Duel exhaust

[Rick 74 MC-8]

Has any one here with a na engine put duels on I want to run two 3" pipes from the manifolds Thu mufflers and out.  Don't want it to be to loud but a low rumble would be nice. I think After removing the otr compresser there would be plenty room.  After reading the earlyer post about straight pipes and performance and MPG boost I think there must be a happy medium. Besides maybe I could pick up some extra revenue blowing the leafs out of the curb lol. Just thinking out loud


                                                                                 Rick 74 MC-8

[lostagain]

3" doesn't sound very big. How about 5"? How big is it off the manifolds?

JC

[Ednj]

Has any one here with a na engine put duels on I want to run two 3" pipes from the manifolds Thu mufflers and out.  Don't want it to be to loud but a low rumble would be nice. Just thinking out loud


                                                                                 Rick 74 MC-8

>
Rick,
That is how the eagles are piped.

[Rick 74 MC-8]

The manifolds are 3" Does anyone have part # for mufflers I might jump 4" seems they are more common Does anybody know if they make a 4" manifold of a source for used manifold  street side will work good curb side will word but a different style would make a cleaner install


                                                     Thanks Rick 74 MC-8

[JohnEd]

In the auto world they shy away from just upping the pipe size.  Seems that  the size increase makes the gas heavier due to the reduced temp that results from gas expansion.  This "problem" is part of the reason that wet wrapping the turbo and manifold and piping up to the muffler increases power and efficiency. I know that back pressure kills the D power but can it be any worse for the gas engine?  I had charts and graphs for my Z car and they showed serious drops in dyno power for an increase in the header pipe diameter and similar losses for increasing the ex tube dia by only 1/16 over the opt.

Getting rid of the muffler is a sure fire good move all around.  Problem is that if you maticulosly engineer the system you can get equal perf from a muffled system.  Lots of spendy engineering on that.

But what I would really like to hear is "are we better off going to twin 4 inch or 3 inch if the manifold is three inch"??  Hope that gets answered.

John

[Rick 74 MC-8]

Just measured again manifolds are 3.5". The current exhaust takes the two 3.5" into a 5" then into muffler then exits  4.5" Its like a leaf blower. Just seems like duels would get rid of the constipation The current muffler is fine I need to do some other exhaust work Any was looking for real world experience

                                                                          Rick 74 MC-8 na

[JohnEd]

Rick,

The straight thru pie will be very loud....from what they say.  I listened to the film of one running and it seemed ok  to me.  What I do know is that if you split the system and run a separate pipe for each bank, well, the noise goes up dramatically.  Didn't that film n the board show the engine running straight out the manifolds and then he re-posted with them run into a common 5 inch pipe.  You be the judge  Its been done and recorded for your listening pleasure.

A turbo quiets it down some.

What do you think?

John

[luvrbus]

What is different on the manifold you need Eagle uses a cast 90 on the curb side and just regular truck mufflers same as C65 Chevy truck with the 366 or 427 engine, duals on a 8v71 will help and they sound nice too.



good luck

[Rick 74 MC-8]

Thanks luvrbus that's what I was thinking I don't want straight pipes  just want it to breath I could live with a rumble I but not draw any more attention when pulling into a campground and maybe pickup a little milage and performance Maybe wishfull thinking but shouldn't be that hard to do



                                                                Rick 74MC-8

                                                                             

[dougyes]

If you already have a good 5" muffler, why not go for dual 5"?

[Dreamscape]

We have dual exhaust on our 8v71N. I thought they would have duals, guess not. I think it's 3" in and I know it's 3" out. Not sure of the brand of muffler, because they were on there when we bought the bus. It sounds good and not too loud.

Paul

[trucktramp]

You could try Pittsburgh Power.  They run a high performance diesel shop and have designed free breathing mufflers for big trucks.  I don't know how much 2 stroke Detroit work those guys do but they were big into N14 Cummins and some Cat motors.

http://wwwpitsburghpower.com

[trucktramp]

sorry but that link won't work.  Try this one.

http://www.pittsburghpower.com

[Rick 74 MC-8]

While doing some research om my back psi vs HP I came across some intresting reading Might be of use in findind cfm scroll to pages 108
http://www.eigenbrodt.se/webmotor/nyhetsfunktioner/f110028%20medium%20and%20heavy%20duty%20exhaust%20catalogue.pdf

                                                                                      Rick 74 MC-8

[JohnEd]

Rick,

The Donaldson site was neat.  I spent 45 min going back and forth in there.  Thanks.

I have always thought that "back Pressure" should be a percent loss per psi.  No doubt I am wrong but I too have that question.  I hope you will post the results.

Thanks,

John