VansAirForceForums  
Home > VansAirForceForums

- POSTING RULES
- Donate yearly (please).
- Advertise in here!

- Today's Posts | Insert Pics

  #21  
Old 11-18-2012, 05:51 AM
jersey jersey is offline
 
Join Date: May 2010
Location: Wharton, Texas
Posts: 122
Default Advantages ?????

What are the advantages of the fuel injected 912 over the standard engine. Is it worth an extra $4000.00 and the cowling redesign.? I'm already experiencing 5.5 gal / hr. fuel burn and 120 - 122 kts TAS at typical cruising altitudes. I'm interested but curious about the net advantage for the effort and cost.

Jersey
Reply With Quote
  #22  
Old 11-18-2012, 01:40 PM
tim walter tim walter is offline
 
Join Date: Apr 2011
Location: san rafael
Posts: 110
Default LOP?

Presumably you can run LOP and get longer engine life and better fuel economy?
__________________
Tim Walter
KDVO
http://rv-12-tim-walter.blogspot.com
kit# 120528
Reply With Quote
  #23  
Old 11-18-2012, 02:25 PM
rvbuilder2002's Avatar
rvbuilder2002 rvbuilder2002 is offline
 
Join Date: Jul 2005
Location: Hubbard Oregon
Posts: 9,035
Default

Quote:
Originally Posted by tim walter View Post
Presumably you can run LOP and get longer engine life and better fuel economy?
The 912iS has a FADEC engine control system. I am pretty sure all the pilot can do is adjust the throttle position, the FADEC system (full authority digital engine control) makes all other control decisions after that.
Reply With Quote
  #24  
Old 11-18-2012, 06:46 PM
splitty splitty is offline
 
Join Date: Dec 2007
Location: Hervey Bay Queensland Australia
Posts: 205
Smile 912iS

Quote:
Originally Posted by jersey View Post
What are the advantages of the fuel injected 912 over the standard engine. Is it worth an extra $4000.00 and the cowling redesign.? I'm already experiencing 5.5 gal / hr. fuel burn and 120 - 122 kts TAS at typical cruising altitudes. I'm interested but curious about the net advantage for the effort and cost.

Jersey
I belive they have a Lower fuel burn for same power output ..Plus No Induction ( Carby ) Iceing & No ongoing Carby Balancing...
Reply With Quote
  #25  
Old 11-18-2012, 07:50 PM
tim walter tim walter is offline
 
Join Date: Apr 2011
Location: san rafael
Posts: 110
Default

Quote:
Originally Posted by rvbuilder2002 View Post
The 912iS has a FADEC engine control system. I am pretty sure all the pilot can do is adjust the throttle position, the FADEC system (full authority digital engine control) makes all other control decisions after that.
sure, but presumably the FADEC has at least best-economy (LOP) and best-power modes.
regardless of how the control is done, my point is that fuel injection adds more flexibility in mixture setting than a carburetor.
__________________
Tim Walter
KDVO
http://rv-12-tim-walter.blogspot.com
kit# 120528
Reply With Quote
  #26  
Old 11-18-2012, 09:08 PM
rvbuilder2002's Avatar
rvbuilder2002 rvbuilder2002 is offline
 
Join Date: Jul 2005
Location: Hubbard Oregon
Posts: 9,035
Default

Quote:
Originally Posted by tim walter View Post
sure, but presumably the FADEC has at least best-economy (LOP) and best-power modes.
regardless of how the control is done, my point is that fuel injection adds more flexibility in mixture setting than a carburetor.
Sorry, I didn't read your post that way.
Since you wrote "Presumably you can run LOP"
My point was, in reality you can't do anything to run it lean of peak.
Only the FADEC computer can, and I have not read anything that says it does. Only that they claim an improvement in fuel economy. That may be just from the fact that the mixture is better controlled through the entire power band, instead of just three phases of mixture as the carbs do now.
Reply With Quote
  #27  
Old 11-19-2012, 09:46 AM
rv6ejguy's Avatar
rv6ejguy rv6ejguy is offline
 
Join Date: Mar 2005
Location: Calgary, Canada
Posts: 5,766
Default

The factory Rotax FADEC is very sophisticated and therefore expensive, given the development and testing behind it. I am not sure if they run LOP.

In our testing with the Bing carbs, they were very well matched to the engine. The average AFRs (measured with a wideband AFR meter) were quite precise in almost all ranges, a little rich around 4500 if I recall. I was frankly surprised at how well they worked. The bigger problem was cylinder to cylinder mixture variation, clearly two cylinders run richer than the other two from EGT and plug color. With EFI, the EGT spread was dramatically less.

At WOT, the carbs showed a slight pressure drop. The larger EFI throttle plate we used and plenum manifold showed no loss in MAP at 5800 rpm so between these two things, the engine picked up 3-5 hp (80 hp test engine). Further independent testing showed fuel flows were about the same amount lower at the same hp. So the gains were small but useful with our system.

In testing the factory ignition, again Rotax engineers got it right. We saw no gains in hp using our programmable ignition however at higher altitudes, there would likely be some gains by advancing timing.

You can see some photos of the testing here: http://www.sdsefi.com/rotax2.htm
__________________

Ross Farnham, Calgary, Alberta
Turbo Subaru EJ22, SDS EFI, Marcotte M-300, IVO, Shorai- RV6A C-GVZX flying from CYBW since 2003- 441.0 hrs. on the Hobbs,
RV10 95% built- Sold 2016
http://www.sdsefi.com/aircraft.html
http://sdsefi.com/cpi2.htm


Reply With Quote
  #28  
Old 11-20-2012, 06:21 PM
splitty splitty is offline
 
Join Date: Dec 2007
Location: Hervey Bay Queensland Australia
Posts: 205
Smile FADEC

Quote:
Originally Posted by tim walter View Post
sure, but presumably the FADEC has at least best-economy (LOP) and best-power modes.
regardless of how the control is done, my point is that fuel injection adds more flexibility in mixture setting than a carburetor.
The FADEC is set by Rotax in the factory to Give the best F/A Ratio at any Air or Engine Temp or Altitude so Only throttle movements are made by the pilot.... Timing & Mixture is all Automatic...!
Reply With Quote
  #29  
Old 11-23-2012, 04:20 PM
Andy_RR Andy_RR is offline
 
Join Date: Oct 2006
Location: Melbourne, Australia
Posts: 427
Default

LOP is a meaningless concept once you have FADEC.
Reply With Quote
  #30  
Old 07-20-2017, 04:37 PM
croner15's Avatar
croner15 croner15 is offline
 
Join Date: Jul 2013
Location: Dallas, TX
Posts: 46
Default #NailedIt

Quote:
Originally Posted by Jetguy View Post
My crystal ball says that will happen in about
5 years so don't hold your breath.
Does this crystal ball also work on stocks and sports?
Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -6. The time now is 03:39 AM.


The VAFForums come to you courtesy Delta Romeo, LLC. By viewing and participating in them you agree to build your plane using standardized methods and practices and to fly it safely and in accordance with the laws governing the country you are located in.