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  #46 (permalink)  
Old 11-30-2012, 03:27 PM
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Originally Posted by ap72 View Post
And how exactly do you calculate the right length for the X-pipe?
H pipe and x pipe either one will need to be with in the range os tuned exhuast length at max tq peak. Which on a car with properly built headers will leave them right at the end of the collectors.

Now for balance both are usally moved out further H pipe will work better a little further back.
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Old 11-30-2012, 07:14 PM
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Yes but i grabbed the c6 video cause you need an engine with high rpm redline, high compression and long gears. Most american cars are geared short when compared to euro toys. They make a system that give the same sound to the c4 as well. But c4 is short gear long stroke and lower compression so you dont get as close to what your looking for.

Borla has been building exhuast with the euro sounds for american cars for many years. It was there claim to fame back in the day.

Hear is what i am saying alot of the sound comes from the muffler. All ferrari sound good right even ones from the 60's before they had x pipes and tri Y they still had the ferrari sound. Most of the rear engine ferraris i have crawled under had dual in and out but single muffler.

If you remove the mufflers from a ferrari they sound as bad as any car uncapped. They sound loud and flat. Now the newer cars with cats and more complex exhuast still hold some of the sound as they have a lot of restrictions in the exhuast. I have removed the exhuast from a few of them and was sure to start the car with the pipes off. Just blah shift blahhhhh. Same as any car without the pipes. Putting quiet mufflers is also bad. You could not belief how much noise there engines make. Loud exhuast actually hides a very ticky tappy engine.

The reason i was asking question is if you calculate x pipe location it usally falls under the trans and does not fit there. For most cars you end up needing to put it where it fits not where its perfect for performance. Your really looking for a musical note in the right octave. You probably want to tune the x pipe for that note not the mathmaticaly perfect location for performance. Ferrari are not tuned for total performance they are tuned to make rich guys happy. Also a high rpm v6 may sound closer to a v12 than a v8. Just trying to help.
wow- le sigh.
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Old 11-30-2012, 07:16 PM
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And how exactly do you calculate the right length for the X-pipe?
Agreed... there would be actual math to figure this out. The biggest problem is the varying temperature which will vary the speed of sound. At least in my opinion. There would be too many assumptions i believe.
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Old 11-30-2012, 07:36 PM
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Agreed... there would be actual math to figure this out. The biggest problem is the varying temperature which will vary the speed of sound. At least in my opinion. There would be too many assumptions i believe.
You can refer to Bells book for the tune exhuast length.
Amazon.com: Four-Stroke Performance Tuning: Fourth edition (9780857331250): A Graham Bell: Books Amazon.com: Four-Stroke Performance Tuning: Fourth edition (9780857331250): A Graham Bell: Books

Yes there is plenty of math. More than i am going to try to teach over this format. He really just touches the subject. Its usally not to important on car since you will normally buy pre fabbed headers and normally they are tuned for middle of the road performance. Fyi i have seen that book in pdf on the net.

I understand why your tuning the headers to tweak the exhuast note just dont think the x pipe is the answer your looking for.

If you are sure temp is the answer buy an egt and some pipe and start testing. egt will give you the real temp inside the pipe the outside pipe temp is not the same as the gas temp. If your trying to calc a factor of mach usaly called z factor but not sure if that is the proper term or just var. to get the air speed inside the center of the pipe you willl need the gas temp.
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