Mailing List flyrotary@lancaironline.net Message #64963
From: Stephen Izett stephen.izett@gmail.com <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: timing on renesis engines
Date: Thu, 11 Jul 2019 08:04:51 +0800
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Thank Matt
An adjustment during cranking (voltage) made sense, particularly for lower energy coils.
I didn’t realise that they adjusted dwell to RPM or MAP these days.

So at say 14v bus the dwell is adjusted from 4.16mS at 0-4400RPM then down to 3.36mS at 7600RPM.
So I’m wondering if the dwell would be safer set at 3.5mS for the sake of the higher RPM's

I have cool air feeding the coils.

Cheers

Steve

> On 10 Jul 2019, at 10:03 pm, Matt Boiteau mattboiteau@gmail.com <flyrotary@lancaironline.net> wrote:
>
> I attached the GM dwell settings for LS2 truck coils. Depending on the RPM & volts, it adjusts the dwell timing
>
> Yes the coils get the bus volts. On most first gen ECUs, all you got was one dwell setting to cover it all. Next generation added battery correction, so at least you could give more timing during crank vs high speed. Latest gen added RPM and MAP to adjust the dwell timing. Tracy's ECU was light years ahead of the curve back in the 2000s. We are 20 years later now and I would guess (don't quote me), you probably just get one dwell timing to cover it all.
>
> Are you going to notice any different, probably not.... Will your coils burn out any sooner? probably not compared to flying hours vs how many hours vehicles get. If you are concerned about coil life, change them every xxx hours.
>
> I'm running megasquirt, so they have RPM vs MAP with a general battery correction applied. Also with the truck coils having heatsinks, perfect place to add blast tubes.
>
> - Matt Boiteau
>> On 2019-07-10 4:31:14 AM, Stephen Izett stephen.izett@gmail.com <flyrotary@lancaironline.net> wrote:
>>
>> Hi Fin
>>
>> The coil trigger will come direct from the processor outputs I expect.
>> So your right, the coils will see whatever the bus is, whatever the alternator is doing.
>>
>> Steve
>>
>> > On 9 Jul 2019, at 10:52 pm, Finn Lassen finn.lassen@verizon.net wrote:
>> >
>> > Disregard. Those drivers are most likely for the injectors. Don't have the EC3 schematic so no clue what drives the coils.
>> >
>> > Finn
>> >
>> > On 7/9/2019 10:35 AM, Finn Lassen finn.lassen@verizon.net wrote:
>> >> All EC3 drivers are IRL530NS power MOSFETs with a on-resistance of 0.1 ohms.
>> >>
>> >> So the voltage the coils see will pretty much be whatever your 12 volt bus is -- whatever the alternator outputs.
>> >>
>> >> Haven't looked at the program code but suspect that coil sees full voltage during the dwell time -- simple on/off.
>> >>
>> >> Finn
>> >>
>> >> On 7/8/2019 9:24 PM, Matt Boiteau mattboiteau@gmail.com wrote:
>> >>> Depends what voltage it's??nominal at.
>> >>> Look at the Miata link, it shows actual GM dwell settings from their ECU.
>> >>>
>> >>> You'll see RPM vs voltage for the dwell settings. I don't know how Tracy's computer handles the dwell.
>> >>>
>> >>> - Matt Boiteau
>> >>>> On 2019-07-08 7:17:34 PM, Stephen Izett stephen.izett@gmail.com wrote:
>> >>>>
>> >>>> So which MS document do we take as being the good oil for the LS2 coils. Is it 4.0mS or 3.5mS ?
>> >>>>
>> >>>> Steve Izett
>> >>>>
>> >>>> > On 9 Jul 2019, at 6:04 am, Matt Boiteau mattboiteau@gmail.com wrote:
>> >>>> >
>> >>>> > That's an outdated page. I'm not sure why they even keep them alive.
>> >>>> > http://www.msextra.com/doc/pdf/MS3baseV30_Hardware-1.4.pdf
>> >>>> > Page 93
>> >>>> >
>> >>>> > Of course that number depends what voltage is consider at "nominal". Not sure if Tracy's changes value based on voltage or not. And RPM vs Manifold pressure
>> >>>> >
>> >>>> > https://www.miataturbo.net/diy-turbo-discussion-14/lsx-coil-thread-82744/page8/#post1380088
>> >>>> >
>> >>>> >
>> >>>> >
>> >>>> > - Matt Boiteau
>> >>>> >> On 2019-07-08 11:58:11 AM, Bobby J. Hughes bhughes@qnsi.net wrote:
>> >>>> >>
>> >>>> >> Matt,
>> >>>> >>
>> >>>> >>
>> >>>> >>
>> >>>> >> How did you end up with 3.5ms for the D585???s? At least one Megasquirt resource shows 4.0ms at 14VDC. My concern is the wide range between Tracy???s LS1 4.3ms and the 3.5ms referenced. If the megasqiurt information is correct then Tracy was very conservative with the LS1 settings. 4.0ms vs 5.6ms.
>> >>>> >>
>> >>>> >>
>> >>>> >>
>> >>>> >>
>> >>>> >>
>> >>>> >> http://www.megamanual.com/seq/coils.htm
>> >>>> >>
>> >>>> >>
>> >>>> >>
>> >>>> >> Bobby
>> >>>> >>
>> >>>> >>
>> >>>> >>
>> >>>> >> From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]
>> >>>> >> Sent: Friday, July 05, 2019 8:03 PM
>> >>>> >> To: Rotary motors in aircraft
>> >>>> >> Subject: [FlyRotary] Re: timing on renesis engines
>> >>>> >>
>> >>>> >>
>> >>>> >>
>> >>>> >> For the LS2 - D585 truck coils, 3.5ms is the recommended dwell.
>> >>>> >>
>> >>>> >>
>> >>>> >>
>> >>>> >>
>> >>>> >> - Matt Boiteau
>> >>>> >>
>> >>>> >> On 2019-07-05 7:37:10 PM, Stephen Izett stephen.izett@gmail.com wrote:
>> >>>> >>
>> >>>> >> Thanks Bobby and Lyn.
>> >>>> >>
>> >>>> >> According to Tracy???s code - 2.6 mSec RX8, 3.5 mSec RX7, 4.0 mSec LS2, 4.3 mSec LS1.
>> >>>> >> I also wondered about the timing difference between the various coils trigger circuit actually firing.
>> >>>> >> Now I suppose that difference might be a few uSec and insignificant, but if its 100uSec
>> >>>> >> then the timing difference between various coil types might become significant.
>> >>>> >>
>> >>>> >> @ 7000 RPM
>> >>>> >> 1 rev takes 8.6mSec
>> >>>> >> So each degree of EShaft rotation is 24uSec.
>> >>>> >>
>> >>>> >> Thanks again for the help.
>> >>>> >>
>> >>>> >> Steve
>> >>>> >>
>> >>>> >>
>> >>>> >>
>> >>>> >>
>> >>>> >>
>> >>>> >>
>> >>>> >>
>> >>>> >> > On 6 Jul 2019, at 2:52 am, Bobby J. Hughes bhughes@qnsi.net wrote:
>> >>>> >> >
>> >>>> >> > Lynn,
>> >>>> >> >
>> >>>> >> > Default is what ever Tracy set it to. The CAS location is not adjustable so default is set in his code.
>> >>>> >> >
>> >>>> >> > Bobby
>> >>>> >> >
>> >>>> >> > Sent from my iPhone
>> >>>> >> >
>> >>>> >> > On Jul 5, 2019, at 12:43 PM, lehanover lehanover@aol.com wrote:
>> >>>> >> >
>> >>>> >> >> What is the "Default" advance? Is that checked with a timing light? Easy starting can be up to 15 degrees of advance. For full power use up to 27 degrees of advance is good up to 10,500 RPM. Boosted engines require less advance as boost increases. Because the effective compression ratio as well as charge temperature is going up. Very high boost my have advance closer to zero. Advance is used to allow full combustion
>> >>>> >> >> of the charge before the exhaust port opens. At higher pressure and temps the flame front speeds are increasing. So, less time is needed. Thus less advance is needed. Lowering intake air temps with an inter-cooler and adding water spray can allow higher boost.
>> >>>> >> >>
>> >>>> >> >> Boosting to maintain sea level performance would probably not shorten engine life. Boosting for additional performance does shorten engine life. The kids get over 600 HP with boosted drag racing engines. This is fine if you only need the engine for 9 seconds. You have to know what the actual advance is to make any decision. Mark the flex plate or flywheel teeth with paint so you can check actual advance during any RPM.
>> >>>> >> >>
>> >>>> >> >>
>> >>>> >> >> It is difficult to detonate an NA engine. It is not difficult detonate a boosted engine.
>> >>>> >> >>
>> >>>> >> >> Lynn E. Hanover
>> >>>> >> >>
>> >>>> >> >>
>> >>>> >> >> In a message dated 7/5/2019 10:22:44 AM Eastern Standard Time, flyrotary@lancaironline.net writes:
>> >>>> >> >>
>> >>>> >> >> Steve,
>> >>>> >> >> I???m running default timing or maybe 1 degree advanced. Early on I experimented with 1-2 degrees advance for many flight hours and did not detect any noticeable change in engine performance. I did push the engine to what I believe was detonation during a ground tuning session. I was tuning under boost (44??? MP) , 7000 rpm with a wideband O2 on each runner and adjusting Mode 9 and Mode 4. With F/A balanced between each rotor and EGT???s under 1600F I was trying to see if increasing timing would lower EGT???s. F/A was in the 11???s. This was at the end of the session and the engine and supercharger were already hot. I think I had added 4-5 degrees advance with no noticeable EGT decrease when I encountered a mild bang or misfire. This condition was well above my 38??? MP limit I sometimes use for takeoff.
>> >>>> >> >>
>> >>>> >> >> I???m curious about the dwell time setting difference between LS1 and LS2 coils. I switched to LS2 coils sometime back with no failures to date. I remember seeing an option setting in some of the code you or Finn posted. Internet research indicates LS2 coils require less dwell time than LS1. Possibly 0.5-1 ms less.
>> >>>> >> >>
>> >>>> >> >> Bobby
>> >>>> >> >>
>> >>>> >> >> Sent from my iPad
>> >>>> >> >>
>> >>>> >> >> > On Jul 5, 2019, at 12:58 AM, Stephen Izett stephen.izett@gmail.com wrote:
>> >>>> >> >> >
>> >>>> >> >> > Hi there Guys
>> >>>> >> >> >
>> >>>> >> >> > Of the guys with Renesis engines using EC2/3 can you comment on your timing settings.
>> >>>> >> >> > I???ve to date left the timing at the default setting figuring its set by the location of the CAS.
>> >>>> >> >> > Not sure if the various coil options have different trigger timing latency.
>> >>>> >> >> >
>> >>>> >> >> > Thanks
>> >>>> >> >> >
>> >>>> >> >> > Steve Izett
>> >>>> >> >> >
>> >>>> >> >> >
>> >>>> >> >> >
>> >>>> >> >> >
>> >>>> >> >> > --
>> >>>> >> >> > Homepage: http://www.flyrotary.com/
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>> >>>> >> >>
>> >>>> >> >> --
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>> >>>> >>
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>> >>>> >>
>> >>>> >>
>> >>>>
>> >>>>
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>> >>
>> >>
>> >
>> >
>>
>>
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