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Spark plugs

dan carley

Well Known Member
Changing my spark plugs on my 0360 180 hp
I have 4 regular plugs and four car plugs
What would be a better plug rem38e or Rem40e

Thanks
Danny
N15vr
 
if your running an electronic with the four auto plugs, there really is no reason to run the long nosed plugs. If your getting fowled plugs with an EI you have engine problems. with the advance on the EI, the mag plugs really dont have much to burn left when they fire.

bob burns
RV-4 N82RB
 
Spark Plug Change

I just changed from aviation REM37BY plugs (8) to NGK BR8ES-3961 plugs with the EMAG auto harnesses. When compared to the aviation plug performance, I found during test flights that the EGT's ran about 150* hotter, and the CHT's ran about 50* colder (when run under the same test conditions as the REM37BY's). Fuel flow was about the same. I didn't note airspeed differences.

These test results seem to indicate a lower power output, with more fuel burning in the exhaust port. I believe this is due to a lower performance spark. Has anyone seen this type of performance difference when switching to automotive plugs?

Would switching to the BR8EIX-6747 plug make a difference

Engine: IO-360 with 8.5:1 compression
Fuel: 93 oct E10 auto gas
Plug Gap: All Auto plugs new and set to .032" gap.
 
Changing my spark plugs on my 0360 180 hp
I have 4 regular plugs and four car plugs
What would be a better plug rem38e or Rem40e

Thanks
Danny
N15vr

The REM40E is a hotter plug. Depends on how your current plug looks like.
 
I just changed from aviation REM37BY plugs (8) to NGK BR8ES-3961 plugs with the EMAG auto harnesses. When compared to the aviation plug performance, I found during test flights that the EGT's ran about 150* hotter, and the CHT's ran about 50* colder (when run under the same test conditions as the REM37BY's). Fuel flow was about the same. I didn't note airspeed differences.

These test results seem to indicate a lower power output, with more fuel burning in the exhaust port. I believe this is due to a lower performance spark. Has anyone seen this type of performance difference when switching to automotive plugs?

Would switching to the BR8EIX-6747 plug make a difference

Engine: IO-360 with 8.5:1 compression
Fuel: 93 oct E10 auto gas
Plug Gap: All Auto plugs new and set to .032" gap.

Hi Fred, this is a very interesting experiment. Are both your ignitions pmags? The only change was the plug wires and the plugs? What timing are you running?
 
Nothing wrong with using the 18mm to 14mm bushing and the automotive spark plug cap on the Magneto side. I have found that the NGK BR8ES are fine for the standard engines, and the BR9ES for the "pumped up" engines. Also, these plugs come in a fixed top and a screw on top. Make sure the screw on top is tight! If loose, it arcs, causes radio noise.

DAR Gary
 
Spark Plug Change

Hi Fred, this is a very interesting experiment. Are both your ignitions pmags? The only change was the plug wires and the plugs? What timing are you running?

I'm running dual PMAGs. The only change between the two test cases was the plugs and plug wires. The timing (per the EI Commander) indicated 25.2* in both test cases.
 
I know this is a slightly older post but thought I might add some info regarding dyno testing we did during the RBAR and airshow days.

We tested a variety of spark plugs and both manufacturers. We found that the Tempest UREM37BY was king. One thing to note was that when using that plug in the high compression IO-540 (it was designed to keep O-235's from fouling) we had to replace them more frequently. We witnessed decreased performance in as little as 100 hours. We got them for free so we just replaced them.

Overall, the Tempest plugs outperformed the Champion counterpart across the board by a small margin. At the time we had a spark plug sponsor and it was not Tempest.
 
Spark Plugs

Does anyone know if there is an auto plug that is equivalent to the aviation UREM37BY plug?

On the last oil change, I switched over to the NGK BR8EIS plugs (8) gapped at .035". While there might have been a slight improvement, performance was still lower as compared to the UREM37BY aviation plugs. I am still seeing increases EGT's and lower CHT's with some power loss (relative to the aviation plugs). I am also seeing much more carbon in the cylinders with some dieseling on shutdown.

On my next oil change (or whenever I take the cowls off again) I'm going to swap out the NGK BR8EIS plugs (gapped at .035") and replace them with NGK BR8ES plugs gapped at 0.045" and see if there is any performance improvement. The test is based on this article: https://www.sciencedirect.com/science/article/abs/pii/S0306261917300673


I know this is a slightly older post but thought I might add some info regarding dyno testing we did during the RBAR and airshow days.

We tested a variety of spark plugs and both manufacturers. We found that the Tempest UREM37BY was king. One thing to note was that when using that plug in the high compression IO-540 (it was designed to keep O-235's from fouling) we had to replace them more frequently. We witnessed decreased performance in as little as 100 hours. We got them for free so we just replaced them.

Overall, the Tempest plugs outperformed the Champion counterpart across the board by a small margin. At the time we had a spark plug sponsor and it was not Tempest.
 
Does anyone know if there is an auto plug that is equivalent to the aviation UREM37BY plug?

On the last oil change, I switched over to the NGK BR8EIS plugs (8) gapped at .035". While there might have been a slight improvement, performance was still lower as compared to the UREM37BY aviation plugs. I am still seeing increases EGT's and lower CHT's with some power loss (relative to the aviation plugs). I am also seeing much more carbon in the cylinders with some dieseling on shutdown.

On my next oil change (or whenever I take the cowls off again) I'm going to swap out the NGK BR8EIS plugs (gapped at .035") and replace them with NGK BR8ES plugs gapped at 0.045" and see if there is any performance improvement. The test is based on this article: https://www.sciencedirect.com/science/article/abs/pii/S0306261917300673

What do you have for ignition? I feel like you are going the wrong way with plug gaps.. bigger gaps mean potentially more ignition leakage through the wires or under the cap. Aviation plugs are gapped around .016 to .018. I feel that I would rather small but reliable spark then big and possibly unreliable due to the higher resistance of large gaps.
 
Spark Plugs

See the above : Dual PMAGS currently driving automotive plugs. Performance comparisons to aviation plugs with NOTHING but the plugs & wires changed.


What do you have for ignition? I feel like you are going the wrong way with plug gaps.. bigger gaps mean potentially more ignition leakage through the wires or under the cap. Aviation plugs are gapped around .016 to .018. I feel that I would rather small but reliable spark then big and possibly unreliable due to the higher resistance of large gaps.
 
See the above : Dual PMAGS currently driving automotive plugs. Performance comparisons to aviation plugs with NOTHING but the plugs & wires changed.

Fred, any chance there is an issue with the wires? I assume your mag checks are good, both ignitions timed properly. Do you see different behavior at all engine settings? I'm running the auto plugs, currently on the BR8ES, and have not been able to see any difference with any plug that's in that heat range. My testing has been far from scientific, and I did this while debugging a bad plug wire. I ended up replacing two or three wires of the original set that came from pmag.
 
Fred, any chance there is an issue with the wires? I assume your mag checks are good, both ignitions timed properly. Do you see different behavior at all engine settings? I'm running the auto plugs, currently on the BR8ES, and have not been able to see any difference with any plug that's in that heat range. My testing has been far from scientific, and I did this while debugging a bad plug wire. I ended up replacing two or three wires of the original set that came from pmag.

Thanks for posting the PP link to your friend to help the folks in Ukraine!
Donation sent. Viva Ukraine!
http://www.rv8.ch/help-people-in-ukraine/
 
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Spark Plugs

Since it was only the plugs & plug wires that were changed from the original aviation plug setup, it's possible that something is wrong with the plug wires. This set came directly from PMAG, and while I did check the resistance of some of them, I didn't do all of them. Next time the cowl is off, I'll check all of them for continuity. All auto plugs I've used to date have the solid tops, and I've been very careful to push the wire cap all the way down onto the plug, and into the PMAG.

Fred, any chance there is an issue with the wires? I assume your mag checks are good, both ignitions timed properly. Do you see different behavior at all engine settings? I'm running the auto plugs, currently on the BR8ES, and have not been able to see any difference with any plug that's in that heat range. My testing has been far from scientific, and I did this while debugging a bad plug wire. I ended up replacing two or three wires of the original set that came from pmag.
 
Spark Plugs

Since it was only the plugs & plug wires that were changed from the original aviation plug setup, it's possible that something is wrong with the plug wires. This set came directly from PMAG, and while I did check the resistance of some of them, I didn't do all of them. Next time the cowl is off, I'll check all of them for continuity. All auto plugs I've used to date have the solid tops, and I've been very careful to push the wire cap all the way down onto the plug, and into the PMAG.

I have since confirmed that all the new spark plug wires are around 110 ohms each, with no intermitance detected. The BREIX plugs came out all dark black like they were subjected to a VERY rich fuel flow. Even the exhaust pipes were black! And I always run LEAN of peak! It's like the plugs are not burning the fuel....

Today I pulled the BREIX plugs (gaped at 0.035") and replaced them with BRES-3961 plugs gaped at 0.045". I've also cleaned the injectors per the Lycoming SB. I will test fly it tomorrow to see if there has been any improvement to the leaning .....
 
I have since confirmed that all the new spark plug wires are around 110 ohms each, with no intermitance detected. The BREIX plugs came out all dark black like they were subjected to a VERY rich fuel flow. Even the exhaust pipes were black! And I always run LEAN of peak! It's like the plugs are not burning the fuel....

Today I pulled the BREIX plugs (gaped at 0.035") and replaced them with BRES-3961 plugs gaped at 0.045". I've also cleaned the injectors per the Lycoming SB. I will test fly it tomorrow to see if there has been any improvement to the leaning .....

Let us know what you find, Fred. Do you have a long taxi after landing? Perhaps lean a bit on the ground too?
 
Spark Plugs

Let us know what you find, Fred. Do you have a long taxi after landing? Perhaps lean a bit on the ground too?

I always lean way past peak EGT on taxing, for exactly that reason. To the point of having to increase the mixture sometimes when I need more power. This week I ohmed out all the ignition leads, checking them for intermitant connections or excessive resitance. No issues found.

I'm seriously thinking about going back to the aviation plugs & harness again to get a better data point on performance.
 
I always lean way past peak EGT on taxing, for exactly that reason. To the point of having to increase the mixture sometimes when I need more power. This week I ohmed out all the ignition leads, checking them for intermitant connections or excessive resitance. No issues found.

I'm seriously thinking about going back to the aviation plugs & harness again to get a better data point on performance.

There are a lot of people flying with the pmags and the auto plugs, and those are what is recommended by the emagair team. I'd keep looking for the root cause of this problem.
 
Spark Plugs

I have since confirmed that all the new spark plug wires are around 110 ohms each, with no intermitance detected. The BREIX plugs came out all dark black like they were subjected to a VERY rich fuel flow. Even the exhaust pipes were black! And I always run LEAN of peak! It's like the plugs are not burning the fuel....

Today I pulled the BREIX plugs (gaped at 0.035") and replaced them with BRES-3961 plugs gaped at 0.045". I've also cleaned the injectors per the Lycoming SB. I will test fly it tomorrow to see if there has been any improvement to the leaning .....

After a long discussion with EMAG support, we've come to the conclusion that my running rich issue may be some sort of timing issue between the aviation plugs and auto plugs. Since the evidence seems to support a late firing, resulting in higher EGT's and lower CHT's, advancing the timing slightly may make a big difference. Since I have an EI Commander that has the ability to offset the timing curve with a a user inputted offset, advancing the timing (in 1.2* increments) is somewhat easy. I'll start at that value, and test fly to see what the results are.

If anyone has an EI Commander that they use with PMAGS, I'd like to know what your setting values are.
 
Call me old fashioned, but the first things I would do:
1. hook up a timing light and check the actual timing against the fly wheel marks. All the electronics get their info from electronics, the fly wheel does not lie.
2. Check the leads are all to the correct cylinders. Ridiculous I know, but worth checking.
3. Where did you source the auto spark plugs ? There are some of dubious quality around….
 
Sparkplugs

After a long discussion with EMAG support, we've come to the conclusion that my running rich issue may be some sort of timing issue between the aviation plugs and auto plugs. Since the evidence seems to support a late firing, resulting in higher EGT's and lower CHT's, advancing the timing slightly may make a big difference. Since I have an EI Commander that has the ability to offset the timing curve with a a user inputted offset, advancing the timing (in 1.2* increments) is somewhat easy. I'll start at that value, and test fly to see what the results are.

If anyone has an EI Commander that they use with PMAGS, I'd like to know what your setting values are.

Checked mechanical TDC timing today, and verified with a timing light. Timing light results where the same as indicated on the EI Commander. Via the EI Commander, increased the Adv Offset by 2.4* and flew the plane. MAJOR difference in performance! I can now run well lean of peak again (similar to where I ran the aviation plugs).

I have no idea why I needed to run these plugs/wires with a more advanced timing. I haven't pulled the cowls to looks at the plugs yet, but will guess that they are no longer black with soot.
 
...

If anyone has an EI Commander that they use with PMAGS, I'd like to know what your setting values are.

Glad you found a solution, Fred.

To answer your question, here's my timing, which is working great.

IMG_9282-1024x1024.jpeg

In words:
RPM max:2816
ADV max: 32.2
ADV shf: -1.4
 
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