Exhaust packing

[Meek_racing]

I'm going to re-pack my Yozza 172 back box to see if it will help reduce some noise. Can anyone recommend me anything decent?

 

[Meek_racing]

Anyone?

 

[quattro]

I use this on my race car
https://www.merlinmotorsport.co.uk/...ncer-packing-material-square-metre-ex-e-glass
I have no experience of the Yozza but the silencer I use is just a straight through piece of perforated tube in a stainless box.
The trick is not to pack it too tight as this will stop the sound being absorbed.
Cheers

 

[M.C..]

JJC do some, never used it so can't say how good it is
http://www.jjcraceandrally.com/autograss/exhaust-silencers/acousta-fil-exhaust-silencer-packing

 

[Meek_racing]

I've bought some Accousta-Fil from Demon Tweeks, they said it was standard delivery so would be some time next week but it arrived next day . Looking on the website I only need to use 240mm of the stuff so a 1/4 of the roll! It will expand when the exhaust heats up...

For reference I was running a decat with Yozzasport 172 race exhaust - measuring 104.4db @ 4k

I will put the cat in with a new gasket kit and pack the exhaust, then do another reading in a few days when it has bedded in.

 

[LiamR172]

When you say 'pack' the exhaust... im guessing its not just a case of packing this stuff in the back box?

 

[Diagro]

That's what I'm wondering ha.

where does it go?

 

[Meek_racing]

correct, the yozza race exhaust has the tip held in place by pop rivets. Simply drill them out, wrap this stuff around the centre baffle twice loosely and then rivet back up. When upto temp it expands and fills the area. This way it does not get over packed and reduce the efficiency. They have a calculator on the website to work out the cut length depending on bore and outside diameter

 

[Meek_racing]

pretty much any other aftermarket exhaust doesn't have this option for repacking which is why I want to keep the yozza if possible.

 

[LiamR172]

Ah so i probably wont be able to do this with my Oreca? Baffles have come lose so need to cut it open and sort it out

 

[Meek_racing]

will probably need to be cut open then tig welded after packing. I guess the good thing about this stuff is that it wont be rammed into the box so the heat penetration wont have any effects on it, if anything it will expand the packing slowly in which time the weld would have cooled down.

 

[LiamR172]

I bought myself a bung which has helped alot for driving around town, ill take it out for blasts and trackdays.

Dont want any attention from thr police or the likes when am driving through the built up town, echos like mad and is faaaaar too loud haha.

Any chance yous could get before and after videos?

 

[NorthloopCup]

You can overpack a silencer and actually make it louder!!

 

[Meek_racing]

Well, took the car into work today as that was the only place I could work in the dry!

Removed the backbox and put to one side to fully cool down which gave me time to fit the cat and new gasket kit in (Thanks to Adam @ Renault Wolverhampton for super fast delivery)

Once the pop rivets were drilled out I used a centre punch and hammer to knock the stream of the rivet out of the hole. The tail was then clamped in a vice which allowed me to knock the back box off. Took some doing as its a tight fit, and was full of dirt and grime caked on with the heat.

Once off... yeah... that's what was left of the packing lol.

I took some time to clean all of the parts down, this then meant I was in a rush before work closed for 11. Unfortunately I did not take any pics of the new packing in place. Left it idle for 10 min and then took it for a few spirited runs down the highway to get proper heat into the back box.

I will test the sound tomorrow when the rain hopefully stops.

Initial results are that it still sounds as loud but less of a drone and no high pitch rasp which the old one had.

 

[Meek_racing]

Quick update, the Yozza now measures 95.4db @ 4,500 revs This should be good for all tracks so will book bedford and Donny once and for all!

 

[Andyman]

Good work. Handy when you can just un-rivet it like that. Very maintenance friendly unlike the majority of systems. Might even get quieter after a few more miles

 

[BIGASH]

Quick update, the Yozza now measures 95.4db @ 4,500 revs This should be good for all tracks so will book bedford and Donny once and for all!

They make me rev mine to 5800 for noise testing so depending on what you rev to i’d double check as they normally like 3/4 RPM

 

[LiamR172]

My car is going in tomorrow to have some exhaust work done. Baffles are knackered so hopefully with that sorted and some new packing it will be a bit better!

 

[Meek_racing]

They make me rev mine to 5800 for noise testing so depending on what you rev to i’d double check as they normally like 3/4 RPM

I'll modify the dash so that it only goes to 5k rpm

 

[-Dan-]

sorry to bring up and old thread but was that reading with you cat in place I take it?

Regards Dan