bellZ71

murphdog, was there any noticable power loss afterwards?? nice job btw.

Murphdog

TS77, I don't think length is extremely critical. I made mine so it telescopes to allow some adjustment. I did start to get some resonance if I shortened it more than a couple inches. I couldn't lengthen it much over 30" because I ran into the driver side frame rail.

BellZ71, no power loss from the resonater. It's capped at the end, so there's no flow through it. The resonator pipe doesn't even get warm more than a couple inches away from the tailpipe.

kbracing96

iTrader: (26)

My cut out is before the muffler, would this still work if i use it for the branch?

thunder550

iTrader: (70)

I need to figure out how this works on two tailpipes. In the instructions on the calculator it says "For a true dual exhaust, input half the total number of cylinders. The 'cylinders per pipe', not the total engine count.", but since I have an X before the mufflers I'm thinking that everything behind the X is essentially a larger single exhaust. I would think that I could put an equal length resonator on each tailpipe (based on the length for 8 cylinders, not 4) and it should work. Thoughts?

Thanks for the pics Murphdog, seems like it's very easy to experiment with that way and find out the correct length before welding a bunch of crap up. That would make it even easier! Are T's like that available at an auto parts store or did you have to order them from somewhere?

thunder550

iTrader: (70)

I would think it would work anywhere. Think about the Corsa mufflers - the resonator in there is at the front of the muffler.

Murphdog

kb, I also think it would work before the muffler. I did mine after it because I had more room back there. Since you already have a cutout, it should be fairly easy to experiment.

Thunder, I'm inclined to think you would put 4 cylinders per pipe in the calculator and then add half the calculated length on each tailpipe. I don't know if this is right or not, guess you will need to try it and see what happens. The 'T' I used is just a piece of pipe that I fish-mouthed on a grinder so it would fit the OD of the tailpipe. I actually drew up a template with AutoCAD and taped the resulting piece of paper to the pipe prior to grinding. The orange stuff you can see in the picture is hi temp Permatex to seal the less than perfect fit. It would be better top weld it once you get it like you want it, but the clamp on version seems to work fine as well.

thunder550

iTrader: (70)

What I was thinking is that once the two sides are merged together with an X pipe, essentially they become one exhaust because the frequencies are merged and then simply directed down two different paths. Splitting the exhaust after the merge point won't change the frequency, I don't think. At least that's what makes sense to me anyway.

I guess I'll just have to experiment with it and see what happens.


Actually after running it through the calculator, we are both getting at the same thing. Either my way or your way, looks like I'll be adding up to 40" to each side. Yikes!

TS77

I agree, I think it works the same either way.

I was playing around with the calculator and noticed changing from 8 to 4 cylinders just doubles the output number. So if you were to input 4 and half that output number, its the same as just putting in 8 cylinders to begin with... does that make sense?

The guys on the mustang forums were getting drone between 2000 and 2100 RPM and they were running dual exhaust. The ended up putting on two 24" branch resonators, one on each exhaust pipe. I ran the numbers through the calculator (2000 RPM, 4000 RPM, 8 cylinders) and it gives 2.061 feet which is 24.7 inches.

Also keep in mind that the auto lounge calculator is designed for actually cutting or adding length to the exhaust pipe, not a branch resonator. But for some reason it seems to work for the branch resonator too. Like Murphdog said, the length doesn't have to be exact. But what seems to have proven to work are lengths between 24" and 32". The shorter the branch resonator, the higher in the RPM it will cancel drone. The longer the branch resonator, the lower in the RPM it will cancel the drone. I actaully just noticed something very simple. Ill draw up a picture and post it.

TS77

It looks really simple. The mustang guys were using 24" branch resonators at 2000 RPM drone so that relationship is correct, and Murphdog is at 30" around 1700 i believe he said (correct me if im wrong). The rest of the numbers just fall into place.

kbracing96

iTrader: (26)

I have a single 4" pipe from the turbo to just after the cut out about 1/3 the way down the truck, then split it into duel 3" (thinking it would be quieter with two 3" Magnaflow offset mufflers then with 1 4" Magnaflow strait through) and it gets louder at 2200+ rpm, just like it did before. According to the calculator, I need to add about 1.75 feet to move the drone from 21-2200 to 4000. Does this sound right?