Nissan's new 400 bhp engine

Discussion in 'General Auto Conversion Discussion' started by Richard6, Feb 2, 2014.

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  1. Feb 4, 2014 #21

    raven-rotor

    raven-rotor

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    Ross

    Sounds like there is a little confusion between the 660cc turbo Suzuki® I mentioned and the new Nissan® 1.5L turbo. Over five years ago I worked with a customer who was part of Arctic Cat's (partly owned by Suzuki®) snowmobile race team. Suzuki's 660cc production turbo car engine was tweaked just a little to make 120HP at 7000RPM which was at 14 lbs. of boost or a little less than 30 inches if I remember correctly. This engine would run flat out in the touring sleds all day long and get pretty decent fuel economy. I built a custom redrive for his engine and he mounted it in a Zenith® 701 with great results. He never even had to give it full throttle for takeoff. He told me the hill climb sled racers would race this engine season after season dialed in for 34 lbs. of boost and putting out over 200 HP at 10,000 RPM without a failure of the base engine- not bad for 660cc.

    If you take the Suzuki® production version 660cc turbo performance and build a new engine at 1.5L displacement you will get 272HP at the same 7000 RPM.
    Derate it some in both boost and RPM down to 150HP and you are still looking at a reliable 1 pound per HP engine package. The same weight as a Rotax® 912i with 50% more HP. Practically doable now with 10 year old technology. IMO that is game changing technology. Also Suzuki®/Arctic Cat® was producing this reliable power level without GDI. That's what excites me about what Nissan® is doing- you can only pray that the race tricks will trickle down into their base production automotive engine in a few years.

    Jeron
    Raven ReDrives Inc.
    303-440-6234
     
  2. Feb 4, 2014 #22

    rv6ejguy

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    Jeron, sorry, I think my post was a bit confusing above- too early in the morning and rushing.

    The base weight of this 1.5L Nissan is impressive, no doubt about that and is possibly due in part to an MMC block and some titanium bits inside (speculating here). Someday we may see some of this technology trickle down into Nissan production engines.

    If this engine does make it into mass production then it looks like a good pick on the surface but I'd really worry about the TV signature on something like this turning a PSRU and prop. I've had many customers dump their G10s for G13s after living with them for a while... A 1.5L 3 cyl. running boost would be worse. There are way around the TV problems but they involve more money and proper testing to fix and validate. I am personally no fan of 1, 2 or 3 cylinder engines in aircraft. Just heard of too many bits cracking and falling off.

    While high hp and rpm figures can show the ultimate strength and design margins of engines (I've seen bike based 1000cc sled engines producing over 500hp on the dyno) this sort of usage doesn't demonstrate directly how much life we might see on a de-rated version powering an aircraft.

    A good breathing, 4 valve 1.5L engine should produce 135hp at 5000 rpm with less than 40 inches Ab MAP and that should still leave us with some decent life if everything is handled in the thermal department properly.
     
    Last edited: Feb 4, 2014
  3. Feb 5, 2014 #23

    cheapracer

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    H2 Busa

    I think the Hartley H2 fits in here somewhere as a real world example ...
     
  4. Feb 5, 2014 #24

    Jay Kempf

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    3 cyl engines are actually quite smooth. Half a V6 basically. 5 cyl engines are really smooth. I have had a bunch of 3 and 5 cylinder cars. Some of the most smooth engines I have owned. 4 cyl VW and Subaru shake like washing machines at certain RPMs. I would much rather fly behind some sort of inline watercooled engine any day. But they haven't had development in aviation since Hitler was funding it. So everyone alive today has an idea that a flat 4 aircooled engine is the pinnacle of engineering. There is a reason why the largest numbers of engines in the world are not flat 4 carburated air cooled engines.
     
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  5. Feb 5, 2014 #25

    rv6ejguy

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    From a TV point of view, 3 cylinders are nasty beasts plus have an annoying rocking couple. Perceived smoothness does not have much to do with TV and in any case, a well designed opposed or inline 4 should always be smoother than a 3. Turning a prop through a PSRU is not the same as in a ground vehicle. You can ask Dan Horton about 3 cylinder engines and TV problems as he has extensively measured TV through instrumentation as well as flown them and suffered failures on them. Solvable but not to be underestimated.

    Jeron can maybe comment on how he addressed the problems on the G10.

    I sold about 10 EFI/ ignition systems for the G10 and the engines ran well but after a few years, 6 of those customers had the system converted over to a 4 cylinder system and switched to G13s. They hated the vibration levels of the 3 cyl. Every one reported a huge reduction in vibration levels with the G13 and less problems with stuff cracking on the airframe as well.

    Generally, more cylinders = less TV.

    The G10 I had a few years back running on a stand was terrible compared to an EA81 I had on the same stand.
     
  6. Feb 5, 2014 #26
    Jeff, while you are halfway there, you are also only half weigh there. Pardon my clumsy attempt at humor, but the first consideration for an engine setup has to be determining how much actual nose weight the airplane can fly with. You will be at a weight disadvantage with any water cooled engine, so every pound you save will be important. Next determine how much actual horsepower the airplane of your dreams can actually use. Ben Haas can tell you about the effects of having more horsepower than you can use. Remember that for every action there is an equal and opposite reaction......and its can be very traumatic when it happens while flying. If you need more power, the great thing about an LS engine is that you can increase its cu in size without increasing its weight. A 346 (350) LS1 weighs essentially the same as a 377, 383,408,415,427 LS engine. Just divide the cu in by 2 and you have the approximate hp that should be available. Actually with a little tweeking and selective parts usage, you should easily exceed that hp rating. I recently purchased some 1998 LS1 heads off Ebay for $125. Think about that, a complete set of aluminum heads with valves and springs and keepers and valve covers for $125. I specifically wanted these heads because they have perimeter bolts on the valve covers and I trust them to seal better than the centerbolt ones. A complete NEW (off a crate engine) truck intake with NEW INJECTORS and Fuel Rail can be had for $200. Used manifolds with the same parts and a throttle body can be purchased for $100. Brand New ALL ALUMINUM LS3 blocks go for $1700 and the LS1 style can be had for even less. By the time you buy and remachine and test a used cast iron block, you will have close to that much in it. It will take some time and money to build a direct drive, but its lighter and you don't usually need a reduction drive unless you can actually use more that 200/250 hp in your airplane.
     
  7. Feb 5, 2014 #27

    RJW

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    Yes. One must understand static, dynamic, and deflection balance in piston engines as well as ignition timing. Once this is figured out it becomes clear how configurations like inline 3s, inline 4s, 90-degree V8s, 90-degree V6s, and bunches of others appear to run “smooth”. With the exception of very few configurations (flat 8, 60-degree V12, etc.) all piston engines must use additional parts to run “smooth”. The extra stuff is in the form of heavy counterweights on the crankshaft and the use of balance shafts. So there are at least two fundamental reasons why “imperfect” configurations with few cylinders like inline 3s will always be less suitable for aircraft than “perfect” configurations—vibration from "imperfect" balance, and vibration from torque reversals.

    If somebody wanted to get serious about building the lightest small aero engine using modern technology then they should build a geared, high rpm, small displacement, probably liquid cooled, and probably single overhead cam flat eight.

    Rob
     
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  8. Feb 5, 2014 #28

    BBerson

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    All engines have torque reversals between the various cylinder. The longer the engine the more complex the problem becomes. It was found in the early days that direct driving a prop with more than 6 cylinders in line was not worth doing.
     
  9. Feb 5, 2014 #29

    Himat

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    I have seen the argument that as a V8 has no torque reversals, there will be less problems with torsional vibrations. After I have been thinking about this for a while, I do doubt if the argument is valid. If the mechanic system including the propeller, engine and if fitted a reduction gear is a linear time invariant system, a property of many mechanical systems, the principle of superposition of forces is valid. A pulsating force can then be deconstructed in one steady state and one time variable force. One possible representation of this time variable force is then as a force with reversals around equilibrium. There is then no difference between a pulsating force with and without force reversals.

    To tie this to the high reving engine, only the frequency of the torque peaks matter as this decide if the system is exited.
     
  10. Feb 5, 2014 #30

    Toobuilder

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    Just so we're on the same page, torque reversal discussion here.
     
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  11. Feb 5, 2014 #31

    stol

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    Huh...... Have you built and flown an aircraft with a V-8 motor in it?????
     
  12. Feb 6, 2014 #32

    raven-rotor

    raven-rotor

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    Ross

    Do have a lot of experience with the 3 cylinder Geo and developing a redrive to handle its torsional resonance quirks successfully. After 19 years I've found that for most folks its just to technical a subject to grasp and solve with common sense solutions. Even Rotax® dumbed down their 505 and 582 gearbox coupler so you just had to rev the engine above 1800-2000 RPM to get above the primary resonance range. Try idling one at 1000RPM if you need a refresher course in what we are talking about when we used the term torsional resonance. The article at this top of this section regarding torsional resonance is a great overview.

    The Nissan 3 cylinder is using Gas Direct Injection and I will make a wild assumption that the timed fuel burn front possible with this sophisticated system will also enable them to modulate the peak firing impulses- which are going to be high with this kind of boost. This is already being done as I'm sure you know on the diesels. Remember we have also not seen the flywheel (and or) generator that is coupled to their hybrid system. I notice they also have no substantial bell housing cast into the block so I'm curious. The resonance IMO could be a challenge with this engine converted to drive a prop- but doable. If Nissan® would hand me one of those engines and borrow me one of their techs on an in-house dyne, I'd be happy to develop a prop redrive for this little guy!

    Hope this helps.

    Jeron
    Raven ReDrives Inc.
    303-440-6234
     
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  13. Feb 6, 2014 #33

    rv6ejguy

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    I understood this engine is driving a gen set so it has no provision for attachment to a transmission.

    I don't believe that GDI offers any significant reduction in TV on an SI engine. A 3 cylinder SI engine of any sort has very similar TV signatures, only high flywheel inertia or an engineered TV absorber systems to tune large amplitudes out of the operational rpm range post-output can tame what is basically pretty nasty coming off the crank. There are many damper/ absorber designs out there but I'd suggest an instrumented approach or at minimum a mathematical approach as I did on my system using Bifillar inertia measurements and Holzer models to calculate resonate ranges and amplitudes. I agree, certainly doable given the right tools.
     
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  14. Feb 6, 2014 #34

    rv6ejguy

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    Ah, no. Any 4 stroke engine with 8 cylinders or more does not technically have torque reversals but there is still torsional vibration in any piston engine, no matter how many cylinders it has. The main concern is the interaction of the two main inertias- engine/ drive gears and driven gears/propeller and the stiffness of each part involved. A V8/V12 system with high stiffness can often be pretty successful with minimal or no damping between elements, even using a light flywheel. With a 2, 3, 4 or 6 cylinder engine, most likely not. You can clearly see this by running the math or if you instrument an engine/ PSRU/ prop setup. With a fixed displacement, more cylinders is always better as far as TV amplitude goes.

    Sometimes people are lucky with very stiff or very pliable elements but it's not a very scientific way of designing a PSRU. In the end, only lots of trouble free flight time can really validate either an eyeballed design or an engineered one.
     
  15. Feb 6, 2014 #35

    Himat

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    No, but I do know that you and others have built and flown aircraft with V-8 motors.
    And you have proven that it does work!
    With a very nice aeroplane.
     
  16. Feb 7, 2014 #36

    Jeffd

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    There is no weight disadvantage when directly comparing the LS engine we are using in the P85 to the M-14 radial engine used in the Radial Rocket. In fact The LS package, with fixed pitch prop, will be about 50-70 lbs lighter than the M-14 package with CS prop. Adding CS capability to the LS package would make it essentially an even proposition. This weight comparison is for the entire propulsion package which includes engine , redrive, prop, engine mount, oil and coolant heat exchangers, exhaust, etc. And bear in mind that the M-14 power to weight ratio is reported to be superior to an equivalent power Lycoming or Continental, I assume at the 350 hp level. The M-14 comes in 360 and 400 hp flavors, no weight difference. The most recently built Radial Rocket RG has an "updated and enhanced" 400 hp M-14 which dyno'ed at 428 hp, for an even better power to weight ratio.

    So... the weight of either propulsion package works nicely in our P85 airframe, which has been structurally and aerodynamically designed for this level of hp. The traumatic effects of having more horsepower than you can use at these power levels? - no trauma whatsoever with the Radial Rocket/P85!

    Our mildly built LS engine should easily deliver 425 hp to the prop. LS power potential is way beyond this, if that is what one wants. Tempting. if you can afford the fuel flow.

    Jeff
     
  17. Feb 7, 2014 #37
    Reply Jeff, I agree with what you said in the example you are applying the conversion to. When you talked of using direct drive, you didn't mention that you wanted 350 hp, or were using it in an airframe that will be significantly heavier than what most of us are dreaming about. Of course, in a heavier airframe you can deal with larger torque moments than someone in most low n slow two seaters can. In your scenario, where the rpms will be greater (3600/4400), you should easily be able to achieve 350 hp with a stock LS3 engine. To get more than that at the rpm range you want, will probably take either a 408/427 cu in combo. You just need to decide which cam will provide opening and closing events complimentary to your needs, and which heads will supply airflow sufficient to the rpms you plan to run. From my research, I don't think LS7 heads would be best. Maybe some LS3 heads, which can be purchased brand new and already CNC'd for about $1200. Thats really a smokin deal. Or you might even be happy with a cheap pair of LS1 or LQ9 heads with a little porting. The LQ9 heads have the same ports as the more expensive and rare LS6 heads,and larger combustion chambers for lower compression in a 4" stroke engine. Coincidentally, I was cleaning up some of my accumulated clutter and stumbled across an old article from Super Chevy Magazine. The article was on building a 427 cu in smallblock Chevy for torque. They were able to get 570 ft/lbs and 512 hp. Torq/HP @ 2600 rpms 507 ft/lbs/251 HP. The torque curve stayed linear and well above 500 all the way to 4000 rpms where it read 570 ft/lbs/434 HP. It reached 348 HP (538 ft/lbs) at 3400 rpms. One of the keys to this was using heads with Edelbrock 170 cc runner heads. Apparently there was some question as to whether these small heads could handle the airflow. This was with a smallblock, so I would expect it would not be too difficult to meet or exceed these results with an LS style engine. One thing, they used an 11:1 compression ratio, which I would consider to be too high for an airplane engine. (Reference Super Chevy April thru August 2005 Follow on articles trying other head combinations) Also recommend Car Craft March 2014 Ask Anything Column by Jeff Smith Max Torque at Low RPM The "Ask Anything" should be a priority read for all the guys who are interested in Low RPM direct drive Chevy (????) conversions.
     
  18. Feb 8, 2014 #38

    rv6ejguy

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    Jeff already has the engine built and dynoed for the P85 project...
     
  19. Feb 9, 2014 #39

    Jeffd

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    And here it is:

    image.jpeg

    The simple cardboard template is in place to double-check the cowl loft line developed using Solidworks.

    Sorry about any confusion - my interest in direct drive was not connected to the P85 project, which was to use a high hp gear-reduced V8 from the outset.

    Direct drive (possibly turbocharged) would be a nice power plant for a smaller lighter airframe that would still accelerate well with the required smaller diameter prop.

    ekimneirbo - thanks for posting the direct drive SBC info - good stuff!

    Jeff
     
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  20. Feb 9, 2014 #40
    Reply You are welcome Jeff. Sorry that I was confused about what you were asking about. Your project looks to be well on its way, and I wish you well in its completion and success.
     

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