LS3 - It's not just for Corvettes

[N201MKTurbo]

2 hours ago, Hank said:

He did mention eliminating static timing. Variabke ignition timing, which we've had in our cars for decades, would help with performance.

While I cruise at almost full throttle, I cannot cruise "pretty close to takeoff MP". Sure would be nice to get back those 8-9" I lose climbing! But that requires adding a turbo, which current FAA regs make extremely expensive. So . . . . .

So, what does variable timing buy you?

Our engines are already set for the maximum spark advance allowable for full power, so variable timing isn’t going to increase the maximum horse power of the engine. It can get you a slight increase in power at reduced manifold pressures, where the detonation margins are a bit bigger. 

The current mag replacement systems do all that, but I haven’t heard of any awesome power and speed increases.

[Dream to fly]

21 minutes ago, airtim said:

If you mean a military budget clean sheet new engine that after certification would be about the price of a new PT6A-67A then yes I would think that it could be designed better. Likely will never happen. The engines we have are great at what they do. 

I think he was referring to flying with more power on Mogas. Most engines especially turbo are against detonation limitations hence the need for lead in the fuel. 

What is antiquated about factory engines today? Most all engines have been upgraded over time.

TSIO-520-J that came in early Cessna 402s are case cracking crank snapping engines that once split can not go back on an airplane. TSIO-520NB engines sold today used in Cape air 402 go to 2000 hours like clock work. reduced 

Remember small valve lycomings with a 1200hr tbo?

Ask a Mooney Bravo owner if he would like to remove the wet head mod on his engine.

In a twisted way look forward to when I need an engine so I can get rid of the dual mag, flat tappet engine I have for a less antiquated IO-390 regular mag, roller cam, surefly ign, power flow exhaust spinning a scimitar composite MT propeller. None of which existed when my airplane rolled out of the factory in 1985.

 

Agreed it will never happen.  I have accepted the fact that change in the aviation world is near impossible.  Putting an auto engine that was designed for vehicles driving on the ground is not a good solution.  Those engines were designed for a purpose to re-purpose them into a different design criteria is not ideal.   To build a ground up engine that uses the tried and true principles of older technology  with new technology makes more sense and should be cheaper than reinventing the wheel.  I ventured into this discussion because of my back ground in  auto/diesel/marine repair but have quickly realized I should bow out for my knowledge is lacking and silly at best.   I concede! 

Joe.

[aviatoreb]

I think there are some nice modern engines designs but mostly they are diesel.  Diamond's conversion of modern Mercedes  in the 135-170hp variants.  EPS group is making an exciting graphite 8 cylinder diesel in the 300-450hp range.   These utterly kick butt over our 1940's era 100LL designs.

 

Edited February 2, 2020 by aviatoreb

[jetdriven]

1 hour ago, Dream to fly said:

I was including experimental to cover all bases. Experimental is alot less headaches but still has rules pertaining to owner built and engine repair.

 

Sent from my E6910 using Tapatalk

 

 

 

Again, what rules are you referring to? I think a builder can put any engine in an airplane they want right?  No? Why?
Guess the question I have, is if there are basically no rules to put an LS3 engine in the RV 10 for example, why has it only been tried once, and why was a spectacular failure.

[Dream to fly]

Just now, jetdriven said:

Again, what rules are you referring to? I think a builder can put any engine in an airplane they want right?  No? Why?
Guess the question I have, is if there are basically no rules to put an LS3 engine in the RV 10 for example, why has it only been tried once, and why was a spectacular failure.

Only the builder can do the work.  If the plane is sold the FAA to my understanding gets involved again.  As wonderful as automotive engines are by design they are not designed to run 75% or better for long periods of time.  The aircraft engine is designed to run at 75% or better for extended periods of time.    The average auto engine never sees 75% for more than a few seconds to a minute during a drive cycle.   If you ran an auto engine at 75% for an extended period it would not survive, the RPM range is too high and the parts are too small.  Bearings and cooling become an issue.  Airplane engines are built big and with girth. The problem with aircraft engines is that they could be way better.  The metal could be lighter and stronger, the control of fuel and spark could be more precisely controlled and the overall monitoring way better.   

There is a company in Orange Texas called Air Ranger and they make air boats that use basically a modified LS engine for the power plant.  They are roughly 350-500HP engines turning 5800RPMs.  They spin a 3 blade prop thru a very large and heavy prop box that puts the prop into the correct speed range.  Cast iron and a very wide rubber belt to smooth out power pulses.  They require frequent oil changes a very large cooling system and those engines take a beating.  Even with updated rotating internals and heads.   The reason those survive as long as they do is the power cycle is constantly changing and the prop is pushing on a gear box separate from the engine.  Air boats don't hold steady the power curve like a plane.  They peak to get on plane then back off to maintain. 

[aviatoreb]

1 minute ago, Dream to fly said:

...As wonderful as automotive engines are by design they are not designed to run 75% or better for long periods of time.  The aircraft engine is designed to run at 75% or better for extended periods of time.    The average auto engine never sees 75% for more than a few seconds to a minute during a drive cycle.   If you ran an auto engine at 75% for an extended period it would not survive, the RPM range is too high and the parts are too small.  Bearings and cooling become an issue.  Airplane engines are built big and with girth. ...

Of course a car engine can run 75% for hours on end.  The question is 75% of what?  When a car engine is rated xx hp they mean peak horsepower for like 15 seconds which is an advertising trick.

Example - the corvair 1960s era air cooled car engine by GM I think was sold as up to a 180hp engine for cars.  I read they are called "downrated" to 100hp engines when used as aircraft engines.  Which at 75% is 75hp.  Which is 41% if that 180hp advertised peak power in cars.  Maybe a lot of car engines can run 41% for long periods?

Again the question is not 75%, but 75% of what.

[Dream to fly]

I give you caught me I for got the word load.  Run a car engine at 75% load, so for basic numbers a 100hp engine running 75hp at 4500 RPMs.  call me after 2hrs of running.

[Tim Jodice]

1 hour ago, aviatoreb said:

They actually get 2600 hrs out of their engine like regular clock work, using some legal system I do not understand where they fly past tbo on a on-conditioning approved monitoring system.  Of course they are putting tons of hours per year on those engines.  I want to say 2600 is something like 2 yrs.

Even better, I bet they weren't getting 2600 out of them in the 60s. 

I have been working on cars for about 20 years and when I first started flying in 2006 I was disgusted by the technology in aircraft engines.

Then one day my alternator felt it needed a day off. It then sunk in that this engine doesn't care and I then started to have respect for the old mags and fuel systems. 

Auto engines with all the cool stuff, dual variable valve timing, coil on plug, direct injection and a variable geometry turbocharger all run by an ECU would not work so well with out electricity. FADEC? Sure not cheap. I think just last year the first FADEC controlled PT-6A  came out  on a PC-12 NGX.

If one of most popular turboprop engines are just getting electronic control it  makes me think it does not bring much to to table that can't already be done with old school systems. 

I dont have much first hand experience with the turboprop industry, those of you that do I would love to hear what it is like to operate one. FADEC or not.

[aviatoreb]

47 minutes ago, Dream to fly said:

I give you caught me I for got the word load.  Run a car engine at 75% load, so for basic numbers a 100hp engine running 75hp at 4500 RPMs.  call me after 2hrs of running.

We agree.  

Someone must be computing the thing we really need to know, which is for a given engine, say the lovely horizontal 4 on my Subaru WRX Sti, how may HP it is happy to make if I were to run it nonstop at that stead load for 2000hrs nonstop.  My car is advertised at 300hp - and boy is it a quick little car if I floor it - which I only do ever so occasionally since it really is excessive acceleration and not useful in any practical way to do that.  I would guess the answer to this question I just asked is 75hp.

[EricJ]

9 minutes ago, aviatoreb said:

We agree.  

Someone must be computing the thing we really need to know, which is for a given engine, say the lovely horizontal 4 on my Subaru WRX Sti, how may HP it is happy to make if I were to run it nonstop at that stead load for 2000hrs nonstop.  My car is advertised at 300hp - and boy is it a quick little car if I floor it - which I only do ever so occasionally since it really is excessive acceleration and not useful in any practical way to do that.  I would guess the answer to this question I just asked is 75hp.

Much of it is the cooling system.   When people bring street cars to the track one of the first things you find out is how good/bad the cooling system is, especially for turbocharged cars.   The mileage/weight and cost requirements mean that it doesn't make sense for the manufacturer to put in a cooling system big enough to handle a situation that nearly no cars will ever experience, so the majority of user cases are covered plus some margin.   "Performance" cars or performance halo cars sometimes get a bigger or slightly bigger cooling system that can handle more power output for longer periods.

So, if the cooling system were designed to sufficiently cool the engine and the oil at max power for long periods, it might not be so bad. 

Even naturally aspirated aircraft engines only produce full power at sea level, where very few of them operate for any length of time.   Even though I run my engine at WOT all the time, it's often only making 65% power.   We know that adding a turbo, even just for turbo-normalization, may affect TBO negatively because of the added stress.

[Blue on Top]

7 hours ago, Dream to fly said:

1) There needs to be a law to protect manufacturing companies from the law suits.

2) If the rules could change ...
 

@Dream to fly  Joe: I honestly and sincerely love what you're saying, but ...

1) We have been looking for this law for over 40 years.  The GA Revitalization Act tried to do this … limiting the liability to 17 years.  Well, it hasn't fared so well.  If the owner changes one part, the 17 years starts again.  No help.

2) We (ASTM) are trying hard to do this.  Part 33 (engine certification) is really not that difficult, but refer back to 1) above.  As a potential, though, if the engine were made "non-required for safe flight and landing" (i.e. as a genset for an electric airplane), it would no longer have to be certificated!

Just trying to support your thoughts, -Ron

[kmyfm20s]

LS3 Power/torque curve included in the chart. 

 

[Dream to fly]

3 minutes ago, Blue on Top said:

@Dream to fly  Joe: I honestly and sincerely love what you're saying, but ...

1) We have been looking for this law for over 40 years.  The GA Revitalization Act tried to do this … limiting the liability to 17 years.  Well, it hasn't fared so well.  If the owner changes one part, the 17 years starts again.  No help.

2) We (ASTM) are trying hard to do this.  Part 33 (engine certification) is really not that difficult, but refer back to 1) above.  As a potential, though, if the engine were made "non-required for safe flight and landing" (i.e. as a genset for an electric airplane), it would no longer have to be certificated!

Just trying to support your thoughts, -Ron

If nobody bucks the system it will never change.  I am so done with the rules and handcuffs.  

[Blue on Top]

2 hours ago, Dream to fly said:

I ventured into this discussion because of my back ground in  auto/diesel/marine repair but have quickly realized I should bow out for my knowledge is lacking and silly at best.   I concede! 

Joe.

@Dream to fly Joe:  Don't you dare back out of this.  I want your input!  

If we can take an automobile engine with all the new technology, is mass produced at a MUCH lower cost and meets all the requirements at a similar (or lighter weight), why shouldn't we try?

Please 

[Blue on Top]

11 minutes ago, Dream to fly said:

If nobody bucks the system it will never change.  I am so done with the rules and handcuffs.  

@Dream to fly  Joe:  Just call me "Bucko!" 

[Dream to fly]

Just now, Blue on Top said:

@Dream to fly Joe:  Don't you dare back out of this.  I want your input!  

If we can take an automobile engine with all the new technology, is mass produced at a MUCH lower cost and meets all the requirements at a similar (or lighter weight), why shouldn't we try?

Please 

Because too many old timers with "don't fix what ain't broke" mentality will buck every turn.  Just like the technology of electric cars, cellphones, steel belted tires, carbon fiber,  etc.There are too many book smart common sense stupid people and too few with a knowledge to make a stand.  If you wish to discuss this further please call me or anyone else who wants my number I don't hide.  701 748 2263

[Volzalum]

2 hours ago, Dream to fly said:

Only the builder can do the work.  If the plane is sold the FAA to my understanding gets involved again.

Not quite correct. The original experimental builder that holds the repairman certificate can do basically anything to the plane including the yearly condition inspection. A subsequent buyer can do everything except the yearly condition inspection. So a subsequent buyer can put whatever engine they want in, they just have to get a condition inspection each year. For experimentals, it’s not called an annual airworthiness inspection. 

[Tim Jodice]

Why is it said that auto engines won't last at high power settings? Honest question.

I owned a Sea Ray years ago that other than liquid cooled exhaust manifolds it looked just  like a small block chevy. I had no problem with it and mechanics at the marina said they rarely replace an engine because it failed because of the design. They said they are usually replaced because they rust from the inside out from lack of use.

Sounds alot like many airplane engines. 

I bring this up because a boat engine that looks identical to an auto engine may spend hours at 3-4000 rpm. In some installations it is suggested that a Mercruiser 350 MPI engine are to be propped to hit 5000 RPM at WOT. 3500rpm would be about 70% power.

  I imagine they do things to help with corrosion but what is done mechanically to a automotive derived engine to have a reasonable life in a boat?

 

[aviatoreb]

3 hours ago, EricJ said:

Much of it is the cooling system.   When people bring street cars to the track one of the first things you find out is how good/bad the cooling system is, especially for turbocharged cars.   The mileage/weight and cost requirements mean that it doesn't make sense for the manufacturer to put in a cooling system big enough to handle a situation that nearly no cars will ever experience, so the majority of user cases are covered plus some margin.   "Performance" cars or performance halo cars sometimes get a bigger or slightly bigger cooling system that can handle more power output for longer periods.

So, if the cooling system were designed to sufficiently cool the engine and the oil at max power for long periods, it might not be so bad. 

Even naturally aspirated aircraft engines only produce full power at sea level, where very few of them operate for any length of time.   Even though I run my engine at WOT all the time, it's often only making 65% power.   We know that adding a turbo, even just for turbo-normalization, may affect TBO negatively because of the added stress.

I agree - cooling may well be the central issue that is descriptive of how much power you can expect from a power plant.

But thinking of this in terms of displacement.  The IO360 in your M20J is essentially a 5.9L engine in modern-car-speak.  So 200hp from a 5.9L engine would be described as loafing along in such a big engine -BIG cylinder 4.  Contrast that to a modern Chevy Corvette engine, this one at 6.2L (essentially same size but smaller cylinders as a V8) sold as 460hp.  https://www.chevrolet.com/corvette-life/engines  So if I sold that engine and said it was 200hp and I downrated it so that it would max at 200hp - from the chart (rpm vs hp) it looks like 2500-2600 is that 200hp number.  If I then said that was max, but you should run it at 75% in cruise - so 150hp, that would be 32% of the GM-advertised 460hp.  I bet it would be a lot easier to keep that V8 suffiently cool and happy if I never expected more than 150hp for more than 5 min at a time and never more than 200hp for 5 min or less.

So I say again, 75% of what.

[jetdriven]

4 hours ago, Blue on Top said:

@Dream to fly  Joe: I honestly and sincerely love what you're saying, but ...

1) We have been looking for this law for over 40 years.  The GA Revitalization Act tried to do this … limiting the liability to 17 years.  Well, it hasn't fared so well.  If the owner changes one part, the 17 years starts again.  No help.

2) We (ASTM) are trying hard to do this.  Part 33 (engine certification) is really not that difficult, but refer back to 1) above.  As a potential, though, if the engine were made "non-required for safe flight and landing" (i.e. as a genset for an electric airplane), it would no longer have to be certificated!

Just trying to support your thoughts, -Ron

The 17 years only starts again for that one part. Not the whole airplane. 

[carusoam]

It’s boat show season in the NYC area...

So We are seeing many Chevy and Ford V8s employed in a pretty harsh environment...

High power, high rpm for hours at a time...

They do get heat exchangers to allow for endless cooling AND keeping saltwater out of the engine...

 

water density seems to have some advantages... prop size is tiny, and heat exchanger equipment is pretty small as well...

In some cases... there is a gear box to change the final rpm of the prop... in other cases the words direct drive is used...

Sometimes the stern drive is a gearbox and prop line organizer/adjuster.... looks a lot like the bottom half of an outboard motor... includes adjusting trim of the drive line during use, and... steering too.

 

I would naturally be attracted to something with a pair of 454s with twin opposite rotating cleaver props...  

Best regards,

-a-

[carusoam]

One interesting note of interest...   precision cast parts have come a long way...

audi diesel engines can handle some really high ICPs...

And they have been used in gasoline applications where turbo boost is in the Uber excessive range...   

Pp thoughts only, not a mechanic...

Best regards,

-a-

[shorrick mk2]

For all the doubting Thomases - thirty years ago Volvo ran one of its stock S60 sedans for 24h at top speed, stopping every two hours to change drivers. So much for the "stock car engine setups cannot run at 100% power".

 

https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.volvoclub.org.uk/press/pdf/S60LandSpeedRecord.pdf&ved=2ahUKEwjF3ICv9bPnAhXiwsQBHftdBfQQFjAKegQIAhAB&usg=AOvVaw2-6AsQHQ5z224UtasNEW_l

[aviatoreb]

1 minute ago, shorrick mk2 said:

For all the doubting Thomases - thirty years ago Volvo ran one of its stock S60 sedans for 24h at top speed, stopping every two hours to change drivers. So much for the "stock car engine setups cannot run at 100% power".

 

https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.volvoclub.org.uk/press/pdf/S60LandSpeedRecord.pdf&ved=2ahUKEwjF3ICv9bPnAhXiwsQBHftdBfQQFjAKegQIAhAB&usg=AOvVaw2-6AsQHQ5z224UtasNEW_l

That is a very interesting experiment.

But is 135mph 100% power for that car?  Just asking.  I don't know.

[EricJ]

1 hour ago, aviatoreb said:

I agree - cooling may well be the central issue that is descriptive of how much power you can expect from a power plant.

But thinking of this in terms of displacement.  The IO360 in your M20J is essentially a 5.9L engine in modern-car-speak.  So 200hp from a 5.9L engine would be described as loafing along in such a big engine -BIG cylinder 4.  Contrast that to a modern Chevy Corvette engine, this one at 6.2L (essentially same size but smaller cylinders as a V8) sold as 460hp.  https://www.chevrolet.com/corvette-life/engines  So if I sold that engine and said it was 200hp and I downrated it so that it would max at 200hp - from the chart (rpm vs hp) it looks like 2500-2600 is that 200hp number.  If I then said that was max, but you should run it at 75% in cruise - so 150hp, that would be 32% of the GM-advertised 460hp.  I bet it would be a lot easier to keep that V8 suffiently cool and happy if I never expected more than 150hp for more than 5 min at a time and never more than 200hp for 5 min or less.

So I say again, 75% of what.

Part of that is operating rpm.   An auto engine output gets geared down in several stages so it can spin fairly quickly to make power, and doesn't need to make much low-rpm torque because the gearing multiplies the torque up for the drive wheels.

In most GA aircraft the engine drives the propeller directly, which is rpm limited to keep the tip speeds from going supersonic.   For this reason comparing torque outputs is probably more fair than comparing hp output, and helps explain why a 200 hp IO-360 has a comparable displacement to a 400-500 hp 5.5-6.2L LS V8.   At 2700 rpm a 200 hp engine is making 389 ft-lbs.   The 6.2L LS3 crate engine makes 430 hp and 425 ft-lbs.   The torque is  pretty comparable even though the hp goes way up on the V8.    On the torque curve published previously the LS3 puts out about 375 ft-lbs at ~2700 rpm, so LESS than the IO-360, and the LS3 is making just under 200 hp at that rpm.    With a direct drive it won't turn a prop any better than an IO-360, and apparently a bit worse using the plot above.  If you could spin an IO-360 at 6000 rpm, it'd make 430 hp, too, but you'd have to add a lot of weight or expense to the rotating components, case, valve train, etc., to make them be able to spin that fast.

The tried-and-true way to allow spinning a motor faster in order to make more power and still spin a prop is to put a gearbox on it.   The Merlin engine did this, so do many radials, so do many Rotax motors, Lycomings, Continentals, etc.   The gearbox adds weight, friction, etc.

If you want a direct drive for minimum weight, and keep engine components light, spin it slow like a typical GA motor, but you need a large displacement to make the torque necessary to spin the prop.   So this is partly why GA motors look like they do.

Edited February 2, 2020 by EricJ