Air Intake-MC8

Sam 4106 · October 01, 2012, 01:41:51 PM

We have an MC8 with an 8V92TA DDEC II. When it was installed a larger air filter was also installed but the air intake was not enlarged. In a thread several weeks ago about an MC8 overheating, Buswarrior posted a link to a Fred Hobe tip about cutting a hole in the side of his MC9 to get more air to his air filter.

While working on our bus for a smoking engine problem I put in a new air filter, but still had 10" of vacuum on the filter minder, so I decided to also cut a hole in the side of our bus just ahead of the radiator screen. With a 4.5" x 13" hole, more sq. inches than the intake of the filter, I now have no movement on the filter minder. The engine can breathe better now. Rather than use a vent cover, like Fred did, I covered the hole with a piece of 1/4" hardware cloth to keep the birds and small debris out. It doesn't look as nice but should be less restriction.

Now there is smoke only on full acceleration from a stop. An improvement for sure. I haven't tested it on a steep hill yet to see if I gained any turbo boost, but I'm guessing there will be a small increase.

Fred said he had more power and better fuel economy with the modification. I think I also have a little more power but I haven't put enough miles on to tell if economy is improved. Overall, I'm happy with the project. Thanks, Buswarrior, for the link and thanks Fred for the tip.

Good luck, Sam

bevans6 · October 01, 2012, 02:02:39 PM

I think the stock intake configuration in the MC-8, my MC-5C, etc, is barely adequate for the stock 270 hp 8V-71N. Go bigger and you need to do things differently. On my 8V-71T install I used a honking big Donaldson ECO-SM filter. My turbo is sitting just off the driver's side valve cover, and the filter sits on the muffler cover, just has a 9" diameter air intake hole facing the firewall. The top just has a reducing elbow to take the 7" air outlet to the 5.5" turbo inlet. Totally simple, but it works a real treat. Only thing I might change is it pulls in fairly hot air from the engine compartment.

Brian

luvrbus · October 01, 2012, 02:07:53 PM

A 8v92 needs 1500 cfm min 1600 cfm is better that is why I use the ECO system nothing any better made for a turbo 8v92

Scott & Heather · October 01, 2012, 04:48:01 PM

I did it too and posted last summer my pics. Used stainless steel mesh to grill over the hole. Works like a charm.

Sam 4106 · October 01, 2012, 05:42:36 PM

Hi Scott,

I remembered you posting at the time you cut the hole in your bus. I tried to find that thread, without luck, before I cut mine, to better orient the location. Would you mind posting a picture of your project again so I can see the finished result? Where did you find stainless steel mesh and how fine is it?

Thanks, Sam

Scott & Heather · October 01, 2012, 05:49:31 PM

Here's the link Sam
http://www.busconversions.com/bbs/index.php?topic=23323.0

The stainless mesh was from the front of the bus passenger side interior...where the air handling for the driver's area was located. Not super fine mesh, but if I need to drive in dusty conditions, I'll just temporarily tape up a furnace filter over the mesh to keep things from clogging my $50 air filter!

gumpy · October 01, 2012, 05:58:41 PM

Quote from: Sam 4106 on October 01, 2012, 05:42:36 PM
Hi Scott,

I remembered you posting at the time you cut the hole in your bus. I tried to find that thread, without luck, before I cut mine, to better orient the location. Would you mind posting a picture of your project again so I can see the finished result? Where did you find stainless steel mesh and how fine is it?

Thanks, Sam

Sam,

Discount Steel in Minneapolis has stainless mesh. I got a piece of "drop" a couple years ago to use in my BBQ grill (haven't done that yet, but I have the mesh

craig

Sam 4106 · October 01, 2012, 06:32:07 PM

Hi Scott,

Thanks for the link. You did a very nice job of restoring your air filter housing and finishing the hole for the air intake. What you and Craig are calling "mesh" is called expanded metal in the metal working world. I looked for some aluminum expanded metal for my bus but couldn't find any with small enough holes locally. So, I used 1/4" hardware cloth from the local hardware store. I usually have to compromise and use locally available materials for my projects.

Thanks for the replies, Sam

Ednj · October 01, 2012, 06:42:56 PM

They have some really nice chrome or stainless engine compartment vents and air intakes at the boat parts house or local marina.

Scott & Heather · October 01, 2012, 06:46:26 PM

Good to know that. I can't tell you how
many times I've asked around different shops for something only to find out I wasn't using the right terminology. Head bangers...

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buswarrior · October 01, 2012, 07:14:01 PM

Thanks, but the credit all goes to Fred Hobe, I'm just the messenger.

I've seen busnuts use two smaller air filter canisters to feed a bigger engine. Tucked in where they were convenient to fit, and then plumbed together with a commonly had large diameter Y-pipe from the plumbing section...

Whatever we can do to let it suck air in as easily as possible helps fuel economy, engine temps, and smoke emissions.

happy coaching!
buswarrior

Scott & Heather · October 01, 2012, 07:38:02 PM

Another kudo to Fred. I've learned much from him and spent some serious time on the phone with him. His site has tons of great material including the air intake hole cutting. That's where I first got the idea. I put my own spin on it but basically the same concept.

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RJ · October 01, 2012, 10:07:27 PM

All -

Lots of good discussion here about getting air INTO the engine, but what about getting it OUT???

Sort of like the pool builder who used 2.5" pipe on the suction side of the filter pump, but only 1.5" on the discharge side, then wonders why he's got poor flow in the pool and unusually high operating psi.

FWIW & HTH. . .

Scott & Heather · October 02, 2012, 05:51:31 AM

I removed my muffler. It's a straight shot down from the turbo to the ground. Loud as can be, but diesels like wide open exhaust. Keeps the temps down too. Anyone want to buy a used muffler?

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Rick 74 MC-8 · October 02, 2012, 06:13:49 AM

On my 8 I took the same approach to get more air but I ran a duct across the top of the engine compartment and opened up the same way the factory did inside the passenger side radiator compartment. To get the air out I drilled a 4 inch hole in the back of the muffler and ran an additional 4 inch exhaust pipe out of it.

Rick 74 MC-8