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Author Topic: Muffler  (Read 3407 times)
Blacksheep
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« on: May 26, 2009, 06:28:35 AM »

Can a new muffler cause a bus to be sluggish on take off? I would think it would since an open exhaust creates more hp. Talking this over with a friend he came up with this thought and I am just curious as to why the sudden lack of power from a dead stop. First if you remember I thought it was the air filter. Now the muffler makes more sense!

Ace
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luvrbus
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« Reply #1 on: May 26, 2009, 06:59:18 AM »

Ace, is your boost pressure the same as before the new muffler, if it is I would check the bypass valve on the blower this will make the engine slow on take off till the turbo spins and makes more air      good luck
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« Reply #2 on: May 26, 2009, 07:31:01 AM »

Ace,don't forget to check the spark pugs and muffler bearing Cheesy

I'll go Quietly now Wink
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« Reply #3 on: May 26, 2009, 04:32:42 PM »

Could be the left over corn expanding.  Where did you leave it?
Jack
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« Reply #4 on: May 27, 2009, 07:22:52 AM »

A stuffed up muffler will most likely cause smoking at full throttle-not at take off.  If you are not getting smoking at full throttle, then it is not the muffler.  Simple-disconnect the pipe to the muffler and drive it-it will be a bit loud, but it will answer your question. Good Luck, TomC
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Blacksheep
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« Reply #5 on: May 27, 2009, 07:44:39 AM »

I doubt the muffler is plugged. The entire exhaust system is new from the turbo! I just noticed a difference in acceleration since it was replaced. Before with the old muffler that had a hole in it, it accelerated much quicker! Now it seems more sluggish!
Just an observation!

Ace
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« Reply #6 on: May 27, 2009, 07:50:51 AM »

I doubt the muffler is plugged. The entire exhaust system is new from the turbo! I just noticed a difference in acceleration since it was replaced. Before with the old muffler that had a hole in it, it accelerated much quicker! Now it seems more sluggish!
Just an observation!

Ace

Ace,

I bet thats exactly what you are felling.

When I redid mine with the dual outputs(easier breathing), I had a noticable pickup on takeoff, but that was it.

You are just feeling the "normal" without the the ventilated muffler casing(isn't that a nice way to say a muffler with a hole in it.. Grin)

Cliff
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« Reply #7 on: May 27, 2009, 08:04:16 AM »

Are you sure it is really slower?  I know in my younger days, putting loud pipes, or even just blowing a muffler, always made it seem faster, but it really wasn't (as proven by my competition).
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Blacksheep
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« Reply #8 on: May 27, 2009, 08:31:22 AM »

Its definitely slower! I NEVER had to floor the pedal. Now its floored until maybe 3rd gear. Before I could half throttle and jack rabbit off from a stop and shift on thru the gears! Now its seems to be a slug!
I have another new muffler compliments of Prevost. I might look at maybe doing some internal modifications to have quiet and performance!

Ace
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« Reply #9 on: May 27, 2009, 09:40:02 AM »

Just a dumb question on my part since I know you just had a bunch of work done on her, but didn't they damage the turbo? Or am I thinking of someone else? When you floor it, does it heave out black smoke?
I'm not the brightest when it comes to these beasts, but I think I'd do as Luvrbus suggested and check the boost pressure and the bypass valve before going any further. It sounds logical, Good luck, Will
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« Reply #10 on: May 27, 2009, 10:07:32 AM »

Ace,

Luvr usually goes straight to the meat of the matter.  Determining the boost pressure would eliminate that turbo they dropped and chipped as having anything to do with your problem.

TomC made good sense, as usual, about eliminating the muffler as a cause.  Disconnect it.  I think you said that you were pondering installing a Prevost muffler anyway so that move would put you half way there in that operation.

Isn't it logical that if you have taken a hit in the power department you are probably going to suffer in the MPG arena?  I think you have good reason to be trying to resolve this......it will probably pay dividends.

Don't forget Sean's dismal experience with "dirt" trashing his 8V92 after an overhaul.  Some real incentive there...you betcha.

The shop you were dealing with got high marks from you.  What do they say?

Thanks,

John
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Blacksheep
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« Reply #11 on: May 27, 2009, 11:04:00 AM »

Hmm, completely forgot about the Turbo incident. Might have to inquire about that!

As for the new muffler? It already has one. Its a long story of how I acquired 2 but I have another new muffler in the shop.

And for the shop that did the work? I actually went camping this past weekend with the owner and his wife. We talked briefly about the smoke and sluggishness on acceleration and I'm sure we can come up with a solution to the problem IF there is an actual problem. It may be me afterall!
It made sense about the NEW muffler having more back pressure than the old one with a huge hole in it.
As for boost pressure? My bus does not have a gauge so I would have to check with the shop to see if they could check it.

Ace
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blue_goose
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« Reply #12 on: May 27, 2009, 02:06:49 PM »

Ace a turbo boost gauge will give you more info on what the engine is doing than anything else you could put on the bus.  They are cheap and only takes a small line going to the dash to install.  From what you have said it sounds like you have a leaking exhaust manifold.  If you have any leaks it kills your turbo boost.
Jack
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« Reply #13 on: May 27, 2009, 02:24:52 PM »

And starts a fire!

In the day it was believed that a leaking muffler or cracked pipe actually increased back pressure in some cases.  That was gas stuff for sure.  That was in the year of BD....Before Diesel.

Great you have such report with the shop.  You made that point many times throughout your adventure.  If it were me, I would be stuck to them as tight as you are.  Good relationships are hard to find....without reservation.

Good luck....and I doubt YOU are mistaken about the power drop....find the cause.

John
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"An uneducated vote is a treasonous act more damaging than any treachery of the battlefield.
The price of apathy towards public affairs is to be ruled by evil men." Plato
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« Reply #14 on: May 27, 2009, 05:00:00 PM »

I had a Donaldson muffler in my MCI 5A. I thought it had too much back pressure. I was chasing causes for running hot. The muffler had a "disc" in the middle, completely blocking "through flow". The exhaust had to go into the holes in the can and go around the blocking disc then exit back through the holes to exit to the tail pipe. So I punched the disc out. Damn it's loud, and I felt that the lack of back pressure resulted in a loss of power Huh May people I talked to said bigger pipe, even straight pipe without any muffler would give more power. I disagree. Like my old Harley, it has WAY more power with a 2 into 1 with a baffled muffler, than drag pipes give it. On that bike it is somewhere around a 10% increase in hp.
Also when I had to replace my heads, (6V92), I had the mechanic adjust the rack to hit a little faster. Properly adjusted it was very sluggish off the line. Now the throttle response is fantastic. This thing hauls a** off the line.

Don & Sheila
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