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Thread: LSx mounted inverted

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    LSx mounted inverted

    Upside down with the crank at the top. Thinking of a direct isolated drive with no propellerforces on the engine, stroked LSx with 427+ cui. 500+ft.lbs of torque @ 2700 is very realistic with a good tune and will give approx 250+hp. That is enough power and will save the weight and complexity of a psru. Planned as a replacement for lycoming 540, so the weight penalty won`t be that bad.

    Oil scavenge from camshaft? how will the lube of the cylhead be? Getting rid of the oil that will pour down from the crank onto the pistons? What are the challanges, and has it been done before? Will the oil that is left in the crankcase sneak down, past the piston oilseal and into the comb. chamber after shutdown?

    What will the expected cruise BSFC be on a EFI LSx running at 2200rpm with say 150hp continous. I mean compared to a leaned out lyc 540. Will there be any significant gain?

    Expected engine life? Can I assume it will be a dependable engine if driven with care and at conservative powersettings? 2000+hrs tbo? This lycoming cost of operation is what I dislike with cyl replacements, overhauls and other expensive stuff.

    Propeller? Fixed and groundadjustables are not considered. Has anybody mounted a standard oilpress adjustable propeller to a autoconversion before? Electrically adjustable then? I guess that will be the best option..? Anybody with experience with that? prices, availability and how they perform compared to a certified adj.propeller

    Thinking of retrofitting that in an old cherokee six. Emptyweight in standard form is approx 1700lbs, max 3400. 100%payload. Beat that

    Yes, I know that cannot be done in the US. But I do not live there. We have several old, restored or modified standard category planes/copters with experimental status here.

    All comments appreciated

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    Re: LSx mounted inverted

    Hello Lars,


    We ran an LS2 engine in a home built bush plane and had over 1000 trouble free hours up on it before it was destroyed on the ground by fire. There was a custom made PSRU on it and no problems with that either.

    If I were to do it again, and this is a long term goal of ours, we would invert the engine, build a housing to support the prop and have bearings in it to handle thrust load and axial loads. An electrically actuated prop would also be nice to have, although we done ok with a wooden prop on the old plane.

    Steve Whitman used to invert a Buick V8 engine, the same engine that is used by Landrover and TVR now. It was originally designed and built by the Germans before Buick got it and most people dont know the engines real history and say Buick designed it. Anyways, I digress.

    With an inverted engine the oil will pool in the rocker covers and you need to pump it back up to a header tank. The problem of hydraulic lock in the cylinders can be solved by using the russian method of removing a spark plug and slowly turning the engine over by hand, or leave the plugs in and turn by hand carefully as it is possible to damage a rod even when hand cranked if you dont know what the forces are meant to feel like. If you have mahcine facilities available, make up an exhaust valve decompressor and use that, but you need to find out how far you can depress the valve and not hit the piston. If it is possible that would be my favourite.

    Other manufacturers such as Mikron have inverted certified aircraft engines and I believe there are some French manufacturers too who have inverted engines. So the problems can be over come and you just have to figure out a safe way to do it. I would like to see more of how Steve Whitman handle his oil problems. I know he had to drill and tap some of the oil galleries but the newer LSx engines may be easier to manage. Perhaps someone with more information on Steve Whitman might enlighten us.

    I have been looking at the Bearhawk for a possible replacement plane and wondered if the engine was installed upright, but in keeping the thrust line correct with the plans it means the top of the engine is about 2 inches above the height of the instrument cluster when some quick measurements are taken. But if the engine were lowered to keep the cowl as intended the thrust line is now maybe 2 to 3 inches lower and I have no idea what negative effect that has. Some planes I have seen flying with thrust lines 4.5 inches lower than the plans state and they fly fine, but I dont know if fine also means safe?

    We found the fuel consumption far lower than a 0-540 and way way cheaper to keep it flying. Parts were cheap even though we used only service parts and never had the engine apart as oil analysis didnt warrant opening it up. The LS7 is what takes my fancy for a new plane and they are getting pretty cheap now considering what you get. We used the mega squirt on the old engine and would use it again this time with fuel injection, not carb.

    Cheers,

    David

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    Re: LSx mounted inverted

    Thanks for a through reply, David

    I was thinking to move the firewall aft (if possible?) and suspend the engine with it`s CG right under the tubular frame to reduce stress and unnecessary weight to support an overhung engine. So the cargo compartment behind the original firewall will be sacrificed. Also need to weld an additional tubeframe forward to give support to a bearinghousing that will hold the propassembly (wheelbearing from a car might work to support the axial and radial forces from the prop). There will also be need for a midaxle between the engine and prop. with a rubberdampener like there is behind the gearbox in any car to reduce torsional vibrations.

    With the engine mounted so far aft will make it possible to make a new much smoother turbine-like cowling which will improve overall propefficiency and large space for radiator/oilcooler so it can be made bigger and thinner with even an electric fan.

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    Re: LSx mounted inverted

    I have done several hrs ground running of a Leyland/Rover V8 in inverted form with a prop from a Cont 300. Prior to testing I left the short block assy inverted overnite with underside of all eight pistons full of 10w oil over a clean sheet of paper- next morning there was not one drop of oil from any cyls-- these were worn ring/pistons as well, not new stuff, So I dont think the oil down past the ring pack is a major problem in the short term, if left for longer periods maybe. our testing was done over about an eight week period & we never experienced a problem in that time.
    Oil & cooling should be kept simple, You can buy external single stage oil pumps that can be mounted down low on the inverted installation if the original engine pump is not suitable & reverse cooling where coolant can exit from say a core plug opening on each side enter via the original T/stat location worked very well in our tests. We simply ran a drain line from each rocker cover into a central sump/tank for the pump to pickup oil from. One thing I would look into if fitting into an A/C would be to add standpipes to the rocker cover drains so that the running oil level in each cover reached up as far as two coils of the valve springs so that splash lube can reach the valve stems- this also helps cool the springs, the drain standpipes would need a small 3/32 hole to allow this oil to drain after shutdown. This 'held' oil must be allowed for in the tank running level. With a V8 any idea of using a valve as a decompression tool or even removing the plugs will not work effectively to remove oil as the inclined @ 45° cyls would keep the oil in that inner half of the cyl and the motor would probably have to be spun over on the starter with all plugs removed to purge oil if it was a problem.
    The whole test scenario was a bit of an anti-climax in a way, we were prepared for a whole host of problems , but really had none of any significance.

    Jac
    Last edited by MKIV; August 22nd, 2009 at 05:02 AM. Reason: xtra info.

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    Re: LSx mounted inverted

    Quote Originally Posted by MKIV View Post
    I have done several hrs ground running of a Leyland/Rover V8 in inverted form with a prop from a Cont 300. Prior to testing I left the short block assy inverted overnite with underside of all eight pistons full of 10w oil over a clean sheet of paper- next morning there was not one drop of oil from any cyls-- these were worn ring/pistons as well, not new stuff, So I dont think the oil down past the ring pack is a major problem in the short term, if left for longer periods maybe. our testing was done over about an eight week period & we never experienced a problem in that time.
    Oil & cooling should be kept simple, You can buy external single stage oil pumps that can be mounted down low on the inverted installation if the original engine pump is not suitable & reverse cooling where coolant can exit from say a core plug opening on each side enter via the original T/stat location worked very well in our tests. We simply ran a drain line from each rocker cover into a central sump/tank for the pump to pickup oil from. One thing I would look into if fitting into an A/C would be to add standpipes to the rocker cover drains so that the running oil level in each cover reached up as far as two coils of the valve springs so that splash lube can reach the valve stems- this also helps cool the springs, the drain standpipes would need a small 3/32 hole to allow this oil to drain after shutdown. This 'held' oil must be allowed for in the tank running level. With a V8 any idea of using a valve as a decompression tool or even removing the plugs will not work effectively to remove oil as the inclined @ 45° cyls would keep the oil in that inner half of the cyl and the motor would probably have to be spun over on the starter with all plugs removed to purge oil if it was a problem.
    The whole test scenario was a bit of an anti-climax in a way, we were prepared for a whole host of problems , but really had none of any significance.

    Jac
    Hi I am at the beginning of the process of turning a rover 3.9L V8 out of a land rover disco series 1 into an engine for my storch. (yes I am hoping for the 760KG rule in the Ultralights)
    MKIV / Jac
    Did you use the Steve Whitman drawings? or do you have another method? what intake did you use? Carbie or EFI? and what was the all up weight of the engine once you were done?
    What aircraft is it going in?

    thanks
    Philip

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    Re: LSx mounted inverted

    Back in the 80s I went to see Lou Ross of Ross Aero. He made planitary gear reduction drive for a wide variety of engines, including the buick, Olds, Pontiac, Rover, TR-8, Chevy V6 and V8, Mazda Wankel engine, etc. I have heard that there were issues with the long term durability of the drives, although I have no personal experience with one. Lou Ross was quite a character. He had a colorful history and was one of those guys who wasn't afraid to try new things.

    The planitary gearboxes he was making had no offset from the crankshaft to the prop so he had the same issues with the crank being too low, that you would have with a direct drive setup. His solution was to invert the engine, just as you suggest. He had done it on a number of engines with only slight modifications to the oil pickup. He connected the oil pickup to the valve covers and did not indicate to me that there were any issues with oil building up in the pistons. Of course this issue with inverted engines is not at all new. Every radial engine has some inverted cylinders, and there were inverted straight and v engines as well. I believe that on some of the big radials the ground crew would rotate the engine through a few turns before starting, this may or may not have been to push oil out of the lower cylinders.

    As someone else has mentioned, there may be a cheap source of reduction drives in the airboat industry. They have some drives that have been around for several decades and seem to be pretty reliable on Checy engines. I doubt that they are typically running very high power setting for long periods of time (they typically have 30 or so gallons of fuel which would not last long pulling 400HP), but they do at least run high power for some period of time when running on land. I doubt that many airboats are maintained as well as a typical airplane so we might guess that these reduction drives are fairly strudy units. Neither the Stinger or Rotator are set up for hydraulic constant speed props but you could use an electric prop (MT makes one and some early model Bonanzas had them, I actually have two electric props from a turbomeca Astazou 700 HP turboprop.) without too much trouble. My worry with these airboat drives is whether or not they could handle the gyroscopic forces of a spin with a heavy prop turning at full speed. I once read that Piper had a dual prop flange or prop extension failure on the twin Comanche when they were spin testing it, and those parts on certified engines are really heavy. I would want to use the lightest prop possible on one of these airboat drives if I was thinking about aerobatics (which I am).

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    Re: LSx mounted inverted

    Thanks for input billy!

    Sounds interesting, but I think it might be alittle too much testpilot involved here. I don`t want to be first man out:-)

    Another benefit with going direct isolated drive would be to have oilpresstube from the cranck into the propeller hub(inside a hollow driveshaft), so you could use hyd controlled propellers as well.

    For cooling I have thought about these heatexchangers http://www.hi-flow.com/HPOC1.HTM. I am thinking of using fuel as coolingsource. Fuel/coolant exchanger. Fuel is stored in large quantities in the wings with airflow over wings cooling it. An additional cabinheater can assist when the biggest power is needed and at low fuelquantities. Cooling circuit will be very light and compact in size. Thinking dual electrical waterpumps and fuelpumpsfor redundancy and capacity when/if needed. Firewallforward cowling can then be fabricated to look like a sleek longnose turbineconversion with a small airintake only for enginefood. Comments..?

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    Re: LSx mounted inverted

    I would suggest an LS7 block as it has several advantages over the other LS blocks. Lighter weight, steel main caps and longer cylinder sleeves which keep the pistons from exiting and rocking.

    Use a LS7 style aftermarket crank with the longer snout to drive a factory single stage dry sump pump. Then you can scavenge the rocker covers and put it in either a factory dry sump or an aftermarket one. This allows greater oil capacity and some of the sumps are shaped differently.

    I've got some ideas on the direct drive but don't have time to elaborate today. You can email me at mike_obrien@raytheon.com
    if interested.

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    Re: LSx mounted inverted

    Quote Originally Posted by DavidGr View Post
    Steve Whitman used to invert a Buick V8 engine
    Oldsmobile, not Buick.
    Wittman's aircraft designs
    Wittman Tailwind Pilot Report
    Steve Wittman - Wikipedia, the free encyclopedia

    similar but not identical.

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    Re: LSx mounted inverted

    Lars,
    You and Mike need to get together. I think you guys are on to something great.




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    Re: LSx mounted inverted

    This is not done on gas engines because the load of the oil on the pistons while running would create forces that will destroy it. The rotating assebly is balaced, crankshaft, rods, pistons, pins, rings, most to less than a gram. When oil pools in the piston at 2700 rpm the several ounces in the pistons at any given time will be thousands of pounds of force on the bottom of the piston. A force for which it was not designed.

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    Re: LSx mounted inverted

    Inverted engines of WWII and today have pretty much demonstrated that oil does not pool in the pistons while the engine is running (throw a glass of water or oil up and down and see if you can get the liquid to stay inside). Also, newer engines have internal geometries that can be used to benefit to direct splashed oil into galleries that direct the oil down into the valve covers, which become the default sumps for the engine.

    One major consideration has been oil seepage past the rings such as has been common with radials - this required a compression relief valve or the removal of a plug prior to start so as to prevent hydraulic lock. But practical examples such as Beechner's work have shown that water cooled engines have tighter tolerances and better fitting rings so oil seepage into the combustion chamber is not an issue.

    I've been looking at this possibility for the last few years but so far haven't had the time to do any more than just research. I'd love to do a boosted direct drive inverted V-8 but unfortunately I have to make a living first.
    "To live is to learn; to learn is to live" (author unknown)

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    Re: LSx mounted inverted

    Childs & Albert's Zero-Gap Second Ring - Test, Review - Hot Rod

    http://www.totalseal.com/pdf/M2_Tool_SteelTopRing.pdf

    Two fantastic solutions to zero gap rings, ..... I Strongly suggest you cosult your engine builder, parts manufacturers prior to twistinting $11k up fot a test fire and run up.

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    Re: LSx mounted inverted

    xxxx
    Last edited by stol; May 5th, 2012 at 12:40 PM.

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    Re: LSx mounted inverted

    The Olds and the Buick aluminum V8s are the same engine with different designed cylinder heads. The problem with the Olds is replacement parts are vary rare for the heads where with the Rover and Buick V6 parts can be adapted easily. Pontiac also used one but it was just the Olds version. Olds changes compression with cylinder heads where Buick used dished pistons. For a long time only the low compression Buick pistons were available; if you needed pistons for your low compression Olds the combo was about 4 to 1. Many times the Olds got Buick heads because they could get parts. Olds heads cant be used on Buicks because they did not cast the extra head bolt bosses in the blocks which also hold the valve train on for those heads.

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