LS1 Engine for aircraft?

[PTAirco]

Reply:Huh? So if my engine is running at 2200 rpm and meeting the needs of the moment, it will make a difference in whether its pulling an airplane or a truck?

Strictly speaking, it does: The analogy would be that the engine in an airplane , is subjected to the same kind of loading as pulling a truck up a steady incline, constantly.

It is not simply the RPM that matters, it is the BMEP developed. You can be be turning the engine at 2200 in neutral, 2200 going up a steep hill or 2200 going downhill. It's clear that it won't be subject to the same strain under all three conditions, even if the RPM's are the same.

A good reason to set up the engine to be a "towing" engine as far as cams and valves are concerned.

[ekimneirbo]

Yes I agree that setting up the engine for lower rpm power is different. Someone previously mentioned that an LS7 might be a good idea. I don't think its the best idea for the very reason you mentioned. The engine has large intake passages and valves and somewhat higher compression so even though its a fantastic engine (and would probably work fine), I have a different way to proceed.

I like the LS7 block because it has steel main caps unlike the other blocks in the LS series. It also has replacable liners where other LS engines can only be slightly overbored or require boring the liner out of the block. It gives you the ability to have 427 or more cubic inches. If you buy a bare block and build it you can select the crankshaft of your choice and use high quality aftermarket rods. (LS1-6 uses powdered metal rods and main caps...LS7 uses Titanium $$$$) You can select the cam of your choice to improve the lower rpm power/torque (as you referenced). The factory LS7 uses a dry sump oiling system but I would go with a conventional oiling setup. Also, I think I would use readily available LS1 heads as they flow well and have smaller passages and valves than an LS7. That should keep costs down and the smaller passages should keep velocity up when a 427 is drawing air thru them.(I bought a used low mile set with valves and rockers for $120 off
ebay) By building the engine from scratch I can use forged pistons and set the compression where I want it.(Note there are also some cheap truck heads which flow extremely well right from the factory.)
I have an article from Hot Rod Dec 2003 where they built an engine for low end torque.They used a Rocket block version of a smallblock Chevy and built it to 450 cu in. Using a very mild cam (Comp Cams XE270HR) they built an engine with a 9.3 compression ratio that runs on 87 octane gas.
It produced ....500 ft/lbs of torque from 2000 thru 5000 rpms. Impresive when you consider that many people believe that torque...not Horsepower moves the airplane. At any rate, there was plenty of HP to go around also.

190hp @ 2000 RPM 247 hp @ 2500 RPM 267hp @ 2700 rpm

Consider that it stacks up well against an O540, but I'm wanting it to weigh less and compete against an O360. An LS engine will have 15 degree heads instead of the 23 degree used on a conventional smallblock, so it may produce even more HP/Torque. (Note LS7 heads are 12 degrees)

So I agree wholeheartedly that you build the engine to provide power where you need it.

The anology about going up hills, down hills , or running 2200 rpm in neutral.
Yes, the BMEP will be different in each of these situations at 2200 rpm, but it will also do the same thing when rising during takeoff, descending during landing, or idling on the taxiway. So the engine doesn't know if its in an airplane or a truck, it only knows its turning 2200 rpm and either has a load or not.

[Midniteoyl]

As a side.. the LS9 block will be available as a replacement for ALL LS series engines in 2009. The LS9 block is about 20% stronger with less voids and stress risers, and able to handle larger bore sizes.

ekimneirbo: its funny, really.. You have all the same arguments I had when first undertaking this project. Experience has taught me that not all is so simple...

[plncraze]

As I was following this thread I remembered reading about Steve Wittman's V-8 conversion for his Tailwind, Chris Beachner's V-8 Special and Ron Vanderhart's V-8 conversion in his Stits Playmate. All these conversions had some things in common:

All three isolated the engine from the prop, either by using a bellhousing on the engine with bearings to support the prop or with a reduction drive

All kept their horsepower expectations low and regarded the published performance figures provided from the manufacturer with skepticism due to the engine's new operating application

All used a eight cylinder engine (Olds/Buick/Rover aluminum block)

Vanderhart had some funny stories about flogging a four cylinder Ford Escort engine around the pattern firewalled because it would not stay in the air otherwise and moving up to a Chevy V-6 before he finally put in a V-8 and figured that he was getting approx. 135 hp from the V-8. He made a point of saying that he was not getting the figures quoted in car magazines for this engine.
For some reason it seems that car engines do not give the horsepower in an airplane that performance specs suggests they should.

[ekimneirbo]

There has been much skepticism over the years about automotive HP ratings
Back in the 50s car makers used to say "wins on Sunday sells on Monday".
Ford started over rating their HP while Chevy began under rating theirs. Since cars were assigned to a racing class by advertised HP, guess who won.

Eventually a new standard way for calculating HP was put into effect and the advertised HP went down and became more authentic. No matter how you look at it, an engine is an air pump and the more air and fuel you can get into it, the greater power you may produce.

I have heard different rationales about why a Lyc will outproduce an automotive engine...and there are some things that have a major effect on the power produced by a given engine. When you look at a Lyc, it has huge pistons. Some people equate that as a major reason that automotive engines can't compete. Another myth in engines is that an engine with a longer stroke will produce more torque than an engine with the same cubic inches that has a shorter stroke.

There are a lot of pros and cons that affect every choice. My feeling is that all aircraft engines are anchient technology, but they do work reasonably well.They are simple to manufacture,build and maintain.

Personally, I find it difficult to believe that with all the improvements and refinements made in the last 60+ years that an automotive engine cannot match the power output of an airplane engine. I think many automotive engines are poor choices for various reasons, but if you select wisely you can find a few that deliver what you need. Even Model T engines were once used to power airplanes.

Just think about the design of these engines. Huge loose fitting pistons that pump oil like a sieve,and hard to start when hot. Inadvertantly shock cool one and your compression and your bank account will both go down...drastically. Flood one, and it just ain't goning to start. Engine castings are crude by todays standards. If you only fly your Lyc once a month or less in the winter your cam will rust and destroy other internal parts.Cylinders crack,cases fret, and magnetos get ADs relegating them to the scrap pile. Continental had a program in cooperation with Honda to produce water cooled engines, but I guess liabilities must have ended that.
Yes its old tech but if properly maintained($$$), they are pretty reliable.
On the other hand, they get annual inspections and frequent replacement of expensive parts such as cylinders in order to maintain reliability. Automobile engines with minimal (oil changes and 1 tune up) routinely go 150K or more.
So which is actually more reliable today?



I had one of the all aluminum Buick 215 V8 engines and put it in a Luv pickup truck many years ago. It was a nice little engine. The high performance cars of today are equaling and exceeding the outputs of much larger high performance engines of yesteryear. Muscle cars such as Camaro and Chevelle and even Corvette had heavy BIG BLOCK engines with 427 cu in. Today you can get a 427 in a SMALLBLOCK . It will weigh appx 150lbs less and make more HP than the old engines. Thats why they deserve a new look for being viable airplane alternatives.

Its really difficult to know what to believe, what is fact and what is fiction.
All you can really do is investigate what you are told and see if you can find a true basis for it. Then decide what what you believe and go with it.Most people want to be helpful, but there is a lot more fiction than fact in much of it.

[PTAirco]

Here is a LS1 engine designed for the RV 10, by Geared Drives who makes the PSRU for it.

The radiator arrangement seems inefficient to me; there is no baffling to actually direct air through it, at least half the area is obscured by the engine in front of it, there is no properly shaped expansion space behind it and the air has to make violent course changes to get to the radiator and to get out from behind it.

It seems to me the worst possible kind of cooling arrangements and downright unworkable, unless I am overlooking something obvious?

[Midniteoyl]

I agree. However, this setup has been used before and seemed to work. Team38 also used it, I believe, with success.

Cant tell in the pics, but are they using exhaust augmentation?

[ekimneirbo]

I agree with both of you, it doesn't look like a good design. I noticed on the Firebird that GM has the radiator hose positioned down a few inches from the top of the radiator. If the radiator is full then coolant will exist at a level higher than the highest point of the cooling system. Since its important to insure that no steam pockets are trapped in the heads, I assume that is the reason gm designed it that way. The high positioning of the radiator in the airplane may be an attempt to insure that coolant is always higher no matter what the attitude of the airplane. Still, I have to say that I have some doubts about the design.

[PTAirco]

"If you mount a prop directly to an automotive crank you can almost bank on it failing."

Hm. Maybe. It works on VWs and all its derivatives. The Beachner Special Buick (Rover V8), had a direct connection to the prop and lasted at least 1000 hours before it crashed for other reasons. Ford Model A, B and Twork fine with a direct drive prop. There are at least two Hawk P6 replicas (and probably more by now) with Chevrolet small block engines with the props bolted directly to the flywheel that are flying for a considerable number of hours now with no problems.


It's well to be concerned with potential problems, but until you go out there and try it, it is just educated guessing.

Which is what aeronautical engineering boils down : "Highly educated guessing worked out to 5 decimal places.... - Fred Lindsley, Airspeed Aircraft.

[plncraze]

I believe all the V8 engine people who run direct drive used some sort of bearing support between the prop and engine. Beachner had a bell housing with bearings inside of the cone to isolate the engine from the prop.

[PTAirco]

I believe all the V8 engine people who run direct drive used some sort of bearing support between the prop and engine. Beachner had a bell housing with bearings inside of the cone to isolate the engine from the prop.

True for the Beachner, but not for the people building those Hawk P6s. (I can't seem to find their website again...). I personally don't like that set-up but they are flying around in them.

I don't believe the Beachner used a flexible coupling of any kind; the stub shaft was bolted directly to the crank, that was the point I was trying to make. I also intend to use a similar set-up, to isolate the crank from gyroscopic prop loads, but I remain to be convinced that a flexible coupling is also necessary.

[plncraze]

I think when the designer of the P6 died it kind of dampened the enthusiasm for the plane.
Are all those running V8's direct drive off the engine using a wood prop?

[PTAirco]

I think when the designer of the P6 died it kind of dampened the enthusiasm for the plane.
Are all those running V8's direct drive off the engine using a wood prop?

I saw one with an Ivo-prop.

[ekimneirbo]

Harmonic Dampners....I have just become aware of the fact that Hartzell makes harmonic dampners for some of their propellers, and apparently they are effective enough to allow engines to operate in all power ranges . Is anyone familiar with these dampners.....Also, the composite props are said to be excellent for not allowing resonance. Any info about this?

[RonL]

Here is a LS1 engine designed for the RV 10, by Geared Drives who makes the PSRU for it.

The radiator arrangement seems inefficient to me; there is no baffling to actually direct air through it, at least half the area is obscured by the engine in front of it, there is no properly shaped expansion space behind it and the air has to make violent course changes to get to the radiator and to get out from behind it.

It seems to me the worst possible kind of cooling arrangements and downright unworkable, unless I am overlooking something obvious?

http://www.homebuiltairplanes.com/fo...1&d=1220545862

I like these kinds of mental challenges, first off it looks to be on a test frame of some kind, and second the air flow might move from behind the radiator, out over the engine, a much too large unit would be needed to take advantage of times when the plane might be stationary and only a small amount of air flow from prop thrust is available, third thing in my mind is that at speed in the air, a much colder and higher velocity air will allow for a much reduced intake area. There is such a thing as too much cooling.

Just a couple of thoughts that first come to mind.

Ron