Forgot to enrichen

Henning said:
Look at the above charts knowing that Rated Power is determined at a mixture far richer than any shown on that graph, and back your claim; because the graph above says otherwise.
Click to expand...

Tell me the difference between rated power and max power?
 
Tom-D said:
Tell me the difference between rated power and max power?
Click to expand...

Max Rated power is what the declared output is under the manufacturer specified conditions. These conditions IIRC are Sea Level, Full Rich, ISO standard atmosphere. Maximum power is whatever you can get out of it in the current moment. That will always be greater when not "full rich" which is what is called for for take off power.
 
Last edited:
Henning said:
That will always be greater when not "full rich" which is what is called for for take off power.
Click to expand...

That is not true. Many Fuel injected engines are self regulating, they will auto compensate. and never be at full fuel flow. But when the DA is right they will be.
 
Tom-D said:
That is not true. Many Fuel injected engines are self regulating, they will auto compensate. and never be at full fuel flow. But when the DA is right they will be.
Click to expand...

Still richer than maximum available power, still richer than 250° ROP. Besides, self regulating still means "full rich" to the pilot. That is what the instructions are.
 
Last edited:
Engine rated power is set during the certification process by the manufacture, and declared on the TCDS.
That is all it is.

Maximum power is the power developed at the DA at the time when the throttle is wide open.

A good example of rated power is the old Franklin 150/165 horse engine. They are exactly the same engine, one is rated at a higher RPM than the other.

The other can be shown when you try to get rated power at altitude. It can't be done.

BMEP, "Break Mean Effective Pressure", is the actual pressure placed on the piston head during the combustion event.

ICPs "Internal Cylinder Pressure", is the actual PSI during the cycle.

Detonation, is the untimed spontaneous burning of fuel/air in the cylinder during the combustion event.

Detonation actually reduces the BMEP, By the untimed occurrence of ignition causing the temps to cool early. thus reducing the ICP.

So fuel mixture has nothing to do with Detonation.
 
Tom-D said:
Engine rated power is set during the certification process by the manufacture, and declared on the TCDS.
That is all it is.

Maximum power is the power developed at the DA at the time when the throttle is wide open.

A good example of rated power is the old Franklin 150/165 horse engine. They are exactly the same engine, one is rated at a higher RPM than the other.

The other can be shown when you try to get rated power at altitude. It can't be done.

BMEP, "Break Mean Effective Pressure", is the actual pressure placed on the piston head during the combustion event.

ICPs "Internal Cylinder Pressure", is the actual PSI during the cycle.

Detonation, is the untimed spontaneous burning of fuel/air in the cylinder during the combustion event.

Detonation actually reduces the BMEP, By the untimed occurrence of ignition causing the temps to cool early. thus reducing the ICP.

So fuel mixture has nothing to do with Detonation.
Click to expand...


All the performance and power charts are predicated on that horsepower output.

I thought Pre Ignition was the spontaneous untimed burning of the fuel in the cylinder?
 
Tom-D said:
Engine rated power is set during the certification process by the manufacture, and declared on the TCDS.
That is all it is.

Maximum power is the power developed at the DA at the time when the throttle is wide open.

A good example of rated power is the old Franklin 150/165 horse engine. They are exactly the same engine, one is rated at a higher RPM than the other.

The other can be shown when you try to get rated power at altitude. It can't be done.

BMEP, "Break Mean Effective Pressure", is the actual pressure placed on the piston head during the combustion event.

ICPs "Internal Cylinder Pressure", is the actual PSI during the cycle.

Detonation, is the untimed spontaneous burning of fuel/air in the cylinder during the combustion event.

Detonation actually reduces the BMEP, By the untimed occurrence of ignition causing the temps to cool early. thus reducing the ICP.

So fuel mixture has nothing to do with Detonation.
Click to expand...

Uhh, no. Brake mean effective pressure is a theoretical value.

http://www.epi-eng.com/piston_engine_technology/bmep_performance_yardstick.htm
 
If you could take off with your lean mixture - then its not lean enough. The engine will run at idle with the mixture almost all the way out - which is where you need to have the mixture if you are ground leaning.

You set the idle throttle you want - and then you lean until the RPM goes up then take it a little more til it stumbles - add some back in and leave it there.

If you try to add any throttle to that mixture you go way LOP and the motor will stumble - which is your reminder you did not do the checklist.
 
comanchepilot said:
You set the idle throttle you want - and then you lean until the RPM goes up then take it a little more til it stumbles - add some back in and leave it there.
Click to expand...

That's how a lot of Cirrus pilots do it.

And then for future use just make a note of where the lever is in relation to the "M•I•X•T•U•R•E" placard and just park it there in the future.
 
So, did I miss something? You lean for taxi, but don't you return to full rich for the before-takeoff-runup? For the short time after that, why would you re-lean? I Lean for taxi but leave it at full rich after the checklist calls for it prior to run-up..
 
Henning said:
All the performance and power charts are predicated on that horsepower output.

I thought Pre Ignition was the spontaneous untimed burning of the fuel in the cylinder?
Click to expand...

Pre-ignition is an untimed combustion event, but the cause is different than detonation.
 
comanchepilot said:
If you could take off with your lean mixture - then its not lean enough. The engine will run at idle with the mixture almost all the way out - which is where you need to have the mixture if you are ground leaning.
Click to expand...

to be effective, the mixture valve in the carb, must be adjusted to an orifice smaller than the idle metering jet.

Let's realize that the idle metering jet is a set size, and the mixture in the idle circuit is adjusted by changing the air bleed in that circuit. not the fuel flow.

To check the idle mixture, simply close the throttle, wait 3 minutes at full rich, then pull the mixture to full lean, as the engine stops the RPM should rise 10-50 RPM.

This is based upon the MA3-SPA carb not any other.
 
Tom-D said:
Pre-ignition is an untimed combustion event, but the cause is different than detonation.
Click to expand...

From what I was taught from early on is that knock/ping/rattle you may get on acceleration is Detonantion. If it is not, then the term does not apply.

That effect is not an untimed combustion event, it is a mistimed combustion event given the combustion properties of the fuel.

That knock/ping/rattle, whatever you want to call it is an event initiated by the spark plug. The fuel mixture is at such a state that it is in a very high energy, fast traveling pressure wave, state.

The highest point of pressure in the cylinder comes at the time when the expanding max pressure wave has reflected back to center and meets at the piston. When that event occurs before the piston has reached top dead center, the pressure wave it meets is great enough that in effect it is similar to hitting a hydraulic lock, and that is what breaks the piston tops.

I was always taught that to be what Detonation refers to.

Two ways to deal with it, richen up the mixture to slow down the pressure front, or retard the time so the pressure front hits around 3° ATDC for optimal effect.
 
Last edited:
Henning said:
From what I was taught from early on is that knock/ping/rattle you may get on acceleration is Detonantion. If it is not, then the term does not apply.

That effect is not an untimed combustion event, it is a mistimed combustion event given the combustion properties of the fuel.

That knock/ping/rattle, whatever you want to call it is an event initiated by the spark plug. The fuel mixture is at such a state that it is in a very high energy, fast traveling pressure wave, state.

The highest point of pressure in the cylinder comes at the time when the expanding max pressure wave has reflected back to center and meets at the piston. When that event occurs before the piston has reached top dead center, the pressure wave it meets is great enough that in effect it is similar to hitting a hydraulic lock, and that is what breaks the piston tops.

I was always taught that to be what Detonation refers to.

Two ways to deal with it, richen up the mixture to slow down the pressure front, or retard the time so the pressure front hits around 3° ATDC for optimal effect.
Click to expand...

:mad2::mad2::mad2::mad2:

Your car is not an aircraft engine, you will never hear detonation in the engines we use in aviation.

When you hear the detonation knock in your car, it is simply running way over square. IOWs the load prevents the piston from going down the cylinder fast enough to relieve the pressure after the spark plug fires the fuel air mixture. That is what happens when you run your aircraft engine at 28"hq and 1800 RPM.

Detonation in aircraft most often happens with misfueling. Remember the AD on the mis fueling in CA.? the fuel company bought a bunch of new engines? all of which had signs of Detonation damaged pistons, fretting cases stretched, case thru bolts. all that stuff, all by less that 5% diesel in 100LL.
 
Last edited:
Getting back to the OP's question.

You did not harm your engine by running it at a setting leaner than full rich for take off. When it runs and make full power you are rich enough.

If you had leaned enough to do any good on the ground, the engine would have quit when you opened the throttle.

So, learn from that and lean more. Your normal procedure is not helping your engine on the ground. pull it until it almost quits.
 
Tom-D said:
Getting back to the OP's question.

You did not harm your engine by running it at a setting leaner than full rich for take off. When it runs and make full power you are rich enough.

If you had leaned enough to do any good on the ground, the engine would have quit when you opened the throttle.

So, learn from that and lean more. Your normal procedure is not helping your engine on the ground. pull it until it almost quits.
Click to expand...

Not so sure this advice is sound. If I leaned for best power on takeoff in my plane my CHT's would be through the roof before I got to TPA.
 
There is no single way to manage your engine, you can use various methods and achieve the desired results. The POH method assures you the ability to produce that result with the minimum knowledge, thought, or operating data.

With more knowledge and engine operating data, you can achieve the desired result of operating the engine in non destructive parameters using different input values.

As long as your CHTs stay below 370°, I don't think there is anything you can do with a control lever that will cause damage. Some things may send the CHT climbing, and that you have to deal with. Above 420° you're getting into an area where you are prone to being able to do quick engine damage with an incorrect mixture setting. Above 475° and we start running into serious metallurgical issues as well.

It's really a shame the TSIOL Continentals didn't work out. Water jacket cooling really does solve a more problems than it causes. The ***** for GA is always the weight.
 
Geico266 said:
Make sure when you move the throttle forward to hit the mixture forward also. Only use full rich on take off, or go around.
Click to expand...

I do this technique and a little self check by sticking out my fingers towards the mixture. If I hit it the mix knob before full throttle I know it's leaned and push it in too. Some planes are separated enough that's not an option though...
 
That's a nice thing about quadrant controls, you put your hand behind it all and go forward.
 
Tom-D said:
Getting back to the OP's question.

You did not harm your engine by running it at a setting leaner than full rich for take off. When it runs and make full power you are rich enough.

If you had leaned enough to do any good on the ground, the engine would have quit when you opened the throttle.

So, learn from that and lean more. Your normal procedure is not helping your engine on the ground. pull it until it almost quits.
Click to expand...



Tom, I respect your mechanical knowledge and was wondering, when you start up on a colder day, or any day, wouldn't pulling carb heat right after leaning help warm up the engine and oil quicker? And you could lean even more maybe ...

Granted, you'd have to be careful, you wouldn't want to do it on dirt or anything but clean pavement with clean air.

Immediate warmer air coming into the induction and chambers should heat the engine up from within quicker I would think. But could it be too much of a shock to the system in some way? :redface::dunno:
 
I have found on really cold days with my Archer the engine can run rough immediately after startup or may not even stay running. Giving it carb heat while running through the checklist and taxiing out smooths it out.

My test is as soon as I get an RPM drop instead of an increase when applying carb heat, it's ready. This usually happens by the time I've taxied out and am ready to start my runup.
 
James_Dean said:
Not so sure this advice is sound. If I leaned for best power on takeoff in my plane my CHT's would be through the roof before I got to TPA.
Click to expand...

Some are like that,, Know your aircraft.
 
txflyer said:
Tom, I respect your mechanical knowledge and was wondering, when you start up on a colder day, or any day, wouldn't pulling carb heat right after leaning help warm up the engine and oil quicker? And you could lean even more maybe ...

Granted, you'd have to be careful, you wouldn't want to do it on dirt or anything but clean pavement with clean air.

Immediate warmer air coming into the induction and chambers should heat the engine up from within quicker I would think. But could it be too much of a shock to the system in some way? :redface::dunno:
Click to expand...
Pre-Heating will do a better job quicker. adding hot air will to some extent help. but leaves us in a situation of leaving the hot air on for take off.

In extreme low temps we operate all the time with hot air on.
 
Got it. Thanks

Carb heat on and let her warm up.

Just don't forget it ...:nono:
 
You must log in or register to reply here.
Back
Top