My 2bular special

The Oily Bits S2 Specific Topics
1

With the extra volume and heat of the SC I had been talking to Jim about trying to increase the flow by going to a larger diameter. Jim wanted to cut my original zaust up to see how it had done with the extra flow. The Bemani kit runs a 3inch diameter up to after the U-bend so the cat went back to Jim to have the taper replaced and run a 3inch through the whole system.
Friday night was fitting time as I was at KH at the weekend and boy is it a mean zaust Jim has made
[image]http://i6.photobucket.com/albums/y201/jamieall/IMG_2190.jpg[/image]
[image]http://i6.photobucket.com/albums/y201/jamieall/IMG_2189.jpg[/image]

Once on the car the true size of the beast is clear
[image]http://i6.photobucket.com/albums/y201/jamieall/IMG_2192.jpg[/image]
For me I think I would like the tip to be trimmed so its not so prominent but it went well at KH and seemed quite quiet but will get the db rating soon.

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[image]http://i6.photobucket.com/albums/y201/jamieall/IMG_2194.jpg[/image]

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Can’t wait to hear a sound clip - it’s the first Exige I’ve seen with an afterburner.

5

nice one Jim/Jamie looks and I’m sure goes!

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Yes it certainly got a lot of attention at Knock Hill I caught a certain reprobate fisting my zaust at KH

7

Thanks guys! Hoo - that’s some tip. There is a reason for it though.
When I first got a look at the Bemani install on Jamie’s car at Knockhill a few weeks ago, I was puzzled by the taper (from 3"dia down to 2.5"dia) just after the 180deg bend from the Cat. The outlet on the manifold/header is 2.5"dia, maybe they thought that bend would reduce back-pressure…but it’s an awkward looking fabricated/welded join between two bends, not constant radius and …er,ok.
Anyway, I wanted a look inside the existing 2bular silencer as some heat marks were appearing - not unexpected after a 100bhp increase. It’s a 2.5"dia core pipe and TBH, should be more with that output but noise regs have to be taken into account.(I have this same size silencer doing some R&D on a Honda Supercharged install at the moment - the owner says it’s too quiet!) Bringing the dia of the rest of system up to 3" would slow down the gas speed and drop the temps inside the silencer but with an increase in core pipe dia comes an increase in noise. I also added a couple of inches to the length of the silencer body - now 24", that’s all you can fit between the “tunnels” on the diffuser (nice work BTW Dave!).
I added the large tip because I might want to fit an insert (hence the holes in the tip). The tip will then act like a Heimholz resonator and it has to have a decent dia to work effectively. I will be making a De-Cat pipe for the Bemani install and the insert is just a possible noise reduction device.

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and erm, yeh, I’ll have to trim back a bit on the tip! Wrong guesstimate on the diffuser length - I’ll blame Ali

9

Had a good day at a sprint today here is a clip of the new zaust and noise reading came in at 98-99db without db killer. An evo owner asked me to measure his 105db at idle and 110db at 5500rpm

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mmm… not having much luck… this says the video ain’t available yet…

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Working now

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sorry jamie…you are on standard induction yes? I was at Rockingham today hoping to get a noise test but forgot! …and are you runnig the “swap out / swap back” decat pipe or a straight through?

but I’m due at Bedford soon so I need to get one done. I dont know whether its just a richer sound! and judging by your video no louder!

13

That db rating was standard induction and sports cat. Which zaust size do you have again?
This zaust is louder than the last and at the noise reading I would be worried about going to a 98db TD as all you need is the wrong wind etc and you are over the limit. Did not have the db killer with me but hope that pould produce a 97db rating will have to wait and see.

14

I think I’m GT3 8", with swap in/out cat and Daytona induction!

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With the cat in you should be around the 97db not sure what the induction kit will do to that though