Air intake scoop

[Jeff Watt]

On my coach the air intake is up high on the driver's side, but it is at the corner. This is the way I see most units. On the road to Canyonville I was passed quite well by a couple in a similar year Marquis. Now I know that coach may have the 600 or 625hp motor, but what I also noticed was the snorkel or duct that was in place so that air was directed into the air intake rather than just sucked into it.

I don't expect this makes a lot of difference, but I am thinking of installing one as I have to drive 3-4 miles each way on gravel everytime I need to take the coach anywhere - drawback of living in the country. The gravel can get really dusty and as the dust swirls around the back of the coach, I am wondering if this vent might help.

Anyone have an idea where they are made. I know I'd have to paint it.

I was somewhat disappointed with the power of the coach in Oregon, idaho, washington Montana hills As I had hoped it would climb the hills a bit better. My 05 patriot seemed to do better in similar mountains granted it was shorter and had one less slide. It seems to me that the cruise waits too long to shift down and by then it is struggling to catch up. So I have now shifted to 5th when approaching a hill (still in cruise) and then let it decided when to shift to 4th; most of the time.

While I am rambling, on the way out I ran the coach just into 6th gear, I.e. about 58-59 mph. On the way home I ran it around 61-62 mph. No noticeable difference in mpg and it may have ran up the less steep hills better.  

Jeff

[Steve Huber Co-Admin]

Jeff,
Re the shift-points, be sure the Allison is not in Economy mode when in the hills as it delays shift points. Coming into a hill, I normally take it out of CC and put it in 5th as soon as I see engine temps rising and RPM dropping, then shift to 4th etc, when the temp increases again (5+ degrees) or the RPMs start to run low. I keep the accelerator on the floor when climbing to keep RPMs up, don't worry about speed and don't go back to CC until I'm back on the flats.
Steve

[Joel Ashley]

I think Roy Warren knows something about increasing airflow, but I thought Monaco had dealt with any such issues by 2007.  I thought I'd read on this Forum about owners building scoops that effectively act like "ram airs", but can't find the thread, so perhaps it was somewhere else, and frustratingly, I can't recall where.  The problem I'd expect from forward facing outer forced intakes is moisture ingestion in wet weather.  Some sort of water divestiture port might be needed at the bottom of the inlet modification or somewhere within the first foot or so of entry.  Just my 2 cents.

Since you encounter regular dust, how long since you checked your filter monitor?  Restriction in the filter or a malformed or otherwise partially obstructed intake tube anywhere along the line could be affecting your hill power, where the engine needs all the cool air it can get.

Joel

[Jeff Watt]

Steve,

I too have been manually shifting the coach as I approach hills as, unless it is of a low grade, the cc doesn't react fast enough (I think) and the coach ends up to slow. Low grade hills on interstates going through n&s Dakota, Nebraska, Kansas, ok and Texas aren't a problem.

Joel,

Good point about moisture. While I do encountere dust on my way in and out of my yard, that is a low frequency activity - 3 trips in/out since January. Have one more this week and then nothing until January. But, yes my air monitor shows getting close to change, albeit the thing reads high even with a new filter.

There is a significant difference (for the better) on the intake on this coach vs. my 05, nevertheless I expect I'll be dropping another $$$ for a new filter.

Jeff

[Jim Nichols]

What ever you put up there for a scoop make sure the the total square inch surface area stays the same as the original opening. I changed my intake from the insde first meaning from the entry of the intake on the left of the engine compartment over to the air cleaner on the right. It originally went through 10 feet of 7" flex ducting. All of our coaches have a water drain built in at the opening. I had sheet metal ducting built to go from the inside drain straight across to the air cleaner with another drain built into the sheet metal for my security. This increased my cfm.  Then I built a scoop on the outside, forward facing and also with drain holes. I started with a 4x8x2 sheet of Styrofoam and cut it into 6 pieces 1'x4'x2" and spray glued them together now having a rectangular box 12"x12"x4'. Started carving it out on the insde to fit the corner and outside to form mold. When satisfied with the dimensions I fiberglassed the outside.  When dry I removed the Styrofoam. I had to reinforce the inside with 1/4" aluminum rod glassed in place.  At the opening I glassed stucco wire lengthwise. There are only 4 screws holding it to the side. I started with an air restriction and solved that and gained better performance. Some mileage increase but mostly when Natasha is driving (not as fast as I).

[Roy Warren Co-Admin]

I don't know if your opening is like mine was, but the hole to the flex hose that connected with the air filter was extremely small in comparison with the hose.  The hose circumference had been reduced to accommodate the hole size and then opened up until it came down between the engine door and the back of the inside of the coach.  I fixed it by increasing the hole size within the air intake and place a pipe which would fit the flex hose.  I extended that hose up about two inches within the intake and then ran it down until I could fit the flex hose onto it with a large ring binder.  I then had to remove some of the engine door frame and it supporting inside frame so that the flex hose could extend down into the engine compartment.  I moved the filter from a fore and aft position in the engine compartment to a position which ran side to side.  This allowed me to lose one 90 degree turn to go into the engine.  This has allowed by air to be increased so that the filter monitor is not near the change filter point as it was always reading in that area, even with a brand new filter.  I believe my mileage has increased by somewhere between .5 and .8 miles per gallon.  It used to be I would never be above 5.2 mpg, but now I am actually over 6 mpg most of the time.  I know some of that increase is because my engine is now in its good running stage (about 99,000 miles) and the increase air flow.  I know that if I changed my muffler and decreased the back pressure it would increase even more.  Good luck.
Roy Warren
2005 PT Vicksburg
C-13

[Jeff Watt]

Just as a follow-up, as I expected from the gauge, the air filter needs replacing. I find it totallly unacceptable that a filter lasts  for only 8000 miles. I counted the number of times I drove to home and back over gravel since the last filer and it is 7 times, I.e. 21 miles (one additional trip was on snow covered).

Now there may have been a couple of miles of gravel during the 8k miles due to construction, but otherwise it was all pavement.

I know there is a significant difference in the piping when comparing my 05 to the 07, but there still is a fundamental flaw or am I the only one having such poor performance from air filters? What have others found with similar coaches? I know the gauge registers restriction even with a new filter so it's like the whole thing is compromised.

If it was a simple little element that could be changed that would be one thing, but these coaches have a large all-in-one canister that is $180. I know $180 is pretty small number in the grand scheme of owning these coaches, but it still p#*%#% me off that it lasts so few miles. My other vehicles run many miles without a filter change, granted the air intake is up front, but still.

Excuse the venting (pun intended), but this is just something I want to know more about from others.

Jeff

[Joel Ashley]

I agree your filter should last longer, Jeff.  Ours has 17000 miles, over all kinds of western U.S. and Canadian and Midwest roads, including hundreds of miles of dusty gravel ones, and is not registering particularly high on the gauge.  I suspect there is something else going on in your case besides a dirty filter.  Unless that 21 miles of home gravel was more like an Arizona dust storm, it shouldn't clog things up.  

I've read that the gauges can be unreliable when reading high, and by simply resetting them even an older filter will then register accurately much lower than before, after a few miles driving to test it.  But others here probably know more about that;  ours has never needed such a procedure.

I reckon the only way to know with any certainty is to remove and inspect the filter to get an idea if it is really the problem, or if something unusual is causing a restriction.  But it sounds like you may have already checked that as you say it reads high with a new filter.  Either Monaco or CAT may have recommendations if you consult them and give them your current filter number and port parameters.

Joel