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PostPosted: March 16, 2018, 11:06 pm 
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Just about to start building a new exhaust system, from the V band on the header to the tip. What are peoples thoughts on exhaust tips and the direction of the outlet? Noise is the big issue so I was think 45 degree downward angle and a slash cut tip. Will 45 degree downward case reflection from the road, is straight out away from the vehicle better. Will actual exhaust tips help noise or just slash cut the exhaust pipe.

What are people thoughts?

Thanks

Graham


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PostPosted: March 17, 2018, 9:19 am 
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Graham, I found that turning the exhaust outward helped a lot. When aimed straight back at the rear fender was the worst. I read somewhere, maybe here, that directly down toward the road gives noise reflections that should be avoided. My guess is that a slash would act as the shorter of the lengths. Exhaust pipe after the muffler is good for noise reduction. Unless you are running the exhaust under the car and out the back, which a few have done, there is no way to do that.

Thicker steel header/exhaust tube should also help a small amount at the cost of adding weight. CRS is a bit less harsh sounding quieter than SS in that matter.

That's the best I can offer. For a track car trying to beat the noise meter, maybe getting it out the left side would help. If your already on the left side and want to reduce driver's noise, relocate to the passenger side.

Managing exhaust noise is part science, part black art. Good luck.

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PostPosted: March 17, 2018, 9:39 am 
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What's a V band?

I put a down-and-out-and-back bend in mine, about 45 degrees on each axis, and cut the tip at whatever angle it took for the plane of the cut to match the car's direction of travel...that cut was an aesthetic choice, so YMMV, but I thought it looked cool so that's what I did.

As far as reflection I think that's a non-issue (the exhaust gas hits the ground about 6" away from the car and is reflected up and away, and I trust the same goes for the sound; it's quieter for the driver with that tip than without) except for something I rather enjoy: it blows dirt, leaves, and other light debris, off the road and away from the car. It's a tiny bit unusual and a tiny bit aggressive, one more reason to give the 4 x 4 guys my "What are YOU looking at?" glare. Of course, with 32 horsepower, I need all the aggression I can get...

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PostPosted: March 17, 2018, 11:13 am 
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Jack a V-band is an exhaust clamp were you weld two flanges to the end of the pipes and there is a band that hold then together. An exhaust joint that you can undo in seconds and is air tight. I think they were first used in the turbo world so you could quickly get the turbos in and out.

http://www.mandrelbends.com/v-bands-ban ... blies.html

An out the back exhaust was the preferred option, but time is against me, so that will be on next years list.

I think the slash cut tip helps because the sound wave does not arrive at the and on the pipe all at the same time, there is a staggered timing, I am sure the effect is tiny but every little helps.


Graham


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PostPosted: March 17, 2018, 1:57 pm 
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I am sure the effect is tiny but every little helps.


This is a case where there is so much noise, little bits don't help much. Humans have such good senses, reducing the sound level by half is only just barely discernable to a person. They measure these things on exponential scales.

The biggest effect comes from having some resistance after the muffler. So moving the muffler towards the V band will help a great deal, every single inch. Having a 90 degree bend after the muffler also helps a great deal. The idea is you need some resistance after the muffler to force the exhaust gasses to dissipate and spread out over time in the muffler. This should not really affect your power.

Sport motorcycles achieve amazing power levels in stock form and yet make little noise. They tend to have small muffler exits. Many street cars have fake exhaust exits that look big, but if you are stopped behind a Porsche or BMW or other high powered car and can look up the tailpipe you will see the exit from the muffler is rather small.

Maybe you can get a little collection of 90 degree bends with a reducer after them or welded up with a piece of a reducer and experiment until you get what you want. You can probably buy those parts for playing with for $10... Then make sometthing nice.

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PostPosted: March 17, 2018, 1:58 pm 
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If you've not seen it, this is a good post about exhaust. Not sure if you are trying to meet a certain limit, or just make the car more pleasant.
viewtopic.php?f=27&t=17503

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PostPosted: March 19, 2018, 9:35 am 
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Went for bigger is better:)

Graham


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PostPosted: March 19, 2018, 4:30 pm 
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That's the ticket. I'm in the process of rebuilding my exhaust right now with a giant 24" muffler to replace the tiny 15" model I thought would be enough when I first built the car. I've lived with the noise for almost 5 years and 50K miles, but haven't quite gotten used to it.

A couple of years ago I tried adding a SuperTrapp at the end of the exhaust. It was quieter, but looked terrible and the exhaust sounded tinny. When it fell off on the freeway I didn't stop to go back and retrieve it.
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PostPosted: March 20, 2018, 1:26 am 
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At least as far as mufflers go, bigger is better is generally a good philosophy.

Personally, I'm a big fan of having a cat in the exhaust too. It's pretty much all benefits, including quieting things a bit. There's really no reason not to on any modern EFI engine. They make some pretty small ones that might still be able to fit in the remaining space as well.

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PostPosted: March 20, 2018, 7:40 am 
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If you have the ground clearance or space along the side of the wheel, running the exhaust out the rear makes a BIG improvement.
DaveW


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PostPosted: April 28, 2018, 5:08 pm 
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Mine ended up being reasonably quiet, or at least not loud enough to bother my wife so far. its 2.5 inch from the turbo into an oval magnaflow which then goes into a 5 or 6 inch round magnaflow. This exits and goes through a cuttout on the back of the rear fender and exits straight to the side between the wheel and the front of the fender. The first muffler is hidden by the front fender as is part of the second. you could roll a tennis ball through the entire exhaust.
Dale


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PostPosted: May 1, 2018, 10:46 am 
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Get a turbo engine ...the only "built in" muffler that makes more power as well :mrgreen:

Seriously: what i learned building mid-ship engine V8 buggies is that turn downs tend to boom right back up (unless exit is all the way back)
Anything exiting before the rear axle is loud for the occupants ... extending the exhaust all the way to the back was really the only quiet solution without choking the engine.

Btw my Truck is twin straight 5" stacks ( no muffler besides turbo) ... fairly quiet on the freeway, unless your foot is in the tank and/or your under an overpass/tunnel :shock: lol


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PostPosted: May 1, 2018, 4:07 pm 
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Location: BC, Canada. eh?
I'm using a Yamaha R1 all-titanium muffler on mine. I have absolutely NO idea how loud (or quiet) it's going to be, but I'm...um...hopeful it will be livable. Supposedly, it has a small 'cat built in, which may help.

I added a polished stainless steel side turn-out, about 75* or so from the muffler, so that the turned-out section is parallel to the front edge of the rear fender. It's closer to the fender than I like (only about 1" away), but I'm hoping the exhaust will have cooled somewhat via the rest of the system.

Even so, I'll be adding stainless "stone panels" to the front of the rear fenders, which will hopefully reduce any issues with exhaust heat on the left fender.

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PostPosted: May 2, 2018, 3:01 pm 
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zetec7 wrote:
I have absolutely NO idea how loud (or quiet) it's going to be, but I'm...um...hopeful it will be livable.

I have some idea. Livable is relative.


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PostPosted: May 14, 2018, 10:47 am 
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Finally got the car up and running with the new exhaust. It work great, the noise is dramatically reduced, a much lower tone, it's still straight thru, but this one has chambers. I was running a SuperTrap muffler to reduce the sound with the old setup, removing that along with the new inlet manifold has made a huge difference on power especially the mid range. It was fast before but now it's crazy fast. I am not sure I like the visual image, the proportions are not good, but you cannot beat the results.

Graham


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