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  #231  
Old 05-14-2022, 08:47 PM
MiserBird's Avatar
MiserBird MiserBird is offline
 
Join Date: Mar 2018
Location: Cornelia, GA
Posts: 83
Default Clamp-on timing light

Does anyone know if an inductive pickup timing light work on shielded spark plug wires? I've often wondered if there is enough image current in the shield to trigger.
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1975 Cardinal RG N1593H since Mar 1993
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  #232  
Old 05-15-2022, 09:32 AM
nomocom's Avatar
nomocom nomocom is offline
 
Join Date: Jun 2009
Location: Caldwell ID
Posts: 275
Default starting questions

Quote:
Originally Posted by N49ex View Post
Regarding the comment about EI needing a revolution or 2 to find TDC, that's very interesting and makes sense. It raises the question though of how it is that everyone with Surefly SIMs talks about how much better their engines start - Does that mean their engines start with 2 or 3 revolutions all the time now and are happy with that/and previously starts were worse than that?
Great question. Back in February of 2021, I complained to Surefly about exhaust system combustion events during in flight mag checks. Bill from Surefly explained the boot up delay as 1/10 of a second. This was enough time to put combustionable mixtures into the exhaust, that were then subsequently lit when the SIM started firing again. He reported they had new software that would shorten boot to 0.002 a second, but were waiting on FAA approval. I had assumed at the time, that it had to do simple OS boot up, but maybe it has to do with a certain number of engine revolutions so the SIM calculates crank position. The 0.002 second fix might have been to have the unit keep track of crankshaft position regardless of p-lead switch position, then when spark is called for it already knows position. Doing a little math, 1/10 of a second is 2.25 mag rotations, 4.5 engine rotations at 2700 rpm. Keeping track of crank position is likely easy to do during a inflight mag check, but will the SIM know position after sitting for a week, and the prop was fiddled with? Doubtful.

How long does the SIM keep track of crankshaft position? Does anyone starting on the SIM only start before 1 or 2 blades? SIM only, since we know impulse couplings are ready to go immediately.
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  #233  
Old 05-15-2022, 11:49 AM
TimO TimO is offline
 
Join Date: Feb 2005
Location: Wisconsin
Posts: 658
Default

One thing I believe I was told by surefly's tech support, way back when I installed mine in the 2 planes, is that they purposely have the mag drop higher than what they could have it. My lightspeed barely drops at all, maybe 20rpm. The surefly is more near 100 I think. They said that they have it tuned to drop that much because people who are upgrading from standard mags would be confused if it didn't provide the expected mag drop that they're used to.
While I don't agree that they took the right path on that, if they indeed did what they told me, it would explain the large drop.

Also, another surefly user told me the mag checks better with that system if you do it over 2000rpm. So I started doing that myself. I don't know that it matters if you choose 1800, 1900, 2000, or whatever number, as long as you develop a routine so that you know when it's varied from what you're used to.

The slow bootup is a little painful, so don't ever expect that with the older software you won't get that boot delay on mag check. I'll be interested to hear what they do for people as far as getting software/firmware upgraded. Would not be fun to have to ship them in, but I bet that's the only solution.
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  #234  
Old 05-15-2022, 07:18 PM
deek deek is offline
 
Join Date: Mar 2013
Location: Flathead Lake Montana - 8S1
Posts: 388
Default

Quote:
Originally Posted by MiserBird View Post
Does anyone know if an inductive pickup timing light work on shielded spark plug wires? I've often wondered if there is enough image current in the shield to trigger.
I know first hand the inductive timing light won't work with a Lightspeed system, you'll need to make a a short length "shunt "out of automotive plug wire to go between the spark plug and mag harness plug cigarette.
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  #235  
Old 05-16-2022, 11:20 AM
lr172 lr172 is offline
 
Join Date: Oct 2013
Location: Schaumburg, IL
Posts: 7,129
Default

Quote:
Originally Posted by MiserBird View Post
Does anyone know if an inductive pickup timing light work on shielded spark plug wires? I've often wondered if there is enough image current in the shield to trigger.
I have never tried it, but speculate that it may not work. The clamp is measuring inductance from when the energy field collapses. The primary purpose of shielding is to capture this and drain it to a ground. If this is effective enough, there may not be a strong enough field for the sensor to capture.

Larry
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  #236  
Old 05-16-2022, 11:24 AM
lr172 lr172 is offline
 
Join Date: Oct 2013
Location: Schaumburg, IL
Posts: 7,129
Default

Quote:
Originally Posted by nomocom View Post
Great question. Back in February of 2021, I complained to Surefly about exhaust system combustion events during in flight mag checks. Bill from Surefly explained the boot up delay as 1/10 of a second. This was enough time to put combustionable mixtures into the exhaust, that were then subsequently lit when the SIM started firing again. He reported they had new software that would shorten boot to 0.002 a second, but were waiting on FAA approval. I had assumed at the time, that it had to do simple OS boot up, but maybe it has to do with a certain number of engine revolutions so the SIM calculates crank position. The 0.002 second fix might have been to have the unit keep track of crankshaft position regardless of p-lead switch position, then when spark is called for it already knows position. Doing a little math, 1/10 of a second is 2.25 mag rotations, 4.5 engine rotations at 2700 rpm. Keeping track of crank position is likely easy to do during a inflight mag check, but will the SIM know position after sitting for a week, and the prop was fiddled with? Doubtful.

How long does the SIM keep track of crankshaft position? Does anyone starting on the SIM only start before 1 or 2 blades? SIM only, since we know impulse couplings are ready to go immediately.
This would be my guess. As long as power is not cut to the CPU, the s/w should be able to maintain the crank position and a s/w change should shorten ramp up with just a p lead on/off cycle, assuming that originally they just initiated the full start up sequence again.

FYI, the mag on a lycoming rotates at the same speed as the crank, unlike most automotive distibutors. The mag has a 2:1 gear reduction at the rotor, while an EI treats it as a crank sensor instead of a cam sensor; This is why they are all wasted spark-they only know crank position and not cam position. The mags use 1:1 because at 2:1, the mag wouldn't have enough energy to spark at lower RPMs; It is simply a PM generator and they need a decent amount of speed to produce enough power to saturate the primary winding of the coil.

Larry
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Last edited by lr172 : 05-16-2022 at 11:36 AM.
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  #237  
Old 05-16-2022, 06:21 PM
N49ex N49ex is offline
 
Join Date: Apr 2015
Location: Wheaton, Illinois
Posts: 162
Default SureFly installation issues - subsiding

My SureFly issues seem to be subsiding! Since I had seen some ragged EGTs on one cylinder since the installation, I decided to do an altitude cruise mag check as well as fly for 5 minutes each on the mag or SureFly separately. Expecting one or the other to show some roughness, surprise, both ran smooth! Apparently the EGT bobbles are either a failing probe or loose connection. And the plane flew about a knot faster on the SureFly than the mag.

The other discovery was that since SureFly significantly shortened the start up time (from 100mS to 2mS) I get no backfire when switching. And, with much cooler temperatures today, the ground mag check RPM drop was closer to 50 or 60. All good!

Reinhard
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  #238  
Old 05-16-2022, 06:41 PM
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Lenny Iszak Lenny Iszak is offline
 
Join Date: Sep 2008
Location: Palm City, FL
Posts: 416
Default

Reinhard,

What was the turnaround time for the startup time upgrade?

Lenny

Quote:
Originally Posted by N49ex View Post

The other discovery was that since SureFly significantly shortened the start up time (from 100mS to 2mS) I get no backfire when switching. And, with much cooler temperatures today, the ground mag check RPM drop was closer to 50 or 60. All good!

Reinhard
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  #239  
Old 05-16-2022, 07:25 PM
N49ex N49ex is offline
 
Join Date: Apr 2015
Location: Wheaton, Illinois
Posts: 162
Default Start up time upgrade

Quote:
Originally Posted by Lenny Iszak View Post
Reinhard,

What was the turnaround time for the startup time upgrade?

Lenny
Mine was a new unit bought a couple weeks ago, so it came with the start up time improvement. I assume you mean sending a unit in to them for the upgrade - unfortunately I don't know if they are actually doing that - if it is only firmware. Sorry, you'll need to ask them. They are very responsive!

Reinhard
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  #240  
Old 05-17-2022, 08:01 AM
pecanflyboy pecanflyboy is offline
 
Join Date: Nov 2011
Location: Granbury, Texas
Posts: 167
Default

Quote:
Originally Posted by TimO View Post
One thing I believe I was told by surefly's tech support, way back when I installed mine in the 2 planes, is that they purposely have the mag drop higher than what they could have it. My lightspeed barely drops at all, maybe 20rpm. The surefly is more near 100 I think. They said that they have it tuned to drop that much because people who are upgrading from standard mags would be confused if it didn't provide the expected mag drop that they're used to.
While I don't agree that they took the right path on that, if they indeed did what they told me, it would explain the large drop.

Also, another surefly user told me the mag checks better with that system if you do it over 2000rpm. So I started doing that myself. I don't know that it matters if you choose 1800, 1900, 2000, or whatever number, as long as you develop a routine so that you know when it's varied from what you're used to.

The slow bootup is a little painful, so don't ever expect that with the older software you won't get that boot delay on mag check. I'll be interested to hear what they do for people as far as getting software/firmware upgraded. Would not be fun to have to ship them in, but I bet that's the only solution.
There is no "designed" RPM drop during an ignition check. The unit makes a spark....period. If you are having a significant drop during this check, it's probably downline or improper installation.

The boot up issue is only a problem if your Bendix style switch is momentarily grounding the SIM during the ignition check. This is discussed on their website. For some reason, new or old, some of these switches momentarily ground the p-leads during the check as the switch is swiftly turned from both through the ignitions. In my situation, turning the switch slowly and smoothly solved the problem. I now have rocker switches on the ignitions. Even though this is not a Surefly issue, they have tried to minimize it by upgrading the units as they mature and better components come onto the market. This does not solve the problem that lives within the switch, it just minimizes it. Consider replacing your ignition switch.

Surefly does not upgrade units. Like most technologies (think iPhone), as they mature they receive upgrades and improvements. The units cannot be "flashed" to upgrade the software. It is built with modules that cannot be re-programmed (FAA cert issue). Anyway, the upgrades of which you are speaking are typically hardware upgrades. Your only option is to sell your unit and buy a new one.

Either way, call Surefly with questions. 817-373-5161

Jimmy$
Full disclosure: I don't speak for Surefly, as I am only an experienced user. However, I have helped them with Tech Support and installations in the past. These are my opinions based on personal experience.
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