IO540 versus IO520 ?

[FullyFlapped]

Not, I hasten to add, anything to do with the contributor of the same name !

I appreciate there might not be a lot of response to this one, but would any engineering types or owners care to give their views on the relative merits of the turbo versions of each of the above ? Particularly in terms of reliability, ease of maintenance (and therefore costs), quirks, gut feels etc etc.

I'm presuming that the relative power ourputs of each are roughly the same - is this correct ?

Thanks,
FF :ok:

[dirkdj]

I have flown behind IO540K, IO520BB, IO550B and TIO541E4A5.
Continentals are much smoother than LYC in my opinion.
The IO550B combined with the TAT turbonormalizer is about the best piston/turbo combo you can get. TCMs can be made to run nicely LOP, running same HP on less fuel.

[javelin]

Now, I believe we are trying to compare apples with pears here because you seem to be comparing the Lycoming IO-540 to the Continental IO-520 ?

The Lycoming is a more robust unit, not as susceptable to crancase cracks as the Continental.

Any turbo'd piston in this capacity has to be treated with respect - no rapid power changes, careful cooldown - basically climb, cruise, descent.

Also, unless you are wanting to go above FL100, why bother ?

If you are in a 210 or Saratoga, both will get along quite nicely without the extra addition of a turbo.

You seem to have been asking similar questions for some time now, I thought you were already sorted with a 210 ?

Jav

[FullyFlapped]

Javelin,
You seem to have been asking similar questions for some time now, I thought you were already sorted with a 210 ?

You got me wondering whether I was losing my marbles, so I just checked. I've never asked this - or similar - question before.

Also, why is this "comparing apples and pears" ? They are both big 6's which put out the same amount of grunt, aren't they ?

Thanks for your interest, but I have my reasons for asking ...

FF :ok:

[camlobe]

Hello FF.
From an engineering point of view:
The (L)TIO 540 series are considered pretty bullet-proof. If handled properly (read sympathically) they will reach TBO without major problems. However, the camshafts and followers are known to fail well before TBO. Initial signs are an apparant drop in performance sometimes masked by the turbo. Later signs are lumpyness, especially at slow running. The ancillaries also tend to be fairly robust, although starters don't last as long as one would like. The dual mags MUST be serviced every 500 hours by a reputable shop. W100 oil works fine. These engines don't appreciate long periods of inactivity. These engines run smoothly when properly maintained and flown. Always lean the mixture during ground operations to prevent plug fouling - they will foul up supprisingly quickly. If the engine(s) arn't running smoothly and you can't clear it, there are big bills ahead. Like all Bendix fuel injected Lycomings, you must learn the 'knack' of starting them warm. There is the situation now where Lycoming have insisted on crankshaft retirement for many of these engines at TBO.

The TSIO 520 series (GTSIO included) engines are renowned for their smoothness. They are, however, considered less tolerant of mishandling by hamfisted pilots. The continous fuel flow system employed is far more user friendly than the Bendix system. One doesn't hear of warm or hot starting problems with these engines. However, like the Lycomings, lean when on the ground. ANY rough running on those engines employing a starter drive adaptor MUST be inspected prior to flight. TCM SB 94-4 latest issue refers. I cannot overstate that your life may depend on it. The cylinders on the 520's tend to be more prone to cracking than on the 540's. The alternators are gear driven on the 520's, so no problems with belt wear or failure. The TCM range of engines do not suffer the premature camshaft and follower wear problems encountered elsewhere. Crankcase cracking isn't unheard of, but I have come across this on the 540's as well. Ancillaries tend to last the distance. W100 works well. Exhaust systems can be expensive to replace IAW FAA AD 200-01-16. However, RAM supply excellent exhaust parts at a good price. RAM's slip joints are far superior to TCM's and are highly recommended. RAM also offer upgrades to these engines. No problems reported, and well worth the money. You also get pretty little stickers to put on your cowlings.

Both engines have well deserved reputations for producing the goods. They cost similar amounts to overhaul. There can be, depending on model, considerable differences in TBO life, which will translate into quite varied total running costs. Each has known 'problem' areas, and both can be maintained by a reputable maintainence facility with experience of these larger GA engines. Neither can be neglected. Depending on model, power outputs are approximately 300 to 400 HP. GAMI-jectors are highly recommended for both types, giving more balanced T's and P's as well as getting the most out of your fuel.

From a pilots perspective:
The 540 feels more powerful, the 520 feels smoother. The 540 will keep running even when it is not right. Often, the first you will know when something is wrong is when you are back on the ground The 520 will tell you right away when it is not right, but will keep going. Both engines can be cruise run 50 degrees lean of peak, thereby preventing detonation while getting the most out of your fuel. There are those who consider the 540 more tolerant of lean running, while others consider the 520 far more economic.

Hope the above is of help. PM me if you wish to discuss further.

camlobe

[Pilot DAR]

I agree with all of camlobe's comments. I will add though, that with lots of time in both normal and turbo 540's in C182 RG, I am very uneasy about the single point failure opportunity that the version of 540 in those aircraft suffered. The dual magneto unit is driven by only one drive gear, and I have seen those gears with two consecutive teeth missing. Fail the gear, fail the engine. I have no idea how this met the certification design requirement fo independant ignition systems!

520's require practiced starting technique, sometimes differing between aircraft.

Turbo 520 prone to easy overboost if you're not very careful with the throttle on the first flight of the day. You can hurt it before you realize what you've done...

Pilot DAR

[IO540]

I don't know enough to add anything to the above, except:

Continentals are much smoother than LYC in my opinion

This is probably because of Lyco's dreadful QA and attitudes to dynamic balancing. If you want a smooth engine, you get the crank dynamically balanced, the conrods weight-matched to under 1 gram (each end is weighed separately), the pistons etc likewise.

There is nothing about the design of an IO540 that makes it inherently rough, IMHO.

The IO540 doesn't like standing around for months; the cams (which are lubed purely by splashing) dry up and then get damaged. At SB569 (the mandatory crankshaft change) engine shops report 80% of the camshafts are trashed. However that could be simply that 80% of GA pilots rarely fly. I do regular oil analysis and see very little metal, but then I fly at least once a week, and almost never less than 1 hour.

On new engines, Lyco are offering roller cam followers, which should make a big difference to the notorious camshaft issue.

[Islander2]

There is nothing about the design of an IO540 that makes it inherently rough, IMHO.How about the appalling design of induction system, that guarantees mixture imbalance and ensures that it operates as six separate engines? It is generally acknowledged that the Continental IO520/IO550s, whilst still leaving a lot to be desired in this respect, are significantly better. It's why, for a long time, GAMI injectors were only able to get the Continental engines to operate LOP with any degree of certainty.

[IO540]

It's why, for a long time, GAMI injectors were only able to get the Continental engines to operate LOP with any degree of certainty.

Is that so?

My IO540 would run LOP from the start, and with the matched injector set from GAMI it runs a bit smoother.

The engine design has not changed at all since at least 1978, looking at the page dates in my engine overhaul manual. The basic design is 1960s.