that the set-up was killing the HP..I went with the rinehart 2in1 and a good tech on the dyno tuner and gained 19 HP over the tru duals

 

Sounds reasonable...thanks for the explanation

 

Good information..sad though, Id really love to have a set of true duals on my Heritage, I think they look great on the softails. sounda like I might be better off to keep running the screaming eagle 16ga that I presently have.
I wonder, is this problem the same with all pipes that are true dual?

 

Yes it is and the only really proper way to "fix" it would be to redesign the cylinder head on the rear cylinder to put the exhaust port on the other side.
Another thing that's often overlooked is that 2 into 1 pipes work better in thelow to mid range because of the physics of exhaust flow.
In a perfect universe true duals really only work right at one specific RPM where the exhaust pulse wave has the right amount of time to exit the end of the pipe.Get reflectedfrom the atmosphere back up the pipe in time to get to the valve at closing time. Higher or lower RPM's will put that wave either into the cylinder or slam into the closed valve and lowering scavenging fficiency.
The big advantage of a2 into 1 system is that theylenghten the duration of the pulse, if not its strength. But more importantlyuse the mass of the exhaust gasses from one cylinder to help 'pull' or scavenge the burned gasses from the other. All over amuch wider, but lowerRPM range.

 

Thanks Citoriplus, great input

 

Huey: Sent you a PM

 

I was really thinking of going true duals also. Not wanting to loose much power or torgue though

Chief101
I am very interested to know how much difference you saw in performance with the PCIII with your SE 16 guage and HD download. I have the same pipes and a HD download on my 05 deluxe. Talked to Jamie at fuel moto and thinking about going with a PCIII also. I have changed out the baffle to the V&H quiet core rather than the large metal baffle that came with the 16ga.. Tried to PM you but would not allow me to send. PM me if you could
Thanks

 

Chief101, I see 05 HD Deluxe is interested inexhaust information. I am[as well as a lot of other guys I'm sure] trying to decipherthe exhaust dilemma. Go for the looks, and loose hp???Go forhp, and takesecond or third choise for looks!!! Any info you could post would be of interest to me, and I'm sure many others. Thanks.