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Higher EGTs after PMAGs

A

Airzen

Well Known Member
Hi Folks,

I recently installed dual PMAGS on my RV-10. However, I am unable to wrap my head around the following observation:

Previous setup: One LS Plasma III + One Slick Mag, at 60% power peak EGTs would be around 1450.

Current Setup: Dual PMAGs, at 60% power I am seeing peak EGTs around 1520.

I was expecting that going full dual PMAGs I would see a drop in EGTs in similar conditions (less wasted energy).

While the engine runs smooth, it appears to me that there are things I should check. Here is what I was planning:
1) Check ignition leads
2) Check Spark Plugs
3) Check for Intake Leak

Thoughts / ideas on what might be happening and what should investigate besides the three things above?

Thanks,
Ashish
 
Have you changed the rating on the spark plugs ?

Have the CHT's changed ?

If they are higher - recheck the timing and remember, it is timed at TDC or a couple degrees after.
 
Airzen said:
Previous setup: One LS Plasma III + One Slick Mag, at 60% power peak EGTs would be around 1450.

Current Setup: Dual PMAGs, at 60% power I am seeing peak EGTs around 1520.
Click to expand...

Given same mixture and power setting, timing has been retarded.

Was the LS Plasma III crank triggered?
 
Last edited:
E-MAG Ignition

As I understand it you have installed two new E-MAG-200-6XL.
As have been pointed out above, the timing has to be set at fly wheel TC mark.
Lycoming factory setting is (20) or 25 deg fixed timing with the Slick mag.
The E-MAG has a default spark advance of +9 deg.
Actual spark advance will be up to (20) or 25 deg + 9 deg = (29) or 34 deg.
This is a significant change from default setting by Lycoming data plate.
Engine is now experimental so you can decide what you want.
It is possible to cause major damage to the engine with to much spark advance. How much advance is to much ? You will hear different opinions.
I have the Surefly and have chosen 25 + 5 = 30 as maximum advance.

Good luck
 
I would recommend the following:
1. call Brad at Pmag
also, if all else is well, the Pmag will give a 9 degree advance with the jumper in, which occurs at about 21.5" MAP. If the CHT's are all good, the higher EGT may be just an indication that more fuel is burning in the cylinder rather than going out the exhaust. I would do an excell spread sheet starting at a rich mixture, taking EGT, CHT, and Fuel Flow readings, and then turning the mixture know 1/4 turn, wait one minute, taking the readings, and repeat until the engine begins to run rough. Circle the highest EGT for each cylinder and I'll bet the CHT's will have dropped from their highest readings. If all is within about 1/2 gph from first to last to peak, injectors are fairly normal.

DAR Gary
 
Details

Yes, now running BR8ES, timed TDC. Earlier it the slick mag had aviation spark plugs and LS had denso and was crank triggered.

The cht in cruise are low 300s. I have been running pmags on 8 as well for last 7 years and haven’t had any problems.

The difference in egt caught my eye and I am wondering about the relative efficiencies of the two setups on the same airplane. Is the new setup inefficient than the previous one?
 
DanH said:
Given same mixture and power setting, timing has been retarded.

Was the LS Plasma III crank triggered?
Click to expand...

What Dan said…..

Assuming install timing before and after is correct, and assuming you set up the pMags with jumper in (strongly recommended), my now very dated memory of LightSpeed ignitions suggest the pMags will have less timing advance than the LightSpeed at that power setting.

Carl
 
crankwheel sensor

Hi Dan - the sensors still there. It's just not being used anymore - waiting till I send my prop to WW for overhaul. Do you foresee any problem with keeping the sensor?
 
calpilot said:
I would recommend the following:
1. call Brad at Pmag
also, if all else is well, the Pmag will give a 9 degree advance with the jumper in, which occurs at about 21.5" MAP. If the CHT's are all good, the higher EGT may be just an indication that more fuel is burning in the cylinder rather than going out the exhaust. I would do an excell spread sheet starting at a rich mixture, taking EGT, CHT, and Fuel Flow readings, and then turning the mixture know 1/4 turn, wait one minute, taking the readings, and repeat until the engine begins to run rough. Circle the highest EGT for each cylinder and I'll bet the CHT's will have dropped from their highest readings. If all is within about 1/2 gph from first to last to peak, injectors are fairly normal.

DAR Gary
Click to expand...

The 6 cylinder EMAG is different from the 4 cylinder and does not have a jumper. With the 6 cylinder EMAG you use the button on the side to program TC, min advance and max advance.

Rob Hickman
N402RH RV-10
 
jumper..

Indeed Rob. There are no jumpers in six cylinder version.

Currently, the PMAGs are set to variable timing (factory default) and timed at TDC ... We did Pull-through tests etc to verify min/max as per the manual.
 
Airzen said:
Hi Dan - the sensors still there. It's just not being used anymore - waiting till I send my prop to WW for overhaul. Do you foresee any problem with keeping the sensor?
Click to expand...

Nope, can't hurt anything. I was just thinking through possibilities for how the timing might get retarded.
 
I found the EMAG did not advance the timing as much as my Lightspeed Plasma III in the factory configuration.


Rob Hickman
N402RH RV-10
 
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