Lycoming 180hp or 200hp - WHAT'S THE RIGHT CHOICE???

[N200PF]

As far as I can tell the 200 hp IO-360 will cost me about 40lbs over the 180 hp.

Is it worth it?!? GPH? Speed? Climb? Heat?

Whatya Think?!?

- Peter

PS - C/S Prop

PSS - Anyone do any homework on the new IO-390-X? It has to run hot with the same block and 210 hp...

[captain_john]

Peter,

Yes, if I were to make the decision right now... it would be IO-390.

Go to Dan Checkoway's site and do some W&B scenarios. The airframe, in my mind is more suited for the heavier nose. Dan says so in his info too.

My reasons are:

1) Well, I am a self admitted power junkie
2) Weight and balance is favorable (can still have 100 lbs baggage too!)
3) Wheel landings are easier (and preferable in an RV according to most)
* I see you are a nosedragger... this is good for you too
4) Heat is unlikely to be a factor because it is mild compression
5) Similar to #4, with low compression it is likely to be less troublesome (TBO, MoGas, cooler etc.)

The trick isn't the block. It is the jugs. There is no replacement for displacement!

I like big jugs!

CJ

[jim_geo]

I like a good set of landing gear myself.

[captain_john]

Oh, and I am really looking seriously at the aerocomposites C/S airscrew too!

Seen it yet?

It is nice!

CJ

[bmurrish]

TShort sent me this website. I think I am almost sold on the idea.

http://www.lazy8.net/fwf.html

[captain_john]

Bill,

For the -8, I firmly agree! If I were building a -8, I would stay with a light para valve, but with lower compression than 10:1.

The -7 is wider, draggier and needs the weight on the nose, I believe.

Nice engine, though!

CJ

[Dan A]

I have the 180 hp Lyc clone in my 8. It is balanced, fuel flowed, and has Light Speed ign on the top. It is really snappy! Pushing the go lever fwd makes it jump!! I'm happy with the lower weight and the performance leaves nothing to be desired.
Dan , Back in the air tomorrow for more testing!

[N200PF]

Hey THANKS everyone!!!

The reason I ask is I flew with a local builder in his 180hp 7A last week and was TRULY impressed with the performance and the 8.2 GPH along the way! (Electronic Ignition). He had some VERY good reasons to run the 180 and I wanted to see what everyone else thought.

I am a power junkie myself which can lead me to make bad choices on occasion. (...like the time I found out that your could fit a Chevy 396 big block on the frame of a 1968 Pontiac firebird if you cut out the wheel wells...YES THAT WAS DUMB but I was in High School. BUT it would do wheelies with the right tires!!!)

- Peter

Please don't start with me on the car. I still get that sick feeling when I think what that High School garage project would be worth today if I wouldn't have re-classed it as EXPERIMENTAL.)

[captain_john]

Sooooo, Peter...

IO-390 for you too? It is the 396 of airplane engines! You can have your old Firechicken back with BUFFALO WINGS!

CJ

[Dan A]

okay, More numbers.. I installed the wheel and gear leg farings and yesterday made another "speed run". At 2450 rpm and 24 in MAP and at 7500 msl,My 8 trued out at 202 mph, burning about 11 GHP. Eat yer hearts out big power guys!
Dan 472DA 14.4 hrs and climbing.

[captain_john]

Nice work, Danno!

Have you got any squawks?

Keep us up to date!

CJ

[Dan A]

The only tweeking I have done is to raise the Horiz. stab about .125 now the elevator trails perfectly and the Vert. stab needed moved a little to the left as the bubble is off by a little bit less than half to the right. I moved it about 3/16 in. to the left but it still needs a little more. I had centered it like the plans say but the other RVer's here said they all had to go about 3/16 in. offset to the left to get the bubble in the center. Other than that she really flys nice. no wing heaviness at all. You all might want to keep the offset in mind when you mont the Vertical stab.
Dan

[captain_john]

Cool,

I am so far away from that point right now, but it falls into the category of "Things I will need to do eventually".

How about some pics?

CJ

[N527TM]

We are going to use the 180 Aerosport, dual light speed and injector tuning. Should have 195hp

What would I gain if it used a 390... 10 hp or 3kts cruze. and more gas burn. weight is just ballast

Bottom line is if you are building an acrobatic ... power is everything.
building a x-country the 180 is my #1

Mike

[N537TM]

All

Has anyone read the vansairforce article on engine hp and Vne?
I didn't know that Vne is a True Airspeed... thought it was Indicated!!

One could get in trouble real fast (pun intended) with a airspeed indicator that reads Indicated.

Mike

[Spike]

That was a very very intersting article. Like you I always thought that Vne was IAS. TAS indicators wont do you any good though unless you take the time to use it to calculate TAS with temperature, etc.

It was definately an eye opening article though.

-- Spike

[mustang]

Spike,
TAS indicators do factor in the OAT, otherwise they could not produce TAS. For a TAS indicator to work it takes pressure altitude, TOAT, and IAS/CAS into consideration.

The thing is, with a proper, moving "Barber Pole" VNE indicator on the airspeed indicator,(not a painted, fixed redline), the VNE IAS changes with altitude and temp. So with increasing altitude, the "Barber Pole" VNE indicator/pointer slowly moves to a lower and lower airspeed value. This is interesting in a jet where you can find yourself in "Coffin Corner". This is an airspeed situation at high altitudes where the VNE on the Barber Pole indicator approaches the stall speed of the aircraft. It is possible to get the aircraft to a point where it is unable to go any faster without violating the VNE, (and activating the "Clacker" mach airspeed warning), and at the same time the aircraft is unable to go any slower due to violating Vs and activating the "stick shaker" stall warning system.

I was once caught in a mountain wave over Iceland in an empty B707 at 41,000 ft. Here the aircraft was being thrust skyward by the wave action, with the speedbrakes extended fully and throttles at flight idle, the overspeed warning clacker was sounding and the stick shaker was activated at the same time! We topped out at 43,000 feet before descending to our assigned altitude and getting things back under control. This was a bit unnerving, to say the least.

Cheers, Pete

[Spike]

Thanx for the info Pete. I was under the impression that the TAS indicators still needed you to manually adjust an outer ring for the OAT to get the right indication. I assume from your posts then that you dont have to do that and they have some sort of temp probe or something?

-- Spike

[jim_geo]

Well now wait a minute ya'll. Recently while looking through some catalogs I spotted a couple of airspeed indicators that you do have to manually change the OAT. So it looks like some you do and some you don't. Loosely on the subject of true airspeed though, several years ago Air and Space magazine did an article on the U2. In this article a U2 pilot said that at the very high altitude and full power it became tricky to turn because the wing toward the inside of the turn would tend to stall.

[cjensen]

that's how it works. the inside wing is moving slower (relatively) through the air. that's why using rudder to control a stall, or recovery from a spin works. you accelerate the inside (stalled) wing to recover lift. next time you're in cruise flight, step on the rudder, and watch the opposite wing...it will rise. it's a really good demo to make sense of the stall/spin recovery procedure.

sorry, not the subject at hand.

pete's description is right on. we don't go high enough in the king air to get the indicated airspeed close to the stalling speed (or even blue line for that matter), but the barber pole and indicated airspeed remain relatively close at high altitudes. if we are FL250 or higher, the barber pole and IAS are around 150-160kts, but our TAS up that high is around 270kts.

pressure alt, TOAT, CAS=TAS