muffler bypass 4 + incorporated 'muffler' (little long again)
12-30-2009, 04:01 PM
#1
Rennlist Member
Thread Starter
muffler bypass 4 + incorporated 'muffler' (little long again)
This is my 4th set of diy muffler bypasses, what's new is that I've incorporated a 'muffler' in the bypass. I need to do a little explaining...
I liked the sound of the bypasses I made previously, they worked well with stock cats. When I changed to bigger sport/race cats, thought things were a little loud for me and put on a set of Roock 450 mufflers (modified stock mufflers I believe). The sound was just about right. I've been on a weight loss mode this winter as many of you here know and wanted to shed the weight of the mufflers. I've always wished I could incorporate some sort of muffler or resonator in the bypasses but there really is not much length/space between the end of the heat exchanger output and exhaust tip. Thought about making some elaborate tubing with a resonator where the stock muffler sits but that would involve quite a bit of pipe and multiple bends. Did some reading on how mufflers work too (learned about expansion chambers/resonators/baffles)... Was staring at the space I had to work with after taking the mufflers off and all of a sudden it dawned on me that if I could fit a pipe on the outer diameter of the heat exchanger it self (not the 2.5" outlet / leaving the 2.5" outlet alone - see pics towards the end) I could get some space/"expansion chamber". Learned from some trials that baffles on the outer edge of the exhaust flow seemed to decreased the higher tones and baffles in the center seemed to decrease the lower tones.
So this is what I've come up with. Found that 3.5" ID pipe fits right on the heat exchanger (the large part, right over the 2.5" outlet - see pic 4). Found some 3.5" pipe with a 3.5" radius 90 bend fit perfectly! Made some baffles with smaller dia pipe bent as shown. Got to play with my stick welder. Painted black using high temp header paint (used my barbeque as my bake oven - worked well and didn't have to try to convince my wife to let me use her household oven).
It sounds not too bad. Deeper/throatier than the 'motor boat' sound of regular bypasses. I could post a vid with sound that I made on my mac if someone can tell me how.
Stock muffler + misc parts = 20.5lbs x2
Muffler bypass/incorporated "muffler" = 3.5 lbs x2
total savings = 34 lbs
I liked the sound of the bypasses I made previously, they worked well with stock cats. When I changed to bigger sport/race cats, thought things were a little loud for me and put on a set of Roock 450 mufflers (modified stock mufflers I believe). The sound was just about right. I've been on a weight loss mode this winter as many of you here know and wanted to shed the weight of the mufflers. I've always wished I could incorporate some sort of muffler or resonator in the bypasses but there really is not much length/space between the end of the heat exchanger output and exhaust tip. Thought about making some elaborate tubing with a resonator where the stock muffler sits but that would involve quite a bit of pipe and multiple bends. Did some reading on how mufflers work too (learned about expansion chambers/resonators/baffles)... Was staring at the space I had to work with after taking the mufflers off and all of a sudden it dawned on me that if I could fit a pipe on the outer diameter of the heat exchanger it self (not the 2.5" outlet / leaving the 2.5" outlet alone - see pics towards the end) I could get some space/"expansion chamber". Learned from some trials that baffles on the outer edge of the exhaust flow seemed to decreased the higher tones and baffles in the center seemed to decrease the lower tones.
So this is what I've come up with. Found that 3.5" ID pipe fits right on the heat exchanger (the large part, right over the 2.5" outlet - see pic 4). Found some 3.5" pipe with a 3.5" radius 90 bend fit perfectly! Made some baffles with smaller dia pipe bent as shown. Got to play with my stick welder. Painted black using high temp header paint (used my barbeque as my bake oven - worked well and didn't have to try to convince my wife to let me use her household oven).
It sounds not too bad. Deeper/throatier than the 'motor boat' sound of regular bypasses. I could post a vid with sound that I made on my mac if someone can tell me how.
Stock muffler + misc parts = 20.5lbs x2
Muffler bypass/incorporated "muffler" = 3.5 lbs x2
total savings = 34 lbs
Last edited by Basal Skull; 12-30-2009 at 05:10 PM.
12-30-2009, 11:28 PM
#5
Rennlist Member
Thread Starter
Quadcammer - Nope, never made any cat bypasses...
David - It does look kinda mean (sounds mean too!)
sfbanches - too bad you're not local and I'd help you make one yourself. I think I spent under $100 in parts. The two 3.5" OD 90 degree 3.5" radius elbows (you can see the part number on some of the pics, the 3.5" radius bend is the key), a 3.5" OD to 3.5" OD connecter (6" long) that I cut in half exactly in the middle of the little bulge so that there's a little of a flare for the tips, a 3" ID connector that I cut up to make the 'baffles', and a couple of T-bolt clamps. Have to look around a little for the 3.5" material as most muffler/parts places don't keep exhaust pipe that big in stock.
David - It does look kinda mean (sounds mean too!)
sfbanches - too bad you're not local and I'd help you make one yourself. I think I spent under $100 in parts. The two 3.5" OD 90 degree 3.5" radius elbows (you can see the part number on some of the pics, the 3.5" radius bend is the key), a 3.5" OD to 3.5" OD connecter (6" long) that I cut in half exactly in the middle of the little bulge so that there's a little of a flare for the tips, a 3" ID connector that I cut up to make the 'baffles', and a couple of T-bolt clamps. Have to look around a little for the 3.5" material as most muffler/parts places don't keep exhaust pipe that big in stock.
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01-01-2010, 05:13 PM
#8
Rennlist Member
Thread Starter
Hi
must be a little more restrictive than using a 3.5" pipe with nothing in it, but looking at the amount of surface area that is altered by the 'baffles', I don't think there is any more restriction cf 2.5" pipe/regular bypass. It is also short and has fewer corners than the alternative I was thinking of with 2.5" pipe and a resonator where the regular muffler is. So it does what I want it to do. I have no way of checking flow/psi loss across it though.
Best part is just thinking up this stuff and making it work.
must be a little more restrictive than using a 3.5" pipe with nothing in it, but looking at the amount of surface area that is altered by the 'baffles', I don't think there is any more restriction cf 2.5" pipe/regular bypass. It is also short and has fewer corners than the alternative I was thinking of with 2.5" pipe and a resonator where the regular muffler is. So it does what I want it to do. I have no way of checking flow/psi loss across it though.
Best part is just thinking up this stuff and making it work.
