HELP!!! getting my exhaust under 75db...

[ke70racecar]

Hi all, we had our second outing yesterday at Sandown now called Soundown as we got kicked out due to the little rolla being too noisy. We tried to quieten it including crushing the pipe to almost flat but it didn't help. Nice waste of $500. We have to be under 75db so what mufflers are you guys using. We've also bought a rear lip and as we are using boot pins they will have to go so the lip can be fitted. Does anyone have a boot locking mechanism they would like to sell, a lock with a key would also be good. Cheers, Glenn

[Matt]

Running a hotdog / resonator + decent sized rear muffler usually shuts them up.

2 1/4" pipe

Also moved the thread + changed the title to help people know what you are asking...

[Vance]

wow! 75db...... thats even tighter than legal street requirements......

[ke70racecar]

Yep, even quieter than my Victa lawn mower.

[Konakid]

Thats absolutely ridiculous

[Jim621]

To be honest, i recon you would need at least one well baffled muffler to get under 75 dba at full noise.....i dont believe its possible with a free flowing exhaust.
Steve

[Celica RA45]

its 75 db from 30metres as the car comes forward and past
im using a 3inch exhaust with a big straight through muffler at the back and just come in at 74db
have you got quads or carbies with socks on the front as that will put you over with the loud induction noise


sandown for sprints has a 75db policy
as it can only get so many noisey days at 95db a year ,state racing v8s etc ,i think it is 11days a year

[Jim621]

Ah, the 30 meters changes everything!
Im used to noise readings being checked at 1meter away from the noise source. im fairly sure thats the standard for testing new exhaust systems.
Steve