How I built my airbox

[Battson]

My airbox has very tight clearances and little room to move, the SCAT tube is only 2.5" long nowadays. It doesn't cause any issues, it is very close to the lower cowl - perhaps 1/4". It doesn't make contact at all, apart from engine start perhaps.
As you say, it's close to the engine's axis of rotation about the engine mounts.

I am sure my airframe is picking up a little extra vibration from the airbox connection to the cowl. But my vibration level is very low, since I got the carbon-composite prop.

[svyolo]

ShowPlanes also has an interesting intake for the RV-10 using dual air inlets from the intake ramps. I like it but I didn't see any provision for alternate air. Most of my flying will be in cool/moist parts of the country and I think it would be a good idea for my build.

[Nev]

Some people, like Robbie Staton, put their in the front baffle in the engine cooling air intake. You can just make out the filter in the right opening (viewer's right).

Others draw air from the back of the baffles through a tube, and face the throttle body backwards.

I’m interested if others have used air intake from the front cooling inlets or the back of the baffles for induction air. Does this make for a simpler intake system ? Are there other pros & cons ?

[Battson]

I am told Robbie build that plane in about 800hrs of work, so it's fair to say he only did things once!


Here are some considerations:

1. The filter area sizing calculations suggest the filter should be too large to fit easily in that baffle, a smaller filter would result in a small loss of manifold pressure

2. Long SCEET duct to the servo - very minor risk of losing manifold pressure

3. Maybe the intake would be robbing air pressure from the plenum area, perhaps. Not sure. There is a lot of air available at those intakes!

4. We had a heavy oil cooler hanging on our baffles, and cracking baffles was a recurring problem in spite of doublers. If you kept the filter box light and used some big doublers, I think it would be OK.

Personally, I think putting the intake in the baffle is an elegant solution, although the filter box may need to be mounted inside the cowling (not in the baffle) to allow for a large filter.

[svyolo]

Nev,
I have a vertical induction Bob 540 with EFI. The EFI throttle body is much shorter than a carb, not sure how tall it is compared to the fuel servo on Bendix style FI. I bought a Van's FAB intake. It will sit higher (hang less low), and I will mount it more rearward than was intended. I think I can keep it either completely inside the cowl, or maybe just a blister. I am going to feed it from the intake(s). Either one intake on the outboard side of one intake, or two 2 - 2.5 inch round intakes in the lower ramp on each side. Rigid fiberglass or CF tubes into the FAB.

If I don't like how it turns out, i will just use the FAB as intended, although it will require a much small external fairing than with a Carb.

[Nev]

I have a vertical induction Bob 540 with EFI. The EFI throttle body is much shorter than a carb, not sure how tall it is compared to the fuel servo on Bendix style FI. I bought a Van's FAB intake.

This is exactly where I’m going with this discussion John so I appreciate your input. I’ve got the vertical fuel servo and the Vans FAB intake, so I was also wondering if I could somehow route air to it from the front or rear of the cooling air intake/baffles rather than fabricating an air intake into the cowl.

I should have the engine on today or tomorrow so I’ll have a much better idea of whether the FAB will protrude below the lower cowl.

Any thoughts appreciated as always.

[Bcone1381]

Any thoughts appreciated as always.

A rubber or silicone Cobra Head Intake? I'm wondering if I could get away with a blister instead of the large Vans intake.


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