Would there be a benefit to having the Surefly fire the top plugs (or bottom plugs) and the mag fire the opposite? (Instead of how it is now, where one mag fires upper bank and opposite lower bank.)

C180_guy wrote:Would there be a benefit to having the Surefly fire the top plugs (or bottom plugs) and the mag fire the opposite? (Instead of how it is now, where one mag fires upper bank and opposite lower bank.)

Yes. If the SureFly is firing all the bottom plugs, your risk of fouling those lower plugs is significantly reduced, even with massive-electrode plugs. The spark is hotter, and will burn off more of the deposits on those plugs. The upper plugs (if all fired by the magneto) are far less likely to foul anyway because of their location. Smoother running engine, reduced likelihood of plug fouling, and better spark performance of the magneto-fired plugs are all positive things.

I skimmed the install instructions for Surefly SIM6C. Will a Horizon P1000 electronic tach still work the same as if connected to a magneto?

In case anyone is interested in my question about the Horizon P1000 and Surefly SIM C6, here is the answer I just got.

The Horizon tach is not compatible as is. We have an interface board to correct that situation, but it is still a couple of weeks out from being approved by the FAA.

Looks interesting. Unfortunately no Mogas allowed though

Mark Y. wrote:Looks interesting. Unfortunately no Mogas allowed though

and also no firewall mounted battery. not enough cranking amps. Is there a logical reason for either of these. Or is it just he way they put in the paperwork

Aviation Consumer published an article on the SureFly and Electroair systems in their August 2019 issue. Sounds interesting to me, and worthwhile... I'm coming up on 500 hours on my mags and will probably rebuild one and replace the other with one of these.

I'm thinking Surefly for me when they get the tach interface done. Like the idea of no triggers and mount just like a mag except you do need to run a power wire to it.

I am keeping an eye on the Surefly too, Marty. Wonder how many HP it frees up in cruise at a given power setting. Regarding the power wire, the battery side of the starter solenoid is just adjacent to the RH mag, so probably would get power there.

C180_guy wrote:Wonder how many HP it frees up in cruise at a given power setting.

According to the Aviation Consumer article, "SureFly does not advertise increased performance, but [they've] noticed that the units allow engines to run better lean of peak, improving fuel economy, and that they may maintain 75% power to slightly higher altitudes... Their goal was the reliability and economy of an install-and-forget magneto replacement."

slowmover wrote:

C180_guy wrote:Wonder how many HP it frees up in cruise at a given power setting.

According to the Aviation Consumer article, "SureFly does not advertise increased performance, but [they've] noticed that the units allow engines to run better lean of peak, improving fuel economy, and that they may maintain 75% power to slightly higher altitudes... Their goal was the reliability and economy of an install-and-forget magneto replacement."

I tried clicking on that article, but I am not a subscriber. Not much of a LOP guy, but what they are saying is that at a given power setting, say 65%, the Surefly lowers the fuel burn. I noticed a reduction from 14.5 gph to 14.1 gph when I switch to fine wire plugs (75 deg ROP at 65% cruise). Be interesting to see what the Surefly does. Kind of disappointing though that at say 65% power it doesn't increase the output a few hp. So, advancing the spark timing only reduces fuel burn; it doesn't increase power output.

Well, not true. Spark advance at part throttle absolutely increased power output by increasing efficiency. Increasing spark advance at part throttle pulls peak cylinder pressure left, closer to top dead center.

Part throttle mixtures are less dense than full throttle mixtures and burn slower. If we keep locked in to the WOT spark advance, peak pressure during part throttle operations will happen well after TDC, throwing wasted heat energy through the exhaust.

Pull that peak pressure left and you’ll get more work out of the same mixture, which means either more power or less fuel required for the same power.

But, by definition, 65% power will always be the same hp value unless you’ve increased the engine’s maximum power output (which electronic ignition don’t significantly do). So, backing the engine down to 65% power you’ll see a reduced fuel burn with the electronic ignition, which is indicative of increased part throttle power production.

I agree CamTom that 65% power should mean the same thing no matter what the ignition system. So, on my IO470, 65% power by definition = 0.65 * 260 = 169 hp. However, are you saying that when one installs Surefly it changes the power setting tables - so, let's say 23/23 used to produce 169 hp at 5000'. With ignition timing advanced, 23/23 no longer produces 169 hp @ 5000' and the power tables have been changed to some unknown set of #'s? Let's say 23/23 now produces more power. The fuel savings therefore would come from backing off the throttle to - who knows what - 22" ? Or, if one kept the power set at 23/23, now the engine is producing 17x hp???

Simpler way to understand would be imagine setting up your cruise at 23/23 at 5000 ft running on only one mag. Say 169 hp. Now kick in both mags, rpm increase and manifold pressure increase - more than 169 hp, but at a higher manifold pressure and rpm for the same throttle position. Adjust prop and throttle back to 23/23 - still 169 hp but at a lower throttle position - less fuel burn for same power. Granted this system won't be as dramatic as this example, but same principle.

Mark Y. wrote:Simpler way to understand would be imagine setting up your cruise at 23/23 at 5000 ft running on only one mag. Say 169 hp. Now kick in both mags, rpm increase and manifold pressure increase - more than 169 hp, but at a higher manifold pressure and rpm for the same throttle position. Adjust prop and throttle back to 23/23 - still 169 hp but at a lower throttle position - less fuel burn for same power. Granted this system won't be as dramatic as this example, but same principle.

What he said - that’s a great example.

The power required to spin the prop at a certain RPM/MAP setting is the same. If you make power more efficiently, you can either run a higher RPM/MAP setting on the same fuel flow or you can dial back to the same RPM/MAP settings as before and save some gas.

I think airspeed is a great way to look at it. Because an airframe needs a certain number of HP to go a certain airspeed at the same loading. so after the upgrade at the same power settings as before ie RPM/MAP you will go faster, that is because you are making more power. Or at the same airspeed as before you will burn less fuel this is because you are at the same power and are now seeing the increased efficiency.

chase7761 wrote:so after the upgrade at the same power settings as before ie RPM/MAP you will go faster, that is because you are making more power.

Right, so let's say 23/23 @ 5000' used to be 65% power (169 hp). Post-Surefly, 23/23 is now 67%, 68% or whatever. So, the flight manual power setting tables are no longer valid.

I like the idea of the engine producing more power at the same (previous to modification) power setting. (It would be nice to know what the percent increase is.) My reason for purchasing Surefly would be increase in power, easier hot starts and smoother running.

C180_guy wrote:

chase7761 wrote:so after the upgrade at the same power settings as before ie RPM/MAP you will go faster, that is because you are making more power.

Right, so let's say 23/23 @ 5000' used to be 65% power (169 hp). Post-Surefly, 23/23 is now 67%, 68% or whatever. So, the flight manual power setting tables are no longer valid.

I like the idea of the engine producing more power at the same (previous to modification) power setting. (It would be nice to know what the percent increase is.) My reason for purchasing Surefly would be increase in power, easier hot starts and smoother running.

Chase is not correct.

The same RPM/MAP settings will provide the same airspeed and require the same amount of horsepower to attain, given that no changes to the prop have been made.

If you increase your engine’s efficiency (such as adding an electronic ignition), you can either achieve a faster airspeed using higher RPM/MAP settings on the same fuel flow as you did before, or you can dial back to the same airspeed/RPM/MAP as previously except at a lower fuel flow.

CamTom12 wrote:Chase is not correct.

The same RPM/MAP settings will provide the same airspeed and require the same amount of horsepower to attain, given that no changes to the prop have been made.

If you increase your engine’s efficiency (such as adding an electronic ignition), you can either achieve a faster airspeed using higher RPM/MAP settings on the same fuel flow as you did before, or you can dial back to the same airspeed/RPM/MAP as previously except at a lower fuel flow.

OK, makes sense to me now. Sticking with the same #'s for sake of discussion, 23/23 is still 65% power, but instead of burning 14.0 gph, the fuel burn goes down to 13.x gph. And, runs smoother, starts a bit easier, etc.

qmdv wrote:

Mark Y. wrote:Looks interesting. Unfortunately no Mogas allowed though

and also no firewall mounted battery. not enough cranking amps. Is there a logical reason for either of these. Or is it just he way they put in the paperwork

They want to ensure you have a big enough battery to kick it over and not kickback would be my guess. I’ve seen where a few guys mounted the Surefly on RV’s but sent them back due to kickback issues. In reality, being experimental they could have set it for a higher advance, but set it so many degrees ATDC to offset the advance and account for such. However, in the end it’s still a programming issue that needs to be resolved. For certified products, that makes it a lot harder with the requisite testing required before it could be released and to get people to go to a dealer to update the software. I personally would hold off on these units until some of the known bugs are resolved.