EI Horsepower

I've been wondering about results after installing E/PMags. Will I see a measurable increase in HP? I need to repitch prop and would like to base that on any HP increase obtained with EI.

Stock O-320 with carb.

Thanks
Pat
RV-6/ 60344, trying to get it flying again.

At OSH in '10 I asked the guys at Eagle Engines how much power increase they saw on the dyno when testing engines.

The guy got all excited and said that when adding one EI, they typically saw a 4% increase and with dual EI's it was an easy 6% and that was without making any changes to the engine.

IF that is true, your 160 hp engine should put out close to 170 hp.

Based on what I've seen with my new ECi O-360 and my old O-290-D2, those number might just be real as I keep over speeding the props I've had made for my engines.

N941WR said:

At OSH in '10 I asked the guys at Eagle Engines how much power increase they saw on the dyno when testing engines.

The guy got all excited and said that when adding one EI, they typically saw a 4% increase and with dual EI's it was an easy 6% and that was without making any changes to the engine.

IF that is true, your 160 hp engine should put out close to 170 hp.

Based on what I've seen with my new ECi O-360 and my old O-290-D2, those number might just be real as I keep over speeding the props I've had made for my engines.

Click to expand...

Usually at sea-level WOT the electronic ignition timing will be the same as with a magneto, so there should be no discernible power increase. To increase sea-level power you might have to advance the timing which could get you into trouble with detonation-caused pre-ignition. You will never hear an air-cooled engine ping as you can in a car.
An engine develops the most power when the cylinder reaches peak pressure about 15? after top dead center. At altitude is where the EI pays off because the advance, based on MAP and rpm, will compensate for the reduced flame propagation speed at the lower charge density at altitude. This will ignite it sooner to get the peak pressure at the right place.
You will have two advantages with EI; much easier starting and more power and mpg at altitude.

elippse said:

Usually at sea-level WOT the electronic ignition timing will be the same as with a magneto, so there should be no discernible power increase. To increase sea-level power you might have to advance the timing which could get you into trouble with detonation-caused pre-ignition. You will never hear an air-cooled engine ping as you can in a car.
An engine develops the most power when the cylinder reaches peak pressure about 15° after top dead center. At altitude is where the EI pays off because the advance, based on MAP and rpm, will compensate for the reduced flame propagation speed at the lower charge density at altitude. This will ignite it sooner to get the peak pressure at the right place.
You will have two advantages with EI; much easier starting and more power and mpg at altitude.

Click to expand...

"Trust but verify." - Something I didn't do when I heard that little tidbit.

I just got off the phone with a premier engine builder and was told that they have not been able to verify any power gains with any EI system.

As noted above, the gain is expected up high but since they do not have an engine dyno in a pressure chamber, they cannot verify any power gains.

However, those with EI's installed do see a power increase or reduced fuel burn. It all depends on where you set the gauges.

N941WR said:

"Trust but verify." ...

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Correction to my post. As I thought more abou this, I realzied that an EI installation could well see an increase in power, even down low.

It depends on where they set the initial timing.

The P-mags by default have an "A" and "B" curve. The "A" curve starts at 25* BTC, just like a normal mag. If people are running that setting, then yes, they probably don't see much of a power/efficiency increase down low at full power.

However, if they are running the "B" curve, which starts at just below 30* BTC, then they will see an increase in power, which could be close to the aforementioned 4 & 6% number.

N941WR said:

Correction to my post. As I thought more abou this, I realzied that an EI installation could well see an increase in power, even down low.

It depends on where they set the initial timing.

The P-mags by default have an "A" and "B" curve. The "A" curve starts at 25* BTC, just like a normal mag. If people are running that setting, then yes, they probably don't see much of a power/efficiency increase down low at full power.

However, if they are running the "B" curve, which starts at just below 30* BTC, then they will see an increase in power, which could be close to the aforementioned 4 & 6% number.

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On a lot of engines with higher compression the static timing is 20? rather than 25?. I would never, ever, consider using 30? initial timing on an engine with 8.5:1 CR, but that's just my choice. Since I installed 9.7:1 pistons, even though Lycoming says use 25*? on the O-235 F,G with 9.7:1, I still backed mine off to 22?, but I'm a scaredy-cat who doesn't want things coming apart when I fly! I have enough trepidation when I fly over the Rockies or Sierras, or the Santa Barbara tower tells me to maintain runway heading out over the Pacific and then forgets about me!

elippse said:

... I would never, ever, consider using 30° initial timing on an engine with 8.5:1 CR, but that's just my choice...

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Yet a good number of people run with the advanced timing without issue. With the P-mags, you can put in a negative offset, so the 25* BTC can become whatever you want it to be.

Forced induction is another reason someone might want to reduce the initial advance.

Speaking of Dyno?s

I?m with Elippse. I have run PMags and LSE in the lab with simulated manifold pressure and watched the advance curves at different rpms. There can be a lot said on this topic.
Speaking of Dyno?s, just about have mine done with full data acquisition. No prop or club, hydraulic load absorber driven from the crank flange. Did some 100% load pull last weekend for the first time. Now finishing up on the cylinder cooling air delivery set up. The donor engine that that?s on the dyno now is a 0-360-A4A bone stock, this will be the test bed. Some of the projects coming up are going to be comparing EI systems and some exhaust and intake mods I?ve done. Seat of the pants claims sure sound good, however I prefer to relay on facts.
Thomas

Another thing to consider with static advance is your field elevation, the baro pressure, and the OAT. On a very cold, clear day near sea-level with the barometer up around 31.5", you're putting a big charge into the cylinder. With every 1" baro pressure increase above standard pressure you'll develop about 3.3% more power, and with every 10.4F decrease below standard temperature you'll see 1% power increase. At 30.9" and 6.5F, you'll get about 8.5% more power.

Better be careful about being over-advanced. You can run with detonation- ping-spark knock and never hear it. If it isn't too bad, it will just give the look through a borescope that someone had been using a ball-peen hammer on the top of your pistons. With more severe ping the ring lands can actually get broken. But with really bad ping, you can get hot spots in your cylinder or your plugs, and then you will have pre-ignition, which can occur as much as 180? before TDC. When this happens the charge is burning as it's being compressed, and the temperatures and pressure will melt holes in your piston in just two or three revolutions. Another thing that can also set pre-ignition off is the use of plugs with too hot of a temperature range. I saw this twice in 2009 at Reno, where the piston got holed.

It will be interesting this year at Reno in the IF1s as they will be able to use EIs for the first time. I don't expect to see improved speeds from the use of EIs because most of the guys compensated for Reno's high density altitude by advancing their timing to about 32?-36? already. Unless you're racing for your house's or car's title, play it conservative!

EI HP

I'm running a stock 320/150HP. Would the A or B curve be best?

Pat