4722 replies to this topic

[siztenboots]

Driveespana.com

that website doesn't work.

[Nev]

I just bought one of the those £15 sounds level Db readers at lunch time. Tested it quickly on my stereo (2 power amps and 8 big speakers) and got a max reading of 114 dB. Will take it out in Nipper later assuming it doesn't rain. Thanks for the tip on getting it

Edited by Nev, 11 November 2011 - 01:24 PM.

[Nev]

Oh dear, bad news... I started Nipper up on the driveway and held the dB meter at 45 degrees to the exhaust at 0.5 metre distance. It measured the volume as 111 dB. This was the measurement just at idle, clearly at 4500 revs it's going to be higher and a drive by measurement (when the turbo is actually operational) will be astonomically higher. Even taking a possible +/ 3 dB error into account it looks like I won't be able to get on any tracks in the UK what-so-ever The only solution will be to install a massive new backbox on there which I am reluctant to do as it will cost quite a bit. If I was to spend anything on the exhaust, I'd rather put a brand new 4" system in to help with flow, which will likely be even noisier due to the larger bore

Edited by Nev, 12 November 2011 - 12:03 PM.

[GeorgeBC]

111 dB at tickover is ridiculous are you sure its accurate? I bet your neighbours love you starting that up in the morning

[hairy]

Yikes! that's some stereo you've got too!

[Nev]

111 dB at tickover is ridiculous are you sure its accurate? I bet your neighbours love you starting that up in the morning

It claims to be +/- 3 db accurate (which is quite a lot (+3 dB means doubling the amount of noise as the scale is logarithmic)). It's noticable if you put your ear near the exhaust that there is a lot of noise (subjectively objviously). Also, I noticed that my video camera microphone distorts badly when near the exhaust. And alastly, when driving I have to wear ear plugs or my ears ring afterwards and have to shout at the top of my voice to talk to passengers when Im on full bore.

Edited by Nev, 12 November 2011 - 12:53 PM.

[GeorgeBC]

111 dB at tickover is ridiculous are you sure its accurate? I bet your neighbours love you starting that up in the morning

It claims to be +/- 3 db accurate (which is quite a lot (+3 dB means doubling the amount of noise as the scale is logarithmic)). It's noticable if you put your ear near the exhaust that there is a lot of noise (subjectively objviously). Also, I noticed that my video camera microphone distorts badly when near the exhaust. And alastly, when driving I have to wear ear plugs or my ears ring afterwards and have to shout at the top of my voice to talk to passengers when Im on full bore.

Not much fun if you want to take it to a track abroad either then as you would be deff by the time you get there. How costly is it likely to be to get it down to a sensible/track friendlyish level?

[Ormes]

I can confirm - it is loud

Nev, this is what I mentioned the other day, used due to heavy noise restrictions for the 24hr race:


Maybe try testing it parked on the road... As I could imagine sound may reverberate around on your driveway?

[Nev]

Yea, the test was on my drive, so maybe the noise was amplified by the house/garage walls, the car was also cold so maybe that increased the noise. Those silencing discs do work, but I think they may increase the back pressure a lot. I have a friend who has some, will ask him when I see him next.

[-Dab-of-Oppo-]

I think they may increase the back pressure a lot.

Sadly you probably will notice a difference using baffles/db killers as they can create a bottle neck. I have some on my Escort rally car and you can feel it's being resticted. I am not keen on them personally but you could look at fitting a cable operated butterfly valve in the downpipe. Same issues though and you will be negatively affecting power when you more than likely will be wanting it the most. Be nice for cruising though, you would be able to adjust it on the fly to suit your mood.

All is not lost on the trackday front there is allways circuit based events such as Trax, PVS etc with track time available, no restrictions on those days.

Edited by -Dab-of-Oppo-, 12 November 2011 - 05:59 PM.

[Nev]

I think I am not going to change the exhaust (to reduce the noise) just so I can get on tracks. This is because I have to draw a line somewhere on this project otherwise it will just drag on and evolve continually and sap my wallet of more and more cash for little return. I think I will just spend my money on petrol and drive the thing more and enjoy it. I am even tempted to abandon fitting my new airbox and throttlebody as this will amount to another £800 or so off of expense due to parts and a light RR/remap session.

[NickB787]

I think I am not going to change the exhaust (to reduce the noise) just so I can get on tracks. This is because I have to draw a line somewhere on this project otherwise it will just drag on and evolve continually and sap my wallet of more and more cash for little return.

I think I will just spend my money on petrol and drive the thing more and enjoy it. I am even tempted to abandon fitting my new airbox and throttlebody as this will amount to another £800 or so off of expense due to parts and a light RR/remap session.

Well said

Nev I know exactly how you feel I have also been doing this also for years and to tell the truth I am getting tired of all the outlay. IF I have a noise issue I will restrict myself to tracks which allow a higher limit. If someone gets the angled sections to work out of the backbox I might then invest

[cnrandall]

I'm surprised you are struggling with noise. Turbo's usually act as a good rotary muffler so it doesn't take much to keep under the limits. My car hardly makes a sound on the track, its actually quite strange!

[Nev]

Yea, I wonder if my sound meter is slightly wrong.

I've posted a video here of it starting up.

[Boombang]

For £9 you can rent the BaT meter http://bookatrack.com/-pp?17 Saves guessing!

[techieboy]

I've got this one and the numbers it's recorded seem to have pretty much tied in with what's been measured at tracks. Happy to stick it in the post to you, if you want to borrow it.

[Nev]

Thats the more expensive one Techie, presumably better accuracy than mine. Maybe if we ever meet one day you could bring it along for a test if you didn't mind a 'turdo' owner using it

I've just ordered up £150 worth of new 3.5 inch and 4 inch I/D inlet pipeing to mate with new airbox design to turbo. The last mod hopefully !

Am hoping this will yield another 10 or so BHP at the top end as there will be less P1 losses accross the 2 pannel filters and a larger bore inlet (with wider circumferance bends) too.

Edited by Nev, 14 November 2011 - 11:07 AM.

[techieboy]

No problems with a turdos, as long as they're not vomiting flames all over it. PM me your address and I'll stick it in the post to you.

[Nev]

No problems with a turdos, as long as they're not vomiting flames all over it.

PM me your address and I'll stick it in the post to you.

I don't think Nipper belches much flame TBH. Though I usually drive behind any VX convoys for obvious reasons, so I dont think many people have seen the exhaust whilst in motion.

Many thanks for posting it over. Have PMed my address

[luke.]

Nev if you ever decide to go to midlands meet again let me know as i would love a pax ride. Obv if i am ever round bristol i will drop you a pm but i doubt it as i rarely pass through those ends. Are you uprating your brakes at all nev? Obviously funds depending because i know how much you have spent already on the engine Surely it would be a worth while investment though