What's wrong with this muffler?

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2nd December 2016, 11:21 AM
mudski

Quote:

Originally Posted by dom14

According to fleabay, stainless steel ain't any dearer than mild steel.
It's that ones that're purposely made for Patrol arent' available cheaper.
I wonder whether I can modify a standard stainless steel muffler of the same size to suit mine.

Of course you can. A muffler is just made at a generic size, and in and out orientation. Its the pipes on either side that matters.

Sent from my GT-N7105T using Tapatalk
2nd December 2016, 11:29 AM
dom14

Quote:

Originally Posted by mudski

Of course you can. A muffler is just made at a generic size, and in and out orientation. Its the pipes on either side that matters.

Sent from my GT-N7105T using Tapatalk

Thanx Mudski mate.
That's what I've been waiting to hear. I like my hobby. :D
Cheers
Dom
2nd December 2016, 03:54 PM
dom14

I'm thinking about getting a reasonably close stainless steel muffler from a wrecker and modify it to suit mine.
Getting a mild steel used muffler is a waste of money I reckon, 'cos it may end up the same way in no time?
2nd December 2016, 05:59 PM
garett

mufflers are over rated just put in a bit of pipe ... :P
2nd December 2016, 06:15 PM
mudnut

You've gone around this all wrong, Dom.

It goes like this: "Honey, the muffler has got some loose baffles (truth), and I have been informed that they could block the muffler and stuff the engine (truth).

After all the trouble I've had with the whole system it would be easier to get a whole new system than mucking around with individual components (some what true). So the engine pipe flange doesn't stuff up, we should get headers (totally true). They should also give us better economy (truth).

Do not however mention the extra ten percent (achievable, so truth anyway) increase in horsepower.
2nd December 2016, 09:55 PM
GeeYou8

On the subject of stainless vs aluminiumised steel, the stainless is more brittle & prone to cracking. Unless it is a show car, go with the aluminiumised steel.
2nd December 2016, 11:10 PM
dom14

Quote:

Originally Posted by mudnut

You've gone around this all wrong, Dom.

It goes like this: "Honey, the muffler has got some loose baffles (truth), and I have been informed that they could block the muffler and stuff the engine (truth).

After all the trouble I've had with the whole system it would be easier to get a whole new system than mucking around with individual components (some what true). So the engine pipe flange doesn't stuff up, we should get headers (totally true). They should also give us better economy (truth).

Do not however mention the extra ten percent (achievable, so truth anyway) increase in horsepower.

Yeah, I know you have evidence to prove the extractors improve the horsepower without upgrading the pipes or the muffler, but I reckon you got lucky with a good set of extractors and a good carby tune up.
Extractors are cheap enough to buy secondhand, but way too much PITA for me right now.
Muffler's gota be replaced. No doubt about that.

Here's the vacuum gauge test on exhaust back pressure.
As you can see the the vacuum isn't dropping as I increase and hold the rpm.

https://www.youtube.com/watch?v=UTK1...ature=youtu.be

So, it appears there isn't much back pressure at the moment, according the vacuum gauge test, but I'm
sure the muffler is gone anyway. Next time the baffles start rattling inside it might block the whole thing.

BTW, it appears it's holding at a higher level(23 InHg) at steady high revving than at idling vacuum(20), then goes even higher(30) when I let go the high rpm.

Does that look all good?!
2nd December 2016, 11:11 PM
dom14

Quote:

Originally Posted by GeeYou8

On the subject of stainless vs aluminiumised steel, the stainless is more brittle & prone to cracking. Unless it is a show car, go with the aluminiumised steel.

Ok, cool thanx. I didn't know that.
Cheers
2nd December 2016, 11:17 PM
dom14

Quote:

Originally Posted by garett

mufflers are over rated just put in a bit of pipe ... :P

I would, when I get to turbo arena. :D
2nd December 2016, 11:25 PM
mudnut

Quote:

Originally Posted by dom14

Yeah, I know you have evidence to prove the extractors improve the horsepower without upgrading the pipes or the muffler, but I reckon you got lucky with a good set of extractors and a good carby tune up.
Extractors are cheap enough to buy secondhand, but way too much PITA for me right now.
Muffler's gota be replaced. No doubt about that.

Here's the vacuum gauge test on exhaust back pressure.
As you can see the the vacuum isn't dropping as I increase and hold the rpm.

https://www.youtube.com/watch?v=UTK1...ature=youtu.be

So, it appears there isn't much back pressure at the moment, according the vacuum gauge test, but I'm
sure the muffler is gone anyway. Next time the baffles start rattling inside it might block the whole thing.

BTW, it appears it's holding at a higher level(23 InHg) at steady high revving than at idling vacuum(20), then goes even higher(30) when I let go the high rpm.

Does that look all good?!

Dunno. Maybe @nissannewby can tell you what is happening.
2nd December 2016, 11:34 PM
dom14

Quote:

Originally Posted by mudnut

Dunno. Maybe @nissannewby can tell you what is happening.

Ok, cool. I send him a PM. Google hasn't turned up anything on high rpm steady vacuum reading and letting it drop quickly.
3rd December 2016, 08:27 AM
GeeYou8

The vacuum gauge readings are exactly what I would expect, back in the 80s some cars had vacuum gauges (marked economy gauges) in the instrument cluster & that is pretty much what you got.
At idle speed the engine is sucking in air through a small gap
At higher RPM there is more air being sucked & the gap is bigger the engine will reach a speed where the manifold pressure limits it so the absolute pressure will be lower (more vacuum), with a blocked exhaust the exhaust pressure starts to limit RPM so the manifold pressure is higher (less vacuum).
When you close the throttle the engine is still sucking lots of air through a small gap so the absolute pressure drops sharply (more vacuum) until the engine slows to idle speed.

The comments in brackets are there to clarify, there is no such thing as more or less vacuum, you gauge reads "gauge pressure" not "absolute pressure" that a MAP (manifold absolute pressure) would read.
Graham
3rd December 2016, 09:08 AM
dom14

Quote:

Originally Posted by GeeYou8

The vacuum gauge readings are exactly what I would expect, back in the 80s some cars had vacuum gauges (marked economy gauges) in the instrument cluster & that is pretty much what you got.
At idle speed the engine is sucking in air through a small gap
At higher RPM there is more air being sucked & the gap is bigger the engine will reach a speed where the manifold pressure limits it so the absolute pressure will be lower (more vacuum), with a blocked exhaust the exhaust pressure starts to limit RPM so the manifold pressure is higher (less vacuum).
When you close the throttle the engine is still sucking lots of air through a small gap so the absolute pressure drops sharply (more vacuum) until the engine slows to idle speed.

The comments in brackets are there to clarify, there is no such thing as more or less vacuum, you gauge reads "gauge pressure" not "absolute pressure" that a MAP (manifold absolute pressure) would read.
Graham

Thanx mate.
The reason I wondered is that I've heard idling vacuum reading is the highest we usually get.
Not sure where I heard it, but somehow stored in my head as an unclarified "fact". :D
It's good to know the real facts.
Cheers
Dom

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