wheels 543 Posted May 3, 2019 Share Posted May 3, 2019 Very much off the topic of boating sorry, but I need some advice if anyone can help. I have some huge hedges around my Home. I am looking at buying a 4n1 pole Hedge trimmer. When I started looking at who had what on Trademe, I discovered that a couple of makes had little baby 4 stroke engines. I thought how interesting. I wonder what they perform like compared to the same CC rating of the 2stroke. Does anyone have a baby 4 stroke of any kind that can give me a run down on how they find it. I am talking just 50 odd CC in size. Quote Link to post Share on other sites
mcp 32 Posted May 3, 2019 Share Posted May 3, 2019 I have a Makita 4st weed eater. It starts easy and is much much quieter than my old Morrison 2st unit. Fuel consumption minor difference in favour of the Makita. I miss my Morrision! Quote Link to post Share on other sites
Ex Machina 365 Posted May 3, 2019 Share Posted May 3, 2019 Got a Honda 4 stroke brushcutter , very quiet and heaps of grunt in low revs . oil change is only 100 Mls of oil . Biggest bonus is not having make up 2T mix if missus or kids want to use it Quote Link to post Share on other sites
Brien 22 Posted May 3, 2019 Share Posted May 3, 2019 My Shindaiwa brush cutter is a hybrid 2-4 stroke. It uses a four stroke cycle but lubrication is maintained by oil in the fuel passing through the sump. This eliminates energy wasted stirring oil. It is responsive quiet easy to start and has been running for 10 years so far. Not sure of capacity, about 40cc I think. Later models are described as 2 stroke so may have moved on or maybe to prevent wrong fuel being added. Quote Link to post Share on other sites
Toltec 7 Posted May 4, 2019 Share Posted May 4, 2019 I have a Honda 4 in one 4 stroke great unit and quiet .Certainly the best unit I have owned and I have had a couple Quote Link to post Share on other sites
Crazyhorse 47 Posted May 4, 2019 Share Posted May 4, 2019 Googled 4 stroke brush cutter generators and lots popped up. Have been thinking of a permanent magnet alternator hooked up to one of those? All little portable generators are 12/ 240v so a waste trying to charge up batteries but a straight 12v....? (Sorry if hijacking thread!) Quote Link to post Share on other sites
SloopJohnB 323 Posted May 4, 2019 Share Posted May 4, 2019 We got a small 4 stroke genny at the club to run the computers very quite, I used my big drill putting in some dynabolts using it no problems. Quote Link to post Share on other sites
Brien 22 Posted May 4, 2019 Share Posted May 4, 2019 Googled 4 stroke brush cutter generators and lots popped up. Have been thinking of a permanent magnet alternator hooked up to one of those? All little portable generators are 12/ 240v so a waste trying to charge up batteries but a straight 12v....? (Sorry if hijacking thread!) Quote Link to post Share on other sites
Brien 22 Posted May 4, 2019 Share Posted May 4, 2019 Have thought the same and researched small diesels. Can't find any around 1 HP. If stuck with petrol may as well use small portable genset as I have done. Quote Link to post Share on other sites
Brien 22 Posted May 4, 2019 Share Posted May 4, 2019 230 Volts through invertor when main engine charge drops to 40 amps. Genset in low speed at about 40 amps 12 volt invertor charge output Quote Link to post Share on other sites
Island Time 1,234 Posted May 4, 2019 Share Posted May 4, 2019 The issue is that every 60 odd amps of alternator takes a hp to drive. The really small engines simply are not powerful enough to make it worthwhile. Quote Link to post Share on other sites
Crazyhorse 47 Posted May 4, 2019 Share Posted May 4, 2019 The issue is that every 60 odd amps of alternator takes a hp to drive. The really small engines simply are not powerful enough to make it worthwhile. Thought the same but then wind turbines would have to fall into that category too, like the one you sold us!? How much horse power is required for the silentwind to put out 20ah? 40? Quote Link to post Share on other sites
Crazyhorse 47 Posted May 4, 2019 Share Posted May 4, 2019 230 Volts through invertor when main engine charge drops to 40 amps. Genset in low speed at about 40 amps 12 volt invertor charge output This has me confused, sorry Brien but 230v through a inverter!? KABOOM! I think you mean FROM an inverter? Inverters are inherently wasteful and the idea is to not have to step up or step down any voltage but straight DC. All (unfortunatly) portable generators are 230 240v unless you go 60hz 110. To make use of that requires a battery charger which is a great idea with "set and forget" but a simple(?) small engine running a perminant magnet type 3 phase alternator and then a rectifier regulator should work? I am talking the tiniest of engines, 22cc 4 stroke, 3.2kg weight and I would expect about 20 amps output at 14 plus volts? Quote Link to post Share on other sites
wheels 543 Posted May 4, 2019 Author Share Posted May 4, 2019 Amps x Volts = WattsWatts / 745.7 (one HP) = Electrical HP Produced by the AlternatorHP x 15% Efficiency Loss = HP LossHP + HP Loss = Total HP Used Quote Link to post Share on other sites
wheels 543 Posted May 4, 2019 Author Share Posted May 4, 2019 This is where the little brief case type 4stroke inverter type generators come into their own. Say a 500Va to 1Kva unit. They idle when no load and when a load is applied, the increase RPM proportionally to meet the load. Quote Link to post Share on other sites
Crazyhorse 47 Posted May 5, 2019 Share Posted May 5, 2019 Amps x Volts = Watts Watts / 745.7 (one HP) = Electrical HP Produced by the Alternator HP x 15% Efficiency Loss = HP Loss HP + HP Loss = Total HP Used I have no problem with that but your are talking an alternator with powered exciter? Quote Link to post Share on other sites
Brien 22 Posted May 5, 2019 Share Posted May 5, 2019 This has me confused, sorry Brien but 230v through a inverter!? KABOOM! I think you mean FROM an inverter? Inverters are inherently wasteful and the idea is to not have to step up or step down any voltage but straight DC. All (unfortunatly) portable generators are 230 240v unless you go 60hz 110. To make use of that requires a battery charger which is a great idea with "set and forget" but a simple(?) small engine running a perminant magnet type 3 phase alternator and then a rectifier regulator should work? I am talking the tiniest of engines, 22cc 4 stroke, 3.2kg weight and I would expect about 20 amps output at 14 plus volts? Quote Link to post Share on other sites
Brien 22 Posted May 5, 2019 Share Posted May 5, 2019 Sorry tried to be too brief. My boat has an Inverter/ charger already fitted. So can be charged from shore power up to 70 amps 14 volts. I substitute a small 1700 Watt gen set that produces 230 volts for shore power when cruising. After using the main engine to bulk charge for 10 or 15 minutes and the charge amps come down to around 40 amps I shut down main engine and let gen set provide 230 volts to Inverter/charger. The gen set is quite happy with this load and settles down to complete the charge at 1500 rpm. Minimal background noise. The gen set when not charging can handle the toaster, or netspresso machine as bonus. If I could find a small diesel air cooled gen set I would consider installing in engine room. Quote Link to post Share on other sites
Crazyhorse 47 Posted May 5, 2019 Share Posted May 5, 2019 Yep, this is the trouble, they don't exist. Even looked at model aircraft engines that run on distillate but noisy as he'll (would cure the problem of giant wedding cakes that like anchoring on top of us!). YouTube has lots of ideas with small brush cutter engines powering small alternators and that's the direction we are heading in. Quote Link to post Share on other sites
Island Time 1,234 Posted May 5, 2019 Share Posted May 5, 2019 Thought the same but then wind turbines would have to fall into that category too, like the one you sold us!? How much horse power is required for the silentwind to put out 20ah? 40? Quote Link to post Share on other sites
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