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RV 4 air intake old vs new

diamondjim

Active Member
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
Jim
 
Can you be a little more specific? Carb or fuel injection? Vertical or horizontal induction? What does the "newer style snorkel" look like?

What do you consider old? The early RV-4 did not have a specific design. Most were home made by the builder.
 
0320 built in 89 , has just a flat area where the intake is. Trying to figure what would be more advantageous. Sorry for the lack of info it's in an rv I am looking to purchase.
Jim
 
Can you post a pic? Is the flat area on the cowling or the "airbox".

Nothing is too difficult to change. But it may require re-painting.
 
Wanting to have the best set up, I figured there must have been a reason they changed the design. I don't have a good picture of the carb air intake. Will update when I do. Thanks
 
Here is the original -4 intake. Early kit 1150 completed in '89. Straight inlet, no filter, very efficient and used with updraft carb. Works good lasts a long time.

Cheers, Hans

mltkci.jpg
 
Can anyone tell me the pros and cons to the newer style snorkel opposed to the older flat style.

Hi Jim, I think you are talking about the squarish inlet style like on a Cessna 140 (and others). I'm no expert but I think the difference is that the newer design offers a tiny bit more ram air effect, possibly better airflow behavior (into the engine), and possibly better filtering. I believe those are all insignificant to typical recreational flying. The most significant difference, IMO, is that the newer design looks better.
 
Wanting to have the best set up, I figured there must have been a reason they changed the design. I don't have a good picture of the carb air intake. Will update when I do. Thanks
 
Hi Jim, I think you are talking about the squarish inlet style like on a Cessna 140 (and others). I'm no expert but I think the difference is that the newer design offers a tiny bit more ram air effect, possibly better airflow behavior (into the engine), and possibly better filtering. I believe those are all insignificant to typical recreational flying. The most significant difference, IMO, is that the newer design looks better.

You are correct, it doesn't have the small snorkel like the pic above. It is the square 140ish style opening. I wondered if the snorkel would be more streamlined and flow better.
 
Air intake

Diamondjim,
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.
https://photos.google.com/share/AF1...?key=NXIwQVlrNFJPTE9NRi1hRkFBUWpLdmtZeWpWWDFR

https://photos.google.com/share/AF1...?key=NXIwQVlrNFJPTE9NRi1hRkFBUWpLdmtZeWpWWDFR

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

Daddyman
 
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Bracket Air Filter

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
Jim

Jim,
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.
http://www.jamesaircraft.com/?page_id=43

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

My 2cents!
Smokey



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 :)
 
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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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