109 exhaust question

[smukai]

I am soliciting suggestions...

I loaned my 1967 IIa 109" Station Wagon to my brother for a few weeks while he was having the diesel injectors rebuilt on his Range Rover Classic.

When it was returned, we found that the muffler had blown a seam and was now a bit noisy. I vociferously blamed him but I do know he isn't at fault (but you have to blame the brother...you just have to).

The exhaust on my truck is a custom job from about 9 years ago when I put a high compression engine in. It is oversized for less back pressure.

Should I find a muffler to splice into the line? Should I have a whole new exhaust built? Is there something (stainless perhaps) else that I am overlooking which would be cool and exciting?

Thanks in advance for the suggestions!

[mongoswede]

I am soliciting suggestions...

I loaned my 1967 IIa 109" Station Wagon to my brother for a few weeks while he was having the diesel injectors rebuilt on his Range Rover Classic.

When it was returned, we found that the muffler had blown a seam and was now a bit noisy. I vociferously blamed him but I do know he isn't at fault (but you have to blame the brother...you just have to).

The exhaust on my truck is a custom job from about 9 years ago when I put a high compression engine in. It is oversized for less back pressure.

Should I find a muffler to splice into the line? Should I have a whole new exhaust built? Is there something (stainless perhaps) else that I am overlooking which would be cool and exciting?

Thanks in advance for the suggestions!

need more info on what you are running for an engine and what you mean by high compression. even so there are so many answers to this question that I suspect just replacing the muffler would be the easiest option.

[smukai]

Engine question

Sorry...I see I neglected to mention that in my original post.

2.25 Land Rover engine w/ 5 main bearing and a high compression head.

My brother and I were joking about putting a Thrush on (just like our Dad does for all our rust buckets back in Maine).

[LR Max]

Take it back to an exhaust shop.

I had a similar thing happen to my custom exhaust (2" all the way through). I basically broke my muffler off.

Took it to a shop and they just fixed it. Put on a good, quiet muffler. Cheap and easy.

[SafeAirOne]

I suspect that the performance gained by using a custom muffler with less back-pressure is imperceptible.

I'd just go with whatever quality, off-the shelf, bolt-on stuff is available. If you want it to last longer before it rusts out, buy a stainless one.

[mongoswede]

a stock 8:1 compression head runs with a super tiny exhaust and doesnt seem to mind. my Saab 900 turbo with 200 hp runs about a 2" or 2.25" exhaust and is happy. I suspect a huge exhaust on an old rover engine is probably not much of a performance gain unless you are running some crazy cam and 12:1 compression.

But I digress. I still vote for a muffler if the rest of the exhaust is in good shape.

[smukai]

If memory serves, I think it is a 10:1 compression. But it has been years since I put the engine in and I would have to go back through records to check it out.

I suspect you guys are correct...the amount of back pressure created by the smaller system is likely minimal.

The rest of the exhaust is in very good shape. I am thinking the best bet is to simply plug in a new muffler.

[artpeck]

The standard formula I was taught for calculating od exhaust pipe sizing is OD = (RPM × Motor Size ÷ 554,177).5 + .098” (the .5 is an exponent)

For our lowly 2.25 engine that yields an od of .95" as adequate if you assume max torque is at 3000 rpm. I know this as my first reaction to the tiny exhaust pipe was that it must be choking the engine. Nope. There is not much engine to choke...

[smukai]

No one said there would be any math....

[artpeck]

My algebra is rusty enough I had to ask my son what to do with the .5 exponent. Hey I work in clothing. Any academic credibility with him was gone at that point.

[kwd509]

Can't resist: ow old is your son?
With my son My credibility went quite early at 10 or 11. Happily, it is returning quickly and taking him to east tennessee to claim the rover seems to have helped

[artpeck]

Just 18 and a freshman in college. And resenting that I started this rover project the moment he left the house. And more so that his oldest sister is actively involved. He and I built up the D-90 however.

[JackIIA]

The standard formula I was taught for calculating od exhaust pipe sizing is OD = (RPM × Motor Size ÷ 554,177).5 + .098” (the .5 is an exponent)

For our lowly 2.25 engine that yields an od of .95" as adequate if you assume max torque is at 3000 rpm. I know this as my first reaction to the tiny exhaust pipe was that it must be choking the engine. Nope. There is not much engine to choke...

My brain just exploded all over the keyboard. Signing off for a nap.

[txffjim]

So far I have learned how to calculate exhaust pipe size and that "vociferously" is a word. Probably version #2.

–adjective
1. crying out noisily; clamorous.

2. characterized by or uttered with vociferation: a vociferous manner of expression.



On my old j**p ( yea- boo hiss) w/ a carbed 4.2L a 2" exhaust and cheapo pep boys muffler was more than enough.
Your muffler probably rusted internally around the weld or may have snapped from not having a exhaust mount nearby.

[Tim Smith]

Forensic analysis:
If you have a leak in the exhaust system (not saying that is the case) then cold air gets introduced to unburned fuel inside the exhaust system on over-run and pop-pop-pop goes the exhaust. If however, you turn off the ignition while engine braking then get ready for a loud bang when you turn the ignition back on.

If your brother is anything like mine, or me for that matter, he was trying to scare off pedestrians and indeed blew the muffler through his own fault. You were right to blame him.

Of course, it's a rover and the muffler could have just needed a day off.

---
As for diameter. I have a 2 inch exhaust on my 2.25 and it does seem to breath better at high RPM's. My highway speed is quick if not illegal. Not very scientific but there you go.

My advice, get a muffler if the rest of the system is good. If not then find a good muffler shop and have the whole thing made up for cheap.