ls3 for aircaft

Discussion in 'Chevy' started by PIRATE, Nov 29, 2015.

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  1. Jan 11, 2016 #21

    rv7charlie

    rv7charlie

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    Does that include the governor, and the weight of a 60 lb c/s prop? :)
    Seriously, if it can be done for that price by someone who's *not* a tool builder and in a reasonable amount of time, I'd be interested, even if it's fixed pitch. Cost? And there's still the issue of handling 200-230 hp with a relatively small dia prop. Pushers force the small dia anyway, but a requirement for extra blades and a low speed efficiency hit are going to be built in.

    The weight (& expense) of the c/s prop & governor could be a deal killer for a lot of airframes; one of the ways to get a V8 to work on an airframe designed for air cooling is to keep the weight down with a wood/composite prop. There was a group effort in the rotary engine community about a decade ago to develop an electric V/P composite prop, but IIRC, disagreements about intellectual property rights killed it before it got to testing stage.
     
  2. Jan 11, 2016 #22

    Toobuilder

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    So in a nutshell, I’m thinking of making a functional replica of the nose of a Lycoming case which contains essentially the front of a Lycoming crankshaft. This “thrust shaft” runs on the standard Lyc front bearing, incorporates a thrust surface riding Lycoming style on the inside of the case, and behind that is a nice ball bearing to stabilize aft end radially. The “case” would be nothing more than two blocks of 6x3x10 aluminum through bolted together, pinned at the split line, and machined as required for bearings, thrust, oil transfer, etc. This case and shaft assembly would be attached to the engine by a birdcage mount – just like a standard aircraft engine mount, but lighter. The only thing left is a way to drive the shaft with the engine – and this could be done with a quill shaft made from a standard automotive axle shaft. The flange of the quill mates to the FRONT of the “thrust shaft”, passes completely through and attaches to the spline output of the Corvette flywheel. The propeller would sandwich the quill shaft against the thrust shaft, locking the whole thing together. Now the quill can be machined to tune for a variety of propeller weights and diameters (by varying the shaft diameter), AND the engine crank will see zero thrust loads – only torque.

    My plan is compromised by a self imposed overall powerplant length which can be no longer than a Lyc 540. This drives the quill shaft to only about 14 inches which is going to be a problem. On top of that is the need to transfer oil for a CS prop from one shaft to another, which takes even more real estate. Making this thing for fixed pitch would be a lot easier.
     
    AdrianS and rv6ejguy like this.
  3. Jan 16, 2016 #23

    BobbyZ

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    At first I thought direct drive would be ok but after looking closely at AC crank bearings that take the loads I wouldn't trust it.Someone mentioned they'd be ok around 200 HP but If only going for 200 HP or so I'd think a LS would be waste and there's probably better options IMHO.

    I thought about using the oil system and possibly using the pan as a integral part of the assembly.Another good starting point would be a Tremec bellhousing like in this link Tremec T56 LS1 LS2 Bellhousing F Body GTO 1386 212 005 | eBay .Even if just to make a bearing to hold the propeller loads etc it would make a decent starting point.

    The LS4 was the one I was thinking of,thanks.If need be the FWD accessory brackets can be swapped over to the RWD blocks to save space.
    .If I do end up going with a LS I might go that route and while it is only a 5.3 I currently have a good set of heads and a Vortech V2 that I could use or possibly go turbo.

    It's still very early in my build/design but if there's a prop that will work in the 3-3250 rpm range for my app I'd probably go without a reduction and just a nice bearing assembly to hold the load.

    I've done quite a few turbo and blower motors over the years but I'm wondering how a LS (or any motor)would do under boost at relatively low RPM's.If you found the right turbo you could easily get some decent boost at low RPM's and probably have some room left over to keep the flow up to maintain boost at higher altitudes.
     
  4. Jan 16, 2016 #24

    rv6ejguy

    rv6ejguy

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    You'll be stuck with a small diameter prop at these rpms and a short 2 blade probably won't absorb 225+hp. That's the main drawback to DD- especially as power goes up, prop efficiency takes a big hit and even more so where low speed thrust is important like on slower aircraft where you really need diameter.

    Turbo DDs are a better solution IMO, you can make the hp at lower rpms, more friendly to prop efficiency but most folks are afraid of turbos of don't understand them well enough to effectively employ them. You match the right turbo for aviation use as most OTS units won't be a good fit for these applications, usually you need to mix and match compressor and hot section components to make it work well.

    The bad things about turbos and FP props is they don't play well together at higher altitudes without serious compromises somewhere.

    You might need to lower the CR if you're running mogas and a turbo.
     
  5. Jan 17, 2016 #25

    ekimneirbo

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    How much hp are you looking for? You do realize that getting too much torque can cause your airplane to rotate when power is applied? Look at the bell housing for the Corvette LS1. If you build a direct drive the housing should have a thrust bearing adapted to mount in it. Suggest you do a search on HBA for existing threads and you will find a lot of discussion on using an LS motor and the pros and cons of a reduction drive.
     
  6. Oct 5, 2016 #26

    MARCVINI

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    Hi. It´s been with great interest that I have been contemplating the idea of using a V8 engine in a direct drive instalation, in inverted form, in a small airplane like Van´s RV7, 8 and now the RV14. Actually, it is in my plans to do so in the near future.
    For quite some time I´ve defended using an aluminum SBC because of its crank thrust bearing solution, since I intend to use a simple, rigid prop extension a la the ones used in those DD Subarus used on Quickies and other small airplanes, but price wise, it does not make sense.
    So, after many discussions with other fellow members of this forum, I ended up "sold" to the LS3.
    Mr. Spencers Ford 302 powered Long EZ shows that to use an engine with the thrust bering in the middle is not an issue. As for prop radial loads on the outer bearing, Mr. Spencers installation has also proven to be non event, even tough using a 9 inch long prop extension and the crank´s main bearing diameter is narrower in comparisong to the LS3´s.
    To sum things up, here is what I finally came up with as my final set up:
    1. Airplane: Vans RV14;
    2. Engine: inverted, DD, LS3 like, with a forged crank, cammed for putting out around 220hp/420ftlb torque at 2800 rpm - a stroked LS3, say, to, 415 ci, could improve those numbers by 10% with negligible reliability compromises;
    3. Simple 4 inch long prop extension, à la those Saber´s (around 6 to 7 lbs);
    4. Light weight propeller à la Cattoes (20 lbs);
    5. Two radiators mounted on the sides of the engine, cool air fed by plenuns;
    6. Only minor modifications to the stock cowling, mostly to the lower half, in order to accomodate the forward projections of the engine´s composite intake manifold and cylinder heads;
    7. Cooling: stock water pump and the use of vent lines to adress air and vapor pockets inside the engine block end cylinder heads;
    8. Lubrication: external, multi stage oil pump, for scavenging oil from the lifter valley cover and valve covers and sending it to an external oil reservoir, for collecting oil from the oil reservoir and to send oil to the engine;
    9. This set up would weigh in from 30 to 50 pounds more than a "stock" IO390 RV14;

    Here is, roughly, what that set up would look like:

    RV14 Taildragger Inverted LSX flying 4 inch 1 instalation projections.jpg RV14 Taildragger Inverted LSX flying 4 inch 1 on the ground.jpg RV14 Taildragger Inverted LSX flying 4 inch 1.jpg

    I would like to appologize to the owner of N214SW for using his airplane as an example. I did so because it was the only "model" I have found that would be suitable to use with my poor man´s design resources.

    Cheers.
     
    Last edited: Oct 5, 2016
  7. Oct 6, 2016 #27

    TXFlyGuy

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  8. Oct 6, 2016 #28

    MARCVINI

    MARCVINI

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    Hi, TXFlyGuy. Your hp and torque numbers are in line with what a bone stock LS3 puts out. I intend to have my engine cammed in order to get the most torque dow low in the rpm range.
    Here are two dyno charts that show what I am looking for:
    LS3_Dyno-Stock-Numbers.jpeg LS3_Dyno-Crane-Cam-2019371 Numbers.jpeg
     
    Last edited: Oct 6, 2016
  9. Oct 6, 2016 #29

    TXFlyGuy

    TXFlyGuy

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    These charts are interesting. But the bone stock LS3 does 430hp and 425 pounds torque max, based on GM Peformance data.
     
  10. Oct 6, 2016 #30

    MARCVINI

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  11. Oct 7, 2016 #31

    MARCVINI

    MARCVINI

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    Hi. Spencers Ford uses a Ford Racing aluminum block and has its thrust bearing in the middle, just like all other 302 derived strokers...
     
  12. Oct 7, 2016 #32

    TXFlyGuy

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  13. Oct 7, 2016 #33

    TXFlyGuy

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    Here is a good chart for a stock LS3: Scan.jpg
     
  14. Oct 7, 2016 #34

    MARCVINI

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    Good!!! Concerning the data from you engine, I thought the short stack exhaust manifolds would limit severely the output. That doesn´t seem to be the case.
     
  15. Oct 7, 2016 #35

    TXFlyGuy

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    I honestly do not know, but the vacuum (low pressure) created around the cowl/exhaust area while inflight should assist with exhaust extraction.

    Have you checked the LS3 Hot Cam, from GM?
     
  16. Oct 7, 2016 #36

    MARCVINI

    MARCVINI

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    I believe you refer to the one used in the 376/480 crate engine. Yes, and it is quite in line with the Crane Cam grind deppicted by the chart I brought above. Since I am nothing more than a lay man on the subject, I am curious about what could be achieved with a custom grind cam, one set to extract the most torque and horsepower only up to 3000 rpm (wich is the rev limit for my prospective instalation). Stroking up to 415 ci (using the factory bore of the LS3 block and 4.00 inch stroke) could do marvels on this regard too. I believe that a powerband similar to the parallel valve Lycoming IO540 could easily be achieved with 427 ci.
     
  17. Oct 8, 2016 #37

    TXFlyGuy

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    Yes, it is basically the 376/480 LS3. Running the numbers with the GM Hot Cam, at 9000' MSL, standard day, at our cruise setting of 3600 engine rpm, we would have 225 hp available. The standard cam engine would be doing 190 hp. After making a short x-country trip at 10,500' in my buddies C-310, I like the idea of getting up high for cruise. I plan to file IFR, and cruise between 8,000 and 11,000 feet. At 11K, the difference is 205hp vs. 174hp.
    Is an extra 35 horsepower worth getting excited about? Hope one of you engine gurus can chime in. Due to prop tip speed limits, 3600rpm is the max available for cruise.
     
  18. Oct 8, 2016 #38

    MARCVINI

    MARCVINI

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    Well, My Friend, I am not ALL that used to using this forum features. It seams to me that your airplane is a T-51 with an LS3 mounted to it!!! What king of PSRU do you use???
     
  19. Oct 8, 2016 #39

    TXFlyGuy

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    You are correct. The PSRU is an Autoflight/Titan gearbox, 1.9 - 1 ratio, manufactured in New Zealand.
     
    Last edited: Oct 8, 2016
  20. Oct 9, 2016 #40

    MARCVINI

    MARCVINI

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    I ask you: what is your take on that PSRU? Are you confident with it? How much does it weigh? Seems to be a nice unit for using with a 5.3 LC9 bolted to an RV10.
     

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