997 GT3 Sharkwerks noise level for Oulton - Page 2 - 911/Carrera GT - PistonHeads UK

My new to me 997 GT3 has a Sharkwerks bypass. It sounds great and not too intrusive when cruising. I'm doing the RS track day at Oulton and have no experience with noise levels. Will it have a problem with the noise test? Is it only static on an Oulton track day or is there drive-by as well? Thanks Bert

Unlikely to pass the static test. X pipe on a GT3 (assuming the side cans are still there) blows about 109db+. . You may get close to the 105 static limit by fitting a bolt on external muffler option but even then..

Bugger, bugger, bugger. I'll get out my noise meter and do a mock test to see how it does. It doesn't seem super loud. I'm sure my engine only revs to 7200 Bert

You can also cap the vacuum solenoid thing and it will stop the valves switching in the side cans, might help a bit as it will force the gasses through the whole silencer all the way up the Rev range.

So two questions...where to get the bolt on muffler? I assume you unbolt the exhaust tips and fit some other widget? Then how do you change the solenoid thing to stop the valve from opening? Cheers Bert

Try this, but not sure it will bolt to your x pipe as it’s designed for a std back box. https://uber9s.com/product/gt3-trackday-silencer/ Or look at decibel devils, these will need a mod/tweak to fit though as won’t sit deep enough. In the rear there’s a solenoid that operates the switchable exhaust, it’s in a rubber mount, top, right hand side of the engine. On the bottom of it there’s an air inlet about 5mm dia . Plug this up with one of those plastic caps used to seal off vacuum pipe, on eBay somewhere and cost pennies.

Just had a thought on this. How hard is it to put the standard back box on? Can it be done without loosening/removing the rest of the system? As I have the old box, it might be a simple option. The depends on whether it is simple/quick! Bert

BertBert said: Just had a thought on this. How hard is it to put the standard back box on? Can it be done without loosening/removing the rest of the system? As I have the old box, it might be a simple option. The depends on whether it is simple/quick! Bert Switching back to the OE silencer is a fairly straight forward job - more so if on a ramp. No need to remove the bumper either. Just make sure that the original silencer has all 4 clamps with it (1 on each outlet) and that the 2 large silencer straps and securing bolts are all ok as they will all be required to refit. Should take no longer than a couple of hours and nothing else needs removing to swap. If it helps I can probably email a copy of the installation instructions to you? On a cautionary note there have been occasions of even standard 997 GT3's failing noise tests at some UK circuits..... Chris

Thanks Chris, instructions would be great (I'll pm you an email address). I don't have a ramp so will be a horrible job to get the rear in the air, but might be doable. I was looking at the uber9s device above (which is out of stock) and thought my fabricator could make something similar using the bolt on track day exhausts that Merlin (for example) sell. Would replace the exhaust tips on either the standard box or the sharkwerks bypass. Bert

Bert, if you get past the static test, there is a driveby up Clay Hill that catches some cars out. I think it's 98 db. Shifting up a gear before you go under the walk over bridge will usually see you safely through without tripping it.

Good to know, thanks! I've driven gazillions of race laps round Oulton and been oblivious to all these shenanigans! Bert (well maybe not quite gazillions!)

What is the static threshold at Oulton. Is it 105?

997 GT3s tend to be about 102-103 static if the exhaust is in good condition at 6000rpm. If in doubt use the vacuum trick to stop the values opening at 4000rpm this will easily pass static. My personal opinion is don't run on track with the vacuum still fixed closed as it puts a lot of heat into the exhaust which I believed cracked a manifold when I used this fix to run at Donny once. Once you have passed static you should be ok with standard exhaust at Oulton working normally http://sharkwerks.com/porsche/technical-articles/1... Edited by Cunno on Thursday 10th January 19:52

BertBert said: I was looking at the uber9s device above (which is out of stock) and thought my fabricator could make something similar using the bolt on track day exhausts that Merlin (for example) sell. Would replace the exhaust tips on either the standard box or the sharkwerks bypass. Bert Our exhaust fabricator is in the process of making another batch of 10 silencers for us. The first 10 sold out quite quickly & everyone who bought one found they did the job.

Cunno said: 997 GT3s tend to be about 102-103 static if the exhaust is in good condition at 6000rpm. If in doubt use the vacuum trick to stop the values opening at 4000rpm this will easily pass static. My personal opinion is don't run on track with the vacuum still fixed closed as it puts a lot of heat into the exhaust which I believed cracked a manifold when I used this fix to run at Donny once. Once you have passed static you should be ok with standard exhaust at Oulton working normally http://sharkwerks.com/porsche/technical-articles/1... Edited by Cunno on Thursday 10th January 19:52 Brilliant and thanks for the link. Very helpful. Bert

nxi20 said: Our exhaust fabricator is in the process of making another batch of 10 silencers for us. The first 10 sold out quite quickly & everyone who bought one found they did the job. Excellent, is there a PH discount available?

BertBert said: Excellent, is there a PH discount available? Email me through the website & we'll work something out

I have this one in the photo. Very easy and fast to fit. I got it from this place about 2 years ago but the weblink is suggesting it's in archive so I don't know if they still offer it. I think they might have had made to order by their fabricator. https://www.actproducts.co.uk/product/si06-porsche... Problem is - I don't know how much it helps with the static test! I will have to try to get a back-to-back test because results have been all over for my car. Without it fitted at Brands it once read 103.4. With this fitted another time it still read over 103 at Brands. It read similar at Snetterton. Whereas back at Brands another time without the silencer at all, it read 101! Anecdotally it helps noticeably with drive-by. At Snetterton I was right on 103db static limit but a couple spectators commented to me that my car was far quieter on the pit straight than a supercharged Civic, for example (which still wasn't tripping the drive-by limit).

BertBert said: how do you change the solenoid thing to stop the valve from opening? Cheers Bert Here you go... https://www.6speedonline.com/forums/gt3-gt2/176141... Is the bypass pipe reversible? It's only a couple of hours job to to replace the centre muffler, but I'm not sure what happens to the flanged bolt-plates that are used to connect to the standard centre muffler when the bypass is fitted. Do they have to be cut off? These plates.... They aren't used when the bypass is fitted, so do they simply slide off the end of the side muffler pipes once the centre muffler is removed? When is Oulton? I'll be fitting a bypass shortly so will have a centre muffler you can borrow for the day if you like? I plan on swapping the centre muffler back in for the one or two trackdays I'll do (assuming the brackets don't have to be cut off the side mufflers)

Sorry about my previous post. Now I've properly read all the other posts (and clicked the links) I realise that: 1) You already have a standard centre muffler, and 2)The information about the vacuum pipe fix was already posted. Removing the rear bumper, and the heat-shields is really really easy and gives you decent access to the centre muffler. Just don't expect everything to be as clean on a UK car as it is on that viper RS pictured above! Oh to live in sunny dry climes...

D.no said: Sorry about my previous post. Now I've properly read all the other posts (and clicked the links) I realise that: 1) You already have a standard centre muffler, and 2)The information about the vacuum pipe fix was already posted. Removing the rear bumper, and the heat-shields is really really easy and gives you decent access to the centre muffler. Just don't expect everything to be as clean on a UK car as it is on that viper RS pictured above! Oh to live in sunny dry climes... Too true. It’s disappointingly cruddy under there... The retaining flanges should still be with the OE box one would hope.

I got curious, and had a couple of hours to spare for once... Easily do-able without a lift if you remove the rear bumper...

Thanks all, looks like some options. Looks like I can refit the standard back box or get an extra gizmo on the back which sounds less faff. I'll do the vacuum thing to help the static test. Although if putting the neck box on is an option I might do that! Choices! Bert

Just for some more context, and to aid in your decision making it took roughly two hours to get the original centre muffler off (to the stage shown in the image in my post above), and I reckon it'll be a similar amount of time for re-assembly. I'll let you know when I've done it... I was taking it very steady and carefully, and will do some spring cleaning while I'm in there. Obviously the process will get quicker with practice and familiarity, but in total it's not the 2 hour job I thought it would be

Holy thread resurrection Batman! My recent 997 GT3.1 purchase has a Sharkweks centre bypass fitted, but unlike the OP, I don't have a standard centre box to refit. I am not going to Oulton this week sadly, as I have a school open morning (I must be doing something wrong here!?) but I do plan to do some trackdays soon, so was wondering what sort of noise levels people have had measured with a Sharkwerks fitted? I was told by someone that it is possible to program a static rev limiter into the ECU, which prevents the car revving past 4k rpm when stationary. Has anyoe had this done, or knows if it works? Cheers Chris

Yes it can be done, I have it on my car. Chip Wizard is the go to guy for Porsche. This will help with static but drive by car still be an issue. Always wise to carry some additional mufflers just in case.

Cunno said: Yes it can be done, I have it on my car. Chip Wizard is the go to guy for Porsche. This will help with static but drive by car still be an issue. Always wise to carry some additional mufflers just in case. Thanks. A friend has an Akra bolt on tailpipe silencer he used to use on his 991 GT3 - I believe this should also fit my 997.1? He's happy to lend it to me for track days, but I think I need to get it tested before wasting money booking something that I get kicked off! I do have a proper microphone which can read up to 130dB which I use at work, so think I'll borrow the Akra bolt on and see how much difference it makes.

A mate of mine has a RS with a SW exhaust as per yours, when tested it would be 108-9dbs @ 6k be interesting to see what you get?