113 Dba!

[Guest wizzyfartbum]

hi,

i have just failed my first sva test yesterday with my 2B. there are a few easy bits to sort out, but more woryingly i had a noise output of 113 dBa!. i have the standard two pipe exaust with 1.6 pinto. i had fit the supplementary baffle, but didn't put in any scouring pads before hand. also the engine wasn't running to well so i need to get it tuned. i am wondering if tunning and putting the pads in would bring it down to bellow 101 or if i need to do something else? Has anyone else had this problem?

 

Also i would like to test the noise level before the next test so i dont fail again. does anyone know of anyway i can do this?

 

thanx ben

[Guest Ant]

Where abouts are you? A few people on here have access to noise meters.

 

Ant

[Guest wizzyfartbum]

Hello,

Im in haringey in north london

chers ben

[Guest timswait]

I had exactly the same set up for the Sva test, 1.6, pinto on twin tube exhaust. Mine too failed noise test on first attempt, in fact the guy at the centre thought the baffle may have been contributing to the problems by resonating and vibrating. I stuffed mine with iron wool and passed easily the next time. In fact I went slightly to town with it, stuffing extra in a few hundred yards from the station and as a result it sounded as quite as the Sierra, lost power badly though. Enthusiatic driving on the way home saw it all blown out in a few miles!

I know it's too late for you now, but if anyone else is reading this then don't put 6000rpm down as maximum RPM on your form. They will test your engine at 2/3 of whatever figure you put down, so the lower you put, the easier the test!

On a separate note if anyone in Kent has access to a noise meter it would be handy for me to check my current set up before Curbourgh.

[Guest Ianz]

Find your local Radio controlled flying club,they nomally have a meter to check the noise of 2 stroke model aircraft.....I should know I belong to Sussex Radio Flying club,based near Worthing West Sussex,or alternatively contact the BMFA,(British Model Flying Association) they may be able to put you in contact with your local club,who maybe able to loan you the db meter......for a small contribution to club funds!!!!!!!

Cheers Ian

[Guest wizzyfartbum]

thanx for everyones help so far. I wish i knew not to put down 6000 revs. i dont know if there is anyway to let more people know. my examiner (really nice guy) told me straight away tht we would have a problem because of it. would you mind telling me what your first dBa reading was tim?

ill try to get in contact with a nearby radio control club coz i really dont want to have to have a 3rd test!

 

Thanx again for all your help. im starting to feel slightly less worried

 

Ben

[Guest bloke]

im curious about what rev limit you can declare?

[Guest Kev H]

im curious about what rev limit you can declare?

 

Look in the Haynes manual in the Technical section for your engine type for the RPM at peak power and put this down on the form. I have a 1.8 Pinto and I think it was 5,400 for this. The examiner then uses 2/3 of this figure.

Kev

[Guest timswait]

Mine was 108DB first try, I don't know what it was when it passed, as it passed so I didn't get any fail form to read the dbs, and it was a year ago now so I can't remember. I do remember that it was a comfortable pass though. That was tested at 2/3 of 6000rpm, as I didn't know about the declaring a low rev limit then! As for how low you can go, 5400rpm will definitely be alright I'd have thought. I read an account (on this site, can't remember where) of someone who mis-read the form and honestly (?) thought it meant peak power rpm, not red line, so put down 4000rpm, and it was tested at 2/3 of this. I think any lower than that would be taking the piss rather!

[Guest timswait]

As for the amount of iron wool, again I can't remember too well, but it was several scourers all teased out to be as fluffy as possible and pushed as far into the silencer as poss. It did make a big difference, and you will hear it, just be careful of blowing it out on the way to the test, keep a gentle right foot, or stop around the corner to do it. The SVA bloke did ask me if I had done something proper to the exhaust or just stuffed it with loft insulation. I said it was kitchen scourers actually, and he shook his head and got on with the noise test! He then failed me because he was too short to reach the handbrake which was annoying though, so I only passed on my third try.

[Guest wizzyfartbum]

i didnt realise they could fail you for something not mentioned first time round surely thats out of order? thanx a lot i'll probably have to put in more than several!!

 

cheers, BEN

[Guest Ant]

i didnt realise they could fail you for something not mentioned first time round surely thats out of order?

 

They can try ... but with me they didn't succeed. The second SVA tester found a number of "issues" which the first hadn't, all related to exterior and interior projections. I had a right argument with him about it which lasted for most of the test. In the end I won

 

Ant

[Guest timswait]

The thing was that first time I had the Sierra seatbelts, and those let hime reach the handbrake, but failed because they didn't retract very well. Second time I had the four point harnesses, which he couldn't reach with.

[Jon Bradbury]

..I should know I belong to Sussex Radio Flying club,based near Worthing West Sussex..

Iain,

 

Do you live in or near Worthing? If so we should meet up. I'm a Worthog man myself.

 

Cheers

 

JonB

[Guest Guy]

The SVA manual of 2000, section 17 sais that the DB measurement is taken at 3/4 of max power output of the engine so if the max power output is 6000 RPM then the reading is taken at 4500 RPM.

 

If a standard Pinto gives max power at 5400 then the reading is taken at 4050 PRM.

 

My SVA thing is quite old so if it has changed to 2/3 then the test should be carried out at 3500 RPM.

 

Maplin do a dB meter, it's stock code is TB57M and it's £50. You'll have to do a measurement as it is to get an idea of the levels your meter sais compaired to the testers setup.

 

I'd just change the numbers on the form and put the wire wool in it, the main thing is not to worry about it, be concerned but don't wory. People have passed with the same setup as you so you should be able to get through.