| Hi Guys.
Here is an update on what I discovered in relation to timing of the Renesis 4 port.
I discovered that the trigger wheel has a stamped arrow at the edge (See top of trigger wheel in photo) and this lines up with a reference point on the front case adjacent and above the e-shaft and trigger wheel. I believe this mark in the trigger wheel is likely 5 degrees ATDC. I used the technique of connecting a manometer like tube containing coloured fluid to one of the plug holes. When I rocked the prop back and forwards I could see a peak in the fluid in the tube very near where that arrow lines up with the reference point on the front cover. I could not read it more accurately than 5 degrees.
I then put a bit of paint in the arrow and used a timing light to record nominal timing of ~16deg in advance of the arrow, meaning 16+5 = 21 degrees BTDC of nominal timing.
I’m hoping someone might be able to affirm I’m on the right track here, or not.
I then adjusted the timing using Mode #8 advancing it 5 clicks (5 degrees) and this was evident in the running engine when rechecked with the timing light.
I called our local rotary engine specialist friend and he said that he sets up RX8 engines with Motec ignitions at a nominal 26 degrees BTDC and that the OEM computers have even more advance for reasons of emission reduction and that retarding OEM RX8’s yields performance improvements.
So I’m wondering what this means.
Can others offer any further feedback on nominal ignition timing of Renesis engines and particularly the 4 Port.
It crossed my mind that different coils might have slightly different trigger circuit delays, therefore changing the timing, but I think any difference in delays would likely be very small and not a significant factor to be considered. We are using LS2 Coils.
I’m a bit shy to simply add 5 degrees of Advance and make the nominal timing 26 degrees BTDC. I thought I might Advance it 3 degrees and test fly it. Appreciate your thoughts here.
I’m wondering the what kind of change those 5 degrees of advance will bring to EGT’s, Engine Cooling and power. Tracy, Lynn H, are you there?
I realise now I should have sorted this out ages ago!
Thanks everyone.
Steve Izett
Thanks guys. Dave, did your measure the timing with a timing light and with the prop on? Must have been pretty windy getting that data! I’ll mark up the ring gear with a TDC mark this morning and measure the current EC2 base Mode timing Which method do people prefer to get TDC? I think I have read about these 3 methods. 1. Rotor #1 equal Screwdriver depth to rotor face through both plug holes 2. Rotor #1 volume null using water in a tube - I think this might be from Lynn H 3. Rotor #2 bisecting Apex seal across T & L spark plug hole Can anyone else tell us their nominal timing at idle. Ours is ~1800rpm. And particularly anyone running a 4 port renesis like Tracy’s RV4. Cheers Steve On 25 Feb 2022, at 6:07 am, Pam & Dave Williams padajute@idcnet.com <flyrotary@lancaironline.net> wrote:
Hello Steve,
My timing is locked in at 35 degrees before top dead center from idle to 6500 RPM. You are on the right track because retarded timing will raise exhaust temperature. I have a 13b with Tracy's EC2\EM2 and the RD-1AB redrive.
Thanks
Dave Williams
-----Original Message-----
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]
Sent: Wednesday, February 23, 2022 6:45 PM
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: [FlyRotary] Timing
Hi friends
On my last flight I experienced high indicated EGT’s so as part of looking into this I would like to check my timing.
I have a Renesis engine and Tracy’s EC2.
In his A8 (Renesis) version of the handbook under Mode#8 Timing Adjustment it says to refer to ‘Initial Timing Adjustment’, however I can’t find any such instructions in this version, probably because it has a fixed position CAS.
Can anyone enlighten me on what the static timing should at a given idle rpm?
Much appreciated.
Steve Izett
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RX8 Trigger Wheel.jpeg
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