Ram Air Speed Difference

[AlanA]

In my 1979 M20J I don't notice much difference, if any, with my ram air on or off. I read an article somewhere where the pilot of the J model said he doesn't ever bother using ram air even in high altitudes because it didn't make a difference. Do you find this to be true? If it is making a difference in your plane, what is difference in speed mph?

[PilotDerek]

I get about a half inch to an in of MP and see about a 1-2 kt increase.

[Bolter]

At most, I think the MP needle twitches when I open ram air on my '83J. I have tried at different temperatures and altitudes, and like the pilot in your article, don't use it at all. This seems to be common sentiment. When you do more research on this, you will find J and newer owners who have even deleted the ram duct to get a slightly smoother cowling.

-dan

[201er]

If nothing else, it's worth a few degrees cooler CHT while LOP

[kris_adams]

Same here. 1-2 kts. I still open it when appropriate.

[Shadrach]

I can't speak to the J, but it makes a noticeable difference in MP in my F. Nearly an inch below 3000K depending on temps. As for performance, I don't think it makes a huge difference in speed. maybe 1-2kts, but I do notice it in terms of climb. Also when running LOP, I notice about a 15 to 20 df drop in EGT if I set the mixture with it closed and then open it.

[Scott Aviation]

When i did my 201 restoration my ram air butterfly valve hinge points were severely worn and the seal was damaged so before paint I epoxied and sealed over the ram air opening and completely removed the cable and brackets. Not only is the cowl cleaner but I don't miss it at all.

[Seth]

In my previous 67F I would also see a noticeable difference in MP and 2-4 knots increase depending on altitude and temperature. I'd use it on long cross countries with clear air. I was always worried about using it near numerous clouds in high temps even if not in them just due to the humidity factor.

Once the air filtration system was updated in the J model the Ram Air became less effective because more air "got through" to begin with. It was eventually deleted.

-Seth

[Bennett]

The LoPresti cowl has a very effective ram air system (see their video). At the 7500:/8500 range I get a full inch increase in MP - a bit less at higher altitudes. Nice "free" boost in MP. % HP increases, which increases fuel flow somewhat, and most importantly, speed. Usually this is 2-3 knots.

[Piloto]

Like any other aerodynamic device the ram air needs airflow to be effective. It will make a noticeable difference at high speed at low altitude. But at medium cruising speeds at altitude the difference is negligible. Without the ram air you will not have a 201 Mooney but a 200mph plane.

José

[KSMooniac]

It makes a noticeable difference on the E/F cowls and inductions systems, and almost none on the J cowls/induction system. In fact, Mooney removed it from the later model J's as the cost and weight was not worth the benefit, and they published a SB that gave instructions for removing it in the field. I did this prior to painting my plane and like the cleaner cowl, and especially the loss of that really expensive rubber seal that is easily damaged.

[1964-M20E]

I mad a diff on my MP 1" or so and you can hear the engin cnahage but for speed I never paid that much attention to the differnece. It woudl be nice if it wer like an afterburner and you could see a signigicant differnece.

[John Pleisse]

I have a 79-J. 1/2 MP at 9k. Not worth the trouble of forgetting to close on decent. There is actually an STC to close the hole.

[John Pleisse]

'KSMooniac' ...........and especially the loss of that really expensive rubber seal that is easily damaged.

And that seal can get sucked in the induction system. I have heard of it happening.

[jetdriven]

Deactivation on a J is accomplished under a Mooney service instruction. M20-93

[bd32322]

I have given up on the ram air in my 87 J altho i think it gives me a little more in climb. Very hard to quantify. Instead my new performance tool is a fuel siphon so that i dump xtra fuel into storage and only use the correct amount for the flight That helps climbs quite a lot. Sorry, went a bit off-topic.

[jfalisi201]

I saw very little change at altitude so I don't even bother using it anymore. Plus there is always that possibilty of leaving it open on landing and ingesting more than air!

[Jsavage3]

1/2" increase in MP is what I see in my J. Increase in speed? Maybe, but too small to notice.

Free 1/2" MP? Yes, I'll take it...

[201er]

I saw very little change at altitude so I don't even bother using it anymore. Plus there is always that possibilty of leaving it open on landing and ingesting more than air!

Don't you have a RAM AIR warning light on the annunciator panel?

[Loogie]

Trying to get rid of the ram air in my 84 M20J, is there an sb that will allow me to do this?  The sb posted earlier doesn't match.  Anyone have any pointers on how to accomplish this?  

[bradp]

I find that the additional airflow makes my induction all wonky (? Turbulent) and I can't do LOP as nicely.


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[Guest]

4 hours ago, Loogie said:

Trying to get rid of the ram air in my 84 M20J, is there an sb that will allow me to do this?  The sb posted earlier doesn't match.  Anyone have any pointers on how to accomplish this?  

This should help.

http://mooney.com/en/si/M20-93.pdf

Clarence

[Brandontwalker]

On ‎9‎/‎20‎/‎2012 at 9:43 PM, PilotDerek said:

I get about a half inch to an in of MP and see about a 1-2 kt increase.

+1

[ArtVandelay]

Trying to get rid of the ram air in my 84 M20J, is there an sb that will allow me to do this?  The sb posted earlier doesn't match.  Anyone have any pointers on how to accomplish this?  

I did this, I accomplished it by giving it to my mechanic, about 5 hours labor. I think I gained 1-2 knots.

[Loogie]

Thanks guys!  Appreciate it!

 

vr

loogie