Need tips building my new exhaust

Jim K
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Re: Need tips building my new exhaust

Post by Jim K » Wed Mar 11, 2009 10:07 pm

For both 2.8 and 3liter na engines Bell gives 2.5" OD. Thats what I have on mine with two free-flow mufflers; no noise and no backpressure. If you're interested in headers, primaries 42mm OD, secondaries 52-55mm OD with the CSC lengths being correct for all around street/trackday use.
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Mats
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Re: Need tips building my new exhaust

Post by Mats » Wed Mar 11, 2009 10:54 pm

Greg Gordon wrote:When I get home I will take a look and post some pictures. If Jim says a 2.5" pipe will fit then it will. However, it must be difficult, because I have three different Milano exhaust systems at home and all have 2.0" pipes that barely fit.

Greg
At least call me a liar to my face will you. :x

:D
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Re: Need tips building my new exhaust

Post by Greg Gordon » Thu Mar 12, 2009 9:05 am

Mats I am not calling you a liar. I have no doubts you got a 2.5" pipe in there. I would just like to see it.

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Re: Need tips building my new exhaust

Post by Micke » Thu Mar 12, 2009 9:42 am

If I recall right the Q4 has 2.25" OE size. So, this must be enough for 232 hp.
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Mats
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Re: Need tips building my new exhaust

Post by Mats » Thu Mar 12, 2009 12:59 pm

Greg Gordon wrote:Mats I am not calling you a liar. I have no doubts you got a 2.5" pipe in there. I would just like to see it.

Greg
Actually, I said 3". 8)

Found some old scans, before digital cams...
Not very good but they show what you want.
Attachments
back-box.jpg
3" + old Supersprint back box.
back-box.jpg (204.34 KiB) Viewed 4210 times
back-box-mounted.jpg
3" right next to the caliper and AR-bar.
back-box-mounted.jpg (239.68 KiB) Viewed 4211 times
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Re: Need tips building my new exhaust

Post by Greg Gordon » Thu Mar 12, 2009 1:52 pm

Thanks Mats, that looks really good. I am going to try and shove a similar setup into a car soon. I didn't think it would fit.

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Re: Need tips building my new exhaust

Post by Mats » Thu Mar 12, 2009 11:41 pm

It does. With a low car you will have some interference with the nut on the AR-bar but that is basically only when going over speedbumps and such excursions.
Keep the pipe close to the body and you need some stiff mounting points to keep it in check. It will give you some noise through the bodywork but I guess we're talking about a car that won't be used to go to the grocery store? :wink:
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Re: Need tips building my new exhaust

Post by Jim K » Sat Mar 14, 2009 10:06 am

I had the car up on the lift today and checked around the rear part of the 2.5" exhaust pipe. There is definitely room for a 3" pipe, no problem, without crushing at all. With a lowered car, both 2.5 and 3"pipes will be too low somewhere in front of the gearbox but a separate flat and wide section with conical ends (with the same area as the pipe) should take care of that. As Mats says, a somewhat rigid mounting arrangement is necessary to prevent the system from banging around.
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Re: Need tips building my new exhaust

Post by Mats » Sat Mar 14, 2009 1:05 pm

Like this you mean?

2" pipe sliced along it's lenght and sheet metal added to keep the cross section equal to a 3" round pipe.
Attachments
middle.jpg
Space saver.
middle.jpg (225.78 KiB) Viewed 4104 times
middle-mounted.jpg
Below the gearbox crossmember
middle-mounted.jpg (147.95 KiB) Viewed 4108 times
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Re: Need tips building my new exhaust

Post by Jim K » Sat Mar 14, 2009 1:51 pm

Yes, something like that but with longer tapered sections before and after.
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Re: Need tips building my new exhaust

Post by Mats » Sat Mar 14, 2009 3:02 pm

Never pleased, are you..? 8)

:wall:
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Re: Need tips building my new exhaust

Post by Flame » Mon Mar 30, 2009 11:18 am

One more photo of a 3" pipe over the de-dion on my gtv turbo, it fits whitout cuting and it dosent make contact whit body or caliper.
Image
Alfa gtv 1.8T -86
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Re: Need tips building my new exhaust

Post by killaz » Sun Aug 16, 2009 12:12 am

Whats the point of 3' pipe when car is n/a and has less than 300 hp? I was reading some articles related to build up of exhaust system and it clearly says that gases are cooled down enough just after 1,5 meters where you can switch to 2,5' pipe. And still, that would be enough for up to 300 hp.

Have a friend in Sweden that drives Saab with 3' piping, but his car is turbo and makes 400 hp / 500Nm.
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Re: Need tips building my new exhaust

Post by Mats » Sun Aug 16, 2009 12:37 am

Where did you get the impression that we were talking about N/A cars? 8)
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Re: Need tips building my new exhaust

Post by Bruce » Sun Aug 16, 2009 3:47 am

... possibly by the O.P.
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