LS3 - It's not just for Corvettes

[McMooney]

13 minutes ago, EricJ said:

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.

Or wait for it, Add forced induction.  that same ls3/lt4/v6 can be made to do the same or better numbers at those lower rpms with a turbo.  probably while running 89 octane, ethanol gas

[N201MKTurbo]

The only way to get an auto engine to a sustained 100% power is for the engine to be at red line RPM and wide open throttle at sea level. Assuming red line is peak torque, it usually is.

Even in the Volvo test, was the engine at red line RPM or as fast as it would go in high gear? That's not 100% power. Probably pulling a heavy trailer in low gear might get you there.

[N201MKTurbo]

Don't forget the Pond racer!

https://en.wikipedia.org/wiki/Scaled_Composites_Pond_Racer

Some of the brightest minds in aviation were convinced that an automotive racing engine could blow away all the WWII technology.

[McMooney]

6 minutes ago, N201MKTurbo said:

The only way to get an auto engine to a sustained 100% power is for the engine to be at red line RPM and wide open throttle at sea level. Assuming red line is peak torque, it usually is.

Even in the Volvo test, was the engine at red line RPM or as fast as it would go in high gear? That's not 100% power. Probably pulling a heavy trailer in low gear might get you there.

there is absolutely no reason you need to run them at 100% power.  actually 100% power doesn't make sense even for airplane engines,  an io360 can spin faster than 2700 rpm and make MORE power while doing it.  might not last as long but hey whatever 100% is just a rating.

rate the auto engine 100% @ 3000rpm  or 3500rpm whatever

[jetdriven]

So,on page 7, an LS3 puts put a tad over 200 HP at 3000 RPM. So we have IO360 equivalent power, but a far more complex and heavier installation.  Electronic fuel injection, water cooling, all of that.  And, as the RV10 builder in Conroe Texas found out,  when  it’s all said and done it is no better.

I mean I’ve been hearing this “auto engine conversions are better than lycoming” thing for 25 years now, but really we haven’t seen it yet. I can’t think that people are all that stupid, or that lazy, or that they just can’t seem to get it together and spit them out. I think it’s just we are not there yet with technology that we have. I mean we were all promised turbine cars and nuclear powered cars and homes 50 years ago as well, but again those have not materialized. Not because we are stupid, but physics and economics are that hard.
I’ve heard of a few short term auto engine powered airplanes, that usually get converted back to aircraft engines after the two or three year experiment either ends in  crashing of the aircraft and the immolation of the occupants (Ravin) or they give up and revert back to an aircraft engine. 

[shorrick mk2]

12 minutes ago, N201MKTurbo said:

The only way to get an auto engine to a sustained 100% power is for the engine to be at red line RPM and wide open throttle at sea level. Assuming red line is peak torque, it usually is.

Even in the Volvo test, was the engine at red line RPM or as fast as it would go in high gear? That's not 100% power. Probably pulling a heavy trailer in low gear might get you there.

The engine wasn't at redline rpm, as top power is at 5200 rpm (below redline). Redline is never peak torque... especially not on turbo engines. Sea level is irrelevant as the engine is turbochaged. 

Was it at 100% power? If the book says 330Nm and 250HP at 5200 rpm, and they ran it against the speed limiter, signs point to yes.

[shorrick mk2]

45 minutes ago, aviatoreb said:

That is a very interesting experiment.

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

135mph is the average speed over 24h, accounting for pit stops. When lapping it was run at 150ish mph (which is top speed) & 5200 rpm.

[N201MKTurbo]

I know our airplane engines look old fashioned and our car engines look like a beautiful piece of jewelry. But I still have to marvel at the reliability of our aircraft engines and how they usually fail very slowly.

So, raise your hand if you have ever had a blown radiator hose? How would that be on a dark stormy night over the mountains?

[jetdriven]

39 minutes ago, N201MKTurbo said:

I know our airplane engines look old fashioned and our car engines look like a beautiful piece of jewelry. But I still have to marvel at the reliability of our aircraft engines and how they usually fail very slowly.

So, raise your hand if you have ever had a blown radiator hose? How would that be on a dark stormy night over the mountains?

My Bmw blew off a coolant hose just last month. It went from operating normally to overheat on the side the road in about 60 seconds

[shorrick mk2]

1 hour ago, N201MKTurbo said:

I know our airplane engines look old fashioned and our car engines look like a beautiful piece of jewelry. But I still have to marvel at the reliability of our aircraft engines and how they usually fail very slowly.

So, raise your hand if you have ever had a blown radiator hose? How would that be on a dark stormy night over the mountains?

Thank lord the barrel - head separations and cylinder cracks happen very slowly, imagine how that would be on a dark stormy night.

An engine that needs 25h oil changes and 500h mag and cylinder changes to marvel at isn't exactly "cross mountains at night in a storm" reliable in my book.

[N201MKTurbo]

5 minutes ago, shorrick mk2 said:

Thank lord the barrel - head separations and cylinder cracks happen very slowly, imagine how that would be on a dark stormy night.

An engine that needs 25h oil changes and 500h mag and cylinder changes to marvel at isn't exactly "cross mountains at night in a storm" reliable in my book.

I encourage you to start an aircraft engine company and save us all!

[chrisk]

6 minutes ago, shorrick mk2 said:

Thank lord the barrel - head separations and cylinder cracks happen very slowly, imagine how that would be on a dark stormy night.

An engine that needs 25h oil changes and 500h mag and cylinder changes to marvel at isn't exactly "cross mountains at night in a storm" reliable in my book.

The Rotax 9 series engines need an oil change every 25 hours if using 100LL.  They can go up to 100 hours on 91 Auto fuel.  --Its not the engine, its the fuel.   I'm guessing an auto engine would need more frequent oil changes when using 100LL.    Of course, you can haul auto fuel to the airport, which is a pain.  And if you let the auto fuel sit to long, it will gum up, which you discover when it clogs/blocks your fuel filter.  --no free lunch

 

[Hank]

1 hour ago, shorrick mk2 said:

An engine that needs 25h oil changes and 500h mag and cylinder changes to marvel at isn't exactly "cross mountains at night in a storm" reliable in my book.

I change Mooney oil at 50 hours, and auto oil at 5000 miles.

I also try to to take either through the mountains at night in a storm . . . . And I lived in WV for 9 years, got my PPL and bought the Mooney there . . . .

[Blue on Top]

18 hours ago, jetdriven said:

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

@jetdriven What you have stated is true by definition, but … the courts don't interpret the law that way.  Cessna's largest, lost lawsuit was on a seat sliding back after a very hard, bounced go-around attempt (stalled and crashed).  The AD had been out for decades, etc, etc.  The claimants said Cessna knew about the problem and did nothing about it.  The jury believed them.  Lawyers will find ways to convince juries that a small replaced part somewhere on the airplane had some little influence on the accident, and that is all it takes.  Aviation needs tort reform and a true limit of liability (unless proven negligent).  Would a case against GM even get to court if your engine quit in a '57 Vette?

[jetdriven]

In the case of the Delrin Lycoming fuel floats, there were many accidents caused by the float filling up with fuel and causing the engine to stop.  They refused to respond to discovery. And when they did, the plaintiff found that the  company knowingly concealed it and had lied to the court about it.

.  So when you say “Tort reform” and “limit liability” you are saying “take away the ability to sue”. Careful with that. It works great until you or someone you know is harmed or killed. 

[jetdriven]

17 hours ago, shorrick mk2 said:

An engine that needs 25h oil changes and 500h mag and cylinder changes to marvel at isn't exactly "cross mountains at night in a storm" reliable in my book.

Maybe you need a different shop , maintenance philosophy, or SOP’s?  
oil changes are 50hr, and I don’t know of any engine that requires cylinders or mags  every 500hr. 
Get a good overhaul done by a good name shop and run it 2000hr.   There isn’t anything better or else we would be doing that. 

[Tim Jodice]

33 minutes ago, jetdriven said:

In the case of the Delrin Lycoming fuel floats, there were many accidents caused by the float filling up with fuel and causing the engine to stop.  They refused to respond to discovery. And when they did, the plaintiff found that the  company knowingly concealed it and had lied to the court about it.

.  So when you say “Tort reform” and “limit liability” you are saying “take away the ability to sue”. Careful with that. It works great until you or someone you know is harmed or killed. 

I think the examples you gave are great examples of legitimate reasons to sue someone or company. In the 80s the 441 came out with a known problem with the trim tab system. People died from it. I think that is another good reason to sue. 

When lawyers go after lycoming (and win) because the engine failed when it hit the mountain that the pilot crashed in to. I think that is why a rebuilt IO-360A3B6 engine is  approaching 40K at $37,405 from airpower. 

[cliffy]

Doesn't Jewel do them for about 1/2 that amount?