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Old 10-26-2017, 12:24 PM
daddyman's Avatar
daddyman daddyman is offline
Join Date: Jan 2014
Location: Fredericksburg, Virginia
Posts: 223
Default Air intake

I also have a 1989 -4.
Mine is an IO-320, so fuel injected.
I have a removable air cleaner that is reusable. It is difficult to take on and off, so I only do it either at the end of th summer or during conditional inspection.
Especially, because I do not fly in a dusty area.

Here is a picture of my inlet. Notice there have bene vibration cracks that have needed repair.

Of note, I do not have issues with the air flow at all. So empirically, it works.


Last edited by daddyman : 10-26-2017 at 12:28 PM. Reason: e-address
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Old 10-26-2017, 03:16 PM
smokyray's Avatar
smokyray smokyray is offline
Join Date: Jan 2005
Location: TX32
Posts: 1,732
Default Bracket Air Filter

Originally Posted by diamondjim View Post
Can anyone tell me the pros and cons to the newer style snorkel opposed to the older flat style. I am looking at an older 4 and it has the flat style air intake. I was wondering if anything can be done or should be done with it. If so does anyone make a kit or can I just make a snorkel. Thanks
Sounds like your RV4 was built and fitted with a Bracket Air Filter from certified aircraft parts.
Many early RV4 builders (me included) had few options in the plans for Carb intakes and filtration as the now standard FAB Air Box wasn't designed yet.
The pre-97' standard RV4 Cowl had the small intake which required fabricating an aluminum Carb induction that fit the intake/"snorkel" as you call it. The "Flat" intake you're referring to is when several builders back in the day simply took an off the shelf Piper or Cessna Bracket air filter box and fitted it on their RV4.
I bet yours is one of these.

Later RV4 (post 1997) cowlings have a larger intake scoop to match the Vans FAB AIR Box intake system. The 0-360 Cowl has an even larger scoop. If I were you and it's running good, don't mess with success.
Cutting the lower cowl to install the scoop and Vans FAB AIR box will cost with paint around $1000 (or more) and may yield 1-2" of additional MP. You could also go with a Sam James cowl, plenum, RAM air intake and re-engineer your entire intake system.

If it were me I'd just spend that money on 100LL and enjoy it.

My 2cents!

Early RV4 with the Bracket "Flat" filter intake set-up. (Savvy viewers will also notice the counter clockwise prop rotation from the LO-360E-1AD)

PS:Much of this corporate knowledge comes from building an RV4 but that's the beauty of this site, learn from others

Last edited by smokyray : 10-26-2017 at 06:02 PM.
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Old 10-27-2017, 06:06 PM
diamondjim diamondjim is offline
Join Date: Jan 2014
Location: sunbury, pa
Posts: 49

Thanks Ray, I think that I will leave it be for now. Looking forward to getting it home.
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Old 10-30-2017, 10:13 AM
theduff theduff is offline
Join Date: Jan 2012
Location: Fallbrook Calif.
Posts: 192

That particular 4 with the RAF paint scheme was odd in a few ways. The builder and a buddy bought a pair of engines off a twin and he got the left hand rotating one. The engines were IO-360's (200 hp angle valves) so he modified his cowl and cheek extensions to clear the intake Sump and tubes. It was heavy and wasn't any faster than the 180 hp ships but it was or is different.
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