How to get exotic sound
TECH Enthusiast
Joined: Nov 2011
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From: jacksonville,fl
I'm still planning hopefully later next year to make my design of over the engine 180 degree headers using tri-y collectors & going 8 -4-2-1. Have decent room under a g-body cowl hood, & will take multiple steps to combat heat. Already have fender vents, will have huge hood louvers, heat shielding under hood ,Possibly heat shield over intake & valve covers, etc, twin fans running full time.
Trying to 180 cross pipes underneath for my application would be a huge mess , super hard to get equal length, & loose ground clearance.. If I didn't have normal AC location, I could cut firewall & trans tunnel for room.
Hope the sound will be worth it.
TECH Senior Member
Joined: Jun 2016
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From: Central Cal.
Here's an easier way- From the right (passenger) bank, run the end cylinders back, and the center cylinders under the engine to the left (driver) side. Do the same for the driver side. Siamese the end cylinder pipes and the center cylinder pipes on both sides. Then join the RH-origin center pipes with the LH-origin end pipes, and do the same on the RH side. Then join the resulting single pipes from each side into one. You have just made an 8-4-2-1 360degree single exhaust.
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Here's an easier way- From the right (passenger) bank, run the end cylinders back, and the center cylinders under the engine to the left (driver) side. Do the same for the driver side. Siamese the end cylinder pipes and the center cylinder pipes on both sides. Then join the RH-origin center pipes with the LH-origin end pipes, and do the same on the RH side. Then join the resulting single pipes from each side into one. You have just made an 8-4-2-1 360degree single exhaust.
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Joined: Oct 2016
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From: PDX-OR-USA
IIRC and that's a long shot 
,, there were only 4 tubes to cross over, and you ran 2 behind and 2 under.. the two under crossed between the engine and trans, The old cars used to have the firewall pushed back about 6" since they were a tub&tube car that was heavily modified.
Over the top exhaust is such a M***** F***** to work on in most American sedans I wouldn't even do it.. The heat and access issues make it just not worth the blood..
,, there were only 4 tubes to cross over, and you ran 2 behind and 2 under.. the two under crossed between the engine and trans, The old cars used to have the firewall pushed back about 6" since they were a tub&tube car that was heavily modified.Over the top exhaust is such a M***** F***** to work on in most American sedans I wouldn't even do it.. The heat and access issues make it just not worth the blood..
TECH Senior Member
Joined: Jun 2016
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From: Central Cal.
It will be impossible to do equal-length 8-4-2-1 headers in a front-engine car. Even over the top of the engine. And for what? Just the SOUND?? So much work for very little real outcome.
Pardon the necro-bump, but my question is related to this thread...... i have a 360 modena gated.... which I was planning to install the race version of exhaust..... it is the challenge stradale exhaust which came in the race car version of the modena. it is quiet normally, but when the valves open it dumps past the muffs. It is a cat back exhaust.
I'm in the middle of installing an ls1 into an E36...... and after a few beers started to look at the challenge stradale (modena exhaust), and wonder how it would sound behind the ls in the E36?
Has anyone tested an italian catback behind an ls..... any links or sound clips? Or should I just put the beer down, and go to sleep awaiting santa clause
wake up the next day and just do the normal swap cat back... magna flow etc.. etc... ??
Cheers guys.
Jeff - San Antonio
I'm in the middle of installing an ls1 into an E36...... and after a few beers started to look at the challenge stradale (modena exhaust), and wonder how it would sound behind the ls in the E36?
Has anyone tested an italian catback behind an ls..... any links or sound clips? Or should I just put the beer down, and go to sleep awaiting santa clause
wake up the next day and just do the normal swap cat back... magna flow etc.. etc... ??Cheers guys.
Jeff - San Antonio
If you want to hear an LS through Ferrari stock exhaust then fast forward to 14:40, saw this the other day on youtube at random
Last edited by 00pooterSS; Dec 27, 2018 at 11:07 AM.
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Exhaust 
TECH Fanatic
Joined: Jan 2018
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Notice how the primaries that run from the collector to the furthest exhaust port are almost a straight line, whereas the primary that runs from the collector to the nearest port takes a twisty path, wrapping around the other primaries... The key thing isn't flat-plane crank, or 8-1 merge, or 180 pairing - the key thing is having the same length from each exhaust port to the outside world, so you get equally spaced exhaust pulses at any RPM.
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Joined: Nov 2011
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From: jacksonville,fl
That is interesting that some have gotten the sound I'm wanting with just true equal length headers & a 2 into 1 merge.
I never did complete my tri-y's to try out, so I wonder if they could really give me the sound I'm after with just one more merge. I think I shot for an even 32.5" primary length
There just seems to be a shortage of good knowledge on this subject.
My application just does not have room under the engine for 180 pipes under it, even if I ovaled the pipes, plus equal length would be hard to do & primary length would be pretty long.
Getting equal length over the engine doing a correct 180 degree merging sequence seems easier to me than it was with my tri-y's pictured..I would need to make bolt together flanges for an over the engine setup to R&R reasonably easy, so that alone would be a little more work. I feel that I could combat the heat issues with MORE extra work, but no way to know for sure other than to try.
SO, if it is possible to get the sound with my tri-y's & a merge, then no doubt that would be the easiest route to complete them & have em ceramic coated after a sound test. Plus I could one day complete & use my cross ram dual plenum intake .
The CGS c-5 that I thought was 180 headers are just equal length 4 into 1's with a very custom merge & a handmade muffler AND A bad *** big bore destroked high revving engine. Part of the deal with any good 4 into 1 headers is having the correct firing order sequence going around in a circle. Can be left or right, doesn't matter.
I never did complete my tri-y's to try out, so I wonder if they could really give me the sound I'm after with just one more merge. I think I shot for an even 32.5" primary length
There just seems to be a shortage of good knowledge on this subject.
My application just does not have room under the engine for 180 pipes under it, even if I ovaled the pipes, plus equal length would be hard to do & primary length would be pretty long.
Getting equal length over the engine doing a correct 180 degree merging sequence seems easier to me than it was with my tri-y's pictured..I would need to make bolt together flanges for an over the engine setup to R&R reasonably easy, so that alone would be a little more work. I feel that I could combat the heat issues with MORE extra work, but no way to know for sure other than to try.
SO, if it is possible to get the sound with my tri-y's & a merge, then no doubt that would be the easiest route to complete them & have em ceramic coated after a sound test. Plus I could one day complete & use my cross ram dual plenum intake .
The CGS c-5 that I thought was 180 headers are just equal length 4 into 1's with a very custom merge & a handmade muffler AND A bad *** big bore destroked high revving engine. Part of the deal with any good 4 into 1 headers is having the correct firing order sequence going around in a circle. Can be left or right, doesn't matter.
Last edited by jlcustomz; Dec 27, 2018 at 09:56 PM.
Flat plane crank IS the important part. Cross planes have an imbalanced firing order giving an extra pulse per side and unequal timing at the merge point. That's where the rumble comes from. If all 8 header primaries go into a common merge then you don't have an imbalance the engine has continuous exhaust pulses like an 8-1 header.
A Y-pipe won't give this sound unless it is at the collector like the headers above have.
180 degree headers are not equal length - in fact they're full of compromises in anything but a mid engined race car. They give a flat plane sound with unequal length primaries.
A Y-pipe won't give this sound unless it is at the collector like the headers above have.
180 degree headers are not equal length - in fact they're full of compromises in anything but a mid engined race car. They give a flat plane sound with unequal length primaries.
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I agree that the rumble comes from unequal timing. But, if the primaries are all equal length, then why would the exhaust pulses arrive at the merge with unequal timing? The arrival time of each pulse only depends on the length of the tube between the exhaust valve and the collector.
TECH Enthusiast
Joined: Nov 2011
Posts: 609
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From: jacksonville,fl
Did some more looking into this & looking at David Campo's stuff. Part of what I was told to do anyways on my tri-y headers was extend the 4 secondary tubes. I guess I'll look into where I could possibly join the 2 sides together by curving the secondary portion of pipes together. As long as my headers are already, an extension could put them crossing over near the rear of my 6 speed, which would have more clearance.
Wonder why David's are for sale now?
Wonder why David's are for sale now?
Last edited by jlcustomz; Dec 28, 2018 at 08:42 PM.
