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  #1  
Old 08-03-2016, 09:03 PM
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Default iStart Automatic Start Systems

I ran into the iStart guys from Granbury TX in one of the Oshkosh exhibit hangars last week. This is a really intriguing start system that digitally takes over the ignition, fuel flow, and mixture during all starts (cold or hot): It basically promises to make engine starts a non-event, particularly for fuel injected engines like my YIO-360-M1B.

Does anybody have any experience or comments regarding this system? I've already blown out one air filter with my pi$$ poor hot start techniques (somehow I didn't destroy FrankenSnorkel, my obviously amateur-built FAB). This seems to be a worthwhile investment if it actually works.
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  #2  
Old 08-04-2016, 07:59 AM
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I think it's going to be a great product for STC installation on a lot of older certified airplanes. In EAB we already enjoy better equipment, not that it matters. We still tend to buy a lot of conveniences we don't strictly need.

At the basic level, the istart system is a computer-driven square wave valve to meter fuel in response to a very simple map, which is accessible for tuning with a laptop. The metering inputs are temperature (taken from a valve cover screw location) and RPM.



RPM and temperature are also the fundamental inputs for a speed-density EFI. As an EAB owner, if I really wanted to automate start mixture, I'd install an SDS EM-5 based EFI, and have map-controlled fuel delivery across the entire operating range.

An EFI maintains fuel pressure all the way to the point of injection, and recirculates unused fuel back to a tank, two physical facts that really damp the possibility of fuel boiling before and during hot start. The istart system pressurizes fuel only as far as the metering valve, and does not recirculate, so fuel can still boil in the flow divider and individual lines to the nozzles. It also does nothing about hot fuel being pushed into the intake manifolds after shutdown. Perhaps it doesn't matter, but these are items of technical interest.

Prefer the simplicity and electrical independence of constant flow injection? Here in EAB we routinely install electronic ignitions with large plug gaps, which tend light off a much wider range of mixtures. Although we tend to talk a lot about LOP operation after installation of an EI, there is a huge improvement is starting and idle performance. EI tends to mitigate the less precise cranking and idle fuel delivery of constant flow. Install two and things get even better.

An obvious "objection" to this sort of system will be "Hey buddy, why not just learn how to start your engine?". That's not entirely fair. The truth is that everybody misses their first shot at a hot start from time to time, and the more you know, the more you know why.

Still, installing an istart will be a little like keeping an ugly mistress. She may may be worth the overhead, but you can't brag on her
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  #3  
Old 08-04-2016, 08:30 AM
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Quote:
This is a really intriguing start system that digitally takes over the ignition, fuel flow, and mixture during all starts
It does not control ignition, but does connect a signal wire to a magneto p-lead terminal to read RPM. The current installation instructions do not mention P-mags or other electronic ignitions.

It does control fuel flow via the metering valve, based on the pre-programmed values. It cannot determine the delivered mixture.
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  #4  
Old 08-04-2016, 10:17 AM
Aggie78 Aggie78 is offline
 
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Default In the interim...

Give this technique a try...I got it while at one of the forums put on by Lycoming last week.

Coming home from OSH, I've used it 4 or 5 times already, and it seems to work pretty well; the big advantage is a much reduced chance of backfire/induction fire because you're not using the boost pump.



Ps-sorry about the guy in front of me noggin showing up in the pic!
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Last edited by Aggie78 : 08-04-2016 at 04:57 PM.
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  #5  
Old 08-04-2016, 11:04 AM
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What does setting the Mixture to Full Rich do if the boost pump isn't on?
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  #6  
Old 08-04-2016, 11:07 AM
Aggie78 Aggie78 is offline
 
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Default Good question...

Quote:
Originally Posted by ccrawford View Post
What does setting the Mixture to Full Rich do if the boost pump isn't on?
Unfortunately, I arrived at the forum late and was settling in as this was being covered.

I believe it had something to do with allowing pressure behind the mixture cut off to bleed down?

Just guessing here...tell you what-I'll email the forum presenter and ask him myself and report back!

Rob
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  #7  
Old 08-04-2016, 11:21 AM
Aggie78 Aggie78 is offline
 
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A call to Lycoming tech support revealed that exercising the mixture control is a way to safely prime...but not OVER-prime the engine.

Apparently, it does release a small amount of pressure (and fuel) built up behind the cut off into the induction system.

I (like Sid) have had an induction "burp" due to over-prime enough to disfigure the K&N induction filter I have mounted on the snorkel.

Anything that stops that is a good thing.

Sorry for the thread drift, Sid.

Rob
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  #8  
Old 08-04-2016, 11:57 AM
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Quote:
Originally Posted by ccrawford View Post
What does setting the Mixture to Full Rich do if the boost pump isn't on?
Rotation of the engine with the starter activates the main fuel pump and moves fuel to the servo just as effectively as the boost pump.
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  #9  
Old 08-04-2016, 09:20 PM
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Quote:
Originally Posted by Aggie78 View Post
Apparently, it does release a small amount of pressure (and fuel) built up behind the cut off into the induction system.
Only true for those fuel controls with a good disk-type mixture control valve (Bendix/Precision and a few recent models from Airflow Performance, the FM150 and FM-200A for example). An older, worn disk valve may leak, and all the drum type mixture valves have a leak rate (standard FM-200 for example), so this priming method won't work...there won't be any trapped fuel.

Not that it matters. I have a drum-type FM-200 and a purge valve, so all pressure is deliberately bled off at shutdown. The hot start "ease the mixture forward while cranking" method works fine without prime, in particular with an EI.
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Last edited by DanH : 08-04-2016 at 09:25 PM.
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  #10  
Old 08-05-2016, 05:31 AM
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Default

Great responses. The iStart folks seek to eliminate a need for specific and varied techniques during hot starts (all starts, for that matter). I see myself settling into effective techniques, eliminating my impulse to spend over $1K on this system albeit its usefulness.
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52F NW Regional/Aero Valley Airport, Roanoke TX (home of DR's Van Cave)
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Catch her on YouTube's "Because I Fly!" channel

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