Fuel Economy Continental TSIO 360F

[Romydog]

I fly PA 28 201T - Turbo Arrow, I average about 11.5 - 12 gals hr, on seeting 2400RPM and 27" manifold - at 55% power its still off 9.5 -10 GPH that the book states (I'm usually around 2,500 -3,000ft).

Anyone has experience on this engine or plane to coax better economy - the engine has only 400 hrs since full overhaul

[bookworm]

So how do you lean it?

[Final 3 Greens]

ROMYDOG

Only flown the odd hour on the turbo Arrow, so not up to speed on what economy to expect.

But just a dumb question, is it definitely an engine related issue?

i.e. could there be an airframe cause - e.g. less than optimum rigging?

Just a thought.

[IO540]

What's the engine instrumentation, and when/how has it been calibrated?

Analog fuel flowmeters are usually pretty useless; a 10-20% error is normal. Mine is between 10% and 50% out, but is the official approved instrument :yuk: I have a Shadin also which is known accurate to about 1%.

You mention 55% power - how is this determined? Only in the LOP region is power reasonably proportional to flow rate. Ultimately, the power will appear as IAS but you don't mention the IAS, and also your speedo might be out. They are rarely checked; the altimeter/static check does not cover the ASI and most don't get checked.

I would start by calibrating the speedo, using the three-heading method, which can be found here (http://williams.best.vwh.net/avform.htm). In light wind, say below 10kt, the formula reduces to the TAS being simply the average of the three GPS speeds. Then you work TAS back to IAS (CAS actually) in the usual way.

If you don't have a decent flowmeter then you are a bit stuffed; you need to calibrate one point on the flowmeter (the cruise flow, perhaps) by doing two flights, both identical in climb/descent but with say 1hr difference in the duration of the enroute section. Start each with a full tank. The difference between the two tank fills will give you the actual fuel usage at that indicated flow rate.

Rigging would probably not make a vast difference, but loading (total, and also the CofG affecting the elevator drag) and having the ball in the middle all help, or not. I find I get another 1-2kt by running down the left tank a bit extra, to compensate for my weight, when flying alone. But if you are say 20% out, or think you are, look elsewhere.

[Romydog]

I lean the mixture to say 350f on cyl temp and about 100/150 degress rich of peak EGT - leaning further induces rough running

[High Wing Drifter]

I would be able to lean to about 10gph with 30" and 2200rpm. Its been a couple of years and I don't have a POH, just the school's approved checklist which says this is 75% (28RT-201T).

[bookworm]

I lean the mixture to say 350f on cyl temp and about 100/150 degress rich of peak EGT - leaning further induces rough running

If you can't lean more than 100-150 degF rich without rough running then you need an engine analyzer and GAMIjectors. Any engine should be capable of running at peak EGT without rough running

[dirkdj]

What Bookworm said is correct, but something must be wrong with your engine if you can't lean more than 100F ROP before roughness.
I would guess dirty fuel injectors or an air induction leak. Check the rubber couplings on the induction tubing.

I have flown a Mooney 231 with a similar engine to yours and after some work, gamijectors and JPI, it would run very nicely smoothly down to 90F LOP. That was somewhere in the 8-9 GPH range.

[bookworm]

What Bookworm said is correct, but something must be wrong with your engine if you can't lean more than 100F ROP before roughness.

Yes, I didn't mean to imply that an engine performing in that way is acceptable. But I do get the impression that problems with balance are much more prevalent in Continentals than Lycomings -- hence the opportunity for GAMIjectors to solve a common problem. Our Lycoming IO-320s with factory injectors run quite smoothly leaned to peak or slightly beyond at cruise power.

[dirkdj]

Bookworm,

At very rich settings the power curve is so flat that the factory standard TCM engine should run smoothly. Some TCM engines have built-in Fuel/Air distribution differences, usually fornt/rear cylinders but these are masked out at rich settings.

if the induction air ducts have leaks, it would be noticeable at idle first. If idle is OK, then I would start with cleaning the injectors. There is something wrong in that engine that must be fixed.

Having an all-cylinder engine analyser such as a JPI EDM-700 would greatly facilitate troubleshooting and proper operation afterwards and pay for itself in a couple hundred hours.

I don't know if this airplane is private or group/club owned and who makes the maintenance decisions.

Dirk