How Good are Modern Auto Engines?

[the_other_dougreeves]

The 24hr of LeMans was this weekend. That's a good torture test for engines - lots of WOT running, changing ambient conditions, engine is packaged in narrow bodywork, not in an open air dyno. Much like putting one in an airplane. These engines still fail, sometimes spectacularly. Puegot clearly had the fastest car this year, but it didn't win. Why? Undersized radiators for one - they spent time in the pit box, cleaning the radiators out. Audi went with a slower but more robust car and won (again). Note that Diesels have won LeMans 3 years in a row now.

If GM can make 5 engines run perfectly on a dyno, well, good for them. I don't care how well it runs in a dyno or a test cell. I want to see it put in service, where the cooling isn't installed perfectly, or some manufacturing flaw isn't detected (do you really think they randomly picked 5 engines off the assembly line and tested those five without any inspection or rework?), where someone uses bad gas that's too low in octane .... you get the idea.

Modern auto engines are good. Ross has mentioned the GM Vortec 4200, someone else the WV/Audi 1.8l and 2.0l turbos ... all good engines. Are they more reliable than Lyclones when installed in aircraft? Dunno, I haven't seen any data that suggests that they are or aren't.

Anyway, yes, the engine may be great, but it's the system that needs to work. This is where the Lycosarus shines - it's simple with respect to its systems. No PSRU. No EI. No water cooling system. No timing advance. No variable valve timing. The engine is most of the system.

Once someone makes an engine and system that works and is shown to be equally or more reliable, it will sell. How many units it sells is a question of how reliable and expensive the system is. If it doesn't work - or worse, it quits working - it doesn't matter howmuch better it should be. Just ask Puegot.

TODR

[rv6ejguy]

4 million test miles before release of product plus they put the engine in an off road race truck and won numerous events then they do the Death Valley trailer towing validation then the cold weather tests and cold weather chamber tests I've described elsewhere previously. That's the real world testing part to add to the dyno validation. Tested well indeed- far exceeding the scope of certified aircraft engine testing.

Dyno testing is always a first step in engine development. No sense in putting an engine in a vehicle if the engine does not last on the dyno first.

All the other parts you mention except the PSRU (not GM developed unfortunately) have been proven, tested and validated along with the engine in the most extreme environments engineers can throw at them.

We're awaiting more news on a new PSRU being developed in the NW for 250+ hp engines. It will be properly designed and testing using modern methods.

[Andy_RR]

Originally Posted by the_other_dougreeves

... or some manufacturing flaw isn't detected (do you really think they randomly picked 5 engines off the assembly line and tested those five without any inspection or rework?), where someone uses bad gas that's too low in octane .... you get the idea.

Of the 800 test engines that Ross quotes earlier, the vast majority are there only to test production processes. They are known as 'off-tool, off process' engines or 'production validation' engines. Most of the effort goes into making sure that the engines that come off the end of the production line will meet the required durability specs - they are not selected or hand-fettled at all.

Some of these tests include 200-odd hours at full power and others are shock cooling tests where the engine is run to max temperature and then flooded with sub-zero coolant before returning to max power again. It makes the 'shock-cooling' that pilots rave about seem comical! In any case the engines must be fully functional and meet specifications at the end of the test. i.e. it they don't just stagger to the finishing line.

The manufacturing and materials technology that is in modern automotive engines is stuff that current piston aero engine manufacturers don't even dream about!

Oh, and active knock control notwithstanding, 'bad gas' (excuse me!) is tested too - I know one major manufacturer tests its ignition calibration by offsetting the timing well past the knock limit and attempting to run for extended periods of time - 10s of minutes without failure - I can't remember the test specification exactly now.

[captainron]

Originally Posted by rv6ejguy

4 million test miles before release of product plus they put the engine in an off road race truck and won numerous events then they do the Death Valley trailer towing validation then the cold weather tests and cold weather chamber tests I've described elsewhere previously. That's the real world testing part to add to the dyno validation. Tested well indeed- far exceeding the scope of certified aircraft engine testing.

Here's a "real world" test that probably wasn't included:

1. Run the engine for an hour and shut it down.
2. Let it sit in the vehicle outside for 8 months.
3. Come back and maybe clean some of the bird's nest out of it. (or not)
4. Throw some jumpers across the battery and fire it up.
5. If it starts and sounds "OK", add a couple gallons of fresh gas to revitalize
the old stuff, then go to full power for awhile with maybe a couple of
engine cuts thrown in to refresh the operator's "skills".
6. Shut it down and go home, while making a mental note to maybe change
the oil "next time".
7. Grumble to friends and colleagues that someone should build a "better,
cheaper, higher tech" engine than that old fashioned stuff.
8. Wait a few more months, and repeat.
9. Keep this test going for 20-25 years.
10. Complain bitterly that the engine had to be topped or repaired at only 1200 hours.

[glenn654]

What is PSRU?.....I need an acronym dictionary.

Glenn Wilkinson

[captainron]

Originally Posted by glenn654

What is PSRU?.....I need an acronym dictionary.

Glenn Wilkinson

According to the "AIA" (acronyms-in-aviation) handbook, PSRU stands for Propeller Speed Reduction Unit.

[rtry9a]

Originally Posted by the_other_dougreeves

The 24hr of LeMans was this weekend. That's a good torture test for engines - lots of WOT running, changing ambient conditions, engine is packaged in narrow bodywork, not in an open air dyno. Much like putting one in an airplane. These engines still fail, sometimes spectacularly. Puegot clearly had the fastest car this year, but it didn't win. Why? Undersized radiators for one - they spent time in the pit box, cleaning the radiators out. Audi went with a slower but more robust car and won (again). Note that Diesels have won LeMans 3 years in a row now.

If GM can make 5 engines run perfectly on a dyno, well, good for them. I don't care how well it runs in a dyno or a test cell. I want to see it put in service, where the cooling isn't installed perfectly, or some manufacturing flaw isn't detected (do you really think they randomly picked 5 engines off the assembly line and tested those five without any inspection or rework?), where someone uses bad gas that's too low in octane .... you get the idea.

Modern auto engines are good. Ross has mentioned the GM Vortec 4200, someone else the WV/Audi 1.8l and 2.0l turbos ... all good engines. Are they more reliable than Lyclones when installed in aircraft? Dunno, I haven't seen any data that suggests that they are or aren't.

Anyway, yes, the engine may be great, but it's the system that needs to work. This is where the Lycosarus shines - it's simple with respect to its systems. No PSRU. No EI. No water cooling system. No timing advance. No variable valve timing. The engine is most of the system.

Once someone makes an engine and system that works and is shown to be equally or more reliable, it will sell. How many units it sells is a question of how reliable and expensive the system is. If it doesn't work - or worse, it quits working - it doesn't matter howmuch better it should be. Just ask Puegot.

TODR

Be careful with assumptions regarding race results- you need to dig into the rules about what are allowed and what are not.

From Wiki encyclopedia
"The Sigma MC74 powered by a Mazda 12A engine was the first engine and team from outside Western Europe
or the US to finish the entire 24 hours of the 24 Hours of Le Mans, in 1974. Mazda is the only team from outside Western Europe or the United States to have won Le Mans outright and the only non-piston engine ever to win Le Mans, which the company accomplished in 1991 with their four-rotor (2,622 cc/160 cu in- actual displacement, rated by FIA formula at 4,708 cc/287 cu in). The following year, a planned rule change at Le Mans made the Mazda 787B ineligible to race anymore. Mazda is also the most reliable finisher at Le Mans (with the exception of Honda, who has entered only three cars in only one year), with 67% of entries finishing.

The Mazda RX-7 has won more IMSA races in its class than any other model of automobile, with its one hundredth victory on September 2, 1990. Following that, the RX-7 won its class in the IMSA 24 Hours of Daytona race ten years in a row, starting in 1982. The RX7 won the IMSA Grand Touring Under Two Liter (GTU) championship each year from 1980 through 1987, inclusive."

[the_other_dougreeves]

Originally Posted by rtry9a

Be careful with assumptions regarding race results- you need to dig into the rules about what are allowed and what are not.
...
Mazda is also the most reliable finisher at Le Mans [/b](with the exception of Honda, who has entered only three cars in only one year), with 67% of entries finishing.

The Mazda RX-7 has won more IMSA races in its class than any other model of automobile, with its one hundredth victory on September 2, 1990. ...

The Mazda rotary has proven to be very reliable in the context of motorsport. Sad that they have been booted from LeMans, but they're active elsewhere. Formula Mazda basically runs spec 13B engines that are sealed during rebuild. Engines often last an entire season.

While this is great with respect to motorsport, an entire season of racing in this kind of formula is about, what, about 200 hours of on-track operation? That's not a great TBO for an airplane engine.

TODR

[rtry9a]

My point is simply that the Rotaries love to run at high power levels, and do so economically for long periods (less efficient at low power levels)- exactly what is needed in aviation. That is a fact often missed in headlines and by the racing community used to seeing only the big names.

Like you said, a race-prepped rotary often is not opened up during the entire season while its piston-powered peers generally carry around spares and are broken down/ overhauled after each race. That great durability, and its light weight, are reasons why the rotary engine has been voted out or penalized in most race categories. The races are mostly rigged by the big money competitors.

[rv6ejguy]

Naw, I don't buy this stuff. I built and road raced cars for 13 years. My piston engines lasted the whole season without coming apart and we won 7 championships- way more than anyone else in that time period.

Engines had stock rods, blocks, heads, bearings and cranks and were pushing over 200hp/ L specific output in turbocharged form. The long blocks were worth less than $3000 complete and came from the junkyard originally. Yearly rebuilds consisted of a valve reface, mag the crank and rods, new rings and gaskets (about $400-$500). I re-used bearings on my 1407cc engine 4 seasons in a row. We raced some fast Wankels but they were no match for us in hp. I beat one consistently which had a close ratio gearbox (I had stock ratios) and he was in the class above me. Our same class car annihilated all the other Mazdas including the best PP ones.

If people are wearing out piston engines in amateur road racing in less than a season, the wrong people are prepping or driving them.