Running Ram Air through the clouds

[GXPD]

On my M20e the Ram Air does make quite a difference.  I gained about 5-6kts in speed with a 1.2in increase in manifold pressure. MVP-50 had readings as attached.  Looks like I also gained about 5HP.  A couple of questions:

• 
  
• Why would the fuel flow increase when I did not change the mixture control?  Do the Bendix FI adjust automatically to air flow?
  
• The EGT#3 increased from 1288 (100ROP) to 1328 (60ROP).  Should I get more power/speed if I richen back to 100 ROP?  Will this put me at 80%?
  

I was flying at 7400' P.Alt. and OAT was 37F.  EGT #3 is first cylinder to peak and the one I usually monitor for mixture.

Thoughts/comments?

[WardHolbrook]

Quote: jelswick

And Lew, I don't think you're being too conservative.  I know I've seen on Discovery, Animal Planet or Nat Geo where some insects and spiders migrate by flying or hitchhiking a ride in air currents at pretty high altitudes (don't remember their preferred flight levels).  Weather baloons have also found insect skeletons as high as 45,000 feet and I'm assuming our engines don't really care if they're ingesting a live bug or just his skeleton.

[jelswick]

Yikes!  I curse the ones that mess up 45T's nice paint on the leading edges, windshield or cowl, but can't imagine what that would be like to hit a whole flock of them like that.  What was that my instructor told me years ago...  What is the last thing that goes through an insects mind when he hits the windshield?  I think the answer was his behind.  Love the AeroShell Flight Jacket Touch and Go product for getting rid of such messes.

[Capt_CrashN_Burn]

Quote: GeorgePerry

I understand that aircraft engines are not "prone" to it, but I've seen plenty of high end auto's that have been driven through water too fast, sucked in some, and the bottom end came out in a violent fashion.  The chances of an aircraft engine doing this is slim but it only takes a couple of ounces of water in a combustion chamber to ruin an engine.

All I'm saying it that I wouldn't chance it.  Bottom Line, visible moisture = closed ram air door

[crxcte]

Steve,

    Thats an interesting graph.  I may get 2-3 kts improvement with the ram door open but not 5-6 kts from your graph.  The increased fuel rate may explain the increase in speed and hp.  I would be interested in seeing the graph after you lean it back out after the ram air.  I always lean after opening the ram door and setting the prop.  

[GeorgePerry]

Quote: Capt_CrashN_Burn

 Say whaaaaaaaaatt??? I've seen high compression diesel engines (20:1) eat some water without kicking the rods out. The only engines I've ever seen hydrostatically lock, are Top Fuel engines when they break an exhaust rocker arm or pushrod. As a matter of fact, a "correctly" running top fuel engine combustion chamber, on TDC compression stroke, is mostly liquid nitromethane. That amount of liquid requires a 100 GPM fuel pump to produce. 

I think you fail to appreciate the volume of water that would have to find its way into the cylinder to cause this. You would need the equivalent of at least 2 showerheads, per cylinder, to run the risk of hydrostatic lock.

[bjmacdonald]

Dear crash n burn, Mr Perry was hammered pretty hard over this topic his ego is a little bruised he needs a little time to heal.  Be kind to him for now.

[GeorgePerry]

BJ, No ego involved here...I'm just passing along what the POH says to do - nothing more nothing less.  With the ram air door open the engine gets unfiltered air.  The chances of hydrostatic lock are remote at best, and I said as much in my earlier posts.  As a racer you should appreciate "taking care of your equipment".  I submit that allowing unfiltered air into the engine when flying through rain is probably not in keeping with that principle.

OBTW I used to race both the 944 cup and Spec e30 series and was a SuperComp instructor with NASA. What a blast!  When my son is old enough I'm going back to the track to teach him.

best...gp

[bjmacdonald]

George i run Midgets part time and my bussiness taking care of gentlemen with expensive toys, i just returned from sebring fla running a retired cup car, you cannot substitute a v8 and big slicks for anything too much fun!!!

[GeorgePerry]

YOU GOT THAT RIGHT!   The best way to make a small fortune...start with a large one and go racing and/or flying.

[N601RX]

IO 360 with 4 cylinders, Compression ratio 8.7

90 cubic inches per cylinder

90 cubic inches=49.87 ozs

49.87ozs/ 8.7-1      -1 accounts for 1 standard atmosphere.

6.47ozs will cause complete water lock

 

Some other things to think about.

1250 degree steam would would have a lot of pressure.  I don't have any steam tables handy right now.

When the Ram air is open it hinges down and blocks the filtered air.  This also blocks the alternate air which comes in the from the back side of the cowling.

As teenagers working on our cars we would rev the motor up pretty high and slowly pour a drink bottle of water down the carburator.  The high temp steam would clean the cylinders of all the carbon and oil off the top of the pistons and combustion chambers.

I would not try this with a plane engine, and would keep the ram air closed when clouds and moisture.

 

[DonMuncy]

OK, I accept the fact that 6.47 oz of water will completely hydrostatically lock a cylinder. At 2400 RPM, what is the time (duration) in which that amount of water must enter the intake.

Don

[Capt_CrashN_Burn]

Quote: GeorgePerry

BJ, No ego involved here...I'm just passing along what the POH says to do - nothing more nothing less. 

[eaglebkh]

Quote: Capt_CrashN_Burn

 Well, that certianly explains why you felt it necessary to whip out your e-penis and brag how much bigger yours was than mine.

 

Typical effing zero. Reads something in a book and thinks they're an expert. I guess that why it takes a college educated man to break something, and a high school educated man to fix it. >:-)

[DaV8or]

We are unmoderated here, so if we want to keep MooneySpace a nice, friendly and useful place to come, talk about Mooneys, flying and build a Mooney community when we need it most, we have to agree to disagree, be civil and refrain from personal attacks. After all, it's not really about proving who's right and who's wrong, it's about sharing and learning. It's not a competition and there is no prize.