I recently posted an 'ask radical' question, and hopefully their technical team will be able to provide some insight.
It wouldn't bother me, but there's 1 track in the UK called bedford autodrome which run these sprint events every year that are great fun.... but my car is 1db too high on the static test, as the circuit has a limit of 101db, and a drive-by of 87.5db. AT oulton park last year with the official MSV equipment, i tested @ 102db static. I already have the silent exhaust with the twin muffler setup.
so i'm just looking for a couple of db to pass, and i can short-shift around the circuits 2 hotspots where the soundmeters are for the driveby, if needed.
last year i looked into getting one of these 'decibel devil' noise cans to add on the back just so i could do this one event, and enquired with @rlm-dan whether it would be safe to use - his response was:
"To be honest we would not add anything more to the twin silencer set up, you have to be careful of restricting things to much – there is a risk of engine damage with two much back pressure, it holds the heat in the combustion chamber.
With the twin silencer set up I think your next issue will actually be in the induction noise that you get from the airbox which is also something difficult to make any better."
So, i gave up on the idea!
I'm curious to know from, well either Dan, or Radical, just how much restriction, if any, can be applied, and for how long - or whether it's always going to do some damage and it's just a case of how much. Is it simply because of too much heat remaining in the chamber as the hot exhaust gases can't escape?
is there absolutely no tolerance on the back pressure VS potential damage to engine? Probably quite a difficult graph to estimate, i know.
WHen i've been track-daying a few times i see the odd professional GT3 team turn up with customer cars; at Oulton park last year i saw a Ferrari 488 GT3 with 2 of these cans stuck on the back.
i also came across this interesting video below where this guy did back to back tests on the dyno with great results, knocking 6-8db off the static noise yet maintaining pretty much the same power. (the sound test video is another vid on his channel)
Obviously, different engine, muffler, a much shorter exhaust than on our radicals etc. so i know i can't use this as an indicator. I'm just desperate to run that 1 event this year so can't let this topic go just yet😆
My only siggestion would be set your throllte full open set screw so you only get ~80% throttle for the test than back to 100 after. Then on the track short shift like you mentioned.
@rojid, Hi.
I'm not sure if this will help or maybe will not be allowed where you are, but in Australia the Porsche Cup Cars running in State Series racing (not the National GT3 Cup) sometimes struggle getting under track day and certain race circuit decibel noise limits.
As a result you see a lot of these... sorry for the photo but I took it back in 2014 when I had a GT3 Cup car myself.
These angles tips simply clamp onto the exhaust ends and can be adjusted in terms of their angle by rotating the angle of the tip. All the ones I saw on this particular track day were pointing to the left and slightly upwards... I then found out that the decibel test station was on the back straight, on the right hand side of the track at ground level... so they were probably just pointing the exhausts in the opposite direction....
I also noted that most had one shorter bent tip than the other and that they always seemed to force the exhaust gasses exiting the tips to mix together... not sure what effect that has?
