HFCs too loud - other options?

[James Junior]

Morning all,

 

Sorry for the long winded post, I just wanted to explain how I have come to this point in the hope of gathering some advice. I have been adding some breathing goodies to my Z over the course of a few months trying to make it sound better and tease out a few extra horses.

 

My intention was to find a set up that gave me stock levels of quietness when cruising and on part throttle, but more drama when pressing on.

 

After much research, firstly I fitted a Cobra exhaust and Y pipe. This made the car sound fantastic and was pretty much everything I wanted in terms of sound - quiet off-load but with a lovely burbly roar on open throttle.

 

However, looking at some sound videos taken by a friend who followed me on some sections of a Euro driving tour I did, the car still sounded a bit subdued.

 

So I added some Cobra HFCs to the mix, having read that HFCs would only make the car marginally louder. WRONG. Holy crap, they were insanely loud! They did definitely make the car feel noticeably quicker to me in the mid and higher rev range though. After coking up they got a bit queiter, but were still too loud for me for daily use.

 

I then fitted a Stillen G3 and this made no difference to the sound at all - it was as if the HFCs were so loud they drowned out any increased induction roar.

 

The problem was that I was now liking the slight increase in power, so I wanted to go quieter without losing the HFCs as they were the single most effective modification in power terms, according to my 'butt-dyno' as the Yanks like to say. So, I tried replacing the Cobra HFCs with a set of Berk HFCs. These were marginally quieter, but if I am honest, they are still too loud for me.

 

It is not just the loudness, but the nature of the sound. Around the mid-range they emit a coarse metallic buzz that is so loud it turns heads. To me it sounds a bit chavvy and completely drowns out the lovely burble of the Cobra exhaust at certain points in the rev range.

 

I had the car remapped via Uprev and it turned out it was overfuelling a touch. With this rectified via the map the noise did actually improve a little, with less trumpety blare. However, I am still not entirely happy.

 

Further adding to my concerns, I was at Oulton Park on Friday and the car only marginally scraped through the static sound test. On track I could barely hear the instructor as he gave me instructions sat next me during my tuition session. (although he did say it sounded awesome!)

 

So for those that haven't dozed off reading my life story, I am looking for any alternatives to try to keep the performance gains of the HFCs as I don't want to go back to stock-cats, but do want to get rid of the blarey sound around the mid range.

 

I have read a bit about Motordyne ART pipes, but don't really understand what these are if I am honest. I have also read something about Motordyne XYZ pipes too, but again am not really sure what these are either!

 

Can anyone give me any advice please? I would really appreciate your input.

[Richf]

Put a stock system back on , it will be quieter and it wont lose a noticable amount of hp

 

Put the stock cats back on , it will lose about 10 hp but you probably wont notice it

 

Buy some of the motordyne decats , they are meant to be quieter than the HFC but you may have mot issues and they are a ludicrous price imo

 

Or just live with it!

 

I made a similar thread when I fitted decats , i still think its loud but my mates reckon is sounds great so i'm sticking with it for now

 

http://www.350z-uk.com/topic/100864-invidia-and-decats-too-loud/

[Jetpilot]

http://www.demon-twe...ng-exhaust-wrap

 

Ok, it may sound odd and like it wont work, but will only cost you a few quid to try if you dont believe it.

 

Wrap your hfc's with heat wrap tape, it completely alters the external tone, wrap up as far up the downpipe as you can reach also, make sure its wrapped tight and properly secured.

 

I passed the Thruxton noise test with hfc and true dual exhaust which is the strictest in the country, 90db and never blacked flagged on the drive by.

Edited November 24, 2015 by Jetpilot

[cmck13]

I, like many on here fitted Berks Hi Flo cats with a stillen y pipe and a scorpion back box, never had any problem with them at all. Just like you I wanted something acceptable and they delivered the goods. Nearly forgot, I have a vortech V3 that has the capacity to be very loud but has just changed the pitch but the volume is no different.

[Richf]

http://www.demon-twe...ng-exhaust-wrap

 

Ok, it may sound odd and like it wont work, but will only cost you a few quid to try if you dont believe it.

 

Wrap your hfc's with heat wrap tape, it completely alters the external tone, wrap up as far up the downpipe as you can reach also, make sure its wrapped tight and properly secured.

 

I passed the Thruxton noise test with hfc and true dual exhaust which is the strictest in the country, 90db and never blacked flagged on the drive by.

 

Interesting, I have wrapped turbo charged stuff in the past and not noticed any difference but its worth a try on my decats, i still have some in the garage

[veilside z]

Yes it's a mixed opinion. Some find the HFC too quiet but all down to the Mix & Match of exhausts and the removal of replacement, of the mid box section too. Then there's the Y and the headers. Its a real challenge to find the ultimate all around sound expected, but once obtained ... Heaven. :yahoo:

[Richf]

Yes it's a mixed opinion. Some find the HFC too quiet but all down to the Mix & Match of exhausts and the removal of replacement, of the mid box section too. Then there's the Y and the headers. Its a real challenge to find the ultimate all around sound expected, but once obtained ... Heaven. :yahoo:

 

for me that involves bolting a turbo on

[nissanman312]

I had the same problem when adding de cats to a cobra

 

Then I paired them with a invidia and it's beautiful now nice and subtle on cruise

 

Then shouts on full throttle

 

 

[Bodyboarder81]

From my experience the traditional style exhaust ( not true dual ) with decats or hfc will rasp . I had a scorpion with hfc and it was chav tastic , really raspy . Then swooped to invidia ... No rasp but slight drone on the motorway . Then I went decats and miltek system ... Again loads of rasp .... Change to the art pipes ( decat with side resonator ) a lot less rasp , no drone ..... Almost too quite !! I've now bought another invidia to pair with the art pipes and hope this to be the winning combo !! Gets fitted tomorrow so will let you know !!

 

My best guess would be for you to get the art pipes .... Quieter than the hfc and good gains .... Only down side is you need a friendly mot place .'

 

Or buy an invidia !

Edited November 24, 2015 by Bodyboarder81

[James Junior]

Thanks for all your responses guys, much appreciated!

 

Jet Pilot - as it happens my car is going into Demon Tweeks next week for the KW V3s to be fitted, so I have bought some exhaust wrap from them and have asked them to whip the HFCs off and wrap them whilst the car is up on the ramp. I will report back on the outcome! Thanks for the suggestion.

 

If that still doesn't do the trick then Josh I will try your suggestion with the Motordyne ART pipes. My MOT testers are definitely a friendly bunch so I am sure we can come to some arrangement, or at least keep my old cats in their store room for when the time comes...

 

I will keep you all updated, thanks again for all the feedback chaps.

Edited November 24, 2015 by James Junior

[Bodyboarder81]

If the cars up in the air then I would suggest trying to wrap the hfc still on the car if possible .... A lot of work / hassle / cost to take them off just to wrap .

[Tarmac@TarmacSportz]

You could get silenced decats or resonated HFCs (at a premium).

[Jetpilot]

If the cars up in the air then I would suggest trying to wrap the hfc still on the car if possible .... A lot of work / hassle / cost to take them off just to wrap .

 

+1 No need to remove them, wrap as high up as possible, my manifolds are wrapped too so that probably helps.

 

Its no bad thing anyway, the hotter the exhaust gases can be kept the quicker they exit anyway

[Richf]

Or

 

[Bodyboarder81]

2 butt plugs ?!

 

You can keep them !

[Richf]

You clearly know more about butt plugs than I do

[Dynamic Turtle]

350z DE - Miltek + Berk HFC is a reasonable mix IMHO, measured when you want it to be, loud when you're pressing on.

 

370ZN - currently running Cobra CBE and Berk HFC and it is VERY loud all the time but I love it, total hooligan car now but you can just about have a conversation if you keep revs below 3k. Apparent increase in subjective power too (not ben uprevved though). Cobra zorst on its own sounded great but the cats make it sound like a nest of very angry....cobras are being prodded under the bonnet.

 

DT

[gstraw]

i am having this issue too!!

My journey has been all with the stock OEM system:

1. Removed both mid silencers. opened up the exhaust and made it a bit raspy which i didnt mind at all.

2. Added Berks HFC and the raspyness was off the scale! it was stupididly loud

3. Put both mid silencers back in with Berks HFC so it was OEM system with HFC. this was pretty much silent. it was almost stock!

4. Removed one mid silencer and have still got HFC.

 

i love how the car sounds in low RPM. anything higher it just gets really raspy. the heatwrap thing might be soemthing for me to try too. However., ive heard it leads to cracking because my exahsut and manifold is mild steel...can anyone confirm or deny this?

 

thanks

[Jetpilot]

ive heard it leads to cracking because my exahsut and manifold is mild steel...can anyone confirm or deny this

 

One of those internet "facts" that just gets bounded about because someone somewhere had it happen once, ive no doubt it does happen, but highly unlikely imho

[sipar69]

As said, it's all about the mix of components. For me, adding Cobra HFCs to the Stillen exhaust produced exactly the sound I was after.

[Jay M1988]

Is the cobra louder than scorpion? My current setup is none silenced decats, stillen y pipe, scorpion exhaust.

 

Would like something with a little more low down growl. I honestly think with cats and oem y pipe the scorpion mad the v6 sound more pronounced.

[Bodyboarder81]

Cobra is louder than the scorpion ...... Yours must be very raspy with decats and scorpion , I know mine was !!

 

Just fitted my invidia with motordyne art pipes ..... Seems to be a good combo , no rasp , real v6 howl on full chat and not to loud cruising . Only done 10 miles , so will see how it sounds after a few 100 .

[Dynamic Turtle]

Motordyne gear sounds immense btw - if you can afford the premium, go for it.

[nissanman312]

Cobra is louder than the scorpion ...... Yours must be very raspy with decats and scorpion , I know mine was !!

 

Just fitted my invidia with motordyne art pipes ..... Seems to be a good combo , no rasp , real v6 howl on full chat and not to loud cruising . Only done 10 miles , so will see how it sounds after a few 100 .

 

You just need to throw it all in the bin and go straight out the side

[Bodyboarder81]

Cobra is louder than the scorpion ...... Yours must be very raspy with decats and scorpion , I know mine was !!

 

Just fitted my invidia with motordyne art pipes ..... Seems to be a good combo , no rasp , real v6 howl on full chat and not to loud cruising . Only done 10 miles , so will see how it sounds after a few 100 .

 

You just need to throw it all in the bin and go straight out the side

 

Sorry ..... Who said that ?! It's got very loud all of a sudden