Author Topic: S-35 Fuel Burn  (Read 2526 times)

Shannon Evans

  • ABS Member
  • Full Member
  • Posts: 11
S-35 Fuel Burn
« on: July 22, 2009, 02:19:10 PM »
Guys, I have been flying an S-35 Bo the last 2 weeks and have not really gotten to do a good cross-country yet . I did fly this morning from K17 (Montezuma, KS) to Tulsa, OK (KTUL). On this trip it seems I burned about 16.5-17gph of fuel. Is this close? I flew at 6000ft at 23X23. I had it running about 75 degree ROP on the EGT gauge. I do not have the GAMI injectors or engine monitor to run LOP. Just wondering what the experts think.  



Shannon Evans

Tom Pelz

  • ABS Member
  • Full Member
  • Posts: 436
S-35 Fuel Burn
« Reply #1 on: July 22, 2009, 11:16:47 PM »
Shannon,

That fuel flow sounds right for a 520.  However, I would suggest running it a bit richer.

One of the problems is the CHT probe was not always on the cylinder with the highest temp.   

Thus, with you flying at 23/2300 the CHT may read acceptable, but you are probably having a cylinder with a cht too high.

I found that out after I put a GEM on my Bonanza.   My EGTs were all over the place and my CHTs were too high on some cylinders, but normal on others.  

That all corrected when I added GAMIs.

A more fuel efficient power setting for the 520 was 21/2300.   When I would get up to 10 - 12 K I would fly at 2400 and full throttle.

Tom

Scott Newpower

  • ABS Member
  • Full Member
  • Posts: 223
S-35 Fuel Burn
« Reply #2 on: July 26, 2009, 12:48:44 PM »
I do not have GAMI's or an engine monitor and run LOP just fine.  Using information from the LOP gurus at APS basically just take the book figures and subtract 1 GPH.  My CHT's are rarely over about 325.

Tom Pelz

  • ABS Member
  • Full Member
  • Posts: 436
S-35 Fuel Burn
« Reply #3 on: July 26, 2009, 01:45:20 PM »
You are probably fortunate to be able to run lean of peak without the GAMIs.    My engine would not run that smoothly, until the GAMI were installed.

Regarding your CHT.  If your have the standard CHT, it give you a reading for only one cylinder, not all six.  

After I installed my GEM, I was amazed at the inability of the aircraft's CHT to represent the other five cylinders.

Tom

Milt Hobbs

  • ABS Member
  • Full Member
  • Posts: 2
S-35 Fuel Burn
« Reply #4 on: August 02, 2009, 07:59:45 AM »
I am also brand new to my S-35.  Will have my first set of long cross countries in about a week.  The instructor I used for the checkout has had a V35 for about 25 years.  She says 15 GPH at 23/23 day in and day out.  I have the Gami injectors and a EDM 800 (of which I am just figuring out the ops).  No plans on this trip to try and run LOP.

My IO 520 has about 1400 hours on it but seems to be running fine...about 1 qt oil every 10 hours.

Will advise on the outcome of the trips.  (4) 3+ hour legs.

Milt

John Collins

  • ABS Member
  • Full Member
  • Posts: 137
S-35 Fuel Burn
« Reply #5 on: August 02, 2009, 10:16:56 AM »
 
Quote from: Milt Hobbs
I am also brand new to my S-35.  Will have my first set of long cross countries in about a week.  The instructor I used for the checkout has had a V35 for about 25 years.  She says 15 GPH at 23/23 day in and day out.  I have the Gami injectors and a EDM 800 (of which I am just figuring out the ops).  No plans on this trip to try and run LOP.

My IO 520 has about 1400 hours on it but seems to be running fine...about 1 qt oil every 10 hours.

Will advise on the outcome of the trips.  (4) 3+ hour legs.

Milt


Must be nice to be rich and be able to afford wasting gas.

65% power LOP is 12.5 GPH day in and day out!

Shannon Evans

  • ABS Member
  • Full Member
  • Posts: 11
S-35 Fuel Burn
« Reply #6 on: August 02, 2009, 02:28:54 PM »


Milt[/QUOTE]

Must be nice to be rich and be able to afford wasting gas.

65% power LOP is 12.5 GPH day in and day out! [/QUOTE]

I though all Bonanza flyers were rich   , at least that is what I will tell myself when I pay all my fuel bills for the time I have "borrowed" the S35.  Near as I can tell the Tulsa trip burned about 16.2gph. I am trying to run 75-100degree ROP. That still shows the fuel flow at 16-17gph on the gauge. Still doing just some quick local solo trips to get more of a feel for the plane. Any excuss to fly the plane will work .

Yes Milt, if I had the stuff I would run LOP, but since it is not "my" plane I am just happy to be able to fly it.

Shannon Evans

Scott Newpower

  • ABS Member
  • Full Member
  • Posts: 223
S-35 Fuel Burn
« Reply #7 on: August 03, 2009, 07:21:33 AM »
I don't normally fly at 23 squared so I didn't know off hand what the fuel flow should be.  I went up today and tried it.  I have no GAMI's or engine monitor.  I settled in at 12.3 GPH which is 64% and that was approx 40 degrees LOP.  It was hot today, 74 degrees at 4500 when I went this morning.  I indicated 165 MPH for a true of 181.5 MPH(158 kts).

John Collins

  • ABS Member
  • Full Member
  • Posts: 137
S-35 Fuel Burn
« Reply #8 on: August 04, 2009, 02:04:09 AM »
In my opinion, it is a myth that you can't run LOP in a Bonanza unless you have GAMI, an engine analyzer, and digital FF. Although I am a great fan of all the above and have them installed in my aircraft, as long as the engine runs acceptably smooth enough for the pilot when operating LOP, all is OK. If your aircraft doesn't run smooth at these mixture settings, then the engine analyzer will help you determine why. If you don't have an engine analyzer, and the engine runs unacceptably rough LOP, just richen the mixture to your normal ROP setting.  GAMI injectors definitely will give you a smoother running engine and will save about a half a gallon or so per hour when ROP and they make LOP operations much smoother on most TCM engines.

I have totally gotten out of the habit of using my JPI to set the mixture, it is solely for troubleshooting and pointing out problems.  I set the fuel flow as the primary means of leaning by using the analog gage to get close and the digital gage to fine tune the fuel flow because the digital lags, while the analog is very repeatable even if not as accurate. If you don't have a digital FF indicator, reduce the analog fuel flow with the mixture until the IAS drops 3 to 8 Kts.  If you notice the CHT drops 20 or 30 degrees F, you are lean of peak.

If you have an engine that runs too rough for your comfort when LOP, then don't run it that way or buy the GAMIs. A good percentage of stock IO520s will run LOP without modification and a greater percentage of IO550s will run LOP without modification.

Mark Callender

  • ABS Member
  • Full Member
  • Posts: 6
S-35 Fuel Burn
« Reply #9 on: September 06, 2009, 01:49:39 AM »
We have our GAMMI's on order but have been running our S35/520 at 75 degree ROP and run pretty consistantly at 14.5 GPH.  Tried running LOP but the engine just ran too rough for me to handle. Look forward to running LOP and hope to do no more than 12.5 GPH.

Tom Pelz

  • ABS Member
  • Full Member
  • Posts: 436
S-35 Fuel Burn
« Reply #10 on: September 08, 2009, 06:55:41 AM »
To beat a dead horse, the problem of flight without the gami injectors is not that you cannot fly lean of peak, but when you are rich of peak and your single point EGT is 100 ROP and your CHT is exactly where you want it, you are probably frying some other cylinders.

When I installed a IO520BA in my Bonanza, I also installed a GEM.  I was amazed at the unequalness of the EGT readings and the CHT readings.

I pulled all of the EGT probes and checked them.   They were correct.  I then talked with George Braly on Compuserve.  He sent me four injectors which I installed per his instructions (Two of the original four were maintained).  

With that minor change, my preGAMIs leveled out my EGT readings and my CHT readings.  

I continued to fly ROP for a couple of years, but then began to make trips LOP.  

The fuel savings was significant.  50 gallons less for a round trip from the midwest to Seattle and back.   AND my CHT were running cooler.

I got 2200 hours from that engine (crack in case began to extend, so it got overhauled).

Point is, level out engine temps which extends life.   So, if I were going to be frugal, I would buy the GAMI before I got the engine analyzer.  Besides, the GAMIs are easier to install.  The analyzer requires significant time to install and possibly another hole in the firewall.

If I were going to choose what order I would install things my Bonanza needs, I would do the following:  1. Speed slope windshild great access to back of panel - and it looks good).  2. GAMI injectors,  3. (tied with 4.) Digital fuel flow (you will be amazed how inaccurate your fuel flow indicator is.  4.  (Tied with 3) Multiprobe engine analyzer.  I was not interested in having an analyzer and fuel flow in one instrument.



TomTom Pelz2009-09-08 15:03:24

Shannon Evans

  • ABS Member
  • Full Member
  • Posts: 11
S-35 Fuel Burn
« Reply #11 on: September 08, 2009, 12:44:06 PM »
Tom

Just for fun I tried running LOP on a trip to Denver a few weeks ago. It seemed to run fine & I was suprised at how smooth it was. However without the engine monitor (& remember it is not my plane) I went back to ROP. Even then only burned a little over 15gph. The Bo is impresive .

I obviously need to get myself in a position to have one of my own. . Anyone need a nice Super III Musketeer

Shannon Evans

Steve Carson

  • ABS Member
  • Full Member
  • Posts: 15
S-35 Fuel Burn
« Reply #12 on: September 09, 2009, 03:20:39 PM »
I haven't run ROP regularly since breaking in new cylinders (and no, I didn't need new cylinders because I run LOP).  At 25/25 during the break-in, 14.5 gph put me 75 degrees ROP (with GAMIs and JPI 700).  I now run at 12gph or less at 2300RPM depending on alt.  Everything is in the green and happy.

Scott Newpower

  • ABS Member
  • Full Member
  • Posts: 223
S-35 Fuel Burn
« Reply #13 on: September 11, 2009, 02:25:13 PM »
 
Quote from: Shannon Evans
Tom

Just for fun I tried running LOP on a trip to Denver a few weeks ago. It seemed to run fine & I was suprised at how smooth it was. However without the engine monitor (& remember it is not my plane) I went back to ROP. Even then only burned a little over 15gph. The Bo is impresive .

I obviously need to get myself in a position to have one of my own. . Anyone need a nice Super III Musketeer

Shannon Evans


What percent power were you running?  Once at 65% and below there's nothing you can do to hurt the engine so if it runs smooth you're good to go.


Bob Ripley

  • ABS Technical Advisor
  • Full Member
  • *
  • Posts: 168
S-35 Fuel Burn
« Reply #14 on: September 13, 2009, 12:24:30 PM »
Make sure you have the fuel system setup completed after GAMI installation. They will send you TCM SB97-3E which spells out the proper procedure. We suggest that the setting be at the upper limit for unmetered pressure or just slightly higher for cooling on T/O and Climb

Bob Ripley

ABS Technical Advisor