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Valley Engineering Big-Twin - Any one flying with one?

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ulflyer(at)verizon.net
Guest

Posted: Wed Feb 17, 2010 10:03 pm Post subject: Valley Engineering Big-Twin - Any one flying with one?

Hi folks,

I posted this some time back, didn't get much response.  Some time 

has passed and other folks may now had one and other that do have had 

some time to form an opinion regarding the engine.



So for those that have or are now flying with this engine, how about 

a little report on how you feel about the engine, it's power output, 

comparison to typical Rotax's like the 447 or 503, and reliability.

Thanks,

jerb

Thom Riddle

Joined: 10 Jan 2006
Posts: 1597
Location: Buffalo, NY, USA (9G0)

Posted: Thu Feb 18, 2010 5:53 am Post subject: Re: Valley Engineering Big-Twin - Any one flying with one?

Jerb,



Jimmy Young posted a lot of useful information about his trials with that engine on his heavy FSII. Do a search and you should find it. Bottom line for him was it was not enough engine for this heavy of an airplane so he finally switched to an HKS (I think). Jimmy, correct me if my memory is wrong.

_________________
Thom Riddle
Buffalo, NY (9G0)

Don't worry about old age... it doesn't last very long.
- Anonymous

elleryweld(at)aol.com
Guest

Posted: Thu Feb 18, 2010 5:59 am Post subject: Valley Engineering Big-Twin - Any one flying with one?

I put over 900 Hours on a 447 Rotax single ignition in my old firestar without a problem  nice little engine in my book easy on fuel plenty of power for a heavy firestar I thought,and I could out climb any thing at any airport and I could stay with a bunch of friends GA planes and go bye a few of them  with it.

     the 503  another good engine  plenty of power some people really think they need it because it has dual ignition compared to the 447 I have flown  with the 503 a lot less hours but plenty of friends have them that I fly with and I can only say they have had ignition problems more than I have on much newer engines 

   just my experience  

 

 

     Ellery Batchelder Jr.

 

 

 

   --

lucien

Joined: 03 Jun 2007
Posts: 721
Location: santa fe, NM

Posted: Thu Feb 18, 2010 7:06 am Post subject: Re: Valley Engineering Big-Twin - Any one flying with one?

 	  elleryweld(at)aol.com wrote: 	
		  I put over 900 Hours on a 447 Rotax single ignition in my old firestar without a problem  nice little engine in my book easy on fuel plenty of power for a heavy firestar I thought,and I could out climb any thing at any airport and I could stay with a bunch of friends GA planes and go bye a few of them  with it.

     the 503  another good engine  plenty of power some people really think they need it because it has dual ignition compared to the 447 I have flown  with the 503 a lot less hours but plenty of friends have them that I fly with and I can only say they have had ignition problems more than I have on much newer engines 

   just my experience  

	




The only engine-out I've ever had flying a 2-stroke was with the 447 and it was an ignition "problem". I put quotes around that because the fault wasn't with the engine, it was a wiring problem of mine that I introduced when I installed it on the plane. 



But you do indeed have one and only one ignition system on the engine.



I did and do feel a little more comfortable with the 503 as a result, but I'll still happily fly a 447 too just keeping the lack of redundancy in the ignition in mind. 



The 447 is the longest-lasting engine in the 2-stroke line followed closely by the 503. The only other drag about the 447 is it tends to run hotter especially at higher power settings. It's basically a suped-up 377 with a much better provision 8 crankcase and bottom end, so the cooling isn't quite as good as on the 503.



But even so, I think Steve Beatty has something approaching 1400 hours on a 447 and it's still going. In the field, there's lots of guys with over 500 hours and getting near 1000 with the 447. 



IMO, the 447 and 503 are aviation's best kept secrets in the 40 and 50hp range. Lots of folks are out paying 10 grand for 4-strokes because they're afraid of the 2-strokes for some reason. But us guys who've spent a lot of time in front of/underneath the air-cooled rotaxen enjoy the higher bang/buck ratio they offer .



LS

_________________
LS
Titan II SS

John Hauck

Joined: 09 Jan 2006
Posts: 4639
Location: Titus, Alabama (hauck's holler)

Posted: Sat Feb 20, 2010 7:29 am Post subject: Valley Engineering Big-Twin - Any one flying with one?

Regardless of all the power claims, the engine did not have the necessary 

power required to fly my plane safely.



--------

Jimmy Young

Jimmy Y/Gang:



The original FS with a 35 hp 377 Rotax was a hot rod.  Flew like a Kolb was 

designed to fly.



I never flew a 28 hp 277 Rotax, but flew with several that performed 

acceptably on Minimax, and other ULs.



I never flew Jimmy's Generac powered FS, but have observed him fly and flown 

in formation with him.



My observations were the engine was anemic and created an unsafe condition 

when flying from anything other than a long paved airstrip.



Just a guess, but the Generac did not come close to producing claimed power. 

I'd put it in the same category as the weak half VW powered N3 Pup my buddy 

used to fly years ago.



Larry Israel and his buddy tried to convert the 2CV Citroen 2 cyl opposed 

(similar to the BMW Boxer but much, much less HP) engine, but could not get 

enough power out of it to make a good alternative 4 stroke UL engine.



Not easy to come up with a good, reliable alternative engine to power UL and 

light planes.  If it was, they would be out there available to buy and fly.



john hauck

Titus, Alabama

_________________
John Hauck
MKIII/912ULS
hauck's holler
Titus, Alabama

Thom Riddle

Joined: 10 Jan 2006
Posts: 1597
Location: Buffalo, NY, USA (9G0)

Posted: Sun Feb 21, 2010 4:58 am Post subject: Re: Valley Engineering Big-Twin - Any one flying with one?

The early FS w/ 377 I once owned, had plenty of climb performance. 



One way to guestimate the actual horsepower being delivered from a 4-stroke engine is by knowing the actual fuel consumption rate of the engine under power. Most 4-stroke engines burn in the range of .42 - .48 pounds of gasoline per hour per horsepower (BSFC). Only the most efficient, usually with computer controlled fuel injection get to the low end of this range. There might be some examples that get better than this but I've never seen one. 



So using these numbers and the actual fuel consumption one can easily come close to the actual HP being produced by the engine. Jimmy once told me that he got on average he got about 2 gph fuel burn rate in the Big Twin when running at around 3400 rpm. Using the thirstiest BSFC of .48 we get only 25 HP being produced at a 2 gph burn rate. At .42 BSFC, it comes to ~28.5 HP. Looks to me like Valley-Engineering and/or Generac have over claimed the engine's HP by a lot.



2 gph x 6 lbs/gal / .48 bsfc = 25 hp

2 gph x 6 lbs/gal / .42 bsfc = 28.57 hp

_________________
Thom Riddle
Buffalo, NY (9G0)

Don't worry about old age... it doesn't last very long.
- Anonymous

by0ung(at)brigham.net
Guest

Posted: Sun Feb 21, 2010 9:02 am Post subject: Valley Engineering Big-Twin - Any one flying with one?

2 gph x 6 lbs/gal / .48 bsfc = 25 hp

2 gph x 6 lbs/gal / .42 bsfc = 28.57 hp



--------

Thom Riddle



 	  Quote: 	
		  >>>>>>>>>>>>>

So using these numbers the rotax 912ul burning 4 gph is only producing at
	


best case 57.14 hp and worst case 50 hp. Lets say 53.57 for the average.

Add 7000 ft of altitude with a loss of 4.25 % per thousand.  For a loss of

29.75 %.   leaving at altitude 37.63 hp at cruse.  Don't sound right.   Or

is the 4.25 % per thousand wrong?   I have had my mkIII912 to 13,000  and

using the same numbers the loss is 55.25%   leaving only 29.6 hp  are these

numbers essentially correct or am I missing something?



Boyd Young MkIII

John Hauck

Joined: 09 Jan 2006
Posts: 4639
Location: Titus, Alabama (hauck's holler)

Posted: Sun Feb 21, 2010 9:25 am Post subject: Valley Engineering Big-Twin - Any one flying with one?

So using these numbers the rotax 912ul burning 4 gph is only producing at

best case 57.14 hp and worst case 50 hp.

Boyd Young MkIII

Boyd Y/Gang:



For my 80 hp 912, 4 gph equaled 5800 rpm or about 75% power which is 60 hp. 

Don't hold me to those figures.  I did it in my 70 year old head.



I can see 95 hp with my 912S.  It burns 5 gph at 5800 rpm which is 75% power 

or 71 hp.



That is interesting.  I am cruising with 11 more hp at 5800 rpm burning a 

gallon more an hour and seeing only a few mph increase in cruise speed. 

However, it is worth the extra fuel burn to have the extra power when I need 

and want it.



john hauck

mkIII

titus, alabama

_________________
John Hauck
MKIII/912ULS
hauck's holler
Titus, Alabama

Thom Riddle

Joined: 10 Jan 2006
Posts: 1597
Location: Buffalo, NY, USA (9G0)

Posted: Sun Feb 21, 2010 9:33 am Post subject: Re: Valley Engineering Big-Twin - Any one flying with one?

Boyd,



912 UL engines are rated at 79 hp continuous at WOT and 5,500 RPM. A normal cruise power setting of 75% x 79 hp = 59.25 HP.  59.25 hp x .42 = 24.88 lbs/hr. / 6 lbs/gal = 4.15 gph.  At .42 BSFC 4 gph is about 72-73% power or about 57 HP.



At higher density altitudes it takes more RPM to get the same HP output compared to lower density altitudes. If a 912UL engine is propped for WOT at 5,500 RPM at around 8,000' density altitude, then WOT at that altitude will be producing approximately 75% power, which is the maximum power available in a normally aspirated engine at that density altitude. 



I normally cruise my Slingshot at 80 mph TAS and at that airspeed in the 2,000'- 4,000' density altitudes in which I fly mostly during the summer, I burn roughly 3.8 gph. If the Jabiru has a BSFC of .42 (as advertised), then my typical flight is at 67-68% power.



3.8 gph x 6 lbs/gal / .42 = 54.28 HP which is about 67-68% of 80 HP which is the max continuous rated HP for this engine at 3,300 RPM. FWIW, my typical cruise speed is a little over 2,700 RPM.

_________________
Thom Riddle
Buffalo, NY (9G0)

Don't worry about old age... it doesn't last very long.
- Anonymous

Thom Riddle

Joined: 10 Jan 2006
Posts: 1597
Location: Buffalo, NY, USA (9G0)

Posted: Sun Feb 21, 2010 9:46 am Post subject: Re: Valley Engineering Big-Twin - Any one flying with one?

Ooops. Forgot to mention. 



Our engines are rated at max power at sea level at standard conditions. i.E. 59F at 29.92" Hg.  The loss of power as density altitude increases is a little over 3% per thousand feet of density altitude.  



-25% / 8(thousand) = -3.125% per thousand feet of DA.

_________________
Thom Riddle
Buffalo, NY (9G0)

Don't worry about old age... it doesn't last very long.
- Anonymous

by0ung(at)brigham.net
Guest

Posted: Sun Feb 21, 2010 9:51 am Post subject: Valley Engineering Big-Twin - Any one flying with one?

2 gph x 6 lbs/gal / .48 bsfc = 25 hp

2 gph x 6 lbs/gal / .42 bsfc = 28.57 hp



--------

Thom Riddle



 	  Quote: 	
		  >>>>>>>>>>>>>

So using these numbers the rotax 912ul burning 4 gph is only producing at
	


best case 57.14 hp and worst case 50 hp. Lets say 53.57 for the average.

Add 7000 ft of altitude with a loss of 4.25 % per thousand.  For a loss of

29.75 %.   leaving at altitude 37.63 hp at cruse.  Don't sound right.   Or

is the 4.25 % per thousand wrong?   I have had my mkIII912 to 13,000  and

using the same numbers the loss is 55.25%   leaving only 29.6 hp  are these

numbers essentially correct or am I missing something?



Boyd Young MkIII

Sorry I didn't proof read,   29.6 is the loss form the average 53.57 hp

leaving 23.97 hp at 13000 ft.  anyway it still don't sound right, maybe the

4.25 % per thousand is wrong.     Or is it 4.25 for the first thousand from

sea level and the percent drops as altitude increases?



Boyd

John Bickham

Joined: 10 Jan 2006
Posts: 170
Location: St. Francisville, LA

Posted: Mon Feb 22, 2010 1:51 am Post subject: Re: Valley Engineering Big-Twin - Any one flying with one?

Don't know if you will find this useful.

http://www.youtube.com/watch?v=THo3IzhX9hI&feature=channel



this is video of Jimmy Y taking off from False River, LA.

not a lot of "leap into the air" for which Kolbs are known for.



Jimmy seems much happier with his HKS.  Look forward to flying with him soon.  Not much flying these past 5 months.  Rain, Rain, Rain.

_________________
Thanks too much,

John Bickham
Mark III-C w/ 912UL
St. Francisville, LA

I know many pilots and a few true aviators. There is a distinct difference that I have the greatest respect for.

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