Gaz6002 Posted April 24, 2008 Share Posted April 24, 2008 I've got a noise tester and I'm soon to have screamer plumbed back in and a Nur Spec RX (the quiet one). I'll report back on my findings. Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted April 24, 2008 Share Posted April 24, 2008 Chris, what do you think to adding a baffle to the wastegate, as a quick & dirty fix Vs plumbing it back into the exhaust? Someone suggested this to me recently and claims it works fine on his single Supe. Ridiculous idea, it may well cause boost creep, it needs either plumbing back in properly, or a silencer fitting to the wastegate discharge pipe (no room, weight to support, heat expansion to accommodate, messy and extra complication are potential issues with that idea). A turbo kit that vents the `gate to atmo' is done like that `cos it's cheap to make and people can be suckered into thinking it sounds "cooool". To a copper it sounds like a wake up call to get the gun sighted up, and to a noise scrutineer it sounds like an excuse to empower himself and spoil your day, and cost you a packet (IMHO). Quote Link to comment Share on other sites More sharing options...
paul mac Posted April 24, 2008 Share Posted April 24, 2008 Not sure how my comments suggest that a Nur Spec is more of a restriction than a stock system? . i meant an aftermarket exhaust with a baffle fitted Quote Link to comment Share on other sites More sharing options...
Gaz6002 Posted April 24, 2008 Share Posted April 24, 2008 Ridiculous idea, it may well cause boost creep, it needs either plumbing back in properly, or a silencer fitting to the wastegate discharge pipe (no room, weight to support, heat expansion to accommodate, messy and extra complication are potential issues with that idea). A turbo kit that vents the `gate to atmo' is done like that `cos it's cheap to make and people can be suckered into thinking it sounds "cooool". To a copper it sounds like a wake up call to get the gun sighted up, and to a noise scrutineer it sounds like an excuse to empower himself and spoil your day, and cost you a packet (IMHO). Out of interest Chris, I've done a bit of digging myself and have some information but what would you say are the criteria for recirculating the dump pipe "properly"? I am aware that you want as shallow an angle as possible going into the down pipe, but is there anything else to consider? Quote Link to comment Share on other sites More sharing options...
SteveR Posted April 24, 2008 Share Posted April 24, 2008 lol cheers Chris, that's my mind made up then. Cheers Si - I'l take a look at the pics anyway (at home - can't get to my hotmail here) Quote Link to comment Share on other sites More sharing options...
bignum Posted April 24, 2008 Share Posted April 24, 2008 Out of interest Chris, I've done a bit of digging myself and have some information but what would you say are the criteria for recirculating the dump pipe "properly"? I am aware that you want as shallow an angle as possible going into the down pipe, but is there anything else to consider? You want a flexi joint of some sort ideally stainless to allow for expansion, this is something i`m looking into also. Quote Link to comment Share on other sites More sharing options...
Gaz6002 Posted April 24, 2008 Share Posted April 24, 2008 You want a flexi joint of some sort ideally stainless to allow for expansion, this is something i`m looking into also. Good point. These things are never that easy. Quote Link to comment Share on other sites More sharing options...
b.weeks Posted April 24, 2008 Share Posted April 24, 2008 Anyone know how "strict" they are at Donington? Was there the other week for Donington and there were some seriously loud cars (over 105dB which is s'posed to be the limit). They may have been letting it go or had clearance from the Council for more noise that day. However, I would like to go back on a regular track day ... but the limit is 98dB (static) - they don't say how loud you can be on the drive by. I have a Greddy Ti exhaust, external wastegate, double d-cat and single. So I'm pushing it! I have a baffle that I can stick in for the test - but won't run with it ;-) Anyone any ideas? Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted April 24, 2008 Share Posted April 24, 2008 Donington still have the occasional noise limit free days, but they are a bit pricey. They are strict, all circuits with noise limits are strict as some jobsworth from the local council gets his jollies from finding a car running over the limit. it's not the circuits to blame, other than they should have fought it instead of rolling over, it's the local councils who see fit to support residents that buy houses near established motor racing circuits, then whine they can hear racing engines. Quote Link to comment Share on other sites More sharing options...
b_have Posted April 24, 2008 Share Posted April 24, 2008 You want a flexi joint of some sort ideally stainless to allow for expansion, this is something i`m looking into also. I played around with making motocross style perforated baffles, inserted into a superdragger. Made a substancial difference,but still around 100db. Eventually bit the bullet and re-routed the wastegate back into the dp and fitted a Tanabe. Almost as quiet as stock now. Quote Link to comment Share on other sites More sharing options...
b.weeks Posted April 24, 2008 Share Posted April 24, 2008 Probably getting off topic but any performance gains from having an external wastegate? Done a search and mentions about noises etc., but not any mention of performance gains. Quote Link to comment Share on other sites More sharing options...
b.weeks Posted April 24, 2008 Share Posted April 24, 2008 Also, is it an option to run with the baffle and keep an eye on EGT and just stop if they get high? Or are there other problems doing this could cause? Quote Link to comment Share on other sites More sharing options...
matt k Posted April 24, 2008 Share Posted April 24, 2008 I've heard a nur spec on full de-cat and it wasn't that loud imho. Quote Link to comment Share on other sites More sharing options...
bignum Posted April 24, 2008 Share Posted April 24, 2008 I've heard a nur spec on full de-cat and it wasn't that loud imho. Joking, mine failed twice @ donington, Quote Link to comment Share on other sites More sharing options...
Wez Posted April 24, 2008 Share Posted April 24, 2008 Probably getting off topic but any performance gains from having an external wastegate? Done a search and mentions about noises etc., but not any mention of performance gains. I have heard arguments that keeping the wastegate exhaust pulses separate from the main exhaust allows for better spool blah blah blah but I noticed no decrement in performance when routed back and neither did Ryan as far as I am aware. It does take the raspy race car feel away a little though. Quote Link to comment Share on other sites More sharing options...
Wez Posted April 24, 2008 Share Posted April 24, 2008 Also, is it an option to run with the baffle and keep an eye on EGT and just stop if they get high? Or are there other problems doing this could cause? Depends on the baffle, I only use the Veilside baffle when driving round housing areas when its late, I certainly dont give it any stick. I did try once and managed less than 1bar boost with high EGTs when I normally run 1.4bar and good temps. Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted April 24, 2008 Share Posted April 24, 2008 Is that a stock cat flexi section? That's what you neeed though, a flexi section to allow for different expansion in the pipe sections. otherwise.... cracks. Welding a cracked stainless tube rarely works as the weld is contaminated by the carbon in the crack, from the exhaust gasses, they always seem to just crack again. Avoiding cracks in the first place is the secret. Quote Link to comment Share on other sites More sharing options...
b_have Posted April 24, 2008 Share Posted April 24, 2008 Is that a stock cat flexi section? That's what you neeed though, a flexi section to allow for different expansion in the pipe sections. otherwise.... cracks. Welding a cracked stainless tube rarely works as the weld is contaminated by the carbon in the crack, from the exhaust gasses, they always seem to just crack again. Avoiding cracks in the first place is the secret. It is. The oem flexi seems better quality than any aftermarket stuff I looked at and happens to be an ideal size to work with my 60mm wg. Quote Link to comment Share on other sites More sharing options...
b.weeks Posted April 25, 2008 Share Posted April 25, 2008 Depends on the baffle, I only use the Veilside baffle when driving round housing areas when its late, I certainly dont give it any stick. I did try once and managed less than 1bar boost with high EGTs when I normally run 1.4bar and good temps. What did you get your dB down to mate? NB when I was at Brands Hatch they did a static test on me - as only one guy testing I just put it at 3000 rpm ... and that was still 98dB with a superdragger exhaust - now have a GReddy Ti. Quote Link to comment Share on other sites More sharing options...
Wez Posted April 25, 2008 Share Posted April 25, 2008 H&S measured it at approx 92db at 3500rpm when they fitted it. Quote Link to comment Share on other sites More sharing options...
Gaz6002 Posted April 25, 2008 Share Posted April 25, 2008 H&S measured it at approx 92db at 3500rpm when they fitted it. Do you know how they measured it? Quote Link to comment Share on other sites More sharing options...
Wez Posted April 25, 2008 Share Posted April 25, 2008 With a sound meter stood behind the car at approx 1m. Quote Link to comment Share on other sites More sharing options...
Gaz6002 Posted April 25, 2008 Share Posted April 25, 2008 With a sound meter stood behind the car at approx 1m. That's damn quiet then!! Money well spent there. Have you been tested at any tracks or done noise restricted laps? Quote Link to comment Share on other sites More sharing options...
Wez Posted April 25, 2008 Share Posted April 25, 2008 That's damn quiet then!! Money well spent there. Have you been tested at any tracks or done noise restricted laps? Nope but the car is so much quieter, even with the carpets etc removed. Quote Link to comment Share on other sites More sharing options...
b.weeks Posted April 25, 2008 Share Posted April 25, 2008 It does take the raspy race car feel away a little though. Are we talking just noise here? Quote Link to comment Share on other sites More sharing options...
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