Figure11 Posted September 16, 2007 Report Share Posted September 16, 2007 Ok got the car booked in. Couple more questions the mechanic asked: What size pipework do I want? What do you reckon? 2.5, 2.75 or 3" front to back or a mix? Twin round center boxes or single large oval? Any help appreciated I don't know much about the theory of exhausts. Mike Link to comment Share on other sites More sharing options...
LostKiwi Posted September 16, 2007 Author Report Share Posted September 16, 2007 I would say not to go bigger than standard as you are already significantly reducing back pressure by going freeflow. I've used a single large dual in/out oval centre box and an even bigger rear dual in/out oval box, but one of my goalks was not to make the car too noisy (and given you are already reducing the number of silencer boxes from 3->2 AND reducing the back pressure by using free flow boxes as opposed to baffled boxes this is something to be aware of). Using single boxes in pairs will almost certainly maintain more of the classic V8 burble if this is what you want. Probably a lot harder to mount though and given space is at a premium it may not be that feasible to put big enough boxes in to keep the noise levels reasonable. In terms of power etc there is not likely to be anything in it. Link to comment Share on other sites More sharing options...
Figure11 Posted September 16, 2007 Report Share Posted September 16, 2007 My current intention is to have a duel in duel out center box and 2 single in single out tail boxes with a duel tail pipe to get the AMG look. If he has a single in duel out with the oval exhaust tips then ok. Will see on the day. I take it that with a free flow exhaust the bigger the centre and rear boxes the quieter the sound? I would like to deepen and accentuate the rumble without increasing the Db. Mike Link to comment Share on other sites More sharing options...
LostKiwi Posted September 16, 2007 Author Report Share Posted September 16, 2007 Apparently the bigger the first box the quieter it is... The more silencing close to the manifold the more effective it is. Mine is definitely louder than standard (but not too unpleasantly so). Link to comment Share on other sites More sharing options...
LostKiwi Posted September 24, 2007 Author Report Share Posted September 24, 2007 You had it done yet??? Link to comment Share on other sites More sharing options...
Figure11 Posted September 24, 2007 Report Share Posted September 24, 2007 Got it booked in just before Xmas. Has to be a working day when I am not working. Don't get many of those! The chap has agreed to let me spend the day with him and document and photograph the process, so I'll do a write up on here when it's done. Mike Link to comment Share on other sites More sharing options...
EddyH Posted April 22, 2008 Report Share Posted April 22, 2008 Did this happen? I'm wanting to get a quad outlet exhaust and I'm just wondering how to spec it. I've found somewhere to do it for what I think is a reasonable price but just want to make sure I get it right. Link to comment Share on other sites More sharing options...
Figure11 Posted April 22, 2008 Report Share Posted April 22, 2008 It didn't. A family emergency swallowed up all the money. I'm trying again the week after next. I'll keep you all informed. Mike Link to comment Share on other sites More sharing options...
Figure11 Posted May 2, 2008 Report Share Posted May 2, 2008 Well I finally got round to it! Decided on the DIY route, so got a mate with a Mig welder and bought a load of bits from Jetex. Got the car up on ramps and stands got started and both looked at each other after 60 fruitless minutes and then went to the local powerflow!!!! The guy there was a diamond. More than happy to help me. 3 hours later using my silencers and pipe we were finished. Here is the result..... And here is what it sounds like.. make sure you speakers are turned up LOUD!!! I know the left one is a bit outa shape. Prolly settled as I drove home. I came home in a gear lower than I should all the way with the biggest grin on my face. Now I have to teach myself plastic welding as they are set wider than normal with small cylinder cans at the rear; so gotta sort out the rear valence (MkOneman are you out there?). It was a useful experiance and the silencers are off the shelf. They big ones aren't a thing of beauty and are a smidgen below the body line, but the x pipe Shane at Plymouth Powerflow fabricated and the sound more than make up for it! Mike Link to comment Share on other sites More sharing options...
EddyH Posted May 2, 2008 Report Share Posted May 2, 2008 I'm curious as to how the extra backbox is mounted as I assume there are potential problems with galvanic corrosion if a steel hanger is welded to the aluminium frame. I'm hoping to sort a quad outlet exhaust soon but think I want a facelift rear bumper first. Link to comment Share on other sites More sharing options...
Figure11 Posted May 2, 2008 Report Share Posted May 2, 2008 The exhaust is not welded to the frame. It is hung on rubber hangers to dampen vibrations. On the drivers side I removed the tow bracket and bolted a rubber exhaust donut onto it and the Powerflow guy welded a hanger to the back box and hung it from there. Mike Link to comment Share on other sites More sharing options...
Oli18 Posted May 2, 2008 Report Share Posted May 2, 2008 Hey mike, That looks SERIOUSLY cool dude!!!!!!!!! Very jealous and can't wait to see and hear it in person at Billing! -Oli Link to comment Share on other sites More sharing options...
A8_Tony Posted May 3, 2008 Report Share Posted May 3, 2008 I feel a bit of a sound off coming on at Billing Looks sweet Mike :D but where's the pics? Link to comment Share on other sites More sharing options...
Figure11 Posted May 3, 2008 Report Share Posted May 3, 2008 I feel a bit of a sound off coming on at Billing Looks sweet Mike :D but where's the pics? Mmmmmmmm sound off! Only if it annoys the campers! As for the pictures in all the confusion I forgot to take my camera. Doh. All I got was this on my phone This is the x-pipe going in. The rest is not particularily photogenic but next time I'm under the car I'll get some. Mike Link to comment Share on other sites More sharing options...
Botang Posted May 6, 2008 Report Share Posted May 6, 2008 Sounds lovely Mike! Link to comment Share on other sites More sharing options...
Figure11 Posted May 6, 2008 Report Share Posted May 6, 2008 Here’s the photos from under the car The X Pipe replaced the H-Pipe. But is attached to the cats with U bolts so I can fiddle. The centre box has been replaced by 2 individual boxes canted at 45 degrees to fit in. Hangs below the body line a bit, but again I will fiddle with it to get it right. The branches then split and go either side of the spare wheel well following the chassis lines to the rear bumper. Two small cans then attach the tips to the end of the system. I am removing the spare wheel well tomorrow and replacing it with a custom built fibreglass well that I am building. This will also allow more room at either side for bigger silencers should I need it. You can see I removed the heat shielding here as I don't think it is needed. The can is much smaller and only dealing with half the gases. Things still to do are fabricate polished stainless surrounds to attach to the rear valance to cover my inept hacksaw work. Plastic welding of rear valence to match up both cut outs. Fit another hanger to take the weight of the system where it splits round the spare wheel well. Here's where I got the bits: http://www.jetex.co.uk/index.php There is a North America connection. These are the bits: Not yet used: May swap these in and move the 2 centre boxes to the back if I fail noise regs. I'll wait until the Boys in Blue suggest it tho. Two of these: and two of these Plus lots of 2.5 inch pipe bends etc. Mike Link to comment Share on other sites More sharing options...
ant Posted May 6, 2008 Report Share Posted May 6, 2008 looks fantastic mike Link to comment Share on other sites More sharing options...
las247 Posted June 28, 2008 Report Share Posted June 28, 2008 Was just discussing doing this yesterday with a mechanic friend of mine, very helpful thank you. Link to comment Share on other sites More sharing options...
Duffy3074 Posted June 28, 2008 Report Share Posted June 28, 2008 Sounds excellent Mike, how is it at speed with the windows up, too noisy for the munchies in the back or relatively subdued. Nice piece of work! Link to comment Share on other sites More sharing options...
Figure11 Posted June 28, 2008 Report Share Posted June 28, 2008 The only time I find the noise bothersome is at low speed when the engine comes under load. Change down and its problem solved, but that means that you are generally in a gear lower than prudent fuel economy dictates. When I did my advance driver training with a police instructor, that was his main criticism of my low speed driving style. The V8 can get higher up the gearbox quicker. At speed you can hardly tell the difference. I took my wife and her friend to see Neil Diamond in Cardiff last week and they had no issues with the noise in the back. At 120 (kph of course) the could still talk and drink their wine in peace and quiet. Under hard acceleration who gives a feck about the volume, it's all about the sound! :D I will however probably move the centre boxes to the end and fit the long resonators I got to achieve a lower octave anyway. Mike Link to comment Share on other sites More sharing options...
LostKiwi Posted June 28, 2008 Author Report Share Posted June 28, 2008 Yep, same thing I noticed Mike... the only time it get annoying is high gears and low revs. Cruising is fine. Full throttle is glorious! :D Apparently the closer to the collector you can get with a silencer the smaller the silencer can be. Don't know how true this is though. Having said that my old 3.9 Rangie has a big box fitted just after the 'Y' joint from the two sides and given the box is about half the size of the one on my Audi and the rear box is less than a quarter the size of the Audi's its actually a lot less boomy down low (but still raucous up high) :D Could also be a function of pipe size too - 2x2.25 vs 1x2.25.... Link to comment Share on other sites More sharing options...
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