Engine inlet grate

Topic: Engine inlet grate (Read 1153 times) previous topic - next topic

Engine inlet grate

April 30, 2021, 10:28:51 am

So in mounting my rear camera I had the pleasure of removing the inlet grate. 11/32 nuts and quite fun removing standing on the bed platform. Once removed I came across other issues. MUD DAUBER NESTS. So I physically removed all I could and vacuumed out . Used my inspection camera to insure there was no more. Wonder if my Precleaner is rated for them. Also one paper wasp nest. I quickly measured the opening size to be 16 square inches. Is this large enough for a 10.8 liter engine? Seems marginal, will look into it more. I have prior removed dauber nests out of my engine air filter assembly but none after Precleaner installation. I will be installing a small wire stainless steel 1/4" hardware cloth over the opening, however this also reduces the opening size. It can be folded into a W and this would resolve that issue I think. Will accurately measure grill size today and get a better measurement. Could easily cut openings larger while off and also incorporate a shade/rain cover.
Scott

Re: Engine inlet grate

Reply #1 – April 30, 2021, 10:46:40 am

I think the wasps will like the 1/4" stuff. That lets them in and keeps other critters out.

Re: Engine inlet grate

Reply #2 – April 30, 2021, 11:04:16 am

By recording air filter minder before and after any modification will tell you exactly how much you have improved/hindered air flow.

Re: Engine inlet grate

Reply #3 – April 30, 2021, 11:06:00 am

Quote from: kb0zke – April 30, 2021, 10:46:40 am

I think the wasps will like the 1/4" stuff. That lets them in and keeps other critters out.

So I saw that Foretravel had used the 1/4 in the basement drain/vent and somehow I've had no prior nests in there. I looked online last night for a hour and only found 1/8 hardware cloth recommended. Too restrictive. We don't have any bug issues we're the coach lives now, this was all prior to purchase last June. Well except on the windshield. I'm just trying to be proactive.
Scott

Re: Engine inlet grate

Reply #4 – April 30, 2021, 11:12:11 am

I removed the inlet grate as well to cut off the old camera, very tough to get at the nuts and washers inside and if you drop one a magnetic wand didn't work because they are stainless. A small hook attachment on the camera snake got them.

Re: Engine inlet grate

Reply #5 – April 30, 2021, 11:12:25 am

Quote from: wolfe10 – April 30, 2021, 11:04:16 am

By recording air filter minder before and after any modification will tell you exactly how much you have improved/hindered air flow.

I was thinking that would figure into it. I do see a set point with the filter minder, but then it seems to stabilize and remain the same. I know we're not supposed to open the filter housing up to inspect, but I have been opening up and cleaning since purchase and glad I did with all the powder in the filter with a only slightly restricted indications. Probably ground up nests? Filter minder verification both directions with the elbow filter being plugged but found on original purchase pre-inspection last year.
Scott

Re: Engine inlet grate

Reply #6 – April 30, 2021, 11:14:20 am

Quote from: Roger & Susan in Home2 – April 30, 2021, 11:12:11 am

I removed the inlet grate as well to cut off the old camera, very tough to get at the nuts and washers inside and if you drop one a magnetic wand didn't work because they are stainless. A small hook attachment on the camera snake got them.

Yes the vacuum worked also. Can was clean prior to hiking it up to the roof. Lol
Scott

Re: Engine inlet grate

Reply #7 – April 30, 2021, 12:47:56 pm

So the inlet tube is 6" OD. this equates to over 25 square inches area ID. The grill calculates to being 20.6 square inches. Probably not a issue on a smaller engine but regardless is is the most restrictive point of the intake causing higher flow across it. It's .090 thick, distance to the plenum. If they were 5/8" .625 instead of 1/2 wide that would bring up to 25.75 Square inches similar to the inlet tube
Is this worth chasing or a non issue
Scott

Re: Engine inlet grate

Reply #8 – April 30, 2021, 12:55:42 pm

Only your air filter minder knows. If no excessive restriction, no problem.

Re: Engine inlet grate

Reply #9 – April 30, 2021, 10:10:24 pm

Knowing that a 25% undersize is a issue at least to me made new inlet grill and will add a cover that my camera will attach to. Just rough cut but so far happy with it.
Scott

Re: Engine inlet grate

Reply #10 – April 30, 2021, 11:11:12 pm

Why do you think the OEM air entry grid is 25% undersized? The 6" connection to the air filter was likely a standard size not a minimum. A bigger air entry won't hurt.

Re: Engine inlet grate

Reply #11 – April 30, 2021, 11:17:08 pm

At least it will match restrictions of 6 inch inlet. Got it welded up will finish soon. My filter minder always gives a initial set point. If that is reduced it's worth it

Re: Engine inlet grate

Reply #12 – May 03, 2021, 02:46:44 pm

So old inlet was 20.6"

Quote from: dsd – April 30, 2021, 12:47:56 pm

So the inlet tube is 6" OD. this equates to over 25 square inches area ID. The grill calculates to being 20.6 square inches. Probably not a issue on a smaller engine but regardless is is the most restrictive point of the intake causing higher flow across it. It's .090 thick, distance to the plenum. If they were 5/8" .625 instead of 1/2 wide that would bring up to 25.75 Square inches similar to the inlet tube
Is this worth chasing or a non issue
Scott

So new inlet openings are six 9.25 inch long cuts at .625 wide so it is 34.7 inches. Actually the 9.25 is 9.5 but reduced because I didn't figure the 5/8 radius loss so just cut it in half. Got the stainless steel screen in and it actually is tighter than 1/4 which is fine and about .025 thick. Not worried about the amount it will block so will just lay flat under grill. Cut stainless and will have enough to do fridge vents with it also. Will sandblast tonight and paint it white. Backdrilled new grill to allow screws from the outside. Riveted nut plates to back side. Some of the holes were cut wide by Foretravel to fit and rivet is actually in space but will still stop rotation during install and removal. Used reduced head 10/32 screws from outside countersunk. Can be seen in photo.
Scott

Re: Engine inlet grate

Reply #13 – May 03, 2021, 04:16:41 pm

Quote from: dsd – May 03, 2021, 02:46:44 pm

Got the stainless steel screen in and it actually is tighter than 1/4 which is fine and about .025 thick. Not worried about the amount it will block so will just lay flat under grill.

Depending on the stainless mesh you have chosen the percent open area can be significantly reduced. Here is a link to a vendor where you can probably select something close to what you acquired.
McNichols

Re: Engine inlet grate

Reply #14 – May 03, 2021, 04:20:50 pm

Please let us know before and after air filter minder readings-- yes, after a couple of WOT, high RPM runs.

Re: Engine inlet grate

Reply #15 – May 03, 2021, 04:56:02 pm

I wonder if this thought will trigger some ideas?
I am willing to bet the mud daubers don't try to get in while the coach is going down the road.
So, with that in mind, what about a "flap" on the inside of the air intake grill?
It would swing up from the air intake velocity created by the engine taking in air.

Again, just thinking here. Hoping someone with the problematic air intake can consider my idea.

Re: Engine inlet grate

Reply #16 – May 03, 2021, 08:45:48 pm

Quote from: bpal – May 03, 2021, 04:16:41 pm

Depending on the stainless mesh you have chosen the percent open area can be significantly reduced. Here is a link to a vendor where you can probably select something close to what you acquired.
McNichols

Square - Wire Mesh - Stainless Steel - 380428 | McNICHOLSÂ®
Square, Stainless Steel, Type 304, Woven - Plain Weave, 4 x 4 Mesh (Square), 0.2220" x 0.2220" Opening (Square), 0.028" Thick (22-1/4 Gauge) Wire Diameter, 79% Open Area
This was as close as I could find. Difference being mine is .025 diameter and the at the .222 spacing. So I have less resistance being .003 thinner. Still puts me above tube restrictions with increased sizing without having to bend into a W. So it will go down flat between opening and grill
Purchased from Amazon

Amazon.com: BAISDY 5 Mesh 30x120cm 304L Stainless Steel Mesh Wire: Home &...

Scott

As an Amazon Associate Foretravel Owners' Forum earns from qualifying purchases.

Re: Engine inlet grate

Reply #17 – May 03, 2021, 09:27:44 pm

It is not the surface area of the wires in the mesh that causes restriction. The effective area of the open space in the mesh gets smaller as the air velocity goes up. The apparent area of the wire goes up due to the airflow around the wire causing the open space to appear smaller to the air flow. Early airplanes used wires to help make a truss out of the upper and lower wing. Performance went way up when the cross section of the wire went from round to airfoil shaped wire even of the same thickness as the round wire.

Just below the roof line where the intake vent is located is a relatively low pressure area relative to still air as the coach moves through the air. A water deflector likely makes this even lower. So the engine is sucking air in from a lower pressure region through a mesh that reduces the effective area of the opening.

Like Brett said a pressure measurement inside the air cleaner before and after under the same conditions is the only way to know how much improvement you really. Maybe Cummins specified a minimum restriction for turbo performance. Who knows.

Here is some technobabble.
https://ojs.unsw.adfa.edu.au/index.php/juer/article/download/920/557

And as the screen gets dirty the issue becomes more pronounced.
Fan Equipment Mesh Screen Cleanliness and Performance Effects | HPAC Engineering

Re: Engine inlet grate

Reply #18 – May 03, 2021, 10:06:17 pm

100% agree but I think preventing this even with a 20% loss yet still larger than the six inch duct is a win win for me. This nest was removed out of the entry to the six inch duct. I've put 7100 miles with in in place. We don't have mud daubers were we live, but we do in surrounding states. I'll cover to simulate the 20.6 inches and calculate for loss over screen, 20% and see were we end up. Also put a bead of RTV along the top to help divert water. Project done. 👍👍
Scott

Re: Engine inlet grate

Reply #19 – May 03, 2021, 11:40:01 pm

Too bad someone doesn't come up with a powered louver door with the control automatically interfaced with the ignition

Re: Engine inlet grate

Reply #20 – May 03, 2021, 11:45:21 pm

Quote from: nitehawk – May 03, 2021, 11:40:01 pm

Too bad someone doesn't come up with a powered louver door with the control automatically interfaced with the ignition

And open forward while under way for ram air or open rearward for rain. Closed for parking. Great idea..
Scott

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