To achieve 400HP out of an IO520-540 engine, you have to blow it to how many inches MP? About 45?
Peter wrote:
To achieve 400HP out of an IO520-540 engine, you have to blow it to how many inches MP? About 45?
Our old TIO-540-AE2A did 370hp on the test stand at 42 inches manifold pressure (it was rated 350hp). So probably just a bit more than 45.
Turbo-normalised IO-720? You’d still have cooling issues though. I don’t think the aircraft reciprocating piston engine can really be optimised much more than what we have at present.
Optimized for what? The world has already been there and done that with piston aircraft engines. Liquid cooling was largely rejected for commercially utilized, volume produced engines.
As an example Pratt & Whitney had no trouble making 2400 HP with air cooling in high volume production but was cooling limited when trying to get to 2800 HP. 125,000 of that individual model were produced.
Perhaps more on topic in terms of power output, the Vedeneyev M14 is a fairly compact air cooled, geared 400 HP piston engine, also produced in volume.
The reason US manufacturers largely stopped building high power piston engines is that they are mechanically complex devices. Below about 300 HP the number of cylinders can be limited to six, turbonormalizing kind of works if needed and a relatively simple air cooled, horizontally opposed engine with no upside down cylinders can be produced, reducing arcane operational and maintenance procedures. Adding liquid cooling for more power detracts from that situation and points one towards turbines, even while some would have us buying high powered, liquid cooled diesels with lots of complexity instead of small turbines. I’m involved in some of that for a niche non-commercial market but the commercial market doesn’t seem to agree.
So what problem exactly are we trying to solve here?
-Low reliability of TSIOL 550 ?
We know the culprit: the cooling system. The main issue is the low volume.
-Do we need it to be water cooled? Not in principle, but due to certification issues, changing for air-cooled may be a sizeable if achievable challenge. Questionable effort due to very low volume. Since you are talking experimental, why not simply go air-cooled, change the cowl design and get rid of the issue?
-Now if we go air-cooled what is the issue with both Lyco and Continental 350hp+ engines?
Low end reliability? Mostly on Lycos, especially when not used frequently. A touring aircraft, by its nature, is going to be used intermittently so this is going to be an issue. On the Conti’s this is mostly resolved with the lower camshaft and good access to lifters.
High-end reliability? THis is an issue with both: you can be lucky if cylinders run 800hrs on regular high-power, high-altitude cruise. Borescope inspections, in-situ valve lapping (aka rope- trick) and some other tricks somewhat extend cylinder life but unless you replace cylinders proactively twice during each overhaul run, the current design, build quality and number of cyls per engine (count=6) will result in frequent cylinder work: a fact of high-power, high-altitude life.
So I am with those who think the wheel has already been invented.
Most of these problems would be much easier to solve with higher volumes, so that is the issue we should solve (volumes) . Rather than introducing yet another engine in low numbers, try to increase the numbers of the existing ones and address the known issues, like quality of valve-seat interface on new cylinders.
PS: some quality engine shops redo valve seat and guides before installing new cylinders to increase reliability…(I seem to recall Barrett did it, @Peter would know)
We know the culprit: the cooling system. The main issue is the low volume.
Cooling systems have always given trouble. All the way back to the Vauxhall Viva, which used to line the motorway grass verges, with steam coming out from under the bonnet 
The only time my Toyota Celica failed, in 15 years, was a loss of coolant.
Thielert had huge problems with their cooling system. They did a big misinformation campaign, saying it was due to wrong engine installation by Diamond, and the DA40 was OK, but only the DA42 was affected.
Very little seems to change. I think in this case the way to fix it is to re-do it, much more substantially.
Peter wrote:
To achieve 400HP out of an IO520-540 engine, you have to blow it to how many inches MP? About 45?
The IGSO 540A1E is rated with 390hp, non turbo, supercharger. Was used in the Dornier Do28-D2.
i extrapolated the charts from the TSIOL 550 A and C variants.
Combinjng the max rpm of the former (2700) with 42 inches would yield 380 HP.
Guessing: 400 HP would require 44 inches.
But the overboost pop-off valve is set at 42.5, probably for a reason…
I hear all of the “go turbine” points, but this is not the point here – really the question is how to make 400 HP + from a 9-liter piston turbo engine. We all know that piston engine hit a wall around 2000 HP , bug we’re talking less than 25% of this.
Replacing cylinders at 600 hours is ok: no worse than the present reality in the TSIOL550 world. Also, keep in mind the 450 HP would be only available for 5 minutes.
I am wondering what the answer of a race engine shop would be if one brought them a TSIOL 550 and said:
“make me a 450 HP engine that is a dimensional clone of this and here’s a blank check ?”
What would advanced metallurgy and machining, EFIS, water cooled turbos, bringbto the party?
..
Flyingfish wrote:
race engine shop would be if one brought them a TSIOL 550
In the past somebody here posted about a TIO-540-AE2A from a Piper Mirage which had been modified for air racing. I remember it was supposed to make 700hp, so twice stock power at an insame manifold pressure.
Looking at cars making much power on a turbo engine is not so difficult. For aircraft it is even easier. Aircraft turbos seem to be oversized at sea level compared to cars in order to cope with thin air at altitude. This is not exact math but the Piper Mirage did full rated power beyond 18000ft where air density is about half that of sea level. So I assume with the wategate fully closed it would make twice rated power on stock turbochargers. From there you can add nitro injection, bigger turbos, intercooler water cooling, higher compression, maybe even use higher octane fuel and probably get well over thousand horsepower from the 540 engine.
But the question is how long that will last. You trade peak power against service life. The real difficulty is not making huge power numbers but to make a reliable engine produce such power all day long. Building an engine for a drag strip is one thing, doing so for 24h at Le Mans another…
I once spoke with a car engineer. He wanted more power for his new car design but was in a constant fight with the warranty department as they calculated every bit of additional torque would make warranty claims on the gear boxes go up on a statistical level and be too expensive in the long run. Now tuning companies can easily extract that torque he had to leave on the table as they do not have to care about paying for gear boxes…
