proper leaning for continental ?

[Jeanie]

I'm used to leaing a Lycoming and have been taught that at altitude you lean it slowly till it runs rough and then enrichen it w/ 2 turns back to smoothe.

But I have heard the Continentals can't be leaned as aggresively... I have no experience w/ them and so I"m wondering what's the best way to lean a little continental? Like a O-230 (might not be the right number but it's a small NA one

 

[Let'sgoflying!]

If Jeanie will allow me to intervene, I might add that we fly out of airports with DA of 7500' in the summer.

 

[Jeanie]

Right, thanks Dave - I forget that some folks don't live up here in the rarified mountain air

 

[timwinters]

If you're flying at altitudes that don't allow over 65% power then you probably can't hurt it no matter how aggressively you lean it.

I'm also a firm believer that CHT's are a major player. My 182 cruises with CHT's in the 300 to 325dF range even in the summer. I don't think I could ever hurt it no matter how aggressively I lean it. OTOH, my 172 ran closer to 400dF CHT's in the summer and I didn't dare lean aggressively down low.

 

[Jeanie]

Well, I'm training a guy in an old C-150 and it doesn't have CHTs - heck it has a barely useful radio... but it does have a Continental engine

 

[Dan Thomas]

Get out the POH for that 150. Find the max power setting given for the DA you are flying in (which would be a full-throttle setting), and see if it gives anything more than 75% power. It likely doesn't, and you can lean that thing any way you like. I would lean it to get max RPM. I bet you have to cruise at full throttle when the DA is 7500, right? We used to run 150s at DAs of 3000+ and unless we ran them hard the airplanes didn't want to fly. Just mush.

Dan

 

[Tom-D]

Pull the mixture out until it runs a bit rough, push it in until it runs smooth. at any altitude, at any power setting.

You can't hurt the 0-200/0-300 or any other small Continental C or 0- series, at any power setting by running it as lean as it will run smooth.

And You can't hurt the 0-200/0-300 to run them full rich at any power setting or altitude either. the only risk being they will stick a valve quicker running rich.

My advice to all my 0-200/0-300 operators is to run it as lean as it will run chocks to chocks.

They love a mix of 3 parts of auto fuel, to 2 parts 100LL

 

[Tom-D]

Well, I'm training a guy in an old C-150 and it doesn't have CHTs - heck it has a barely useful radio... but it does have a Continental engine

Those are the good ones...... keepem light, flyem often.

 

[Tom-D]

Get out the POH for that 150. Dan

You'll find the advice given is what the POH says, and if you think about it, that's lean of peak.

 

[Let'sgoflying!]

It is difficult when there is no cht.
I still think it is possible to damage a cylinder.
My opinion:
The baffling could be inadequate or there could be other issues that might make running at max power, esp. while in a nose high attitude a bit risky. Say it is 100F out, they are fully loaded and they want to practice Vx. Would you all still say take it to peak?

 

[Tom-D]

It is difficult when there is no cht.
I still think it is possible to damage a cylinder.
My opinion:
The baffling could be inadequate or there could be other issues that might make running at max power, esp. while in a nose high attitude a bit risky. Say it is 100F out, they are fully loaded and they want to practice Vx. Would you all still say take it to peak?

Yes..

 

[Dan Thomas]

A typical EGT/CHT/ power graph like the one above usually shows EGT peaking somewhere past the best-power setting. This graph reads lean on the left, rich on the right, and best power is found in the gray stripe down the middle, which equates to highest RPM on a fixed-pitch prop. As we continue to lean the EGT and CHT will both continue to rise a bit, then fall off. Lean of peak is way over on the left edge of the graph in the "Best Econ" stripe, and POHs usually take their fuel consumption figures from that neighborhood. Some POHs will tell you this, some won't, but without such aggressive leaning you'll always burn more fuel than the POH says in its cruise charts.

An awful lot of Avgas is wasted these days. Some pilots never touch the mixture control except to shut the engine down. Even if they went to best power they'd be much better off; they'd keep the engine clean, get better performance, and save some money. Look at the fuel consumption line at the bottom.

Dan

 

[Tom-D]

A typical EGT/CHT/ power graph like the one above usually shows EGT peaking somewhere past the best-power setting. This graph reads lean on the left, rich on the right, and best power is found in the gray stripe down the middle, which equates to highest RPM on a fixed-pitch prop. As we continue to lean the EGT and CHT will both continue to rise a bit, then fall off. Lean of peak is way over on the left edge of the graph in the "Best Econ" stripe, and POHs usually take their fuel consumption figures from that neighborhood. Some POHs will tell you this, some won't, but without such aggressive leaning you'll always burn more fuel than the POH says in its cruise charts.

An awful lot of Avgas is wasted these days. Some pilots never touch the mixture control except to shut the engine down. Even if they went to best power they'd be much better off; they'd keep the engine clean, get better performance, and save some money. Look at the fuel consumption line at the bottom.

Dan

That proves you can't harm any engine by removing fuel, all you can do is remove power and temperature.

In a C-150 your VSI is your power meter. climb to altitude, level off set RPM, pull mixture until it stutters, push it until it runs smooth. trim to level flight, adjust the mixture to see if you can make the aircraft climb, if you can, trim to level flight again. If you pull it out, and it descends, push it in.

a little at a time.

 

[Jeanie]

Great Thanks. The plane simply didn't climb well Saturday and it was quite cool. I figured it's either the prop or the mixture wasn't at max power for take off.

So if we want to set it for max power for take off do we have to run it up to full throttle and lean it to best RPM?

The other thing is the owner is an A/P and works for CBP (border patrol on their helicopters - he's the Huey expert) so it's not like he doesn't understand engine things.

The guys on the ground noticed smoke coming from the plane when we applied full throttle for the go part of the touch and go.... I thought it might have something to do w/ being too rich.

I had asked him about leaning it till it's rough and then smoothing it out and he just isn't comfortable w/ that yet- he's a little tentative as a pilot that's why he's asked me to fly with him to help him regain his confidence.....

 

[Clark1961]

So if we want to set it for max power for take off do we have to run it up to full throttle and lean it to best RPM?

That's pretty much the standard procedure for high DA airport operations. If you aren't at a high DA and leaning is required for best power then some work needs to be done on the carb or engine.

 

[Tom-D]

Great Thanks. The plane simply didn't climb well Saturday and it was quite cool. I figured it's either the prop or the mixture wasn't at max power for take off.

So if we want to set it for max power for take off do we have to run it up to full throttle and lean it to best RPM?

YES !

The other thing is the owner is an A/P and works for CBP (border patrol on their helicopters - he's the Huey expert) so it's not like he doesn't understand engine things.

turbine mechs don't always understand all they know about recips.

The guys on the ground noticed smoke coming from the plane when we applied full throttle for the go part of the touch and go.... I thought it might have something to do w/ being too rich.
At a high DA you were probably way too rich.
I had asked him about leaning it till it's rough and then smoothing it out and he just isn't comfortable w/ that yet- he's a little tentative as a pilot that's why he's asked me to fly with him to help him regain his confidence.....

He's probably listening to too many Old Wives Tales about running lean of peak. Do as I suggested, and prove it too him, or he'll have a stuck valve in less than 500 hours.

It's a tough little engine, but it does not like lead, it was designed to run 80/87 Red, and running 100LL is way too much lead. the two biggest problems with the 0-200 is lead from running on 100LL and carb icing.

Lean, lean, lean or fix, fix, fix, take your choice

 

[Tom-D]

I had asked him about leaning it till it's rough and then smoothing it out and he just isn't comfortable w/ that yet- he's a little tentative as a pilot that's why he's asked me to fly with him to help him regain his confidence.....

ask your turbine mechanic, what happens in a turbine when you remove fuel, does it heat up? or cool down?

 

[brcase]

Great Thanks. The plane simply didn't climb well Saturday and it was quite cool. I figured it's either the prop or the mixture wasn't at max power for take off.

So if we want to set it for max power for take off do we have to run it up to full throttle and lean it to best RPM?

The other thing is the owner is an A/P and works for CBP (border patrol on their helicopters - he's the Huey expert) so it's not like he doesn't understand engine things.

The guys on the ground noticed smoke coming from the plane when we applied full throttle for the go part of the touch and go.... I thought it might have something to do w/ being too rich.

I had asked him about leaning it till it's rough and then smoothing it out and he just isn't comfortable w/ that yet- he's a little tentative as a pilot that's why he's asked me to fly with him to help him regain his confidence.....

With Black Smoke coming out of it and it not seeming like it is performing correctly I would be concerned that the primer is leaking (into the engine) or something else is causing it to run to rich.

Brian

 

[Jeanie]

With Black Smoke coming out of it and it not seeming like it is performing correctly I would be concerned that the primer is leaking (into the engine) or something else is causing it to run to rich.

Brian

~~~ I expect that he just had it set too rich with the mixture. Next time we fly we'll have a talk about it.

Thanks Everyone

 

[Fearless Tower]

OTOH, my 172 ran closer to 400dF CHT's in the summer and I didn't dare lean aggressively down low.

I'd recommend reading John Deakin's AvWeb ariticles on leaning - IIRC, the highest your CHTs will get is right about 50 deg ROP. Leaning will actually bring the temps down. Leaning too agresively may make the engine run rougher, but it will not increase the CHTs.

 

[poadeleted20]

I'm used to leaing a Lycoming and have been taught that at altitude you lean it slowly till it runs rough and then enrichen it w/ 2 turns back to smoothe.

Lycoming just says "enrich to smoothness" without specifying any number of "turns" -- just whatever it takes.

But I have heard the Continentals can't be leaned as aggresively... I have no experience w/ them and so I"m wondering what's the best way to lean a little continental? Like a O-230 (might not be the right number but it's a small NA one

Continental doesn't put out as detailed advice as Lycoming does on its web site, but my experience with normally aspirated smaller Continentals (like the O-200/240/300/470) says the same technique will do you just fine.

 

[poadeleted20]

It is difficult when there is no cht.
I still think it is possible to damage a cylinder.

At high DA's, there's no way you'll damage a cylinder in a normally aspirated engine with "lean to rough, enrich to smooth" in cruise unless there's something wrong with the engine or its cooling system (crappy baffles or the like). And unless your engine is quite exceptional, you'll be at or rich of peak on all cylinders with this technique -- I've checked this out with engine analyzers many times in many different planes over the years.

Likewise, if you use the "lean to peak RPM" for takeoff at 5000 DA or above, the engine should be perfectly fine.

 

[Steve]

An awful lot of Avgas is wasted these days. Some pilots never touch the mixture control except to shut the engine down. Even if they went to best power they'd be much better off; they'd keep the engine clean, get better performance, and save some money. Look at the fuel consumption line at the bottom.

Dan

I made a 135nm flight (each way) out and back on Saturday. Going out I flew at "best power" and coming back at "best economy". Noting the fuel flows and airspeeds the difference was ~$30 in fuel burn and 10 kts in cruise speed. This was on an IO-540.

 

[denverpilot]

Not to throw a wrench here, and generally I agree with the O-200 series with the "you can't hurt it" commentary...

But until you get above about 10000 DA in the O-470, you can still produce over 65% power and you're not down in the "lean it to whatever you want" range. Enriching to "smooth" my still put you square in the fabled "red box" of high cylinder pressures.

According to my perusal of our 1975 C-182P manual (it's not a POH), and studying the "red box" charts, you need to enrichen to 200-225 degrees rich of peak CHT or go to LOP (virtually impossible with the O-470s induction system but sometimes do-able by cocking the throttle plate by backing off slightly from WOT and using a Carb Heat temperature gauge to get an optimal temperature for fuel atomization with partial carb heat) to stay out of the "red box" doghouse.

All that hoo-hah above to set the stage for... I usually need 2 1/2 to 3 half turns in from CHT peak or engine roughness to get a 200 degree drop. The O-470 as installed on most Skylanes with limited cowl space and with GOOD baffles, needs a bit more help from fuel to cool off. In almost any climb up here at always high DA, or a hot day even in cruise, the cowl flaps may need to be open.

I was recently talking to Kent on the phone lamenting that it was hard to cool the beasts up here, and he reminded me that denser air down where he lives means he actually gets some cooling through the cowling on "his" 182, whereas up here, we struggle to shove enough air through to cool off the engine.

So something to keep in mind. The O-200 may not cook itself in a C-150/152, and the O-470 might in a C-182 up here. The engines would otherwise have the same leaning procedures and I would agree that "enrichen to smooth" generally works... But the bigger engine is cranking out more heat overall and may need a combination of faster climb speed (slower climb rate), say 100 MPH in the climb, keep the cowl flaps wide open, give her another twist in of the mixture knob, and watch those CHTs. They're still the limiting factor up here, even if the book says "lean to peak" is okay at 65% power.

If you don't have enough air removing heat on a hot day at 65% power, you're still abusing the cylinders above 400.

Same thing happens up here with turbofan engines... The limiting factor becomes temperature at high DA airports.

 

[Tom-D]

Not to throw a wrench here, and generally I agree with the O-200 series with the "you can't hurt it" commentary...

But until you get above about 10000 DA in the O-470, you can still produce over 65% power and you're not down in the "lean it to whatever you want" range. Enriching to "smooth" my still put you square in the fabled "red box" of high cylinder pressures.

According to my perusal of our 1975 C-182P manual (it's not a POH), and studying the "red box" charts, you need to enrichen to 200-225 degrees rich of peak CHT or go to LOP (virtually impossible with the O-470s induction system but sometimes do-able by cocking the throttle plate by backing off slightly from WOT and using a Carb Heat temperature gauge to get an optimal temperature for fuel atomization with partial carb heat) to stay out of the "red box" doghouse.

All that hoo-hah above to set the stage for... I usually need 2 1/2 to 3 half turns in from CHT peak or engine roughness to get a 200 degree drop. The O-470 as installed on most Skylanes with limited cowl space and with GOOD baffles, needs a bit more help from fuel to cool off. In almost any climb up here at always high DA, or a hot day even in cruise, the cowl flaps may need to be open.

I was recently talking to Kent on the phone lamenting that it was hard to cool the beasts up here, and he reminded me that denser air down where he lives means he actually gets some cooling through the cowling on "his" 182, whereas up here, we struggle to shove enough air through to cool off the engine.

So something to keep in mind. The O-200 may not cook itself in a C-150/152, and the O-470 might in a C-182 up here. The engines would otherwise have the same leaning procedures and I would agree that "enrichen to smooth" generally works... But the bigger engine is cranking out more heat overall and may need a combination of faster climb speed (slower climb rate), say 100 MPH in the climb, keep the cowl flaps wide open, give her another twist in of the mixture knob, and watch those CHTs. They're still the limiting factor up here, even if the book says "lean to peak" is okay at 65% power.

If you don't have enough air removing heat on a hot day at 65% power, you're still abusing the cylinders above 400.

Same thing happens up here with turbofan engines... The limiting factor becomes temperature at high DA airports.

When did the thread make the turn from 0-200/ C150 to 0-470/C182?

 

[Tom-D]

you'll be at or rich of peak on all cylinders with this technique -- I've checked this out with engine analyzers many times in many different planes over the years.

The Continental chart shown in this thread tells us you are wrong, it will be LOP and way down the back side, so far in fact that 1 or more cylinders are starving for fuel, causing the vibration you feel.


OBTW, that chart came from page 63 of the " Tips on Engine Care " put out by TCM.

 

[denverpilot]

When did the thread make the turn from 0-200/ C150 to 0-470/C182?

When Ron said the same technique would work on all normally aspirated Continentals and listed the O-470 is when my eyeballs bugged out of my head.

Please, by all means... No intent to thread jack away from the O-200. Just thought that Ron's statement was flat wrong for the engine I know the best out of his list, the O-470.

 

[Tom-D]

When Ron said the same technique would work on all normally aspirated Continentals and listed the O-470 is when my eyeballs bugged out of my head.

Please, by all means... No intent to thread jack away from the O-200. Just thought that Ron's statement was flat wrong for the engine I know the best out of his list, the O-470.

I didn't read that, but that'll do it.

 

[timwinters]

I'd recommend reading John Deakin's AvWeb ariticles on leaning - IIRC, the highest your CHTs will get is right about 50 deg ROP. Leaning will actually bring the temps down. Leaning too agresively may make the engine run rougher, but it will not increase the CHTs.

I have and I don't argue his position. However...

Leaning and running LOP with a fuel injected engine is completely different than doing so with a carbureted engine. This is especially true if the fuel injected engine has GAMIs.

Both my previous plane and present one have 6 cylinder continental engines. Both are carbureted. Both have engine monitors. One thing I can say is that with these two birds, unless I'm running full rich, there will be at least two cylinders in the "red box" and no matter what how I aggressively I lean there will be two cylinders in the "red box". This is because Continental's induction systems are so screwed up. I can never maintain an EGT spread of less than about 75 to 100dF. So, there's just no way to avoid the "red box" at lower altitudes except to throttle back and that just goes against my grain. You basically have 6 individual engines up front all doing their own thing.

I spent two full days a few years ago going through my 182s inductions system, replacing all the flexible connectors, clamps and fixing all the leaks. After this exercise my EGT spread was down to 20dF. But that only lasted for 2 to 3 months and then it was back to where it was before.

Life's too short...run the airplane. I worried about it when I had my 172...I don't now in my 182.

The other way to look at it is that by leaning aggressively I’m saving about 3 GPH. Over 1500 hours at $4 per gallon I’ve saved enough money to pay for replacing all six cylinders…twice

 

[poadeleted20]

When Ron said the same technique would work on all normally aspirated Continentals and listed the O-470 is when my eyeballs bugged out of my head.

Please, by all means... No intent to thread jack away from the O-200. Just thought that Ron's statement was flat wrong for the engine I know the best out of his list, the O-470.

Well, I've only got a couple of hundred hours flying the O-470, but that's how we leaned 'em, and the cylinders never cooked. And this was with an outfit which called for 24/2400 (instead of the book 26 inches) for climb power for Aztecs in order to "baby" the engines.

 

[Tom-D]

Leaning and running LOP with a fuel injected engine is completely different than doing so with a carbureted engine. This is especially true if the fuel injected engine has GAMIs.

GAMI's only calibrate the fuel flow to each cylinder so they will peak at the same temps, by allowing for the induction design. they do not change the method of leaning.

Fuel air ratios are fuel air ratios, change that any way you like, and you will get the same results. The problem with the carb systems, is the induction system will deliver uneven fuel supply to the cylinders, due to a single point supply, thus each cylinder will peak at different temps/fuel flow. this is why the leanest cylinder can be on the LOP side of the curve, and all others can be on the ROP side, and running at best power or richer. Thus when you try to get all cylinders in a carb system to place all cylinders on the LOP side you will have 1 maybe more cylinders in the lean misfire condition.

That is why many pilots believe the carb system can't be run LOP. Single point fuel injection systems exhibit the same symptoms, it's only the multi point systems that ca be calibrated to run properly at LOP.