Quietest exhaust system

Discuss mechanical problems here.
Forum rules
By using this site, you agree to our rules. Please see: Terms of Use
Post Reply
Michiel
Minor Friendly
Posts: 97
Joined: Sun Feb 03, 2019 10:09 am
MMOC Member: No

Quietest exhaust system

Post by Michiel »

I have fitted a new standard mild steel single box 2-piece system but above 50 it has a booming sound and banging on the overrun. Not just the 'parp'. My car is a very standard 1098 convertible. I know it will get quieter a bit after a while and cars made more noise back then, but still..
How can I make this quieter. I did a lot of searching here and found that:
1. adding a box at the end and making it a twin box system will do a lot to reduce noise.
2. the second box should be stainless because it does not get hot enough to evaporate water (rust)
3. stainless system are noisier in comparison to the same mild steel setup.
4. big bore (1.5") is noisier.

Options?
The only available twin box systems are large bore (1.5") stainless but is that quieter?
OR
I could add a stainless second silencer at the back of my new mild steel 1.25" system. This should be large bore to avoid strangling the engine? I found a stepped reducer (1.5 to 1.25) but could not find a 1.5" separate stainless silencer. Anyway, will this solution be quieter?
Finished rescuing a 1967 2-door. Define finished....
kevin s
Minor Legend
Posts: 1375
Joined: Tue Mar 26, 2013 8:20 pm
Location: Chelmsford, essex
MMOC Member: No

Re: Quietest exhaust system

Post by kevin s »

stainless in it's self isn't noisier, it's used in many modern cars. It's often perceived as noisier because the stainless systems are made of thinner material as they don't corrode, also most aftermarket stainless systems are marketed as some sort of performance upgrade which means less baffles and more reliance on absorption in the silencers.

As you say it's not easy to get a small bore silencer or one that is not aimed at the performance market, one option might be to try another minor front one on the back, it will last a at least a coupe of years and mean you can get an idea of the effect without much outlay.

I wouldn't worry too much about restriction if you still have the standard carb / exhaust manifold.
JOWETTJAVELIN
Minor Legend
Posts: 2775
Joined: Mon Dec 12, 2011 7:20 pm
Location: LANCASHIRE (paradise)
MMOC Member: Yes

Re: Quietest exhaust system

Post by JOWETTJAVELIN »

It could be resonating through to the car if the exhaust is too close to or actually touching the bodywork. This may not be apparent by viewing it when the car is stationary. The worst area for this is the front where it leaves the engine and passes through the hole to go under the floor. If the noise disappears when you take a sharp bend fast that would be the problem. The old ‘original’ exhaust pipes were one piece throughout and the down pipe at the front was curved, not a straight pipe bent like so many of the recent examples.
User avatar
mobylette
Minor Fan
Posts: 278
Joined: Sat Feb 13, 2010 5:02 pm
Location: Croydon
MMOC Member: Yes

Re: Quietest exhaust system

Post by mobylette »

Have a look here:

http://www.everyexhaustpart.com/cart/cu ... encer.html

They do 1.25 inch. I have used them and Jetex exhausts to make up a system for my Land Rover. Very pleased with the products.
Image
Michiel
Minor Friendly
Posts: 97
Joined: Sun Feb 03, 2019 10:09 am
MMOC Member: No

Re: Quietest exhaust system

Post by Michiel »

Many thanks. Three helpfull answers! So if restriction is no problem I'll get a stainless 1,25" box from that shop to add at the rear.
Finished rescuing a 1967 2-door. Define finished....
Clayton James
Minor Friendly
Posts: 52
Joined: Wed Nov 18, 2020 8:20 am
MMOC Member: No

Re: Quietest exhaust system

Post by Clayton James »

I found this list on the internet, maybe you want to check it out:

https://soundproofnation.com/quietest-p ... e-muffler/
jagnut66
Minor Legend
Posts: 3635
Joined: Fri Apr 11, 2008 7:28 pm
Location: Mansfield, Nottinghamshire.
MMOC Member: Yes

Re: Quietest exhaust system

Post by jagnut66 »

3. stainless system are noisier in comparison to the same mild steel setup.
Before I ever got round to fitting a 1275 engine to Abby I swapped her old rusty exhaust for a standard diameter stainless system (supplied by Bull Motif at the time).
I didn't find this any noisier than any of the mild steel systems that I heard, plus I always remember one chap commenting that he was 'surprised' when I told him that I had fitted a stainless system, as 'it still sounds like a Minor'.
She even still 'parped', just like a good Minor should! :D
Best wishes,
Mike.
1954 Series 2: 4 door: "Sally" -- Back on the ground with (slave) wheels and waiting to be resprayed......
1970 Triumph Herald 1200: "Hetty" -- Driven back from Llangollen in Wales (twice.....)
Sleeper
Minor Legend
Posts: 1045
Joined: Tue Nov 08, 2016 3:18 pm
Location: Manchester ( Damp and Miserable ) and that's just the wife...
MMOC Member: Yes

Re: Quietest exhaust system

Post by Sleeper »

Thinking out loud....

I wonder what diameter the silencer pipe was on a LE Velocette?


John ;-)
James k
Minor Addict
Posts: 704
Joined: Tue Nov 11, 2014 3:59 pm
Location: Hastings
MMOC Member: No

Re: Quietest exhaust system

Post by James k »

I fitted a new two piece mild steel exhaust from ESM a few years ago and it turned the car into a fighter jet! It's so loud it makes me not want to drive. I've even been told off at the petrol pump by another owner for fitting a 'boy racer exhaust'! I'm still on a quest to find a quieter one.
jagnut66
Minor Legend
Posts: 3635
Joined: Fri Apr 11, 2008 7:28 pm
Location: Mansfield, Nottinghamshire.
MMOC Member: Yes

Re: Quietest exhaust system

Post by jagnut66 »

I've even been told off at the petrol pump by another owner for fitting a 'boy racer exhaust'!
I hope you mean in jest, as I find it unsettling that one owner should take it upon himself to 'discipline' you for something 'he' disapproved of. After all how did he know that the noise level wasn't because you'd fitted a larger engine and what then? Is he going to go round the Nationals 'disciplining' those whose car mods he disagrees with??
:lol:
There'd be a riot! Victor Meldrew lives! :lol:
Mind you members getting their faces in the papers for a punch up at the MMOC National, considering that most people probably think Morris Minor owners to be quiet, peaceful souls, eccentric but harmless (the impression I get of what people think of us anyway)....... might prove mildly amusing.
Good luck with your quest for a quieter exhaust though and don't rule out stainless.
Best wishes,
Mike.
1954 Series 2: 4 door: "Sally" -- Back on the ground with (slave) wheels and waiting to be resprayed......
1970 Triumph Herald 1200: "Hetty" -- Driven back from Llangollen in Wales (twice.....)
User avatar
Monty-4
Minor Addict
Posts: 699
Joined: Sun Oct 26, 2014 7:17 pm
Location: Gloucestershire
MMOC Member: Yes

Re: Quietest exhaust system

Post by Monty-4 »

Despite having one (that I find to be too noisy) I do wonder if the larger bore exhausts really offer any advantage given we spend most of our time below around 3000 rpm. I've been considering reverting to a 1.25" mild steel system with a reducer to retain the 1.5" LCB manifold. Then again, how about twin 1.25" exhausts - double parp?!
68' 4-door Saloon, another 'Monty'.
philthehill
Minor Maniac
Posts: 10767
Joined: Thu Jul 19, 2012 12:05 pm
Location: Hampshire
MMOC Member: Yes

Re: Quietest exhaust system

Post by philthehill »

Larger bore exhausts are only of benefit if you are getting more fuel mixture into the combustion chamber which results in needing to get more exhaust gases out.
Fitting a LCB is more about overcoming valve overlap than LCB exhaust bore size.

kevin s
Minor Legend
Posts: 1375
Joined: Tue Mar 26, 2013 8:20 pm
Location: Chelmsford, essex
MMOC Member: No

Re: Quietest exhaust system

Post by kevin s »

it's not the larger bore that makes it noisy its that they usually come with straight through absorption type mufflers, changing the front muffler in the large bore for one with some baffles and/or resonant chambers would make it much quieter.
Post Reply