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Author Topic: Increasing Exhaust Efficiency -- ideas being sought  (Read 3976 times)
Brian Diehl
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« on: April 03, 2008, 08:24:49 AM »

I now have over 4000 miles on my ISM re-power in my 96A3 bus.  I'm now looking to increase efficiencies where I can.  When I did the re-power I reused the muffler my 6v92 was using.  The muffler is a Donaldson M120131 F1.  This muffler has both the inlet and the outlet on the same end of the muffler and has fairly good flow ratings.

Exhaust Flow CFM @
3" Hg     2" Hg     1" Hg
-----     -----     -----
2913      2378     1682

The issue with this is the number of bends I had to put in my exhaust to connect to the muffler.  The turbo outlet on the ISM points to the rear of the engine (front of the bus).  So, I had to do an immediate 180 turn to reorient the exhaust towards the back.  Then I had to do another 180 turn to go down and into the muffler inlet (now exhaust is flowing to the front of the bus in the muffler).  Then the muffler redirects the exhaust back another 180 degrees and forces the exhaust to exit out the rear of the muffler.  So, you can see there are a lot of turns in the exhaust system.  I'd like to find a way to have only the first 180 degree turn and drop right into a muffler and then exhaust out the back of the muffler.

The problems I've run into is according to the Donaldson web site this is essentially the highest flow muffler they offer in the small space it occupies.  I'd love to run the M090535, but don't know how I would get a 51" long muffler into the back of the bus.

The M090535 has these specs:
Exhaust Flow CFM @
3" Hg     2" Hg     1" Hg
-----     -----     -----
3260      3100      2340

So, I'm looking for ideas .... I want to stay with the 5" exhaust at a minimum.

Any thoughts on how to improve this setup?

Keep in mind the MCI muffler fits up between the tag tire and the bumper.  The M120131 muffler is 29" long and there is no way I can see to put a longer muffler in the existing space unless I'm missing some reconfiguration options.

Thanks!
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Don Fairchild
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« Reply #1 on: April 03, 2008, 08:46:15 AM »

Brian

The book shows the ISM exhaust flow of a 500hp 2100 rpm engine at 2341. I don't know what hp you are running but your do need to delete some of those bends. Have you looked at the walker site to see if they might make something that would work for you. a side or top inlet with a end out let sounds like the one you would want.

Good luck.

Don
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Brian Diehl
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« Reply #2 on: April 03, 2008, 08:51:01 AM »

Don,
I'm running at 400HP, but can be reprogrammed to 450.  So, I need to make sure I accomodate a 450HP setting if I ever decide to go that route.  Can you look up the flow required at 450HP and 400HP?  Also, what was the Hg back pressure allowed?

Walker mufflers?  The website looks like an automotive website.  Is there a particular page that would be a good starting point for me?
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Brian Diehl
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« Reply #3 on: April 03, 2008, 08:54:01 AM »

Hmm, asked to soon.  I found the Walker Heavy Duty site.

Would these be better than a "regular" muffler?

http://www.walkerheavyduty.com/products/Engine_Brake_Silencers.asp
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skipn
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« Reply #4 on: April 03, 2008, 09:00:09 AM »

Brian

   Couple of ideas........

Coated, Ported and Polished Exhaust Manifolds
from http://www.pittsburghpower.com/

   They also have some high flow mufflers but appear to be 51" also


    Skip
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Brian Diehl
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« Reply #5 on: April 03, 2008, 09:12:02 AM »

Brian

   Couple of ideas........

Coated, Ported and Polished Exhaust Manifolds
from http://http://www.pittsburghpower.com/

      Skip



I like the idea of the ported/polished manifold, but not at $1000!  Maybe I will do some porting myself and gain some benefit. 
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FloridaCliff
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« Reply #6 on: April 03, 2008, 09:13:19 AM »

Brian,

I used the Walker site to get all the parts numbers I needed when I redid my 4905's exhaust.

Compare your local prices to http://www.rockauto.com/.  At the time they beat out everybody.

Good luck,

Cliff
« Last Edit: April 03, 2008, 09:17:31 AM by FloridaCliff » Logged

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Don Fairchild
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« Reply #7 on: April 03, 2008, 09:23:11 AM »

Brian

Go back to the walker site and go to commercial mufflers and page 270. Look at the 21147, 21584 and 21835 I did not look at the flow rate of these but one of them might work for you.

The exhaust flow for a 400 hp at 2100 is1853 and 450hp is 2030

hope this helps

Don
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TomC
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« Reply #8 on: April 03, 2008, 09:34:04 AM »

Stay with that same muffler but reposition it next to the transmission.  Then you can run a pipe that is relatively straight back from turbocharger to the muffler by the transmission, then the tail pipe can come to the back of the bus by means of a relatively straight pipe also.  Even running the pipe back almost to the rear axle, even though a longer distance, will again eliminate those 180 turns and be able to use much straighter lines.
I have the same type of muffler, 5" same side inlet and outlet.  When I bought it you could look inside and see no baffles.  Even though I have 3 sharp 90 degree turns, it is still more free flowing than the giant stuffed up muffler (66" long and 13" in diameter) that was on it originally.  Good Luck, TomC
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« Reply #9 on: April 03, 2008, 10:19:24 AM »

Brian

Go back to the walker site and go to commercial mufflers and page 270. Look at the 21147, 21584 and 21835 I did not look at the flow rate of these but one of them might work for you.

The exhaust flow for a 400 hp at 2100 is1853 and 450hp is 2030

hope this helps

Don

Thank you Don!  I appreciate the part numbers and CFM information!
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skipn
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« Reply #10 on: April 03, 2008, 10:36:23 AM »

Brian,

    Since you are looking at the exhaust side of things are you still running the stock
 intake sizes.    Mostly wondering about the intake part that directly accesses the
 outside air. On my 8 it seems to be a rectangle affair just infront of the drivers side
 radiator. Looks a little small to me?

Skip
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Stan
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« Reply #11 on: April 03, 2008, 12:12:54 PM »

Thinking along the same line as Tom, leave the muffler beside the engine facing back with a 180 feeding it and a 90 out to the side.
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HB of CJ
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« Reply #12 on: April 03, 2008, 01:28:44 PM »

Yeah, my best guess here is that you have way too many bends in the pipe.  Going to a larger flow muffler without addressing the root problem is not really going to help.  Neither is going to a larger diameter pipe keeping all the bends of the same radius.

Someway we need to put on our thinking caps and come up with a good idea/plan to open up the restrictions with your exhaust system.  Quiet is good here, along with MINIMUM turns and stuff.  Perhaps you can send us some pics of your present system.  Sure we can fit it.  Smiley Smiley Smiley
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Dreamscape
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« Reply #13 on: April 03, 2008, 01:31:07 PM »

Can't help you Brian,

But I sure wish I had the problems you had with your exhaust.  Grin

You did a great job and had a great visit with you and your wife.

Good Luck and Happy Trails,

Paul
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skihor
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« Reply #14 on: April 03, 2008, 01:43:35 PM »

Aero makes a high flow w/ 5" in/out. Supposed to increase HP & MPG.
 http://www.aeroexhaust.com/five_inch_muffler_5050xl.html
I have a 90 / 90 on my 6V92 it seems to work fine. My turbo outlet faces the front of the bus also. I have a short straight then 90 w/ a short straight, then another 90 into the muffler, and a long bend 90 out beyond the body. If you can use long bend 90 that's better.

Don & Sheila
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skipn
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« Reply #15 on: April 03, 2008, 01:44:39 PM »

HB of CJ

http://home.earthlink.net/%7Ediehls0792_1/BusSection10.html

 Two thirds down on the left is a great picture of what he has.
 While you are at it gander at the rest of Brians project.....Probably the best
 documented repower I have seen in a very long time.



   Skip
« Last Edit: April 03, 2008, 01:56:12 PM by skipn » Logged
Sam 4106
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« Reply #16 on: April 03, 2008, 02:01:53 PM »

Hi Brian,
You have probably already thought of this,but I wonder if you could get a different turbo that would direct the exaust to the front of the engine (rear of the bus)? If I remember right, you already changed your turbo so that is probably too expensive an option. Or, would it be possible to build a bracket to remount the turbo (turn it upside down) so the exhaust comes out toward the front of the engine? Then if you could find a muffler with the inlet on the side and the outlet on the end you could reduce the number of turns a lot. Just some random thoughts.
Good luck, Sam 4106
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« Reply #17 on: April 03, 2008, 03:35:31 PM »

Brian, I have a new old stock Nelson muffler 5 in and 5 out on the other end. Its 24inches long and 24 wide. If you can use it I'll make you a smoking deal. After looking at your page, I would come off the turbo and 90 down and 90 again into a muffler. Then exhaust out the rear. This muffler is not straight thru.  Tom Y
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Tom Yaegle
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« Reply #18 on: April 03, 2008, 06:01:46 PM »

I am looking at the same issue with my Series 60.  My engine is set at 475 and I am pretty sure I am not getting that level of power.  The two areas I am looking at are the exhaust and air intake.  Don gave me some guidelines for the air, but I have not looked at exhaust  requirements.

When I was building my truck motorhome, I made a manometer to measure back pressure.  Very simple device to make and we are not talking about big pressure.  Easy to hook up with a truck, but not as easy to do with a bus with engine in back.  Guess I will have to talk the better half into riding in the back and marking the high and low levels when I hit it hard.

I currently have a 5 inch Aero and less bends than Brian.  I am not real happy with the lack of noise reduction with the Aero.  Sounds good some of the time (like coming into a rally with the jakes on Grin), but no good way to be a good citizen in residential areas.  It does not have a flow rating, but the folks peddling the unit talk in glowing terms about "free flow".  I will probably have it for sale in the near future.

I think it is Walker who has a 6 inch inlet/outlet muffler, but I don't think I can get it in.  I am now looking at using two smaller 5 inch mufflers.  I think I can get then in if I put them in a vertical position.

Concerning the air inlet, my tattletale suggests that my vacuum is kind of high even with a fairly clean air cleaner.  I am using the air cleaner that came with the engine, but it was a cowl unit so, had some ram affect.  The element has a pretty high rating, but it must not be enough.  Next week I plan to do a short drive with no air cleaner to make sure it is not some other restriction. 

I am looking for a smaller air cleaner to use on the driver side, coupled with the existing unit.  Have not had a chance to look around the wrecking yard to get ideas.  It has to be reasonably small to fit on the driver side because of the engine off set, and other issues.

Jim
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Jim Shepherd
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« Reply #19 on: April 03, 2008, 07:00:50 PM »

Brian, I have a new old stock Nelson muffler 5 in and 5 out on the other end. Its 24inches long and 24 wide. If you can use it I'll make you a smoking deal. After looking at your page, I would come off the turbo and 90 down and 90 again into a muffler. Then exhaust out the rear. This muffler is not straight thru.  Tom Y

Wow, thanks for the kind offer Tom!  Could you tell me the part number on the muffler?  I can't make it out in the picture.
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Brian Diehl
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« Reply #20 on: April 03, 2008, 07:16:25 PM »

I am looking at the same issue with my Series 60.  My engine is set at 475 and I am pretty sure I am not getting that level of power.  The two areas I am looking at are the exhaust and air intake.  Don gave me some guidelines for the air, but I have not looked at exhaust requirements.

.
.
.

I am looking for a smaller air cleaner to use on the driver side, coupled with the existing unit.  Have not had a chance to look around the wrecking yard to get ideas.  It has to be reasonably small to fit on the driver side because of the engine off set, and other issues.

Jim

The muffler problem is very real with our buses.  I'm still unsure how I want to go.  I really like the idea TomC presented about putting the muffler up by the transmission, but I really don't think it will work on my bus given how wide and low the AutoShift is.  Tom Y.'s muffler looks to be short enough to fit in the area where my current muffler is.  The real question is if it has the flow rating for the motor.

On the air filter I reused the air filter from the 6v92 that was originally in the bus.  I have as yet been unable to get any vacuum to show up on the flow restriction tell tale.  I think the bigger filter, compared to what was in the truck, is the difference.

In reply to Skip's message about intake.  The intake on the A3 series of buses was redesigned.  It has an 8" intake coming down from above the driver side radiator.  I think it flows plenty of air.  I am going to take apart all the pipes on the turbo outlet/intercooler side of the system and tweak them a bit.  I want to take and chamfer the inside edges of the pipe in a 45 degree angle to help the air flow stay as laminar as possible as it goes from joint to joint.  I think chamfering down the edges will help as the pipes have an 1/8" wall thickness.


Don and Sheila,
The 5050XL Aero muffler sounds like it might do the job, but it is 30" long.  I think it would be a tough fit due to having to get a 90 degree angle into the front and an exhaust tip off the back.  I also couldn't find any flow ratings for the muffler.  Have you used or heard this muffler?  I wonder how good of a job it actually does. 

Jim, is the Aero on your bus the same as the 5050XL?  If so, then it sounds like it doesn't do the job good enough.

Thanks for the ideas guys.  I'll research some more and see what I can figure out for this.
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« Reply #21 on: April 03, 2008, 07:32:16 PM »

Brian, It has Nelson 12C91.  I think the 91 is the year.  Tom Y
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« Reply #22 on: April 03, 2008, 07:54:02 PM »

I thought Craig Shepard told me at the Minnesota mini-bus rally last year that a 2 stroke needed more intake air than a 4 stroke.  If that is true an air filter from a two stroke should provide plenty of intake air.

I remember commenting about the air fiter on either Brian Brown's bus or Craig's bus being awful big, but when we went and looked at the air filter on my Series 60 it was about the same size.
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« Reply #23 on: April 04, 2008, 03:39:01 AM »

Brian, we are somewhere in the Atlantic ocean on the way home from a cruise that Pat earned.  As a result, I do not have the specific information of the Aero muffler.  However, I am pretty sure they only make one 5 inch muffler.

I think it is too early to pronounce the muffler too restrictive. 

After I posted the last time, I finalized a plan to check both the air cleaner and muffler.  I am going to make a short run on the paved, steep road in front of our house without the air cleaner element to make sure the restriction is not in the plumbing (will use the tattle tale to measure).  At the same time, I plan to weld a bung in the exhaust and hook up a manometer to measure exhaust back pressure.  I think I can get that done early next week if the weather holds.  I will report back after I do the test.

Jim
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Jim Shepherd
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« Reply #24 on: April 05, 2008, 04:37:54 AM »

If you have anything less than a 12V-71TA in the bus, then a single 5" exhaust system will be sufficient.  Even the new trucks with catalyst and particulate traps are just using a single 5" exhaust.  When the horsepower gets above 550, then dual exhaust are used.  Without the catalyst and particulate traps, a 5" exhaust will accommodate 600hp (in 4 strokes) easily in single configuration.  6" is hard to work with, hard to find, expensive and takes a lot more room.  Good Luck, TomC
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« Reply #25 on: April 05, 2008, 08:07:28 AM »

Brian, It has Nelson 12C91.  I think the 91 is the year.  Tom Y

I've done a bunch of different Google and Ryder Fleet Products searches and can not find the Nelson 12C91 muffler.  Does anyone know where I can find the specs on this muffler?
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Brian Diehl
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« Reply #26 on: April 05, 2008, 08:08:51 AM »

If you have anything less than a 12V-71TA in the bus, then a single 5" exhaust system will be sufficient.  Even the new trucks with catalyst and particulate traps are just using a single 5" exhaust.  When the horsepower gets above 550, then dual exhaust are used.  Without the catalyst and particulate traps, a 5" exhaust will accommodate 600hp (in 4 strokes) easily in single configuration.  6" is hard to work with, hard to find, expensive and takes a lot more room.  Good Luck, TomC

You definitely would know about this TomC!  Although the idea of 6" pipe is nice .... you know ... "Bigger is Better"!!!  and the tim allen Tool Time Moto "More Power"! 

I think I'll stick with 5" pipe.   Smiley
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Brian Diehl
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« Reply #27 on: April 07, 2008, 10:39:07 AM »

Brian, It has Nelson 12C91.  I think the 91 is the year.  Tom Y

Tom,
Do you happen to know what this came off or what it was intended for?  I've talked to Ryder Fleet Products and Nelson technical support and neither of them show the 12C91 as a valid part number.
-Brian
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« Reply #28 on: April 07, 2008, 07:15:26 PM »

Brian, Thats the only number on it. I got 2 of these when I bought the L10s. They were for Gilig buses with L10s. This is your goverment dollars at work. They must hold up well because they never changed them. The in side has a 5 inch pipe with about 1/4 inch holes and forms a cone with holes in it also. Hopes this helps.  Tom Y
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« Reply #29 on: April 07, 2008, 07:17:39 PM »

Brian, Heres what I think is the outlet.  Tom
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« Reply #30 on: April 07, 2008, 07:26:46 PM »

My 92 is straight pipe. It is not noisy and I got rid of a ton of heat, especially around the transmission. Probably not for everyone, but I would not have it any other way.

This also eliminates the back pressure issue and in turn eliminates the need for an aftercooler.
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Brian Diehl
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« Reply #31 on: April 07, 2008, 07:30:24 PM »

My 92 is straight pipe. It is not noisy and I got rid of a ton of heat, especially around the transmission. Probably not for everyone, but I would not have it any other way.

This also eliminates the back pressure issue and in turn eliminates the need for an aftercooler.

How loud is this setup?  My existing muffler is not what you would call "quiet"!
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« Reply #32 on: April 08, 2008, 12:02:35 AM »

Brian,

I had the same thought as Stan.  Turn your muf around and get in the front with a single 180 or two 90's.  The ex would then be a little further to the front of the bus with a single 90 but thats no biggie.

My REAL question is "just how much back pressure do you have?"  The muf flow is speced with 1, 2, or 3 inches of Hg.  OK, just where are you?  I know that all those bends are really to be avoided....no question.  BUT, if you have no appreciable back pressure you are picking fly shxx from pepper....maybe.  At any rate I would really like to know what the back pressure is so I could access how much improvement I have created if I change ANYTHING.  I hate that part where you hear "I think it was PRETTY bad...and now I think it is MUCH better.  Sure SEEMS to be STRONGER".  WRETCH!

You have done the absolutely best engine swap I can even imagine. Shocked  I want to be like you when I grow up( Roll Eyes) and I am twice your age already. Grin

Admiringly,

John

PS:  If you test the pressure at the output of your compressor turbo and then get a read on the intake manifold, would that tell you how many pounds you are dropping across the "intercoolers"?  Wouldn't a filter minder at the input to the turbo evaluate the efficiency of your filter and plumbing to that point?

Lots of power and efficiency is burried in the heat loss of the ex system before the turbo and that heat also detracts from the comfort of the bus.  Heat wrap would seem to be a "gimmie".   Wouldn't want to go through that expense if I wasn't sure my current system was as efficient as i neededn and there weren't changes in the near offing.

Some thoughts only.
« Last Edit: April 08, 2008, 12:26:17 PM by JohnEd » Logged

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