REFLECTOR: ram air

[J.F.Sheehan at larc.nasa.gov]

Johnny
I believe the adapter and filter I am using is an FM-200 I don't know if that
 will work on the IO-540K engine.The folks at Airflow were very helpful when I
 called them. that was 5 years ago before they had a catalog etc. I think a
 few minutes on the phone would be worth the time. they list a complete
 injector and ram air system but you probably will not need the whole thing,
 just some of those parts. You can certainly take ram air in through a filter.
 I would make the filter box about twice the volume in order to slow the air 
and increase volume. The loss through a good filter (K&N) would be very small.
 The system I went with was really an alternative to taking air off the NACA.
 I was concerned about cooling the engine and always ingesting dust that ends
 up on the top of the airplane. So now if i am in a dusty area I taxi on
 filtered air but usually take off with ram air on. Sometimes if the weather
 is bad wet/snow etc I use filtered air for take off and don't really see any
 loss of power. Of course I am at sea level and usually not above 90.
Good luck. My preference for airflow was I wanted good equipment attached to
 the engine. There have been many horror stories (maybe urban legend) about
 folks who have ingested parts of filters and alternate air doors etc.

 Jack
N55XL
Race 55

> Jack
> 
> Do you have the kit or part number?  Lots to chose from at airflow
> performance.  I have a 540K 300 HP which will be different from the 540C/D
> but should get me into the right area of the catalog.  Also plan on pulling
> cold air through the filter because of the DA in Arizona. I like the scoop
> attached to the fuselage.   Thanks.
>                                             Johnny Thompson
>                                             Sahuaria Az -5 RG
> 
> ----- Original Message ----- 
> From: <J.F.Sheehan at larc.nasa.gov>
> To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
> Sent: Wednesday, July 05, 2006 8:21 AM
> Subject: Re: REFLECTOR: ram air
> 
> The theoretical is possible with a very good designed intake. The practical
> gain in manifold pressure is somewhere between 1/2inch and 1 inch MP. The
> opening of the ram air scoop should be sized for the volume. The passage to
> the servo should be a little larger to allow the volume to expand thus
> maintaining the same pressure at the servo. I used a air scoop from Velocity
> I don't know if it is on the store web site but you can call. The scoop is
> mounted under the airplane just forward of the firewall with the end of the
> scoop coming up right behind the firewall. I have the scoop attached as part
> of the lower cowl. If I had it to do over I would make it attached to the
> fuselage so that i did not have to remove the scat hose connecting the scoop
> to the servo each time I removed the cowl. (Hind sight) Thw scat tube (4
> inch dia) is connected to a  airflow performance adapter (made for IO-540).
> (www.airflowperformance.com) It has a butterfly valve which allows me to
> select ram air or filtered air. The filtered air is taken from inside the
> engine compartment through a K&N air filter attached to the adapter. ( race
> car style).
> In flight I see a difference of 3/4 inch MP at 10K feet between the filtered
> air and the ram air. Photo of adapter shows the air filter the open end of
> the adapter goes to the scoop. it is important to get the scoop opening at
> lest 3/4 inch away from the fuselage in order to be out of the boundary
> layer to keep the drag a low as possible. scoop needs a nice rounded edge
> not a sharp edge.
> I think it was worth the effort and expense
> 
> Jack Sheehan
> N55XL
> Race 55
> 
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