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Discussion in 'Firewall Forward / Props / Fuel system' started by Armilite, Aug 10, 2019.

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  1. Aug 18, 2019 #61

    Armilite

    Armilite

    Armilite

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    That's coming from a Guy who has admitted to not ever building a 2 Stroke or 4 Stroke, has just recently bought a Broken 4 Stroke Engine to learn something, but still hasn't done anything yet, but he's an Expert in every field on here. Always ready with a Snide Comment, but no Good Info to contribute. Did you READ that 2 Stroke book yet I gave you links to, what over a year ago? Just like you, most people on here don't rebuild their own Engines and the very few who do, don't usually make Improvements. There called a Parts Changer, not Rocket Science. Engine Builders, Machine Parts, use better Parts than Stock, make things like a Tuned Pipe, add EFI, etc. I don't care if I get any replies, my goal is to show people their Engine can make more HP and still be reliable. I try to show web links when possible so they can READ for themselves.
     
  2. Aug 18, 2019 #62

    Armilite

    Armilite

    Armilite

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    ============================

    Do you have a Copy of this "wood bar dyno spreadsheet" that was posted on this Eagler's Nest forum? I would like to look at it. Those Bars are more for Testing the Engines Max HP at Rpm. As I said, it's not going to really tell you the fine Tuning Points down to a 1/10th of a hp, like Testing a Stock Air Filter vs a K&N on these Small Engines. You would need a lot of these Clubs to do that. I would like to see the results from both a Dyno and a Club on the same Engine also. Most Dyno Sheets use 250rpm/500rpm Increments, and they are only Interested in Max HP. I would do it in 50rpm/100rpm Increments if the Software let you go that low.
     
  3. Aug 18, 2019 #63

    Armilite

    Armilite

    Armilite

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    ===============================

    While the Club Prop could give you a Good Ballpark HP@rpm, it's not going to give you what you need to for Testing all the different Parts down to 1/10th of 1hp. Just the 377UL/380/380HO can vary from 35hp to 57hp, and 68hp if used at 112%. That's one heck of a lot of Club Props to make. I have probably seen (4) different 380HO Dyno prints, 57.26 to 64hp using 7000rpm to 7250rpm. (3) had large Dead Spots in the Power Band. So I would say Max 57-58hp if finely Tuned.

    Skidoo's eTec's have a better EPA Rating than it's 4 Strokes.

    Correct, Airflow(CFM) and Hp are loosely related, the AFR is what is Important, for 2 Strokes it's AFR 12.3, (12.4 ideal), 12.5, 12.6, etc. An Engine is an Air Pump, it can only move so much Air (CFM) at a given rpm.

    Most people just want to know Max HP@ rpm, I want to know that and also what each Stock Part makes, vs other Aftermarket Parts. You could put 5 different Brand Name Header Exhaust on a 4 Stroke and have 5 different hp results, it may be just only a 1/10th of a hp, might be 1-3hp. A seriously doubt any Club Prop is going to give you that Info.

    When you Pick/Size a Prop it's from your Max HP@rpm. The Peak Flow/HP Calc gives you a good Ball Park number to work with. You do have some dyno prints posted, but you really don't know what they all tested. Like the 380HO, if I was going to Design a UL Tuned Pipe for 6500rpm, I would use 368cc/7cc= 52.5hp round down to 52hp. The 380HO wasn't Sold in the Continental USA, so you would have to mill your 377F/377UL/380 Heads anyway for the 380HO(11.2cr) or 11.5cr Max I would prefer to use. With a Dyno, you could start out with the Standard 9.6cr, then go up .5cr(10.1cr) Dyno, go up .5cr(10.6cr) Dyno, go up .5cr(11.1cr) Dyno, go up .5cr(11.6cr) Dyno. If i could get up to 50-52hp@6500rpm I would be happy.
     
  4. Aug 18, 2019 #64

    Vigilant1

    Vigilant1

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    I'm not a member of that board, so I don't have copy of that spreadsheet. But it is just adapted from the Eiffel's equation as given in the previous HBA discussion here ( https://www.homebuiltairplanes.com/forums/threads/yourdyno-com.31082/#post-459318 ), if you'd like to build your own spreadsheet it wouldn't be hard. The discussion in the thread above contains some worked examples using Jan Carlsson's spreadsheet, so you could check your work that way, if you want.

    Yes and no. When you put a particular bar on the engine and then run it as fast as she'll turn, that will produce one "dot" for your dyno graph at one RPM and one HP. If you then make a change (different air cleaner, timing, intake runner length, etc) and the engine now spins that club faster, you know for sure, within the limits of your tachometer (and the optical ones are darn accurate) it is making more power at the previous max RPM (because it now has enough power after the change to hit that RPM and then spin the club faster), but the new "dot" you'll get for your new graph will be at a higher HP and a higher RPM.
    Now, to make a full dyno curve you'll need a few clubs. Most folks building/tuning airplane engines aren't much concerned about the max HP (or torque) their engines can make at 500 RPM, they'll make clubs that will cover the engine's output at their anticipated climb and cruise RPM, and a "too big" and a "too small" club on either side to assure they aren't leaving any available power on the table.
    You can cut as any clubs as you need.
     
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  5. Aug 18, 2019 #65

    Armilite

    Armilite

    Armilite

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    ================================================

    First, the term DYNO is a Machine that measures HP, Torque, many different things, like Rpm, Water Temp, EGT, CHT, AFR, GPH, etc.

    2nd, the proper Term is "Club Prop" that has (1) use to measure Torque at (1) Specific RPM.

    3rd, No, till now in 40+ years I have never seen a "Club Prop" put on an Ultralight or Kitplane. Just as people use the word Ultralight for all of these Planes, is wrong! If it doesn't make USA PART 103 Spec's, it's not an Ultralight, it's an Experimental, but today with the Rules change, it might be Classified as a Light-Sport.
     
  6. Aug 18, 2019 #66

    n3puppy

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    Well now I can see the reason for a lot of your confusion.

    HP as no bearing on VE calculations.


    I urge you to re-read your post #27 on page two of this thread.
    It is a great explanation of Volumetric efficiency
    But you will also find no reference to HP being a part of the equation


    "Volumetric efficiency in an internal combustion engine design refers to the efficiency with which the engine can move the charge of fuel and air into and out of the cylinders. It also denotes the ratio of air volume drawn into the cylinder to the cylinder's swept volume. [1] More specifically, volumetric efficiency is a ratio (or percentage) of the mass of air and fuel that is trapped by the cylinder during induction divided by the mass that would occupy the displaced volume if the air density in the cylinder were equal to the ambient air density. The flow restrictions in the intake system create a pressure drop in the inlet flow which reduces the density (unless boosts like turbos or superchargers or cam tuning techniques are used). Volumetric efficiency can be improved in a number of ways, most effectively this can be achieved by compressing the induction charge (forced induction) or by aggressive cam phasing in naturally aspirated engines as seen in racing applications. In the case of forced induction volumetric efficiency can exceed 100%."

    Do you see any reference to HP there? Of course not, because the Volumetric efficiency is all about airflow, not HP

    Once you wrap your head around this concept I am sure you will see why the PEAK flow calculator has problems estimating HP.

    Using the calculator backwards, to estimate VE instead of HP is not what the author had expected. It compounds the errors. F89CA9B1-D631-4F9D-B924-B20231E863EC.jpeg
     
  7. Aug 18, 2019 #67

    litespeed

    litespeed

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    I think this is going around in circles, which is fine at NASCAR.

    Yes, technically a club is not a dyno. However not all dynos provide all the numbers you suggest like cht, water temp etc.

    You need sensors to do that either already on the engine or added for testing. Either way it can only tell what it has sensors connected for.

    Therefore a club prop dyno can tell all of those things via the instruments of the aircraft.

    So when you wind up the prop too either the desired or max revs
    , you take a snapshot if those readings. Even if simply via a camera.

    So in effect you can get the exact same details needed. Graph the results and work from there.

    The only issue is lack of airflow for cooling but dynos have the exact same problem and add supplemental cooling to overcome this. For us , use a big fan.

    This is not rocket science.
     
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  8. Aug 18, 2019 #68

    Armilite

    Armilite

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    I see this example For little industrial engines:

    An engine of 22 claimed HP at 3600 RPM should be able to swing a 46.4mm x 46.4mm cross section club that is 696mm diameter at that RPM.

    An engine of 23 claimed HP at 3600 RPM should be able to swing a 46.8mm x 46.8mm cross section club that is 703mm diameter at that RPM.

    An engine of 28 claimed HP at 3600 RPM should be able to swing a 48.7mm x 48.7mm cross section club that is 731mm diameter at that RPM.

    And =SUM(0.0532*(696/450)^5*(3600/1000)^3) gives you 21.96861934 (22hp)

    What I don't see is how they came up with the 46.4mm x 46.4mm and 696 Numbers.

    They don't specify what kind of Wood they used.

    As I said, I doubt this would work for what I'm talking about, Testing these parts down into the 1/10th of a 1hp. But it might be good enough to Test once you're done.

    Each Engine HP@rpm is going to be different, so a lot of Clubs. For these Part 103 Ultralights you probably only need a 30hp, 35hp Prop Clubs. You know from R&D Aero's 277UL Dyno Sheet Stock it made 25.4hp@6000rpm. It already uses Max CR 11.8cr, so Bigger Carb, Porting, use a little higher 6500rpm, and a Tuned Pipe or a better Muffler is about all you can do. 268cc/7cc = 38.2hp@6500rpm is about Max. You can see by the Dyno Sheet it started losing power after 5500rpm, so either Carb or Exhaust. I would like to get a hold of one of them Scat Hover Craft exhaust pipes or Dyno Sheet to see if it makes a difference. They rated it 28hp@6400rpm.
     
  9. Aug 18, 2019 #69

    Vigilant1

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    It can be calculated using the formula. In this case, they put in the claimed HP of the engine (22) and the RPMs at which that HP was supposed to be achieved (3600). You can either re-arange the equation so you are solving for the club diameter (red 696 shown in the solved equation) or, I suppose you could just keep plugging numbers into that slot in the equation until it gave the answer of "22". And that number would be 696, which is the length of the club (its diameter). Then, the club's cross section is square, and each side is always 1/15th of the club's length, so 696mm/15 = 46.4mm.
     
  10. Aug 18, 2019 #70

    Armilite

    Armilite

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    ==============================
    The Calc only Ask:
    Displacement: 368cc
    Volumetric Efficiency: You don't know (But Using that known 57.26hp you dial in the VE which comes in at 94% = 57hp)
    Engine Type: 2 Stroke
    Peak Power Engine Speed: 7000rpm

    It Generates this by your Input, at 94%:

    Peak Intake Flow Rate: 86 cfm 40 litres/sec
    Peak Horsepower: 57 crank hp

    You know from the Dyno Print it made 57.26hp@7000rpm (Fact)

    You can see by the Dyno Sheet it made around 52hp@6500rpm. (Fact)
    Porting Specialist Simple Rule: 368cc/7cc = 52.5hp@6500rpm (Fact)
    BMEP/PLAN Formula says: 52.1hp@6500rpm (Fact)

    At 100% 368cc at 7000rpm the 380HO can only Flow Max 91cfm. (Fact)

    Stock Skidoo 670(669cc) Dynoed 115.7hp@7750rpm = 94% Fact Tuned Pipe!
    Stock Skidoo 617(617cc) Rated 106.0hp@7750rpm = 94% Fact Tuned Pipe!
    Stock Skidoo 583(580cc) Rated 98.0hp@7750rpm = 93% Fact Tuned Pipe!
    Stock Skidoo 521(521cc) Rated 89.0hp@7750rpm = 94% Fact Tuned Pipe!

    Stock Rotax 277UL(268cc) Rated 26hp@6250rpm = 65% Muffler!
    Stock Rotax 377UL(368cc) Rated 35hp@6500rpm = 63% Muffler!
    Stock rotax 447UL(436cc) Rated 40hp@6500rpm = 60% Muffler!
    Stock Rotax 503UL(496cc) Rated 50hp@6500rpm = 66% Muffler!


    Now, None of these Dyno Prints even come close to 68hp 112% 102cfm. You can't have it both ways, either it's 112% 102cfm 68hp or it's 94% 86cfm 57hp. (3) other Dyno Sheets say Max 56hp@7200rpm - 62hp@7400rpm. All (3) have terrible Power Bands. Which is most logical 94% or 112%? I'll go with the Math on the Airflow. Hp range 56-62hp Max.

    The 277/377/380/447/503 is probably limited to Max 38mm Carb.

    Here is one says 377 Sled Pipe not to bad, but Power Band is too High for UL use, about 61-62hp@7450rpm. But Only about 48-49@6500rpm.

     

    Attached Files:

  11. Aug 18, 2019 #71

    Armilite

    Armilite

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    Ok, now it makes sense. I'm Brain Dead.
     
  12. Aug 18, 2019 #72

    n3puppy

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    Lets look at some of your FACTS from your Post#70 above. I put your statements in italics ( sorry I don't know how to make pretty colors ...)

    The Calc only Ask:
    Displacement: 368cc
    Volumetric Efficiency: You don't know (But Using that known 57.26hp you dial in the VE which comes in at 94% = 57hp)
    Engine Type: 2 Stroke
    Peak Power Engine Speed: 7000rpm


    FACT - The calculator is named
    PEAK INTAKE FLOW RATE/PEAK INTAKE HORSEPOWER CALCULATOR
    FACT - It was designed to calculate FLOW and HP
    FACT - It was not designed to dial in a horsepower to estimate VE
    FACT - You are using the calculator in a way not intended

    It Generates this by your Input, at 94%:
    Peak Intake Flow Rate: 86 cfm 40 litres/sec
    Peak Horsepower: 57 crank hp
    You know from the Dyno Print it made 57.26hp@7000rpm (Fact)
    You can see by the Dyno Sheet it made around 52hp@6500rpm. (Fact)
    Porting Specialist Simple Rule: 368cc/7cc = 52.5hp@6500rpm (Fact)
    BMEP/PLAN Formula says: 52.1hp@6500rpm (Fact)
    At 100% 368cc at 7000rpm the 380HO can only Flow Max 91cfm. (Fact)


    Yes all of those are facts - but
    You forgot the three BIGGEST FACTS
    1) You KNOW from the Dyno Sheet airflow is 102CFM @7000 rpm
    2) You KNOW from the Dyno Sheet airflow is 95CFM @ 6500 rpm
    3) You KNOW from the Dyno Sheet a 377 CAN flow More than 100% and 91CFM. It can Flow 102CFM at 7000RPM and 104CFM at 7500Rpm
    You can't leave out FACTS because you don't like the result.

    Stock Skidoo 670(669cc) Dynoed 115.7hp@7750rpm = 94%
    Stock Skidoo 617(617cc) Rated 106.0hp@7750rpm = 94%
    Stock Skidoo 583(580cc) Rated 98.0hp@7750rpm = 93%
    Stock Skidoo 521(521cc) Rated 89.0hp@7750rpm = 94%
    Stock Rotax 277UL(268cc) Rated 26hp@6250rpm = 65%
    Stock Rotax 377UL(368cc) Rated 35hp@6500rpm = 63%
    Stock rotax 447UL(436cc) Rated 40hp@6500rpm = 60%
    Stock Rotax 503UL(496cc) Rated 50hp@6500rpm = 66%


    NONE OF THOSE VE% NUMBERS ABOVE ARE FACTS - They are Guesstimates from the calculator

    Now, None of these Dyno Prints even come close to 68hp 112% 102cfm. You can't have it both ways, either it's 112% 102cfm 68hp or it's 94% 86cfm 57hp.
    FACT - There is a third option you are conveniently forgetting
    7000 RPM 112% 102CFM 57HP
    FACT
    - The third option is the ONLY DYNO MEASURED OPTION of the three.
    FACT - Your options 1 and 2 are calculated GUESSTIMATES


    (3) other Dyno Sheets say Max 56hp@7200rpm - 62hp@7400rpm.
    All (3) have terrible Power Bands. Which is most logical 94% or 112%? I'll go with the Math on the Airflow. Hp range 56-62hp Max.


    FACT
    - you are not going with the math - you are ignoring it
    You are not doing math, you are blindly following the output of a calculator that the author admits guesses HP. Along the way you conveniently forget what the Dyno Says

    If you were doing Math using actual Dyno measurement you would know
    CFM x 28316.85 x 100) / (CC x RPM) = VE%
    (102CFM x 28316.85 x100) / (368cc x 7000rpm) = 112.12% VE 69B81449-02FF-4D7E-A15B-C3FDD68DD236.jpeg 7ABE5ACB-7311-4706-BF45-9594DE704A0A.jpeg


    .
     
  13. Aug 18, 2019 #73

    n3puppy

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    I am also having trouble finding the Wood Dyno spreadsheet

    Did find this data the Eagles nest forum
    https://www.eaglersnest.com/forum/index.php?topic=281.0

    It has the spreadsheet results for 6 lengths of wood.
    28,30,32,34,36,38
    Also shows the formula to make your own spreadsheet
    Put in my tablet and got same anwers as the posting

    I attached the printouts below - but may be hard to read if you don't actually go to the link 7F861849-C5A5-4AB2-AD80-544B1F51FB3F.jpeg 4EFACA42-24C4-42F7-AC9C-86B1D861FE50.jpeg
     
    Last edited: Aug 18, 2019
  14. Aug 18, 2019 #74

    pictsidhe

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    Here's my club dyno spreadsheet. I had to write it myself, like most of the spreadsheets I use. It is based on Eiffel club formula found online.
     

    Attached Files:

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  15. Aug 18, 2019 #75

    pictsidhe

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    WTF? I've been rebuilding engines since I was 9 years old. I wasn't as good back then, but I've had a lot of practice since. I had to rebuild the engine for my first car before I could drive it, that was an unusually powerful and frugal engine that did 80k in 3 different cars. I designed and built my first tuned pipe at 13, from old washing machine panels. I couldn't find any formulae in my magazines or the local library. The internet was just a twinkle in Tim Berners Lee's eye, so I derived my own. It worked. Does that make me a parts changer?

    Your goal seems to be spam us with endless posts based on magazine articles, adverts and dodgy online calculators whose theory you don't understand. You show hotrod stuff, nothing that is built to run for long periods at high throttle. You don't do any own your own math or research, just find hyped products to bolt on and people to do work for you.

    How many engines have you stripped down that ever ran again? I've done three just this weekend, side jobs from my day job.

    Oh, I built a few of my own rockets when I was 10. I made the motors for them. From junk and chemicals, none of the off the shelf hobby nonsense we have now. I guess that does make me a rocket scientist?
     
    Last edited: Aug 18, 2019
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  16. Aug 19, 2019 #76

    PW_Plack

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    I've found it avoids wasting time if I just skip over posts which appear to be based on the notion that a wall of text is more powerful than concise thoughts.

    I have an engine project coming up, and I think if I post about it I'll do one of those build threads that doesn't allow comments, just to avoid this phenomenon.
     
  17. Aug 27, 2019 #77

    Armilite

    Armilite

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  18. Aug 27, 2019 #78

    Topaz

    Topaz

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    Indeed. Gentlemen (and you know who I mean), if you don't knock it off, I'm going to lock this thread. Keep bickering like you have, and I will. PM sent to both of you.
     
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  19. Aug 28, 2019 #79

    n3puppy

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    BUYER BEWARE - found something interesting digging into the Lifan manuals and literature

    Home Depot lists the 24HP Model number as LF2V78DS in one spot and 24 MHP in another

    The Lifan site has a listing for the 24MHP 690cc. - Number LF2V78DS
    BUT - when you go to the owners manual - It brings up the 640cc 17 HP version

    When you go to other distributor websites around the world(Canada Australia) you get these kind of interesting specs

    Max Power Output 24 Hp
    Recommended power usage - 18.5Hp @ 3600 RPM

    Makes me think the 24HP must be at some much higher RPM - maybe 4500-5000ish ?

    A8847396-634B-43E1-A360-7A51C2FD620F.jpeg 69805889-9D65-419B-9424-FE60FC63C938.jpeg
     
    Last edited: Aug 28, 2019
  20. Aug 28, 2019 #80

    Topaz

    Topaz

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    Yes, most of these industrial motors seem to generate maximum power at about 4,000 RPM. Nothing unusual about that.
     

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