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The Terrifying Tale of FrankenSnorkel !

scrollF4

Moderator, Asst. Line Boy
Ambassador
<<WARNING: NOT FOR THE FAINT OF HEART OR STOMACH>>

Just in time for Halloween, let me tell you the chilling tale of a poor tortured FAB snorkel, one like so many others, that began its life as one whole and complete fiberglass item with dreams of living in a mighty fire-breathing 200hp IO-360. However, as (mis)fortune would have it, this snorkel ended up in a 180hp IO-360 firewall forward kit.

Again, like so many others, its kitbuilder saw need to dismember the snorkel horribly into two separate end pieces:

FP26082014A00017.jpg


The snorkel's dismembered limbs were drawn to separate locals, then bolted under high tension to horrible machines of torture with names like fuel injection servo and intake ramp. Oh, the horror:

FP26082014A00018.jpg


Then, the kitbuilder mutilated the poor snorkel to cram its mangled body into the most agonizingly tight spaces:

FP26082014A00019.jpg


Oh, the horror...

FP26082014A0001A.jpg


Hideous metallic probes and studs were riveted to the snorkel's neck, like electrodes on a Hollywood monster:

FP26082014A0001E.jpg


When the mad kitbuilder was satisfied with his sadistic placement of the snorkel's two limbs, he hideously grafted them to the center part he had surgically removed before, transforming the once-beautiful fiberglass snorkel into.....FRANKENSNORKEL!!! :eek:

FP30092014A00023.jpg

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The mad kitbuilder wrapped poor Frankensnorkel in layer upon layer of rotting, festering, skin, making the monster even more monstrous:

FP13102014A00022.jpg


....to be continued in episode 2....
 
Episode 2

He then clothed Frankensnorkel in the brightest ghost-white clothing, hiding the horror that lies just beneath the rotting skin:

FP13102014A00023.jpg


And now, doomed to a life of torture under the cowl of an otherwise beautiful RV-7A, one can find the desperate gasps of the pitiful...
the wretched...


(wait for it)


FRANKENSNORKEL!! :eek:

FP13102014A0002D.jpg
 
Cowl clearance??

Scroll, are you sure that your snorkel will clear the cowl? I thought mine was done when I was at that stage, but wound up visiting the bandsaw and belt sander again for further 'slim and trim'. After a while I started saving "spare" pieces...



- Roger
 
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FrankenSnorkel

That sure is a terrifying tale. But I'm spooked as to why all that was necessary.
I've done four snorkels. One for the Doll, and three for other builders, and non of that was necessary! Are you sure you started with the correct snorkel? I wouldn't bet my life on it, but I believe there are two models.

I start by fitting the left baffling to the engine. Then I remove the front baffle piece that the snorkel fit to. Then I clamp the snorkel's flange to the throttle body, and swing the snorkel up until it just about hits the starter. Using the angles that attach the front baffle to the engine, I trace a cutting line on each side of the snorkel at the proper height and slope so as to match the front baffle. When I cut the snorkel, I add enough length to the cut to allow for the K&N filter to fit. Then I install the front baffle and cleco the snorkel to it using the mounting angles. Now you can see exactly where to cut the square hole in the front baffle, but I don't do that until the next step is complete.

(Note: I rivet a .040 doubler to the front baffle, and use the rubber seal of the K&N filter to make the seal with the baffle instead of using the filter mounting hardware. If you plan to use the mounting hardware the snorkel is not cut shorter to allow for the filter)

I cut off the snorkel's mounting flange at the throttle body. That angle is never quite right! With the mounting flange drilled and bolted to the throttle body, I glass the snorkel back to the flange at the correct angle.

The only cutting done to the snorkel is at the mounting flange, and to the other end to match it to the front baffle. There is nothing that horrifying about it!

As to cowling clearance.....it is very tight. It is important that the gap between the spinner back plate and front of the cowling be kept to a minimum!

The Doll has to places where the inside of the lower cowling contacts the snorkel during high G flight. I used a couple pieces of the nylon material Van supplies for the flaps to wear against the wing to insulate the contact points with the cowling.
 
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Danny,
Your sig file says angle valve motor. The OPs is a parallel. They are different widths.

While I imagine one can install the snorkel on a parallel valve without cutting it, its my opinion that the filter sits to far outboard and it affects the outboard baffle position negatively where it interfaces with the cowl.
 
FAB rework

I think my extreme snorkel rework was due to the cold induction manifold & adapter pushing the fuel servo farther forward... Many possible combinations.
- Roger
 
Scroll, I feel your pain!

I used an IO360 with ECI cold air induction and the fit wasn't even close! I,m talking off by more than 1 inch on the inside and 3 inches on the outside plus it made contact with the starter flange and the alternator. I started out doing what you did to make it fit but was so totally turned off by the results that I tossed it in the junk and built one from scratch. Not that hard to do and ended up looking better than I dreamed it could! Give it some thought and feel free to call me with questions. It can be done!

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photo%25204-1.JPG
 
Very funny and well written tale of horror. I was involved with one of the very first applications in an RV8 around 1998 or so. Doesn't look like anything has changed. It was indeed horrifying.....
 
Stupid question?

I'll be the guy... What mod requires this to be done.. Aftermarket cowl? I thought the FAB intake was essentially right out in front. :confused:
 
I'll be the guy... What mod requires this to be done.. Aftermarket cowl? I thought the FAB intake was essentially right out in front. :confused:

Both cowls are available from Vans. One has the FAB air inlet directly out the front and the other uses square air filter just inside the left cowl opening.(This is the one where you need a snorkel.) The difference is vertical vs horizontal induction.
 
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This is the stock RV-7 cowl for an IO-360M1B 180hp horizontal induction setup, and the FAB came with the firewall forward kit. The engine is a factory-new stock Lycoming YIO-360M1B, and the baffle kit is also the stock Vans kit for the same engine. With the snorkel centered on the fuel injector, the FAB extended an inch past the left intake ramp and side wall. Vans confirmed that this snorkel will be too long since it's intended for the 200hp version.

Danny, thanks. I did a lot of what you described, but I'm gonna need more practice.

Paul, that looks great! I may give you a call later.
 
Danny,
Your sig file says angle valve motor. The OPs is a parallel. They are different widths.

While I imagine one can install the snorkel on a parallel valve without cutting it, its my opinion that the filter sits to far outboard and it affects the outboard baffle position negatively where it interfaces with the cowl.

Yes, I realize that the parallel valve engine has less room to work with, but one of the engines I did was a Superior I0360 parallel valve with the new metal cold air sump. The snorkel fit the same way with a little more "centering" work at the flange. I figured at the time that the difference in the fit was because of the non Lycoming sump with placement of the throttle body close, but not exactly the same as the Lycoming.

I think Van sell two different snorkels. One for the parallel valve cylinders, and a longer one for the angle valve engines. I could be wrong, but I seem to recall that one snorkel part number was: ???? and the other snorkel was the same number with a -1 after it! (????-1)
YMMV
 
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Yes, I realize that the parallel valve engine has less room to work with, but one of the engines I did was a Superior I0360 parallel valve with the new metal cold air sump. The snorkel fit the same way with a little more "centering" work at the flange. I figured at the time that the difference in the fit was because of the non Lycoming sump with placement of the throttle body close, but not exactly the same as the Lycoming.

I think Van sell two different snorkels. One for the parallel valve cylinders, and a longer one for the angle valve engines. I could be wrong, but I seem to recall that one snorkel part number was: ???? and the other snorkel was the same number with a -1 after it! (????-1)
YMMV
Danny,
The catalog shows one induction kit (-1) for the IO-360M1B and 1B6 engines going into the -7 or -8. The dimensions must be the same.

With the -7 I trial fit a snorkel to the cold sump with AFP FM200 controller and it would have required major changes to it and or the cowl, did not use it. With the 8, same set up except FM150 controller, the snorkel fit perfect, made one small mod to clear a bolt on the starter.

Things get complicated if the fuel controller is different than what comes with Vans engines. The FM150 is the same.
 
Paul K: Any concerns for galvanic corrosion between the aluminum rivets and the carbon? The potential voltage is about 1.5 volts.
 
Possibly, I set the rivets in wet epoxy and they get a good looking over at every oil change. I check the filter just because it is so easy to remove and that let's me see the rivets. I also check any contact points and so far, nothing.

For the future, fiberglass is also available in sock form and you really don't even need to use a sock. I was not going to paint it originally, liking the looks of carbon, but in retrospect would not use carbon again. It's hard to work with.
 
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Scroll
Is this some Holloween tale, just drill a hole in the front of the cowl like everyone else and skip all this nonsense.
 
Scroll
Is this some Holloween tale, just drill a hole in the front of the cowl like everyone else and skip all this nonsense.

That's what I did with the 7 and FM200. The engine liked ram air, I could feel difference after take off when it was opened. But then I had a rinky-dink internal filter that could have been improved.
 
Scroll
Is this some Holloween tale, just drill a hole in the front of the cowl like everyone else and skip all this nonsense.

Ok, educate me please: Is there a horizontal snorkel option for the horizontal induction IO-360? I agree that it would have been easier to build...

...but my other hangup involves that guppy-mouth intake hole under the prop spinner. I just don't like the look, but I really do love the clean cowling look without the center intake. That's one of several reasons why I chose the IO-360.
 
Your Frankensnorkle made up my mind, I did what Bugsy said.
I just drilled a big hole under the spinner yesterday.
I have a parallel valve IO-360 with Superior cold air sump and Airflow FM-150 injector.
I'm using a nifty tubular aluminum housing with a K&N cone filter inside. That's attached to the injector by a 3" X 4" adapter hose. I'm planning to mold a fiberglass fairing around it...
 
Guess I was lucky, with my snorkel missed all the vital components. A lot of
moving and repositioning to make it fit. But with the Precision Throttle body it cleared everything.

Smilin Jack
wgraxd.jpg
 
Why not straight in?

Why don't you make a large NACA opening like the Mooney and go straight in to the servo?
 
Grubbat,
To answer your question about an NACA duct, on my RV-8: I Trial fit a 7" long piece of 3" hose from the injector body inlet. The end of the inlet hose is mostly outside the slope of the cowl.
If you used an NACA duct, there would be very little to no room for an air filter.
I'm trying pieces from a Spectre universal remote air filter, here is a link:
http://www.summitracing.com/parts/spe-9833/overview/
It has a cone shaped K&N filter inside. I'm ditching the short end and using a 4"x3" reducer hose to connect the wide end to a Flyboy Accessories fuel injector inlet adapter.
http://www.flyboyaccessories.com/Homebuilder-Accessories-s/3.htm
The smaller inlet end sticks out into the airstream, a few inches behind the propeller.
 
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Why don't you make a large NACA opening like the Mooney and go straight in to the servo?

Because I really like the appearance of the RV-7a nose with no intakes under the spinner. I'm sticking with the snorkel-to-left intake approach. The jury's still out on whether I'll replace FrankenSnorkel. :eek:
 
I'm trying pieces from a Spectre universal remote air filter.....
It has a cone shaped K&N filter inside.

Scott,
No point in re-inventing the wheel. Sounds like a 4" dia base x 5" long cone filter. If so, it doesn't provide nearly enough media area to avoid a significant pressure drop. Don Rivera was kind enough to measure a similar filter for me, a K&N RU3120 with the outlet spigot removed. The test assumed 1400 PPH for the 390. Your demand would be a little less, but probably not enough less for a good result. Restriction gets worse when dirty.

The canister was 6" diameter, but otherwise is about what you're trying. Sorry.

PA120005.JPG


PA120003.JPG


PA120002.JPG
 
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Has anybody put a snorkel on an Airflow performance throttle body and if so, how did you do it ?
 
This is the stock RV-7 cowl for an IO-360M1B 180hp horizontal induction setup, and the FAB came with the firewall forward kit. The engine is a factory-new stock Lycoming YIO-360M1B, and the baffle kit is also the stock Vans kit for the same engine. With the snorkel centered on the fuel injector, the FAB extended an inch past the left intake ramp and side wall. Vans confirmed that this snorkel will be too long since it's intended for the 200hp version.

Yes! Exactly what I have and is exactly what I'm seeing ... I was puzzled by everyone who had the snorkel "just fit"; you can't really mess this up given the non-negotiable locations of the servo intake and left ramp.

I'm feeling "son of FrankenSnorkel" coming soon.

How did you support the center section when you glassed it? foam inside? Did n't look like it..
 
If foam sculpting isn?t your forte and you have CAD skills and a 3D printer (or access to them) it?s possible to 3D print the ?plugs? with PLA. After fiberglassing, you warm the the part in the oven to 150F for an hour and it becomes soft enough to pull out.

Details here: http://elder.ninja/blog/p/7512
 
Yes! Exactly what I have and is exactly what I'm seeing ... I was puzzled by everyone who had the snorkel "just fit"; you can't really mess this up given the non-negotiable locations of the servo intake and left ramp.

I'm feeling "son of FrankenSnorkel" coming soon.

How did you support the center section when you glassed it? foam inside? Did n't look like it..

WJB,
I screwed each end of the snorkel to their positions on the fuel injection servo and the baffle, then laid two pieces of wetted cloth in place to bridge the gap. This essentially tacked it all into a single piece. The gap between the pieces was small enough that the cloth didn?t sag. Once cured, I removed the snorkel and laid up the rest of the fiberglass.
 
Interesting and timely thread for me; I'll be attacking the snorkel soon. Danny King, I've cut and pasted the instructions you laid out here. Paul K, I've downloaded your photos for future reference. Absolutely love the way it looks on the airplane. Since you're also in Michigan, if there's any chance I could see your aircraft in person, I'd be most grateful for the opportunity. I'll buy lunch. Lunch and dinner. In fact, I'll pay your grocery bill for a week... maybe.
 
After all the tales of whoa, surprisingly mine fit with lots of trials and small cuts at baffle side. No butchering and glass work. Appears it is designed to fit a real Lycoming and not a clone. Getting the filter in was challenging due to tight space. I had to take a lot off of the cowl and made a filter cover cap that tied in the snorkel side, side baffle and cover. RV-7A, Vans standard Lycoming IO-360 180 hp.
 
Not sure about your X across the face of the filter. Is there a purpose for it? U may be cutting off 10-20% of the airflow. And u want all u can get. Previous threads about screen material in front of oil coolers indicated significant reduction of airflow. Maybe the engineers will chime in.
 
Scott, later in the process you'll be adding baffle sealing rubber. If you expect it to lay and seal tightly, now is the time to adjust the relationship between the cowl and the baffle tin.

For example, across the lower segment of the opening, the rubber will be fastened to the underside of the fiberglass, and extend rearward over the top of the aluminum, just in front of the filter opening. To put the cowl on there must be enough clearance for the rubber flap to be popped into place, past the aluminum. So, the underside of the glass should be about an 1/8" above the aluminum after the engine mount has settled a little, and the horizontal gap should be about 1/2". To gain the gap you can shorten the aluminum or the fiberglass. I usually say shorten the glass, because doing so moves the ramp forward in the upper cowl.

The outboard baffle wall should probably be moved inboard a 1/4" or so, again to get that optimum 1/8" between the backside of the fiberglass and the face of the aluminum.

Please excuse me if it was just an interim photo with the adjustments still to come. The point is that it is real important to get baffle fit correct at this point in the build, or you'll have trouble later.
 
I started out doing what you did to make it fit but was so totally turned off by the results that I tossed it in the junk and built one from scratch.

photo%25202-1.JPG

Beautiful work Paul.

It's generally easier to start from scratch with a foam form, and the results are better.
 
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On X it is for structural support to tie it all together. I am aware of a decrease in the perceived inlet area from the X portion. Do note that it is above the filter with a gap, permitting full air flow to the filter. Also photo is in progress. About 1/4 ? removed from cowl and rubber attached as well as a taper in corner for cover to match cowl curve. Rubber fits great this side, right had a wrinkle that needed a slit.
 
IMG_8523

IO-360-M1B Supplied by Vans.

Note the part number. The-2 would suggest that there may be up to 3 iterations of this part. Mine was delivered late 2017.

This is how mine fits as well, more or less, and I also have a -2 snorkel and same engine. It seems that the outside edge of about 1 inch too far outside (same with the inside edge); I would expect that the duct would fit nicely along the flat part of the cowl. This one rides up on the outside curve of the inlet, and comes close to the edge of the horizontal ramp and to the vertical part of the baffle just inside the right edge of the inlet. No real room for a conical piece here help seal the lower cowl rubber, or nice edge distances otherwise (See DanH's earlier response)

Is this what "normal" looks like? Seems consistent with Ed's:

Front view:

i-T5RHC5S-M.jpg


Side view:

i-cbH4HcK-M.jpg
 
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This is how mine fits as well, more or less, and I also have a -2 snorkel and same engine. It seems that the outside edge of about 1 inch too far outside (same with the inside edge); I would expect that the duct would fit nicely along the flat part of the cowl. This one rides up on the outside curve of the inlet, and comes close to the edge of the horizontal ramp and to the vertical part of the baffle just inside the right edge of the inlet. No real room for a conical piece here help seal the lower cowl rubber, or nice edge distances otherwise (See DanH's earlier response)

Is this what "normal" looks like? Seems consistent with Ed's:

Front view:

i-T5RHC5S-M.jpg


Side view:

i-cbH4HcK-M.jpg

Just to be clear Bill, I am happy with the position of my snorkel. I don't think it would have been possible to move it any further inboard. Note my case baffle seems further outboard than yours, and there is only just room for the forward screw. A conical gusset may be possible, slightly covering the corner of the filter, but I plan on fitting the baffle seals first to see how things work out.

In my experience the filter is just slightly too big for the inlet ramp, requiring modification of the baffles in all directions, incuding fore and aft, but that is certainly easier than major surgery on the snorkel.

I do wonder though what part number the OP's snorkel had, and anyone else who had to modify the snorkel?
 
First get the cowl completely fitted and detailed. Hinges, Skybolts, screws, seam gaps, inlet spigots, everything.

Then get the aluminum dead on. There is no reason to believe the ramps and walls will be in the right places if clecoed together right out of the box, just like snorkels don't always fit right out of the box.

Then do whatever is needed to the snorkel, which includes just fabricating one which fits your particular combination of parts.

We're not talking wing spars here. Forget part numbers. Build something.
 
Harley style baffles

Finished up baffles after snorkel fit- besides the inlet adaptations I used backing plates with nut plates to seal all rubber to baffle aluminum for no seepage gaps. I struggled with my 9 to seal bottom edges when attached with just rivets. Then painted high temperature flat black and baked in oven. With the chrome valve covers and stainless screws I like the Harley biker look. Also reinforced the oil cooler mount to rear and side and added a oil cooler shutter.


 
To Scott especially, but everyone really --

On the intake flow into the filter, you really want to avoid sharp edges on plates that the flow has to go over as it turns down into the filter. Ideally you would want to have a radius lip all around the perimeter of the filter. This is difficult because the filter is using almost all the available space. But the big filter isn't helping much if the flow is restricted getting into it.

When flow goes over a sharp edge, it separates. The best-possible result is that the flow just goes straight, as if the sharp edged plate was literally a stencil for the allowed flow area. In reality, the effective flow area is reduced even further beyond just the 'stencil' projection. Do a google-search on 'vena contracta'.

The installation that Paul K posted in the Picasa gallery is better, with the doubler/cover plate with the bend-down transition edges. Even better would be to roll those edges in a circular radius down, rather than just an angle bend.

It would also be OK/helpful if you can install semi-circular lip radius around the filter perimeter that projects above the plane of the baffle and filter. Any smooth radius transition is better than sharp edges.
 
On the intake flow into the filter, you really want to avoid sharp edges on plates that the flow has to go over as it turns down into the filter. Ideally you would want to have a radius lip all around the perimeter of the filter .

Noted, I don't disagree but lot of things require compromises when building. We will see by my empirical testing in flight. My cover installation was to tie the snorkel, baffle assembly together as a solid unit with too little real estate to fit the filter. The x gave it the strength for a thin sheet to conform to the complex shape without buckling. I agree a sharp edge will not promote laminar flow but will act as a weir causing some turbulence. The question is does that cause any effect to the engine's needed airflow. In flight the inlet is pressurized so worse case is wide open throttle at redline during initial climb out. I believe there must be substantial excess flow capacity and area since the same filter is used for the 360 and 540 with two more cylinders by Vans web site.
 
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