ram air system on Mooneys?

[PMD]

Sorry to just barge on in here and ask a lot of dumb questions, but I have to plead relative ignorance on this subject, so where better to find good answers than the home of the faithful??

 

I am trying to learn as much about the ram air systems on Mooneys as I can find.

 

Particularly, does the IO390 mod retain this system?

 

Who is the manufacturer of the airbox and ductwork, as well as element?

 

I ask this because I am interested in either duplicating or simply using the same hardware in a different airframe IO390 mod with new cowling.

 

Sadly, I have not been inside of a Mooney cowling for about 30 years.

 

Regards - PMD

[MB65E]

Can't stand the system... Cool in theory but multiple people think it's poorly designed. In a new installation I'd highly avoid it! The HP acro airplanes I've messed with have always had a "cold air induction" system involved. This is basically a fresh air scoop that is moved forward as close to the prop as possible. Early designs were sharp funnels to capture the air. Reno guys have proved a tear drop shape/ blended airfoil into the intake was more efficient. If it's on an experimental your in luck, certified Good luck. I'd even avoid the air filter. Take a look online.

-Matt

[N601RX]

If its experimental, I like this system.  Its filtered Ram air that is always on.

 

http://www.jamesaircraft.com/Induction.html

[PMD]

Thanks for the answers.  I was being a bit shy as an outsider to flat out ask how well it worked, but really that was what I was wanting to know as well.

 

I have always been bothered with air filter elements that can build up ice and snow forcing the alternate air door to open, and have wondered why the simple paths used in turbines to let ice and rain separate out from the intake airflow are not being used in recip induction tracts.

 

Basically, IF I continue to be stupid enough to want to do an STC from scratch, I want to optimize all of those things that OEMs do so poorly - cowl, exhaust and induction - realizing of course that even fully amortized to a reasonable size installed fleet base - a conversion (from 0-360 to IO-390) is worth far more than a good example of the stock airplane.  Need to find someone with PMA approval to supply the bits (exhaust is obvious, intake not so much).

 

How are the IO-390 mods doing in Mooneys?  Stock exhausts or Powerflow being used?

[orionflt]

The mooney ram air system bypasses the filter and gives you direct unfiltered air allowing for an increased manifold pressure (aprox 1") by removing the restriction caused by the filter. Mooney recommends this system only be used at altitude where there is no danger of ingesting foreign objects due to the lack of filtration. I will say that with the newer filter technology that restriction has been reduced significantly. I installed the challenger filter on my C and saw an inch of difference at 8500 ft, I was suitably impressed with the results, was defiantly worth the money IMHO.

Brian

[Hector]

The mooney ram air system bypasses the filter and gives you direct unfiltered air allowing for an increased manifold pressure (aprox 1") by removing the restriction caused by the filter. Mooney recommends this system only be used at altitude where there is no danger of ingesting foreign objects due to the lack of filtration. I will say that with the newer filter technology that restriction has been reduced significantly. I installed the challenger filter on my C and saw an inch of difference at 8500 ft, I was suitably impressed with the results, was defiantly worth the money IMHO.

Brian

Can you provide a P/N for that filter? I'll like to try it on my C.

[Hector]

Never mind. Found it!

[jetdriven]

Thanks for the answers. I was being a bit shy as an outsider to flat out ask how well it worked, but really that was what I was wanting to know as well.

I have always been bothered with air filter elements that can build up ice and snow forcing the alternate air door to open, and have wondered why the simple paths used in turbines to let ice and rain separate out from the intake airflow are not being used in recip induction tracts.

Basically, IF I continue to be stupid enough to want to do an STC from scratch, I want to optimize all of those things that OEMs do so poorly - cowl, exhaust and induction - realizing of course that even fully amortized to a reasonable size installed fleet base - a conversion (from 0-360 to IO-390) is worth far more than a good example of the stock airplane. Need to find someone with PMA approval to supply the bits (exhaust is obvious, intake not so much).

How are the IO-390 mods doing in Mooneys? Stock exhausts or Powerflow being used?

PT-6 turbine engines use an inertial separator but it lowers torque ~10-20% by restricting airflow. So we only used them in icing conditions. The best modification to older mooney airplanes would be an optimized intake tract like a M20J has, with very low restriction. Interestingly an RV-8 has a very similar intake system but it is made of fiberglass with smooth transitions. Our ram air is disabled but from other observations it's only worth a fraction of an inch of MP, or around 1-2 HP.

[PTK]

I removed the ram air system when I had my J painted.

My decision was based on the advice of Mooney legends such as Mr. Bob Kromer and also of Mr. Bill Wheat.

On the J it only adds maybe 1/4" mp for maybe 3 hp at best. This is why Mooney dropped it.

As Bob Kromer puts it: Not sure if you can measure the effect of 3hp at cruise speeds!

I have the system available for sale (cable, knob, along with the microswitch for annunciator.)

If anyone is interested please pm me.

[FloridaMan]

I see between 1 and 2" with the ram air with the lopresti cowling. I think the addition is due to the closeness of the port to the prop and that it takes advantage of prop pressure.

[Jsavage3]

I have the ram-air system on my '86 J model and I like it. I usually use it above 3'K in winter and above 5'K in summer (fewer bugs up there) and, of course, only in VMC. I see 1/2-inch of extra MP when I open it up...

Log me as a +1 for the ram-air system...

[OR75]

On a 77J:

I see 1/3 to 1/2 in of MP @ 8000ft

Not sure I would install it if an STC was available (I bet the STC would be $$$) but since it is there , I won't remove it

[autopatch]

Interesting comments. I've previously been told by several people that I consider knowledgeable to remove the ram air system as being useless. Does the 1/2" MP increase overcome the speed penalty for having a hole in the cowling? - (Also a 77J)

Sent from my iPad using Tapatalk

[OR75]

Not sure there is a speed penalty because of the ram air hole . The hole is close enough to the prop that the flow is unlikely to be laminar in that area even if the area was smooth.

[Bob_Belville]

In my E and I suppose most pre J systems the MP difference for RAM air is 1" or slightly more. I think the J filtered air intake is improved and the RAM gain is less.

[Marauder]

Same observation on my F.

[DaV8or]

To the OP-

 

If you are going to build your own, I would study the Lo Presti ram air system they have for Mooneys. The factory ram airs on Mooneys are not good examples and should not be copied in any way, or used as a measure of success, or failure of the ram air concept. The vintage Mooney ram air "works" only because the closed, filtered induction is so bad. The modern Mooney ram air doesn't do much because it is under sized and perhaps not in the best place. The Lo Presti seems to have worked out a much better balance and the shut off valve mechanism is 10x superior in construction and function.

 

http://www.speedmods.com/m20cowl.htm

[Skybrd]

I see between 1 and 2" with the ram air with the lopresti cowling. I think the addition is due to the closeness of the port to the prop and that it takes advantage of prop pressure.

I have a J and Lopresti with ram air and it works great. I only use it on trips at altitude and clean air. It's like a poor mans supercharger. One thing is to not forget to shut it off when going lower and dirty air conditions.