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What about the stock Euro airbox with a snorkel to the front grille to bring in cold air? Or a real or repro GTA style box. Should quiet things down well and reduce your incoming air temp a good bit too, if you're running open carbs now.

Sound limits are what they are, alas. Good luck getting them changed. My guess is your exhaust is more of an issue than your intake. What are you running? At Laguna, have your exhaust exit on the left side of the car, if you don't already.

Andrew
 

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I agree, stock air box should work fine.
I had a similar experience years ago at Sandown race track in Melbourne. For an Alfa club sprint there, seeing all the locals drive in off the street, fit extra mufflers to run for the day, then take the mufflers off to drive home. A bit back to front.
 

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You may be interested I the set up I have, its fibreglass, however I don't know if it's still available,
It's made locally by Vin Sharpe,
Here are the contact details,
PACE engineering A R
Motor Replacement Parts - Park Orchards, VIC

3 Tralee Crt, Park Orchards VIC 3114
Phone
(03) 9844 0147
 

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Richard Jemison
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Airbox

Look at post 114 at the mods done to a stock airbox to fit 45mm Webers. This same box was opened to fit 50 mm DCO webers but was replaced with a larger custom airbox with more "volumn".

http://www.alfabb.com/bb/forums/motorsports/146464-old-alfa-racer-pics-so-west-div-6.html

You won`t have power loss loosing the "Airhorns". Note the openings in the Webers is flared as well as the inside of the airbox.

You should always know the location of the sound meter. Normally on the outside of the track. A curved outlet to direct the exh noise to the opposite side is a common application.

Airhorns open to the engine heat is a holdover from Alfa`s racing little 1300 and 1600 cc motors. Intake tract is long enough without them and the cold air box is going to produce gains in itself. Know of any real modern rac cars using open airhorns in the eng compartment?

Here`s more info for you:

http://www.alfabb.com/bb/forums/motorsports/146536-air-intake-webers-105-track-car.html
 

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Mikegtveloce. I know it may be a big off topic, but any chances of putting up some pictures of your car?
Thanks
 

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Thanks guys for all the good ideas! It really is amazing how the alfabb can provide access to so much good experience and knowledge.

Andrew: I had my mind set on using relatively short full radius velocity stacks, because my mechanic has insisted that the stock euro air box/filter set-up will rob power. But, at this point the car is just sitting because really I got tired of the meatball flag out there. So, I like your suggestion and think I will start here just to get out and see if the intake noise is contributing to my problems. I have this set-up already and have just never used it. I assume that I can open up the ports from 40 to 45 easily enough and bolt it on to see how it goes.

For exhaust I'm running a 2.5 inch pipe with a round resonator in the front position and a magnaflow of some sort in the middle position. The pipe used to end just behind the middle muffler and pointed down toward the track. I was registering about 94-95 dB this way. My muffler guy suggested that adding length to the pipe would help, and I extended the pipe out the back, with a subtle bend toward the left side of the car as you suggest. This brought me down to about 92.5-93.5 dB, which was working out ok until they lowered the limit from 92 to 90dB. I'm open to suggestions here as well, but thought I would work on the induction noise first, as it's wide open and howls like a banshee right now.

Spannerman: It sounds like you have tracks down there with similar sound limits? Here in N.Cal it's really only Laguna Seca with this problem. We have other great tracks, but LS is my closest track and I have the most experience there. So, I want to continue my effort to reduce my lap times. I recently added a close ratio gear box, and I'm dying to see what I can do with on the track I know well. I'm reluctant to drive hours further to run at other tracks. But, it may come to that. At least I do have options.

105Junior: Something like this is what I had in mind. Are you running some kind of velocity stack inside it? I will write to the supplier to see if they still make this. Thanks for posting it.
Yes there's velocity stacks inside, I suggest instead of writing a quick phone call will be the best approach to getting a fast response.
 

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Pipercross 600 Series Sealed Airbox - Demon Tweeks

pipercross makes what you want. If there will be a noticable advantage over a well midified stock airbox I doubt it if I am honest.
I have seen Dyno results off custom made airboxes with short stacks where the modified Alfa airbox had better performance.

you can improve the intake soundlevel by putting insulation material under de hood.

In Holland the sound level is limited at 89 db, Zolder in Belgium even lower AND more stricktly .

Is it measured static or at speed on the track? In the UK I had static at Castle combe, failed first time at 1 db...warmed the car up and it was just ok...
 

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I just added soundproofing to the hood of my GTV, which has Weber 45s and low restriction air cleaners. It does a good job of quieting the induction sound. Here's what I used: Item # SP-250, Soundproofing Foam On Wicks Aircraft Supply

I made a pattern for each hood insert area, cut the foam to size with scrissors, and used a contact cement obtained from our local automotive paint store. It was an easier job than I expected and looks good, too. However, I will confess that the foam is Scuderia Non Originale, and the PC police will complain if I let them see under the hood.
 
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