100HP at FL10

Discussion in 'Firewall Forward / Props / Fuel system' started by Jay Kempf, Oct 9, 2019 at 2:17 AM.

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  1. Oct 9, 2019 at 2:17 AM #1

    Jay Kempf

    Jay Kempf

    Jay Kempf

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    Was reading through a bunch of old threads about Suzuki and Honda based engines available in the HBA world. $10-15k buys you a bunch of R&D and a decent FWF/FWA package at about 100hp plus/minus. So I started looking around at engines (again).

    What I started seeing is that there is a lot of crate replacement engine innovation going on right now. 100HP/Liter is pretty much the standard now. Direct injection is common. Lots of forums full of tuners out there doing some pretty amazing things with 1-1.5 liters 3-4 cyl inline. A lot of these engines like the Chevy Spark are all aluminum, tiny packages, and over 100hp. There are some heavier larger displacement stuff out there as well for larger packages. Then I started looking at Yamaha and Suzuki outboard powerheads. Same thing. Lots of evolution in the last 5 years.

    I was just looking for candidate motors that the majority of the block/head/scavanging system/turbo and intake exhaust fits in about 24" high 18" wide 24" long. Seems the auto world has figured out that small, light weight high output reliable engines that can put out a lot of power at a best efficiency point is aligned with hybrid, high fuel mileage goals.

    Interesting that they are die casting blocks and heads now in high volume on these small engines going into inexpensive autos in Asia. Certainly they are not developing this stuff for the bloated USA market.

    I can grab a complete engine off of ebay running, low mileage for hundreds. Not a bad platform to experiment with. 100hp turbo 4 stroke well under 200lbs... possible? Rotax already makes a box to bolt up.
     
  2. Oct 9, 2019 at 4:28 AM #2

    Terrh

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    I do not think there are any sub 200lb 100+HP auto engines, especially not with a turbocharger attached.

    I hope that I am wrong about this.
     
  3. Oct 9, 2019 at 5:29 AM #3

    mm4440

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  4. Oct 9, 2019 at 10:52 AM #4

    sming

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    Ok, it's a bit heavy but what about a 235lbs 105HP turbo diesel (with intercooler and all) ?
    Surely a petrol one is doable...
     
  5. Oct 9, 2019 at 6:54 PM #5

    Terrh

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  6. Oct 9, 2019 at 7:00 PM #6

    Terrh

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    The n/a SOHC EJ25 subaru engine has probably the best power:weight ratio I can think of for an auto engine, you could probably run one at 130HP all day long with some reliability upgrades (mostly better oil pickup and proper bearing clearances for running hard), they're about 250lbs w/ alternator and cooling system.

    A lightweight 100+hp diesel intrigues me a great deal, especially if redrive bits already exist for it and the engines are available, reliable, and inexpensive.
     
  7. Oct 9, 2019 at 7:33 PM #7

    Hephaestus

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    Aerovee turbo vw kind of fits that ballpark. Although there's discussion if it's reliable enough in current form.

    Corvair turbos have been done as well.

    I was reading a bit on a mildly boosted c85 last night that sounded promising.
     
  8. Oct 9, 2019 at 8:36 PM #8

    saini flyer

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    litespeed likes this.
  9. Oct 9, 2019 at 9:06 PM #9

    PW_Plack

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    AeroMomentum claims 85 HP, but doesn't say whether that requires the optional tuned exhaust. And the weight quoted is "dry," without what is likely 30+ pounds of oil and coolant.

    For the target weight and power mentioned above, snowmobile and personal watercraft engines will be a better starting point than automotive. Mass-production auto engines will always prioritize low cost over low weight.
     
  10. Oct 9, 2019 at 11:36 PM #10

    Jay Kempf

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    Agreed, the Yamaha sled engine is pretty much there. But the website link is showing a 4cyl. The little 3 cyl turbos seem ideal. The turbos probably aren't big enough to keep up at altitude.

    Have a look at what GM/Opel is developing:
    https://www.autoevolution.com/news/gm-opel-sidi-engine-family-explained-68707.html

    They will make a large number of these and they will fill recycling yards. Simple, light, compact. If this was there already I would just grab one and start developing around it.
     
  11. Oct 10, 2019 at 6:28 AM #11

    cheapracer

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    People need to get it out of their heads that Subaru engines are light, it is a myth, they are not.

    Upon saying that, the old Subaru pushrod engines are quite light, EA81 of course commonly used in numbers of light aircraft.

    Jay, modern engines still suffer from needing to package DOHC, VVT etc that adds pounds, a number of older engines are still quite light, the Suzuki G13B is till an option for many for good reason and meets your criterium.

    http://www.aeromomentum.com/am13.html

    Of course bike and snowmobile engines meet it with ease.

    https://www.rotax.com/en/products/rotax-powertrains.html
     
  12. Oct 10, 2019 at 6:38 AM #12

    cheapracer

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    Many auto engine weights quoted by manufacturers include 'fully dressed' items such as air con and power steering pumps, clutch and other items. Some even with water and oil to protect themselves from liability if a cable/chain etc snaps when a technician is removing the engine.

    Aircraft engine advertisers on the other hand tend to offer you the absolute barest weight they can to attract you to them, and note that many don't have the 20 to 30 pound flywheel/clutch attached.
     
  13. Oct 10, 2019 at 1:48 PM #13

    aeromomentum

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    Well, we got 89.4hp on the dyno with our header and a full exhaust with muffler. The factory rating for the base engine is 74hp with their exhaust manifold and full exhaust with cat and muffler. Some of the difference may be due to tuning but the factory does a fairly good job (at peek power) with tuning today. Of course at other places on the map they are more concerned about emissions and drive-ability so can not maximize power.

    The full cooling system wet is under 10 lbs.

    Radiator 3.38 lbs
    Radiator water 1.6 lbs
    Aluminum expansion tank 0.39 lbs
    Expansion tank water 0.38 lbs
    Engine water 2.9 lbs
    minimum hose, tube w/water 1.1 lbs

    Total 9.73 lbs
     
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  14. Oct 10, 2019 at 2:53 PM #14

    Jay Kempf

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    The stuff that I really like seeing is die casting blocks and clever designs with reduced parts count. The exhaust in the engine I showed is in the head and the turbo assy bolts directly to the head. Remember that everyone is focused on cost now one part of cost is cycle time through assy, the other is just the weight of the materials. So by focusing on cost they are starting to focus on weight. Weight also goes against gas mileage now to a minor extent against crashability.

    When I started looking at engines again earlier this week I was looking for a pushrod i or v 4 but they are all way too big for my needs. The older suzuki 3 cyl is a very robust and simple engine but alas iron block as I remember with an aluminum head. Loved that engine. Used to have one of the early Metro's. That thing was dirt cheap to operate and maintain. At this point I don't think we are going to get away from overhead cams on small engines in this class. 1.0 liters is plenty. I looked a lot at 4x4 750-1000cc engines. There are a lot of good choices there. Polaris/BRP makes some really nice compact aluminum engines in that category. Can be had used for cheap and rebuilt to zero time for cheap. I don't think a turbo set up for a ground vehicle is going to work.
     
  15. Oct 10, 2019 at 3:00 PM #15

    cheapracer

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    As I emphasized above, it only matters what it weighs, what it's made of is completely irrelevant.

    Ultimately the older original Suzuki GSX-R 750 and 1000, were primarily oil cooled over air (not water), and still one of the lightest motorcycles made, you might look into those or Yamaha FJ1200 air cooled engines if you want to stay away from water cooling.

    I have an FJ1200 engine in bits at the factory if you need the weight.
     
  16. Oct 10, 2019 at 3:23 PM #16

    Jay Kempf

    Jay Kempf

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    Don't want to stay away from water cooling. It is easier to fair and hide a radiator duct for a motorglider. Easier to bury and engine deep inside the fuselage and you don't have to worry about shock cooling, mixture, carb ice, yadda with a well thought out fuel injection system combined with a proper thermostat. There are plenty of modern sport craft engines out there from sleds to 4x4 to bikes. Bikes tend to be the high revving end of the spectrum. 4x4 more torque and better packaging. Sleds are in the middle. I think about a 800-1000cc 2 cyl with a turbo kit would be perfecto for what I am looking for. The 2 cyl engines are way more compact. Most are single overhead cam not set up for big revs but perfect for a mild amount of boost.
     
  17. Oct 10, 2019 at 3:36 PM #17

    Jay Kempf

    Jay Kempf

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    Just found BRP 900 ACE turbo 3 Cyl. Sheesh! Now that's a proper engine.
     
  18. Oct 10, 2019 at 4:36 PM #18

    cheapracer

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    Neither do I, but it seems to be a common theme among flyers.


    No problem, you merely use a higher ratio PSRU. I have seen some of the Yamaha 600s running 3:1. Of course you are also multiplying the lesser torque x 3, rather than the "more torque" (a very arguable point) by say 2:1 = status quo.

    Piston speed is what's important, not rpms (unless of course so low you can eliminate a PSRU). A short stroke Rotax 912 at 5800 rpm has a similar piston speed to a number of long stroke Lycomings at 2800 rpm for example.
     
  19. Oct 10, 2019 at 7:11 PM #19

    Jay Kempf

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    Agreed on piston speed. That is why a torque monster is a better choice than a motor that makes all it's power through higher RPM bands. And that is why a simpler lighter motor with a moderate turbo would be a good choice in my opinion. But it is all about power to weight in the end and then packaging for drag reduction for me. At some point soon I'll grab one of the choices on my short list and start experimenting. Motor has to be figured out long before the rest of the airframe. I have my airframe to the decision point of power plant. Just at the beginning of the first wave of acquiring CNC equipment and skills. That is all going really well so engine tech is next up. Now I can make all the parts I couldn't before.

    Assuming a smallish turbo motor: For takeoff you would need to be able to overdrive a fixed pitch prop that was pretty coarse. So it might limit its RPM for the first part of the takeoff roll until the prop starts to work. That means a pretty gutless start to the takeoff roll because you can't get the turbo to kick yet. Does that makes sense. You want a fairly high volume turbo for the cruise and max RPM so that you have that HP available at altitude (oxygen limit say). So how does one go about selecting a turbo for such an application. Run the NA engine candidate to collect airflow at different RPM? Use software to simulate, and if so which software? Then match turbo to best cruise performance target? Climb target? WOT top speed? All of the above?
     
  20. Oct 11, 2019 at 8:33 AM #20

    PW_Plack

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    I was quoting the website. Sorry!

    Mark, does your "dry weight" include engine oil? If it does, I apologize and stand corrected. The total of the weights you quoted for coolant would be only about three quarts. Does that really do the job?
     

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