# HOME DEPOT LIFAN ENGINES

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

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1. Aug 16, 2019

### Vigilant1

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2. Aug 17, 2019

### Armilite

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Those are for Engine Testing to give a load for Certified Airplane Engines which there is usually (1) Type like a O-200, not 30+ different CC 2 Strokes or these Small Honda/Clone 4 Strokes which there is 25+ different Brands and many CC Size. Sure isn't going to tell you crap about changing to different Air Filters, only a Dyno will.

3. Aug 17, 2019

### Vigilant1

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You could cut 5 or 6 clubs in less than an hour and use them to find the torque/hp curves for all types of engines of the appropriate size. And you can use them to test/retest the same engine after making modifications (air filters, timing, or a new cam, etc). It's very simple and this simplicity makes the readings more repeatable. It >is< a dyno, but you record the results manually.

akwrencher likes this.
4. Aug 17, 2019

### Armilite

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On many of these Dyno results, you don't really know what they were really Testing, so you have to take them as they are. Did they add a bigger Carb, did they use a different tuned Pipe, raise the CR, etc. You really don't know.

5. Aug 17, 2019

### Vigilant1

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It is more fundamental than that--you don't even know if the dyno is accurate--when it was last calibrated, how it is being maintained, etc. These commercial dyno shops want business, and folks who go to dyno shops want high numbers. And they tell their friends . . . "That Jim-Bob really knows how to run the dyno to get the best results from an engine. Look at this chart from my last run! You should give him a try!"

Last edited: Aug 17, 2019
6. Aug 17, 2019

### Armilite

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First, you have to understand, Stock Engines aren't built to make Max HP or you Happy, they're made to fit into a Hp Categories for the Manufacture so he can sell you the next lastest and greatest Engine for more $with a little more HP. No, I didn't miss your point. The Peak Flow Calc doesn't know what your Tuned Pipe was Designed for. You are correct, the HP will fall off shortly after it's designed Max Rpm. Stock rpm for Skidoo Fan Cooled Sleds is 7000rpm, for Ultralight use, 6500rpm is Industry Standard. CFM is figured from your Bore & Stroke & rpm used. Were not building Race Engines, were building these for plane use. Every Engine has different Port Sizes and a Max Size Carb that can be Bolted on. For example, my Standard Skidoo 335(78mm x 70mm) 334.6cc Single, Intake Port is 25mm x 47mm = 1175sq mm and came with a 32mm Carb, rated 20hp@5500rpm, and used 9.0cr, and my Skidoo 340 TnT (78mm x 70mm) 334.6cc Single, TnT Intake Port is 29mm x 47mm = 1362sq mm and came with a 38mm Carb, rated 26hp@6500rpm, and used 10.5cr. So 1175sq mm to 1362sq mm = 16% more Air at any given rpm! With a 32mm carb the 335 is Starving for Air above 4500rpm on the Top End. Max Carb that can be Bolted on a 335 Cylinder without Machining, I think is 36mm. The 340 TnT Cylinder can use up to a 44mm Carb. We are given by the manufacture, Skidoo/Rotax that a Standard: 377/380 with 30mm Carb = 36hp@7000rpm and uses 9.6cr! Volumetric Efficiency = 60%. 380HO with 30mm Carbs = 48hp@7000rpm and uses 11.2cr! Volumetric Efficiency = 79%. The 380HO Dyno Sheet that shows 57.26hp@7000rpm! Volumetric Efficiency = 94%. It has a fairly Smooth Power Band, not 100% perfect, but Good. I have seen a few 380HO Dyno Sheets making 62-64hp @ 7250-7400rpm with terrible Power Bands. We don't know what they really Tested on any of these, what Carb Size was used, what the Pipe was Designed for, if the Engine was Ported, if the CR was raised, account these Dyno Sheets don't say. So for the 377/380 we have a best Dyno Sheet Powerband at Max 57.26hp@7000rpm and shows making about 52hp@6500rpm. 368cc making 52hp = 94%. Which Is right inline with my 670 dyno Sheet. Is the hp off 1-2hp, could be, but unless you have a Dyno in your pocket it's the best we have to use. Do most of these Engines need bigger Carbs, Yes. All Rotax UL Engines use 36mm Bing 54 Carbs. Hirth's and Simonini Engines use 34mm. You can see where the 277UL is Starving for Air on the Top End after 5500rpm. 377UL Single 36mm Bing 54 35hp 377F 30mm Mikuni 36hp 380HO Pair of 30mm Mikuni 48hp The Peak Flow/HP Calc Says: Please note, the Horsepower figure is a rule of thumb approximation, unlike the Flow Rate figure. Volumetric Efficiency: (Unmodified engines are about 90% / engines with modifications are about 95% / seriously modified engines can achieve 100% or more) Now they don't tell you, but this was probably Designed for Motor Cycles which are big in the UK, which most use a Tuned Pipe, which is why they say (Unmodified engines are about 90%). Many Snowmobile's and Ultralight Engines only use Mufflers which are 20-40% less efficient. Hence a 277UL with a Rotax Muffler Dynoed 25.4hp@6000rpm = 65%. If, a Good Tuned Pipe was added, say 30%, now equaling 95% = 36hp@6000rpm, 37hp@6250rpm, 39hp@6500rpm. If, you use the 7cc Rule of Thumb for 6500rpm, 268cc/7cc = 38.2hp@6500rpm is possible with a Good Tuned Pipe. 1971 335(334cc) Standard 20hp@5500rpm with 9.0cr, with a Muffler. A little less than 50%, 48% efficient. 1971 340 TnT(334cc) 26hp@6500rpm with 10.5cr, with a Muffler but with Larger Tubes. = 50% 1971 340 Blizzard(334cc) 36hp@????rpm with ??.?cr, with a 1st Generation Tuned Pipe. = 70% 7. Aug 17, 2019 ### Armilite ### Armilite #### Well-Known Member Joined: Sep 6, 2011 Messages: 3,022 Likes Received: 243 Location: AMES, IA USA ========================== True, there are some unscrupulous people in the World, but most are Honest. Do they all know How to run the Dyno, do they move the throttle at an even pace? If I was Paying to have my Engine Dynoed, I would be there to watch everything. You can Dyno the same Engine on 6 different Dyno's and there will be so much +/- in hp. I'm not going to argue over maybe 1-2hp. 8. Aug 17, 2019 ### Armilite ### Armilite #### Well-Known Member Joined: Sep 6, 2011 Messages: 3,022 Likes Received: 243 Location: AMES, IA USA ================================= If it's so easy, then Why haven't you, or anyone else on here done it? 9. Aug 17, 2019 ### Vigilant1 ### Vigilant1 #### Well-Known Member Joined: Jan 24, 2011 Messages: 3,744 Likes Received: 1,655 Location: US I don't need a dyno. You're the person who said you did. I brought up this approach. You've said you've never heard of it. So I explained the basics and provided a lead on where you could learn more. n3puppy gave you more info, documentation, and photographs. You're welcome. Good luck. Last edited: Aug 17, 2019 10. Aug 17, 2019 ### Armilite ### Armilite #### Well-Known Member Joined: Sep 6, 2011 Messages: 3,022 Likes Received: 243 Location: AMES, IA USA ============================ Yes, it's nice to know your Fuel Burn Rate. Most 2 Strokes with Oil are running a 12.4 to 12.8 AFR. If you compare the Stock 277UL R&D Aero Dyno Sheet to their Tuned Pipe. At say 5500rpm, both show 1.8 but your talking 23.2hp@5500rpm vs 26.2hp@5500rpm. This was done in the early 90's. Stock 277UL Dynoed 25.4hp@6000rpm. http://www.rotaxservices.com/dyno.html#13 277UL with R&D Aero Mild Tuned Pipe. Dynoed 30.5hp@6250rpm. +5.1hp. http://www.rotaxservices.com/dyno.html#14 11. Aug 17, 2019 ### n3puppy ### n3puppy #### Active Member Joined: Jun 25, 2019 Messages: 35 Likes Received: 9 Once again you are ignoring the facts shown by the377/380 Dyno graph. The 377/380 is not 94% Volumetric Efficient at 7000 rpm At 7000 rpm the engine is Flowing 102 CFM 368CC flowing 102 CFM @ 7000rpm = 112% VE Do you understand the equation for Volumetric efficiency? It is very simple Measured CFM / ( Engine Displacement x RPM) No need for HP to figure Volumetric Efficiency No need for CR to figure Volumetric Efficiency No need for Exhaust type to figure Volumetric Efficiency No need for ANY other engine parameter NONE of those things affect the Volumetric Efficiency Equation All you need to know is airflow, displacement and rpm The formulas for 2 stroke engines are shown below in spreadsheet format so you can create your own Calculator 2 stroke described in Cubic inches (CID) (CFM x 1728 x100) / (CID x RPM) = VE% 2 Stroke described in Cubic Centimeters (CC) (CFM x 28316.85 x 100) / (CC x RPM) = VE% Let's try the 377/380 engine that you posted From your Dyno Print - 368 cc @ 7000rpm @102CFM (102 x 28316.85 x100) / (368 x 7000) = 112.12% VE Want more proof? Your calculator says the same thing In the appropriate fields enter: Use = Metric Displacement = 368 CC Aspiration Type = Normally Aspirated Volumetric Efficiency = 112% Engine Type = Two Stroke or Rotary Peak Power Engine Speed = 7000 rpm Hit "Calculate" Button Result - Peak Power Flow Rate = 102 CFM EXACTLY what the DYNO showed Every time you post that the 377/380 is 94% efficient at 7000RPM, you are posting proven false data. Every time you post volumetric efficiency for any other engine based on the calculator (not measured) you are also posting potentially false data. BMEP numbers would be 100% correct. Your choice for what you want people to see - False data or correct data Last edited: Aug 17, 2019 12. Aug 17, 2019 ### n3puppy ### n3puppy #### Active Member Joined: Jun 25, 2019 Messages: 35 Likes Received: 9 For anyone reading Armilites previous post #50 He posted a calculator to compute CFM flow for an engine based on VE. However, please be advised, he failed to mention it is only for 4 stroke motors. If you size a carburetor based on this calculator for a two stroke - you must multiply the answer by 2 to get the correct CFM requirement. Otherwise you will buy a carburetor half the size you need It is a bit confusing because he loaded 2 stroke engine data (368cc@7000) without specifying it only works for 4 strokes. 13. Aug 17, 2019 ### pictsidhe ### pictsidhe #### Well-Known Member Joined: Jul 15, 2014 Messages: 6,441 Likes Received: 1,672 Location: North Carolina You'll notice that he doesn't get many replies... 14. Aug 17, 2019 ### Armilite ### Armilite #### Well-Known Member Joined: Sep 6, 2011 Messages: 3,022 Likes Received: 243 Location: AMES, IA USA ====================================== You made reference to a Club Dyno, there is No such thing! A Club Prop is for Testing Normal Certified Airplane Engines which are turned at less than 3000rpm. Most People, don't Modify or Upgrade those Certified Engines. You also said it would be easy to make one, which it is not. Most people don't make their own Props, let alone a (4) Blade Club Prop. A Club Prop is not going to give you the Info you want making all of these different changes on these Small 2 or 4 Strokes, your maybe talking .1hp to 10hp Range. Some people have made their own Dyno, but very few. The cheapest Commerical made Used Dyno I have seen was$2,500. New their \$6000+ depending on what accessories you want.

15. Aug 18, 2019

### Vigilant1

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You don't need to a carve a propeller. These "clubs" are lengths of wood that are square in cross section and 15 times as long as they are wide. Can you operate a table saw? A circular saw with a straightedge? You can make one in a few minutes, plus a few more minutes to make a prop hub and to balance it. There--you own it forever. Now make 5 more.
As for "nobody here has made one"--here's a photo that rockydog posted of one he made and used. More here. Now I suppose you'll tell him it doesn't work. Or that there's no such thing.

16. Aug 18, 2019

### Armilite

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If you look at your numbers, if it's 112.12% VE and 102cfm the Engine would be making 68hp, not 57.26hp what the Dyno Sheet Says. In the Peak Flow Calc 368cc at 7000rpm and making 57hp it's 94% VE which is also a hell of a lot more Logical than your 112.12%.
=SUM(86*28316.85*100)/(368*7000) = 94.53606755% VE for 57hp!

ENGINE LITER HP RPMS BMEP
380HO 0.368 57.26 7000 144.5

PLAN:
CYL RPMS STROKE MM BORE MM P = PSI L A N BHP ENG
2 7000 61 62 144.5 0.200131234 4.677196354 14000 57.4 380H0 SKIDOO

17. Aug 18, 2019

### pictsidhe

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It would be easy for me to make a test club. So easy, that I'll make half a dozen of different sizes so I could take 6 different power readings per engine tune. Other people are not so skilled. I did consider building my own dyno, but decided that clubs would be enough unless I get heavily into engine testing. Just because you don't understand something, doesn't mean that nobody does either. Hell, there are even things that you understand that I don't.

Air flow and power are only loosely related. Especially with 2 strokes, which have an annoying habit of blowing a lot of charge out the exhaust without burning it. Thats why new EPA rules have resulted in some new engine designs. I have a chainsaw that inducts both fresh air and fuel laden air. The ports are arranged so that fresh air is the stuff that tends to escape unburned, which keeps the EPA happy.

18. Aug 18, 2019

### n3puppy

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Armilite -
Since clubs are not used for anything but certified engines, can you identify the certified engine in this video - I can't quite tell what it is.......

Also - maybe you can contact the fellow in the video and let him know that he made some major mistakes in his video - saying he was using a Dyno

19. Aug 18, 2019

### Armilite

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OK, Einstein, yes it's x 2 for a 2 Stroke what were talking about, I thought self-explanatory since at 94% it says 86cfm, 45.5cfm x 2 = 91cfm at 100% VE is what it makes for 7000rpm. Also what the Peak Flow Calc says at 100% VE. Then explain how the 377UL uses a Single 36mm (86.2cfm) Carb and it can't FLOW 91cfm or your 102cfm at 7000rpm, physically Impossible and most 377 Sled Motors only came with a Single 30mm Carb (59.8cfm) rated 36hp@7000rpm by Skidoo! The 380HO had (2) 30mm carbs which can Flow 59.8cfm x 2 = 119.6cfm total, but the 380HO(368cc) engine turned at 7000rpm, can only make 91cfm Max.

By the Calc 368cc at 7000rpm making 57hp = 94% and says 86cfm. At 112% making 102cfm = 68hp. Now which is more Locical, Dyno says 57.26hp@7000rpm or 68hp@7000rpm? VE is based on Engine CC at RPM vs HP made.

By the Calc 368cc at 6500rpm making 53hp at 94% says 79cfm.
By the Calc 368cc at 6000rpm making 49hp at 94% says 73cfm.
By the Calc 368cc at 5500rpm making 45hp at 94% says 67cfm.
By the Calc 368cc at 5000rpm making 41hp at 94% says 61cfm.

20. Aug 18, 2019

### n3puppy

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Once again you don't seem to understand the facts

The Dyno sheet is correct. The Peak Flow Calculator is wrong.

The author of the program admits the HP number calculated by the program is a GUESS
The fact he chose to warn about the errors should be your first clue not to trust them.

"Please note, the Horsepower figure is a rule of thumb approximation, unlike the Flow Rate figure"

In this case the GUESS is 19% off (68hp guess, vs 57hp actual)

The 94% number probably looks more "logical" to you because you seem to have been using the calculator wrong, and quoting incorrect results, for almost four years
https://www.homebuiltairplanes.com/...e-flow-rate-peak-horsepower-calculator.23885/

For many years, most people believed the earth was flat. It was hard for them to accept the fact the earth is round, even when confronted with the actual data.

In the the engineering world, the actual data is

ANY Two stroke 368 cc engine @ 7000 rpm flowing 102CFM has a volumetric efficiency of 112%
That is pure proven math - no guessing.

In this 377/380 engine, that 102CFM of air makes 57Hp.
1 HP requires 1.79 CFM
Those are facts.

Last edited: Aug 18, 2019