[nismoman]

just got back from donninton park from a members track day:chuckle: when i ran last year i managed two laps then i was black flaged for noise 109db,(day over ).so when i ran at the national skyline meet,i stuck the bung in the exhaust but only managed 1 lap befor being black flaged for noise again 103db (to be expected ).so when i went down to santa pod for the jap show i was talking to mark from abbey who suggested,landing me a lagged silancer pipe to fit in were the d-cat pipe was(thanks for the offer mark:bowdown1: ) but whilst down at santa pod one of the exhaust manufactures said thay would make me one as a demo f o c:chuckle: so the following monday i take my car to have the silancer fitted,were we allso notice all the packing has gone from one of the silencers so this is allso replaced,im then thinking this should now be quieter ,after going for a run it,s slightly quieter .i know if i put the bung in it just kills the cars performance with back pressure,so i cut the reducing pipe of the bung then replaced it with a perforated pipe,stuck it in the exhaust lots quieter and the car seems to run ok,due to the perforated pipe on the bung.so imagine my thoughts when on lap 3 i get black flagged for niose and then i,m told it,s 109DB:runaway: .thay remembered my car from previous visits,and suggested i had a word with the noise control officer situated in the control tower,who turned out to be very helpfull.as we disscused the problem and my attemts to quieten the exhaust ,he said the problem with my car and high powered turboed cars is induction noise not exhaust niose ,with cars having air filters mounted out side the bonnet having the same problem,in our disscussion i mentioned the T V R running round ,but like the man said thay dont create much induction niose.SO MY QUESTION IS CAN ANYTHING BE DONE TO QUIETEN INDUCTION NOISE my r34gtr runs about 600/630max bhp with blitz nur exhust and apexe filters with nismo air flow meters :wavey: NISMOMAN (SORRY ABOUT THE LONG WINDED POST)

 

[Mookistar]

correct me if i'm wrong, but i was always led to belive turbo cars made less induction noise than N/A.

as the combustion sounds on a N/A simply come out of the inlet and straight out the airfilter, whereas on a turbo, the sound has to travel all the way through the boost pipes intercooler, turbo's and then filters.

a TVR would suffer from lots of induction noise, esspecially on cone filters, its also why most hot hatches sound like V8's with an induction kit


i might be so far off the mark, but i dont think induction noise would be an issue?

mook

 

[Cord]

Still struggling with this one!!

I'm not an expert on this, but i'd be REALLY suprised if it was induction noise? Usually the turbo etc,, kills a lot of the sound. If you did want to quieten it then going away from pod filters would be the first step, the stock airbox with a decent filter is actually a very good bit of kit, and I'm sure that you can get a fancy Nismo bit that bolts under the bonnet to direct air into it (think Nito??? had one) Also the ARC airboxes are a truly lovely bit of kit. ( I want one but they are £££'s)

Maybe get a noise meter (some Nokia phones have them in-built) and do a standing check with the engine up in the revs.

So was the 109db was with new centre silencer, re-packed rear and shortened bung? Hmmm, thats still bloody loud. I know that racing cats will remove a fair bit of noise, but exactly how much, and how much extra back pressure they'll give you i'm unsure. And they cost a fortune, so that probably rules them out.

I know the blitz nur, is renowned for being a VERY loud exhaust, maybe try measuring sound from some other exhausts?

The HKS super silent hyper muffler is a good free flowing item that is about as quiet as I've heard a performance exhaust.

Also my Fujitsubo giken is fairly quiet.

One fo the Trust ones is reasonably quiet (with the other being very noisey but i can't remeber which is which!!)

 

[r33 v-spec]

Yes you could try moving away from the induction kit and by trying a stock airbox. Maybe pick one up from here 2nd hand, or Middlehurst. I still prefer this myself to the pods, but then again at your power level, maybe this might not be efficient.

As for the duct that Nismo do, this is only able to fit on the Nismo R-Tune bonnet, if its the one that Nito had. But then again you have the bonnet, and i remember you saying that you'd ordered this duct aswell...

 

[nismoman]

thanks for your coments:bowdown1: as i said in my first post this was the opinion of the noise control officer at donnington park who was saying it,s a common problem with high power cars,and from there experiance it,s induction noise thats the problem which i,m not saying i agree or disagree with it just seems after playing with my exhaust it has definatly made my car quieter,befor when i would drive on the motor way at about 80mph in top gear you could,nt have a conversation or even attempt to listen to the radio ,but now since the exhaust mods it,s drasticly quieter,so i do know that it has made the exhaust alot quieter, but get it on a track and the car is still 109db,so it does suggest it could be the induction noise,like the guy said they have lots of cars come to the track that will pass a static noise test ,and have past all the noise regs for new car designs,but once you rag them round a track the induction noise makes them to loud to meet the 98db limit.he was saying some of the brand new porches,ferraries,astons and two of the new super bikes are way over.so he does seem to have a point.cord i was talking to rod the other week with regards to exhausts,and like he said we could always get (mr super bike man )to make me a custom exhaust,but is it the exhaust thats making all the noise on a track day,i cant be the only one thats came across this problem,stock air box may be the answer ,but will it work ok at the bhp i run ,i know the z tune run a fair few bhp,s but is that a custom made air box just for the z tune.keep you coments coming please :wavey: NISMOMAN

 

[Howsie]

Forget the noise. Please post pics of the car!!!

 

[r33 v-spec]

AFAIK the Z-Tune has the same airbox, obviously with the Z-Tune air cleaner conversion duct and maybe Nismo panel filter or some upgraded filter

 

[Cord]

I really feel that your Blitz exhaust is the root of the prob, they really are very loud.

Am sure somebody (we may have one) will have a stock 34 airbox for you to try, with a decent panel filter i can't see it effecting your engine drastically. And if you do find the Nismo bit that i was on about it will certainly give the airbox a real good air feed at speed.

There is a thread somewhere on here with a list of exhausts and noise, on it a dude has a noise meter that he will lend, maybe it's worth giving him a shout, got to be easier than keep doing track days!!

 

[JapFreak786]

i'm not helping to the question much,but i must say when i heard NITO's old R34 at JapFest II,the sound it made was awesome,the turbo/exhaust or whatever it was,it just sounded immense!!

this car is also very loud,still remember how it sounded when you turned it on at Gaydon last year
I know the noise that air filters make can vary,couldn't you just see if changing to a filter that makes less noise (if that makes sense?)
As the Apexi filter/Blitz SUS that we have fitted to our GTS's make difference noises,the Apexi being louder when you let off the gas,but the SUS louder when you are accelrating.

 

[Gambachi]

I did see a post on the sxoc regarding noise and trackdays. One of the posts clearly showed that the Blitz Nur Spec R could hit 121db @ 4000 rpm and was by far the loudest exhaust you could get so I would probably think that its the Nur Spec causing your grief on the track.

I am a noob with a GTR though as my previous car was a 200sx with a Nur Spec and while the induction noise was loud (Blitz Sus) the exhaust was very, very loud when pushed.

 

[hissingsyd]

Hi Nismoman

As Cord says fit the HKS silent power rear silencer.
I am currently running 500bhp with HKS front pipes, decat & the silent power rear box. Standard air box with Nismo panel filter. 95db measured at MSA sprints, track days and club events. Approx 30 events never been pull aside for noise.

 

[763paf]

Hi Nismoman

As Cord says fit the HKS silent power rear silencer.

I agree. Much "softer" exhaust

 

[EvolutionVI]

Nürspec is way too loud,changing the filters will show no noise reduction,the sound that comes from the filters will not be shown on the db-meter,it´s only the exhaust,change it to the HKS Silent Power(i have it on mine) or something similar and you will never get pulled out again:wavey:

 

[NITO]

Nismoman,

I'll be selling my full Titanium HKS Kansai exhaust (which is good for 600bhp as mine maxed out at this with this system) and R34Airbox with carbon insert and Nismo Z tune carbon under bonnet ramair intake shortly if you're interested.

The exhaust is around 93db at 5100rpm. The induction noise is much much quieter. Ironically I preferred the oe airbox to the HKS T04Z intake on my Nur. I'm not a fan of loud pipes and bungs, the full titanium system only weighs about 6kg too.

Regards
Nito

 

[chris_s]

you can get enclosed induction kits im sure a decent one will not only reduce noise levels but increse heat shelding prob giving you a couple more bhp

i saw one on a almera at pod a yr or so back it was running 11s so they cant be that bad and i know its not just the filter that was letting it do that lol

i think bcm or bmc somthing like that make them

 

[Scott]

The main problems with running 'pod' type filters is the reduction is dirty side duct length when compared to a stock system that is designed that length for a reason and probably has NVH devises (Helmholtz resonators, Qtr wave tubes, or perforated holes), situated where the standing waves occur. Turbos do change the induction noise buy chopping up the sound waves, but they also create a lot of high frequency noise themselves.

But as has been mentioned before, get rid of the Nur exhaust, probably the biggest culprit (80%), then if you need to loose more Db fit a std air box. You could always duct some extra air into it from the inner wing etc.
What you'll loose on restriction you'll gain on cooler charge air.

 

[r33 v-spec]

To be honest the Z-Tune air cleaner conversion duct helps alot with the stock airbox, as the scoop sits right behind the grille in the bumper and has a much larger opening than the stock air guide.

Plus with the addition of the side blocker removed, it would help considerably