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Topic: Air intake design (Read 781 times) previous topic - next topic

Air intake design

Hello all,
This is my 1st post here, but I've been visiting for awhile. I recently purchased a 98 U295 36ft, but had owned a 98 U270 34ft. As I was doing an initial cleaning, I found an unusual amount of dust in the cabinet above the bed, especially around the service door for the back-up camera. Until last week, I had always been curious as to what purpose those vents surrounding the back-up camera served.  It never occurred to me that's where the air intake was for the engine. Now, and I mean no disrespect, but what moron could have possible thought that was a good place for the engine to get air? I suppose it's like breathing underwater through a straw: it can work as long as you stay very still and calm, but probably not so much if you're moving around. I'm not an engineer, nor do I play one on TV either, but it seems like a poor design and even if a slight drag/vacuum is created while in moving forward, it could cause the engine work harder for air. Not only that, but driving on dusty roads, any dust would be sucked into that cavity and eventually the bedroom. So, unless there's a logical explanation for my simple mind, I plan to add a second intake source for air. 

Re: Air intake design

Reply #1 –
Next,

Here is a link to what John H has done on this problem.  Read over his various post on this subject.  Here is a link to get you started. Air Filter - Engine   

Pamela & Mike
Pamela & Mike 97 U 320

"It's not what happens to you, but how you react to it that matters."

Re: Air intake design

Reply #2 –
Thanks, I did read through that post, but it's more about the filter and not really the location of the intake. I do agree about the intake being up near the top, just not where FT put it. I have a idea and I'll post pictures once I'm done. This coach came with a few projects that need done. One was a small residential refrigerator that just didn't look or fit right, so I replaced it with a SS Dometic 4 door - but that's a different topic.

Re: Air intake design

Reply #3 –
It sounds like your upper cabinets may be missing the piece of wood that seals off the backup camera area. I drove mine while I had it off when I was replacing the camera, and DW let me know that was a NO-NO. If it *is* installed, then you would benefit from some kind of gasket or seal around that cover. We do not get dust if it is in place.
 
Trent

Trent and Jean Eyler
2000  U295  4003  WTFE  ISC  350
Build#5603 MC#17385

Re: Air intake design

Reply #4 –
Rear Air Deflector
I think this was the link that should have been attached. It works as designed and in all the years I have had mine on I never really needed to change filter, but did just once as I had a spare anyway.
You can make one easily or get one made. I use to make them to order (around 50 ) or so for Forum people but "closed the factory- so to speak"
JohnH
Coachless, now use aircraft. 2003 Ford Travelair TC280 class C. Super shape. Just for 1 yr .
1994 Ford E350 ClassC,total renovation inside and out. Now sold.
2000 U295  36' Cummins 350 c/w Banks Stinger, Resonator upgrade,Solar, LED lites.Residential fridge with slide out pantry. Build 5674. Sold
ex 92 GV 022C ored Cummins. Sold
ex 95 GV240 cat 3116. Sold
2017 Mini cooper s & 2016 land Rover LR2 HSE  LUX.
jhaygarth@aol.com    SKP #130098
treat everyone as you would like to be.

Re: Air intake design

Reply #5 –
I think Next hit the nail on the head.  This is a poor location for the air intake, the low pressure zone feeds dust into the intake.  I suspect the intake area around camera is well undersized for efficiency as well, being a few slots milled into alloy plate. 

Side intake would be better methinks. 

Welcome to the forum, NextForetravel. 

"Not so  long ago we were a nation of risk takers, riding five million pounds of  thrust straight into space."  Joe Gresh
Chuck Pearson
1996 U295
2018 Can Am X3 TurboRS

Re: Air intake design

Reply #6 –
Quote from: Chuck Pearson –
I think Next hit the nail on the head.  This is a poor location for the air intake, the low pressure zone feeds dust into the intake.  I suspect the intake area around camera is well undersized for efficiency as well, being a few slots milled into alloy plate. 

Side intake would be better methinks. 
 

I have posted better photos on the forum of this mod.
If I can find them .........
Justin & Cathy Byrd
1995 U280 "Old Faithful"
36' Build #4673
C8.3 Cummins
Allison MD3060R 6 speed - retarder
Powertech 10KW  4cyl Kubota

Re: Air intake design

Reply #7 –
Quote from: Chuck Pearson –
Side intake would be better methinks. 

Chuck,

That is where at least some of the Nimbus air intake is located.(just below the upper clearance light) It has been reported that in some cases that location causes the air filter to fill with water when the coach is driven in the rain.  In some of the GVs of the early 90s they had the air intake low behind the rear tire which caused much the same problem with dust/trash.

Pamela & Mike
Pamela & Mike 97 U 320

"It's not what happens to you, but how you react to it that matters."

Re: Air intake design

Reply #8 –
Quote from: FourTravelers –
I have posted better photos on the forum of this mod.
If I can find them .........

Again my concern would be driving in a rain storm, that scoop could be overwhelmed by water sheeting down the side of the coach.

A soaked and consequently perforated air filter media and dusted engine would be a high price to pay.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Air intake design

Reply #9 –
Lets face it - on a diesel pusher, finding a good location for engine air intake is difficult.  Any place aft of the rear wheels is gonna be a very "dirty" environment, both in terms of trash ingestion and in terms of air flow.  To me (a non-engineer), optimum placement of the air intake would require two things.  First, to minimize exposure to dirt and trash, locate the intake as high above the ground as possible.  Second, locate the intake where it will see the smoothest, least "disturbed" flow of air.  I have provided a couple sample photos of air scoops below.  One of these, mounted on the roof of the coach, in a spot that is not "blocked" by the A/C unit, would meet both of my requirements.  Other than the occasional ingested bird, the air entering at that point should be pretty clean!

A coarse filter screen could catch the unfortunate birds, and a water trap could divert any rain or snow that entered the scoop.

I offer this idea FREE to all Forum members.  No need to send money...but cheap wine is always appreciated.    :thumbsup:
1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: Air intake design

Reply #10 –
Use of the better filtering, More performance, bluetech Donaldson upgrade foam air filter element would eliminate the engine damage from water injestion damaging the paper element and double the hours between filter changes needed
"Riding and rejoicing"
Bob
1997 U320 40' Mid entry, build 5132,  wtbi ce27, 4th owner
2007 Solara convertible
2 prodeco tech outlaw ss electric bikes

1095 watts solar
08 Ls 460 and a sc430
2000 Ford F-250 superduty 4x4

Re: Air intake design

Reply #11 –
Quote from: wolfe10 –
Again my concern would be driving in a rain storm, that scoop could be overwhelmed by water sheeting down the side of the coach.

A soaked and consequently perforated air filter media and dusted engine would be a high price to pay.

The inlet inside the housing behind the scoop doesnt allow water down the intake, it is elevated, water runs out and down. Filter stays dry.
Justin & Cathy Byrd
1995 U280 "Old Faithful"
36' Build #4673
C8.3 Cummins
Allison MD3060R 6 speed - retarder
Powertech 10KW  4cyl Kubota

Re: Air intake design

Reply #12 –
Quote from: FourTravelers –
The inlet inside the housing behind the scoop doesnt allow water down the intake, it is elevated, water runs out and down. Filter stays dry.

Thanks, for the clarification.  That is a critical part of the modification.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Air intake design

Reply #13 –
The main reason I came up with my design was after driving between Yuma and S Diego a bunch of years ago thru heavy rain and sleet.After the high pass I started to notice some rough running of engine and by the time we arrived at destination I could hardly climb a short steep incline to park. I checked the air filter and it was soaking wet then looked for a cause. Took me minutes to figure out what caused it- the intake and location. I took the filter out and layed it under coach for night hoping the engine heat would dry it out. It did and I replaced it as it looked fine and no breaking of paper etc. All was good again so I decided to make the style of Deflector shown in previous post. This has worked flawlessly ever since and does not look ugly or obtrusive. I have driven in lots of rain and snow since and no water gets in. I have removed the end cylinder cap to look at filter and it stays clean and dry and my engine temps have not changed 1 degree since install. I did extend the overhang another 2" to better help keeping the camera clean and dry.
Foretravel Tech looked at it when we were there a few years ago and thought it great idea as he mentioned they see LOTS of crap etc in there when servicing.
JohnH
Coachless, now use aircraft. 2003 Ford Travelair TC280 class C. Super shape. Just for 1 yr .
1994 Ford E350 ClassC,total renovation inside and out. Now sold.
2000 U295  36' Cummins 350 c/w Banks Stinger, Resonator upgrade,Solar, LED lites.Residential fridge with slide out pantry. Build 5674. Sold
ex 92 GV 022C ored Cummins. Sold
ex 95 GV240 cat 3116. Sold
2017 Mini cooper s & 2016 land Rover LR2 HSE  LUX.
jhaygarth@aol.com    SKP #130098
treat everyone as you would like to be.

Re: Air intake design

Reply #14 –
Quote from: wolfe10 –
Thanks, for the clarification.  That is a critical part of the modification.
If I can find the photos........ ::)  I'll post them again, it;s easier than trying to describe it.

But I understand the concern, I was troubled by it too, I have checked for water intrusion a couple of times and all looks good.
Justin & Cathy Byrd
1995 U280 "Old Faithful"
36' Build #4673
C8.3 Cummins
Allison MD3060R 6 speed - retarder
Powertech 10KW  4cyl Kubota

Re: Air intake design

Reply #15 –
FourT,

I know we are getting off track but....

Is your coach one of the ones that has a Donaldson water separator in the air tube?
Here is a link to what I am talking about. H000878 Donaldson In-Line, Vertical Separator | MRO Stop Technology

Pamela & Mike
Pamela & Mike 97 U 320

"It's not what happens to you, but how you react to it that matters."

Re: Air intake design

Reply #16 –
Yes, or one very similar to it. It is a Donaldson vertical separator just ahead of the horizontal air filter.

I will post some pics in another thread..... IF I can find them, (recently changed laptops) trying to get organized. :-[
Justin & Cathy Byrd
1995 U280 "Old Faithful"
36' Build #4673
C8.3 Cummins
Allison MD3060R 6 speed - retarder
Powertech 10KW  4cyl Kubota

Re: Air intake design

Reply #17 –
A P.O. of our coach made a modification to the original intake system. He added this stainless steel scoop over a hole cut into the air box where the lower and upper intake tubes meet. The tubes are offset, upper tube located in the very corner of the coach and the lower tube is offset inward to allow for the taillight assembly.

I did not like the fact that the PO relied on the water separator to keep water out of the filter canister.
As Brett mentioned in his post...... not a good idea.

I modified the PO's modification by adding a PVC sleeve inside the air intake and sealing around it to prevent water from just running down into the cyclone air separator. Air must enter from the upper part of the box a few inches above the bottom of the air box.
I also added a screen to prevent larger bugs and debris from entering the box. 

I like the idea of cleaner air entering from the side verses the rear "back draft" area.

 Would I have done this mod? Probably not...... I would have left it as FT had it. But I decided to leave it and improve on it.



Justin & Cathy Byrd
1995 U280 "Old Faithful"
36' Build #4673
C8.3 Cummins
Allison MD3060R 6 speed - retarder
Powertech 10KW  4cyl Kubota