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Rod Bower induction system ?

Done two of them, first on the -10 and the second on a friends -7. Both where installed in James cowls, the -10 was a near "drop in fit", the -7 (200hp, forward intake) was a perfect fit.

I'm planning a 3rd on my -8.
 
Done two of them, first on the -10 and the second on a friends -7. Both where installed in James cowls, the -10 was a near "drop in fit", the -7 (200hp, forward intake) was a perfect fit.

I'm planning a 3rd on my -8.

Nick,
With the perfect -7 fit, what induction system was this with and was it with AFP?
 
yes, I used one on my -7,IO-360 w/ james cowl, AFP injection. It was not a drop in unit, but to be fair I bought it used from another builder and I think it is the bigger IO-540 unit.

I would do it again.
 
The -7 has a bendix clone (Silverhawk, I think), and a machined adapter (provided by Rod) from the servo to the filter.

The overall length has got to be pretty close to that of the AFP.

This was used with the forward facing injected cowl from James. http://www.jamesaircraft.com/679Cowls.html Bottom of the page.

I don't have any pictures on my phone, but next time he's over or I grab the plane I'll take some.
 
Rod Bower system

Did it on my -10. It goes together well. Modified my vertical to a horizontal intake with an elbow from Rod and have the intake forward right behind the prop. A bit of fiberglass work on the cowl but it came out fine. Rod's video is very helpful. Not flying yet so no info there.
 
Did it on my -10. It goes together well. Modified my vertical to a horizontal intake with an elbow from Rod and have the intake forward right behind the prop. A bit of fiberglass work on the cowl but it came out fine. Rod's video is very helpful. Not flying yet so no info there.


Same here...... I was the first of Rod's new aluminum elbow. I had a few minor issues, but worked through them with Rod's assistance.
 
I did the RB induction on my RV 7, with IO 360 A1A 200hp...it was very easy drop in.. see more pics with my link below.

IMAG0123.jpg


IMAG0048.jpg
 
Benefits?

Just curious for those that are flying with the Rod Bower deal. Is it providing any measurable benefits? I think that is the important question.

I am considering it for my IO390. I have talked to a couple of people that have said there was no real benefit. It looks cool but added work to the build.

I'm still very interested but weighing the conflicting information.

Thanks in advance.
 
Does this product only interface with the SJ Cowl? I'm planning vertical induction with stock cowl.
 
...... Is it providing any measurable benefits? ...... but added work to the build.......

I'm running the Bower Ramair behind the James cowl with the round inlet on my 360(~190hp). In June at the SARL, Wenatchee race, Bob B and I were comparing notes. He is running a RV-7, IO-375(205hp) with the Vans smooth cowl (intake air in the cowl inlet). Both of ran about 204mph on the course, I was showing almost +1"MP more than he had. The Vans system is supposed to very good at pressure recovery, so I suspect my ramair and cowl was a horsepower equalizer.

I don't know that is it more work, just different work.
 
When I open the butterfly valve, I am seeing an increase of at least an inch of manifold pressure, depends on speed, and altitude.

Most I have seen is 1.8" as I recall.
 
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Mike, is that between Ram and Alternate Air? Also is it harder to install the RB mod on standard cowls? (RV10 specifically)

That is between having the valve in the intake closed, or open. When the valve is closed, it is using alternate air from the lower cowl area.

As to doing the install, mine is a standard cowl, Rod makes the carbon fiber scoop unit, or you can make your own, like shown in this thread.

Rod used my cowl to prototype the mold for the scoop, and he did the actual install work, so I have not actually done one of these.

But, I do have a fair amount of knowledge/experience with composite work, and I am quite confidant that it is an easy install.

Look through this thread, pretty much shows what is needed------remember as you are looking at it, this shows changing from a completed stock vertical intake, to Rod's ram setup, if your were starting from scratch, it would be easier to just get the correct length cables, and have the servo set up for the correct mixture and throttle rotation etc. I had to send my servo back to Airflow, and have them change things around a bit.

All very doable, and the removable lower scoop really gives you a good access to the lower part of the engine without having to remove the entire cowl.
 
I have been using the Rod Bower system for three seasons now. The first year I seldom used the RAM air door as I really like to fly with filtered air. The RAM air setting was only used when very high or during races. The engine will really work when you open that baby up down low with all levers full forward.
However I did an in air test after the first year of flight and I know use full RAM air except for landing and taking off, short flights and flights under 2000agl.
This is what I found. If I was running at twenty two squared leaned to best power I would get a repeatable speed. If I then opened the RAM door and pulled the throttle back to twenty two squared again, I could repeatably get 3 to four knots more in speed with the RAM door open vs closed at the same power setting. There are a couple of reasons for this, my speculation, the air flowing through the filter does not flow as well and more importantly the air drawn through the filter is warm lower plenum air. It is almost like running carb heat.
 
Mike, is that between Ram and Alternate Air? Also is it harder to install the RB mod on standard cowls? (RV10 specifically)

You can view the photos on my build site for the new elbow and cowl scoop for the RV-10. It's different from the earlier version that Mike has on his 10.

bob
 
I did one on my 7 about 3 years ago with AFP. He only had a scoop for the 8 at the time and I modified it to fit the 7. That was quite a bit of work but it turned out nice. I get at least an 1" or more MP over my friend's 8 with stock Vans intake. I just finished putting a system on a friend's 7 with Silver Hawk servo and the 7 scoop. Scoop fits great and it was a real easy install. Don
 
I get at least an 1" or more MP over my friend's 8 with stock Vans intake.

Typical quote, but again, a comparison of filtered (stock Vans) to unfiltered (Bower with butterfly open). Take the filter out of a stock snorkel and compare, or compare filtered performance for both.
 
Thanks for all the feedback. My problem is that I have a horz. cold air induction and a cowl with a scoop so I am looking for a simple fix.
 
Typical quote, but again, a comparison of filtered (stock Vans) to unfiltered (Bower with butterfly open). Take the filter out of a stock snorkel and compare, or compare filtered performance for both.
That's the whole idea of ram air induction, you can switch it to unfiltered ram air at altitude. You might get more MP taking the filter out of the Van's snorkel but you can't do it in the air. The Mooney 201 had the same type of system.
 
2 cents worth on ram air induction....

There is no question best manifold pressure is achieved with direct ram air. The unanswered question is how much better is it than filtered air.

That depends on the efficiency of the filter system. Seems to me Dan Checkoway did some experimenting in this area and found with his system the difference was minimal, like about a half inch. He had the standard filter connected to the left intake baffle area which also benefits somewhat from ram pressure.

With the 7A I had an internal K&N cone filter and it cost some rpm drop and 1 inch of MP until opening direct ram after take off. I could feel a surge when opening the valve and liked it a lot.

The prime advantage of the internal filter is it provides for more air across the top of the left side of the engine and for oil cooling.
 
Bower Ram Air

A question for those of you with glassed non removable on Bower scoops.
How do you remove and install the cowl? I have a snorkel and have issues removing the cowl relating to the air seals in front. It has to drop straight down to clear the spinner. So if it has to drop straight down, how do you attach the connector between scoop and filter housing? Can you reach through the inlet to work the connecting tube in place?
 
I have about 1/2" space between the intake and the air cleaner. I attach the neoprene sleeve to the air cleaner. When you get the lower cowl up in position you can just work the sleeve around the intake with your finger.
 
Larry, don't buy into the "1 inch more" fantasy, in particular if it makes your airplane harder to service.

They're either talking about (1) a comparison between two different airplanes with uncalibrated MP gauges, or (2) the difference between sucking open the plastic reed valves on the Bower canister to tap low pressure lower cowl air, vs filterless outside ram air. No doubt there's an inch difference in the second case, but it's because the filtered performance is so bad. To make it worse, the lower cowl air is hot.

Apples-to apples: An ordinary Vans filtered snorkel from the left cowl intake will provide higher MP on takeoff than the Bower running filtered (probably 0.5" Hg). Install a larger filter media to feed the snorkel and the gap becomes even greater. The custom work to install a Vans snorkel with a bigger filter will be less than the custom work to install a Bower, and there is no cowl fitment issue.

In cruise, with the Bower butterfly open (unfiltered) you might get 0.2"~0.3 Hg more than you will with the standard filtered snorkel. The difference will decrease with increased media area feeding the snorkel.

As for a dedicated front intakes, filtered vs unfiltered, again it's mostly a matter of media area. By measurement, the filter drop across a big K&N (#33-2124) is, at worst, about the same as Rod reported for his intake with the butterfly wide open. Put another way, it's possible to fly filtered all the time and lose nothing.

BTW, when you hear claims of 1" or more, consider the hard physical facts. Around 175 knots true at 8000 feet is a typical cruise for a clean RV with an IO360. Assuming a standard day atmosphere, the absolute maximum available ram is 1.15" Hg. That's pitot pressure, 100% conversion of dynamic to static pressure. Capturing 100% is physically impossible in the case of an engine intake, as it is not a pitot, i.e. it has an open exit. To get 1" more MP than your friend's RV would require that he is taking his intake air from someplace with less than static pressure. It's clearly nonsense, even if he was sucking it from inside the lower cowl...you know, like a Bower running filtered.
 
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A more relevant data point

This will help give apples to apples data along the line that Dan Horton is suggesting.

I have a ram intake similar to a Rod Bower system, in fact I use his ram-air shut-off butterfly valve and his conical K&N filter. But instead of pulling air in through the reed valves from the lower cowl, I have a sealed can that transitions smoothly to a 3" scat tube that runs up to an intake in the middle of the intake baffle 'ramp' in the cooling air intake on the left side, in about the same location that Van's filter would go.

So, I can tell the difference between ram air and filtered air through the cooling intake.

At cruise power (24" 2400 rpm) the difference is 0.25" hg.

At take-off power at sea level, the difference is about 0.3" hg.

My ram inlet is a crescent shape under the spinner, kinda like a P-51, and it has fairly generous lip radius so it does not separate on the intake side when there are large flow angles from prop swirl (many Bower intakes have too sharp a lip in my opinion).

Anyway, I think it is as good as it can be, and it is only 1/4 inch of MAP better than pulling filtered air in through the cooling intake.

If I had it to do again, I think I would opt for the Van's snorkel, enjoy the smooth cowl aesthetics and concentrate on putting radiused edges on the filter intake in the cooling ramp to maximize flow through the big rectangular filter ( Like Dan C. did some time ago).
 
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I've got the standard Van's snorkel, and I am extremely impressed with the MPs that it provides.

Looking at the recorded engine monitor and EFIS data, I see that the MP increases during the take-off roll. The MP reaches the value seen before engine start about the time the IAS hits 60 kt. The MP is about 0.2" above the pre-start value by the time the IAS hits 85 kt. At 185 kt IAS, the MP is about 0.9" higher than the ambient pressure (based on comparing MP against pressure altitude, after correcting the MP for the known 0.2" error). My data suggests that Van's snorkel is recovering roughly 50% of the available ram pressure rise. That is excellent, considering that there has to be some pressure drop over the filter, and it takes a delta pressure to push air through the induction tract (i.e. the pressure at the start of the snorkel must be higher than the MP, or the air wouldn't flow).

I know that my MP indication reads about 0.2" high at high MP, based on comparison of the MP with engine stopped on the ground to the pressure altitude. I'm not sure what my MP calibration is at lower MP, so I've only looked at data from close to 30" MP. The data at higher altitudes give similar results, but I don't know the MP gauge calibration that those lower MPs, so I've ignored those data points.
 
I have been using the Bower system for three full seasons. I am happy with the performance with the valve open but when drawing filtered air from the cowling it is like having carb heat on. Last year I made a new canister and ran filtered air all the time. My take off power is much improved and tests at 8000' demonstrated a very slight loss of MP using the new airbox vs the Bower system with the door open/unfiltered RAM air. I flew the whole season with the new set up and felt better about having filtered air all the time and also the much better takeoff performance. One of the advantages of the Bower system is that with the door closed and drawing air from the cowling it would almost eliminate the chances of having snow block the inlet filter in winter flying conditions.
This winter I was looking at some old data and pictures and it appears that at altitudes 13 to 18,000 feet the Bower system shows an advantage, five knots, over my new all the time filtered air-box. Perhaps as the air gets thinner the filter restricts airflow more then at lower, higher pressure, altitudes. When the flying season starts I will get some same day comparisons at different altitudes, to record differences in MP and airspeed. I can easily swap airboxes without removing the cowling.
I really like Steve Smith's idea about drawing air from the inlet baffle for the Bower system.
 
Returning to that 1" stuff, filters don't have that much pressure drop, even filters badly undersized for the application.

On a professional flow bench, at mass flow equivalent to the IO-390 at 2700, a little RU3120 cone had a measured filter pressure drop (difference between filter and no filter in the same airbox) of 4.0" H2O. That's 0.294" Hg.

The large, flat plate, deep pleat 33-2124 had a filter pressure drop of 1.9" H2O, or 0.14" Hg.

In a well designed system, that's the entire penalty for filtered air. Any additional loss is because of poor system design.
 
Steve and/or Dan,

So if I dispense with the idea of ram air (Bowers or otherwise), is there a smooth version of the RV-10 cowl from Vans, or is my only option the Sam James Cowl? Also, am I correct in thinking that the main (perhaps only) difference between the two would be the shape of the inlets??
 
Steve and/or Dan,

So if I dispense with the idea of ram air (Bowers or otherwise), is there a smooth version of the RV-10 cowl from Vans, or is my only option the Sam James Cowl? Also, am I correct in thinking that the main (perhaps only) difference between the two would be the shape of the inlets??


Mike,

I'm not sure I understand what you mean by a "smooth version" of the cowl. The newer Van's cowls are now being shipped with primer applied.

The James cowl for the RV-10 is no longer available. I know where you can get one really cheap if you want one. It was surplused and replaced with a standard Van's cowl. Many of the installs of the James cowl on the RV-10 have been problematic.

bob
 
Steve and/or Dan,
So if I dispense with the idea of ram air (Bowers or otherwise), is there a smooth version of the RV-10 cowl from Vans, or is my only option the Sam James Cowl? Also, am I correct in thinking that the main (perhaps only) difference between the two would be the shape of the inlets??

Couple things....

Both a pitot type inlet (straight shot into the throttle body) and a snorkel type (air ducted from the cowl cooling inlet) are "ram air". As delivered, the Vans snorkel may deliver a little less pressure at the throttle body, but its been shown the difference isn't much, and improvements are easy and obvious.

The Showplanes RV-10 cowl appears to incorporate some nice snorkel improvements.

James stopped making an RV-10 cowl when it wouldn't cool. However, they built a least one of the last with 6" (ballpark) inlets, and its owner reports good cooling. Are they making them again? I dunno.

Last, you have endless options if none of the above seems right. Build what you want. It's the really cool thing about what we do!
 
expected MP

I dug up one of my Dynon data logs.
altimeter setting 30.19
DA 10591 indicated altitude was 9000 using the standard snorkel and filter.
PA 8765
OAT 13c
TAS 169kt
FF 8.6 gph
MP 21.5 In Hg
RPM 2605

I looked up the standard altitude and found that at 9000 ft the std pressure is 21.4 inches Hg.

The Dynon log does not record indicated airspeed. A question for the Engineering gurus, do the pressure to airspeed charts relate to indicated or true airspeed?
The chart that I have has 150kt at .5358 psi and 180kt at .7786 psi
1 psi = 2.0362 in Hg so .5358 psi should equal 1.09 In Hg and .7786 psi should = 1.58 In Hg. Yes / No ?????

I am quite certain that filtered vs unfiltered air in the Bower system will yield 1" of difference due to the fact that the pressure in the lower cowl is lower than the upper cowl (my pressure differential is about 10 inches of water) as well as the airflow restrictions due to the reed valves and filter.

Has anyone removed the filter on a snorkel and done a comparison flight?
 
I dug up one of my Dynon data logs.
altimeter setting 30.19
DA 10591 indicated altitude was 9000 using the standard snorkel and filter.
PA 8765
OAT 13c
TAS 169kt
FF 8.6 gph
MP 21.5 In Hg
RPM 2605

I looked up the standard altitude and found that at 9000 ft the std pressure is 21.4 inches Hg.

Here's a snapshot from my Dynon 180. Not an exact set of conditions as above but thought it was a close comparison. Running a Bower RamAir.
cae755d2abfde5fc087bcab520df2eb4_zpsbb21d79b.jpg
 
Thanks.

..for the responses guys. Bob, when I said smooth, I meant without the snout out front (i.e. capturing air from the inlets above). Dan, you hit the nail on the head regarding "what's available." I realize there are lots of ways to skin this cat, and just wanted to know what aftermarket cowls might meet my needs/desires. The showplanes cowl looks nice. I wonder if there have been similar issues with inadequate cooling that Sam ran into..?
 
I dug up one of my Dynon data logs.
altimeter setting 30.19
DA 10591 indicated altitude was 9000 using the standard snorkel and filter.
PA 8765
OAT 13c
TAS 169kt
FF 8.6 gph
MP 21.5 In Hg
RPM 2605

I looked up the standard altitude and found that at 9000 ft the std pressure is 21.4 inches Hg.

The Dynon log does not record indicated airspeed. A question for the Engineering gurus, do the pressure to airspeed charts relate to indicated or true airspeed?
The chart that I have has 150kt at .5358 psi and 180kt at .7786 psi
1 psi = 2.0362 in Hg so .5358 psi should equal 1.09 In Hg and .7786 psi should = 1.58 In Hg. Yes / No ?????

I am quite certain that filtered vs unfiltered air in the Bower system will yield 1" of difference due to the fact that the pressure in the lower cowl is lower than the upper cowl (my pressure differential is about 10 inches of water) as well as the airflow restrictions due to the reed valves and filter.

Has anyone removed the filter on a snorkel and done a comparison flight?

The pressure to airspeed charts are for indicated airspeed, assuming zero ASI instrument error.

8,765 ft pressure altitude = 21.6 in HG static pressure.

169 kt TAS at a pressure altitude of 8765 ft and 13 deg C = 144 kt indicated airspeed (I?m assuming CAS = IAS for simplicity).

144 kt IAS = 1.0 in HG delta pressure. I.e. the maximum possible pressure at the entrance to the induction tract = 21.6 + 1.0 = 22.6 in HG.
 
pressure

Thanks for the info Kevin.

I think before I rip my cowl apart, I need to see how much pressure I am actually losing from on top of the filter to the plenum area of the snorkel.

More on this as it develops. Its going to have to wait till the snow goes away a bit which I hope will be soon.

looking at hydroguy2's D180, it looks like he is getting 21.5in Hg at 10500.
the standard pressure should be 20.37. looks like he's getting about all there is to get.
 
filter comparison

I set up my flow bench to flow 250 cfm with nothing on the vacuum side, then placed several items on it to see how they flowed.

33-2060 std snorkel filter with a square plenum = 243cfm
RU-2520 Bower filter with plate on open end. not installed in can. = 250cfm
In can with valve open = 249 cfm
in can with valve closed = 225 cfm.

The Bower reed set up is about 5.76 sq inches area with reed open, but they cover a large portion of the filter.
a 2 15/16 hole has an area of 6.77 sq inches. This is the ID of the Bower valve.

I like the Bower install. the scoop is nice, the can fits nice, but I think that a better set up would be full time filter with an efficient alternate air.
 
I set up my flow bench to flow 250 cfm with nothing on the vacuum side, then placed several items on it to see how they flowed.

33-2060 std snorkel filter with a square plenum = 243cfm
RU-2520 Bower filter with plate on open end. not installed in can. = 250cfm
In can with valve open = 249 cfm
in can with valve closed = 225 cfm.

The Bower reed set up is about 5.76 sq inches area with reed open, but they cover a large portion of the filter.
a 2 15/16 hole has an area of 6.77 sq inches. This is the ID of the Bower valve.

I like the Bower install. the scoop is nice, the can fits nice, but I think that a better set up would be full time filter with an efficient alternate air.

I recently got to spend a couple weekends flying a friend's RV7 in formation with the Bower setup. Those numbers jive with the incredible lack of power with the valve closed down low. It is kinda' like flying with full carb heat on, or even more dramatic.
 
RV-10

I performed a condition inspection last week on an RV-10 with the Rod Bower setup that has an air filter hanging off of the engine mount and a long scat tube down to the intake. I was shocked at the loss of performance on takeoff. It is noticiably different by a huge amount. I performed another takeoff and opened the bypass at 10 feet in the air and the engine surged, and I mean REALLY surged. There is at least 2-3" of MP loss from what I can tell. I have another RV-10 now that I am doing a condition inspection and it has the filter removed, so that it is ingesting unfiltered WARM cowl air for takeoff.
I do not like this set up. My opinion only.

Vic
 
Ram air vs extra drag

I wonder if the protrusion from the bottom snorkle creates more drag? It must. Then the question is does the extra little mp make up for the drag. I doubt it.
 
I performed a condition inspection last week on an RV-10 with the Rod Bower setup that has an air filter hanging off of the engine mount and a long scat tube down to the intake. I was shocked at the loss of performance on takeoff. It is noticiably different by a huge amount. I performed another takeoff and opened the bypass at 10 feet in the air and the engine surged, and I mean REALLY surged. There is at least 2-3" of MP loss from what I can tell. I have another RV-10 now that I am doing a condition inspection and it has the filter removed, so that it is ingesting unfiltered WARM cowl air for takeoff.
I do not like this set up. My opinion only.

Vic


Interesting.......

For the first RV-10, I'm not sure why there is a long scat tube running down to the intake. Did they not make the cowl mod? The standard install for a RV-10 should only have about an inch or two.

Why did the second RV-10 remove the air filter? A perception that the filter is causing a performance issue?

The question I've been attempting to quantify is it a MP loss with the cowl air or a MP gain with the ram air open? The numbers from the bench from Lycon are impressive, but I'm not aware of any other credible a/b test. There clearly is a difference between the two modes. The question is how does the cowl air mod compare to the standard FAB? Is there any credible test that can be performed, unless both options are installed in the same aircraft and engine?

I'm not sure comparing MP at WOT means anything with different engines, ignitions, etc. But I'm clearly not an engine expert either.

bob
 
What Bob said..

I too would like to better understand this modification, along with a meaningful evaluation of the pros and cons.
 
I have it and fly with a rv-8 at the side and the mp is the same with the snorkel configuration and the risk to eat something, if i have to make another rv i will not install a RAM.
 
I certainly dont want to throw Rod under the bus, he was great helping me get it installed with a crossover exhaust and vertical induction (not easy), but I wouldnt do this mod again. First, my engine runs considerably hotter when its closed so I've pretty much been forced to running it open all the time and I know others that do the same. I do get about 1.2" jump in MP when I open it, but I tend to believe it is just choked down when closed (like Mr. Card observed), so I dont believe that MP jump is a true gain over a standard filtered setup.

I dont like running unfiltered air through my engine all the time. At this point I have an $850 unit that I dont want, but eating that cost, taking it out and redoing this seems like quite a pain. JUst one of those lessons learned when you build one of these....sometimes you swing and miss. This is just one man's opinion and 100 hrs experience.
 
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