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Starting engine


larrynimmo

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This works really well for me:

At shutdown, throttle to 1200 RPM.  Then slowly bring mixture to cutoff.  The engine will sputter and then shutdown.   Leave the throttle where it is at.   Should have no problem starting 4hrs later... just like any other hot start.

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I may have to take this back but so far since we installed the SureFly EI it doesn't seem to matter re hot or cold technique. Engine starts in one revolution... just like my cars. 

I thought Lycomings fuel injection hot start problems were a fuel issue, the hot fuel vaporizes, so no fuel to burn, don’t see how Sureflys would help?

 

 

Tom

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4 hours ago, ArtVandelay said:

I thought Lycomings fuel injection hot start problems were a fuel issue, the hot fuel vaporizes, so no fuel to burn, don’t see how Sureflys would help?

 

 

Tom

Yeah, I thought so too. But apparently the very strong fire helps.  

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It’s the strong fire.  Lynn installed a slick start booster and the hot starts are eons better with a stronger spark compensating for feeble slick mags.  

I’m still not sure why boost pump helps me during hot starts though.  Tried it yesterday and my wife was impressed that the plane turned over in two turns heat soaked on a 95-degree day. It might be that I’m developing fuel flow that’s not vaporized in the lines earlier than if I pressurized the lines, cut everything off and allowed the engine driven pump to deliver a fuel bolus during cranking.  (I don’t have a leaky engine driven fuel diaphragm).  I think it’s just the former technique allows some additional fuel to vaporize during the start procedure.  My primary problem with hot start previously was that I’d kinda get it to catch and it would die or I’d flood it and then go back to the embarrassing flooded start three hand needed to avoid starting up like a Cirrus scenario.  

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  • 2 weeks later...
On 9/13/2019 at 3:55 AM, ArtVandelay said:

I thought Lycomings fuel injection hot start problems were a fuel issue, the hot fuel vaporizes, so no fuel to burn, don’t see how Sureflys would help?

 

 

Tom

The hot fuel in the injector lines from the spider vaporizes and then it dumps into the cylinders. So it automatically floods it after a hot shut down. That’s why the engine sounds like bacon frying whenever you’re pushing it back into the hanger. That’s the vaporized fuel bubbles pushing the liquid fuel through the injectors into the cylinder and it sizzles when it hits hot engine parts. 
If you start it hot then do not prime it, it’s already primed so to speak. Turning the fuel pump on while cranking allows the fuel  pressure to stabilize when you start it. . Otherwise it will start and then die as  the air bubble passes through the fuel pump and it cannot maintain fuel pressure. 

Edited by jetdriven
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The hot fuel in the injector lines from the spider vaporizes and then it dumps into the cylinders. So it automatically floods it after a hot shut down. That’s why the engine sounds like bacon frying whenever you’re pushing it back into the hanger. That’s the vaporized fuel bubbles pushing the liquid fuel through the injectors into the cylinder and it sizzles when it hits hot engine parts. 
If you start it hot then do not prime it, it’s already primed so to speak. Turning the fuel pump on while cranking allows the fuel  pressure to stabilize when you start it. . Otherwise it will start and then die as  the air bubble passes through the fuel pump and it cannot maintain fuel pressure. 

But how would electronic ignition make hot starts easy as Bob mentions above?


Tom
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1 hour ago, jetdriven said:

It fires the over-rich mixture. 

I know I'm sounding like some kind of evangelist for the Surefly EI but so far the performance exceeds my high expectations.

I have not been flying since my Aspen was off getting the MAX upgrade but it got installed Friday which involved a round trip to 8A7, about 40 minutes each way. 2 hot starts on the 8A7 ramp were great. I climbed to 8500 on the way back and pulled mixture back to LOP... little 4 banger ran smooth with all cyls 60+ LOP.  (That was under 7 gph and speed slowed to perhaps 130-135 ktas so not where I'd cruise but it ran smooth.) I wish there was some way to see how far BTDC the EI was firing...

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Just now, RLCarter said:

Shouldn't that be in the documentation?

The SEM has variable timing capability. At start (below 500 rpm) the timing is TDC. At higher power it is 20d BTDC to match the other MAG and the Lycoming data plate. But at lower power settings, at altitude, it can advance the timing considerably. What I'm curious to know is what that goes to real world. 

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25 minutes ago, RLCarter said:

Shouldn't that be in the documentation?

Unfortunately, no.  the timing advance is undocumented.  supposedly you can call sure fly and one of the engineers will talk u thru how it works.

I'm having about the same experience as Bob,  hot starts are much improved since the installation of the surefly; no longer scared to taxi for fuel 8)

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10 minutes ago, McMooney said:

Unfortunately, no.  the timing advance is undocumented.  supposedly you can call sure fly and one of the engineers will talk u thru how it works.

I'm having about the same experience as Bob,  hot starts are much improved since the installation of the surefly; no longer scared to taxi for fuel 8)

Glad to hear that the fancy electronic ignition  akes yiur E as easy to start as my factory C.  :P

After fueling last night, I let go of the key too soon, so my entire done-it-wrong restart may have lasted 10 seconds; it's usually less.

Hope to see everyone next weekend.

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Glad to hear that the fancy electronic ignition  akes yiur E as easy to start as my factory C.  
After fueling last night, I let go of the key too soon, so my entire done-it-wrong restart may have lasted 10 seconds; it's usually less.
Hope to see everyone next weekend.

Hank, see you in PCB!


Methinks you’re grasping... How does that O360 do on 7 gph 60 LOP?


Sent from my iPad using Tapatalk
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10 hours ago, McMooney said:

Unfortunately, no.  the timing advance is undocumented.  supposedly you can call sure fly and one of the engineers will talk u thru how it works.

I'm having about the same experience as Bob,  hot starts are much improved since the installation of the surefly; no longer scared to taxi for fuel 8)

From another post...

The SureFly (missing) advance curve has been bugging me, so I spoke with Jason Hutchison at SureFly. He confirmed that they removed it from the website. He said it was an oversimplification and technically incorrect. He also said that they decided for reasons he declined to elaborate on not to publish the corrected curve(s). He was pretty forthright and I didn't get the sense they are trying to hide anything. I suspect that they are tired of "experts" opining on the details of their design. OK, I get that -- I probably wouldn't get too far trying to get Subaru to send me advance curves for my Outback.

Here is what I did learn: The primary design goal of the advance is to adjust timing so that the peak pressure point (PPP) is about 13 degrees ATDC which they found to be close to the Maximum Brake Torque (MBT) angle for most engines in cruise operation. Operating at MBT gives the greatest efficiency. The use of MAP and rpm is analogous to the old auto distributors that had centrifugal and vacuum advances. At 24" MAP and above, the SureFly will be at base timing. Below 21" it will be fully advanced.

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On ‎9‎/‎21‎/‎2019 at 8:53 PM, jetdriven said:

The hot fuel in the injector lines from the spider vaporizes and then it dumps into the cylinders. So it automatically floods it after a hot shut down. That’s why the engine sounds like bacon frying whenever you’re pushing it back into the hanger. That’s the vaporized fuel bubbles pushing the liquid fuel through the injectors into the cylinder and it sizzles when it hits hot engine parts. 
If you start it hot then do not prime it, it’s already primed so to speak. Turning the fuel pump on while cranking allows the fuel  pressure to stabilize when you start it. . Otherwise it will start and then die as  the air bubble passes through the fuel pump and it cannot maintain fuel pressure. 

So lemme get this straight...and by the way, what you say makes sense. Often with this new engine, my hot starts want to die after start up...doesn't matter how good it works, it usually runs for a couple seconds then runs out of gas...by the time I get back on the key, it starts right up. The old engine never did that, a hot start was easy and it didn't seem to ever falter. So, where does the fuel pinch point occur? I'm always afraid of the boost pump because I don't want to flood the engine when hot. I don't have to tell you how embarrassing that can get.

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