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  #1  
Old 03-11-2018, 07:46 PM
N729LS's Avatar
N729LS N729LS is offline
 
Join Date: Apr 2015
Location: Mesa, AZ
Posts: 108
Default Alternative starters with "snorkel" inlet?

The RV-8 I purchased has the "snorkel" inlet and cowl.
The previous owner souped-up the angle valve IO-360-A1B6
with 10+:1 pistons and the little SkyTec 149-12LS starter is
really hard-pressed to turn it over. The recent replacement
starter (shiny case) has actually made it worse.

I would like to get a higher torque starter, so I was wondering
if anyone has had success in fitting the E-drive starter (current
part #ELZ-8021), the NL starter (current part #149-NLR) or
the HT starter (current part #149-12HTL) to an -8 with the
snorkel inlet & cowl.

It's hard to tell from the pix on the SkyTec web page which
would work at all and how much rework to the inlet would be
required for each. Comments on any & all appreciated.

Thanks,
Andy
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  #2  
Old 03-11-2018, 08:04 PM
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Captain_John Captain_John is offline
 
Join Date: Jan 2005
Location: KPYM
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Default

Bite the bullet, modify your snorkel and install the B and C.

I did it and am thrilled to bits!

You will be too.

CJ
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  #3  
Old 03-11-2018, 10:29 PM
Chkaharyer99 Chkaharyer99 is offline
 
Join Date: Oct 2011
Location: Pilot Hill, CA
Posts: 823
Default

I replaced a broken Skytec Lightweight starter on my RV-8 (IO-360) with the B&C starter.

In my case it wasn't a drop in, no hassel, replacement. I had to modify the snorkel to accomodate the offset of the B&C. I also required a mixture lever with a greater offset in order to clear the starter. The Bendix FI and B&C are an interference fit. They nestled tightly together requiring some slight modification.

The B&C spins the prop on the first attempt and spins it faster than the SkyTec it replaced. The SkyTec often required 2-3 bumps before it would even turn the prop.

No weight benefit in my case. I think I gained a pound. For me it was worth it.

Call B&C. I think you'll be impressed with their customer service. I am.
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  #4  
Old 03-12-2018, 04:23 PM
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JohnInReno JohnInReno is offline
 
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Location: Prescott Valley/Chandler AZ
Posts: 300
Default Battery

Quote:
Originally Posted by N729LS View Post

I would like to get a higher torque starter,

Thanks,
Andy
How about a different approach. An EarthX Lithium Iron battery has about 20% higher voltage to the starter. It made my starter problems disappear and saved 10 pounds in the process.
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  #5  
Old 03-19-2018, 12:52 PM
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N729LS N729LS is offline
 
Join Date: Apr 2015
Location: Mesa, AZ
Posts: 108
Default Update on alternate starter

I chose to try a couple of things in series, in an attempt to learn more about my starter issue. Some results documented below; final results in future post.
  1. Discuss the problem with other guys that have high-compression IO-360s in their planes.
    I found that the issue of hard-to-start high-compression engines with PC-680 powered systems is very common, even with non-LS starters. "Bumping" the prop, as well as preheating the oil and pulling through a few blades were suggested. Nobody with this set-up (HC, PC-680,SkyTec) reported no problems.
  2. Change to higher torque starter: I had very good luck with the Skytec 149-NL starter on my last plane, which also had a high-compression angle-valve IO-360.
    However, that plane had 28V systems, not 14V like my RV.
    I was able to determine that the SkyTec NL starter would fit without any required modifications to the snorkel! I did have to grind down two unused bosses on the starter, which took about 10 min.
  3. Debug the power-to-starter system in detail.
    I checked every connection, every wire, both contactors and the battery. I used a meter in addition to the volts and amps readouts on the EFIS (requires >1 person) and checked first without load and then under load.
    I used jumper cables from a running car to power the system in various locations, including with the aircraft battery completely removed from the system
    I removed the lower plugs for a while to make these tests easier on the new starter.
  4. Net result - Everything in the starting system was working as expected, except that the 6-month-old PC-680 was badly overworked during starting, with voltage dropping well below the desired 9V minimum.
    .
  5. Next Step - Based on the recommendation here, and some on-line research, I decided to bite the $450 bullet and order the EXT900 battery from EarthX. This will fit into the existing battery box, and should provide both more volts and more amps to the starter.
    Results to follow...
Andy
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Flight Reviews, Dynamic Prop Balancing
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Last edited by N729LS : 03-20-2018 at 09:04 AM. Reason: emphasis
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  #6  
Old 03-22-2018, 11:22 AM
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N729LS N729LS is offline
 
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Location: Mesa, AZ
Posts: 108
Default Starting Power

Just another informational addition:

Cranking an engine with an electric motor/battery combination requires both torque, and power.
  • In the simplest sense, the torque produced by an electric motor is directly proportional to the voltage across it, and inversely proportional to its speed. The voltage produced by a battery is dependent on the amperage it produces.
  • Volts * Amps => Watts (a measure of power)
  • Torque * RPM => Horsepower (also a measure of power)
Unlike an electric motor just driving a steady load, if we can get a cylinder to fire at the proper time, that will provide an positive torque on the engine, reducing the load on the starter and making everything better. But if the starter can't get the blades moving fast enough, and you have an ignition with fixed timing, it's possible to get a cylinder to fire too early and produce a negative torque on the engine - a backfire - which completely disrupts the starting process and may even damage components (typically the starter).
SO... we need both
  1. an electric motor (starter) design that can, given some known voltage, produce enough torque to get the prop moving and keep it moving fast enough to avoid a backfire, and
  2. a battery that can provide enough power, both volts to make torque and amps to sustain it.
Of course, a too-small starter (LS?) will never make enough torque, and a too-big starter (e-Drive?) is just dead weight. Understanding all that, and assuming a proper starter design we can compare a few 12V variations of battery to power it. I have also included a typical 24V combo. I think this clearly demonstrates why the PC-680 has difficulties and why the 24V systems are trouble free.
Code:
Concorde   Odyssey    EarthX               Concorde
CB-25XC    PC-680     EXT900               CB-35AXC
----------------------------               --------
 24.5       15.4       5.4        lbs        32.5
 big       medium   smaller       size       BIG
 12         12         13.2       volts      24
 513        170        400        CCA        665
 625        520        840        PCA        818
 6156       2040 :(    5280       CCWatts    15960! :)

FWIW,
Andy
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  #7  
Old 03-24-2018, 08:20 AM
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N729LS N729LS is offline
 
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Location: Mesa, AZ
Posts: 108
Default Success!

Last post from me for this topic!
I got the EarthX EXT900 battery installed. It required some modification to the PC-680's battery box and some creative routing of the big wires to make it all connect up. And...
The system (EXT900 battery + 149-NL starter) works like a charm! Turn the key and the prop spins! Couldn't be more pleased for now.
Andy
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  #8  
Old 03-24-2018, 09:04 AM
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M McGraw M McGraw is offline
 
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Location: Greenback, TN
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[/quote]...I was able to determine that the SkyTec NL starter would fit without any required modifications to the snorkel! I did have to grind down two unused bosses on the starter, which took about 10 min
Andy[/quote]

I have an RV14 with what I assume is the standard Vans snorkel. My IO-390 came with the Skytech starter you want to replace. I hated it within days of operation. I did the same as Andy and replaced it with a Skytech NL-149. The Skytech instructions even tell you which two lugs to grind off and how deep to grind. I absolutely love the NL series I made no modifications to the snorkel or electrical system and it cranks everytime, as it should.

Marvin
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  #9  
Old 03-29-2018, 06:44 PM
drakerv drakerv is online now
 
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Location: Redmond Wash
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Skytec 149-NL starter
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  #10  
Old 03-30-2018, 09:05 AM
Robert Anglin Robert Anglin is offline
 
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Location: houston, texas
Posts: 900
Default Also.

You may also wish to check your starter wiring. We have seen that #4 can make a starter turn a little slower, were # 2 will feed the starter a little better and it will turn a little better. We have found that it is best to start at the source and work your way down stream in order to make sure you have full flow to start with, rather than the other way round.
Hope this too helps you. Yours, R.E.A. III # 80888
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