Whoa ... "Stihl's" new saw
- Thread starter cary911
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Carbs on saws have had the best part of a century to evolve to where they are today. Fi tech in small 2 stroke engines is very new. Once its properly implemented, tested and revised it will be seen as a big asset to the modern gas chainsaw. I support any new tech that will keep my loved small 2stokes in my hands into the future. For a while in recent years the 2 stroke was heading for the grave.
So why no 4 stroke chainsaw yet? To big and heavy? You would think they would work on that idea and stop burning oil. That would help the environment.
Canyon Angler
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In the marine market, 2T did go to the grave, with the exception of the Johnson/Evinrude ETECs.
Now outboards weigh a ton, cost a fortune, drag the transoms of old boats down to the waterline, and can barely wallow up over their own bow waves.
YAY!
Yes, too heavy. And, oil still burns and when it breaks down, the engine is in severe trouble. If the oil in the crankcase is too low, running a 4-cycle that way is almost like straight gassing a 2-cycle. You also pick up more parts with the 4-cycle.
Dolmar had a complete 4 cycle in testing, I remember seeing the IPl a time or two. In the end it was just too heavy and underpowered for the weight.
Yes I know all of that. They make those 4 stroke string trimmers with the rubber band for a timing belt. Idk I think a fuel injected 40cc 4 stroke saw would kill in the home owner market kind of like having a 60 volt chainsaw. I know a lot of people who hate mixing gas and messing with the carb to keep the thing running.
Too heavy. Not only the extra weight of the valve train but four strokes make less power per cc than two strokes, so the engine has to have more displacement. The additional parts for the four stroke's valve train adds to the complexity and the cost. Normal four strokes won't run in any orientation- they need to have the sump at the bottom so the oil can collect (either wet sump or dry sump). Saws have to be able to run in any orientation even upside down.
Stihl's "four mix" solves the orientation problem by using oil in the fuel. So they're no cleaner than two strokes but still heavier, more complex and more expensive.
Makes sense. Flip it up side down and oil every where except where it should be.
Fuel inject saws idc I'll buy one in 20 years.
Fuel inject saws idc I'll buy one in 20 years.
That`s not right. M-Tronic regulates first with the ignition timing and second with the fuel flow. A change in ignition timing gives immediately a change in the running characteristic. If the fuel flow is changed it needs "some time" (milliseconds) until the change occurs in the engine. (because of the way from the carb to the crankcase and through the transfer ports into the cylinder) Both regulating sequences work together so that the change is slight and smooth and is not noticable for the user.
anyone remember the oil injection system on the 2 stroke bikes? no mixing
Don't forget, cost far more to service & have shorter service intervals. I had an injected Mercury Salty 115hp with a stainless Vengeance prop on my little half cab fishing boat. Had I wanted a 4 stoke, max size motor I could have run was a 70 from memory. Ya one of them e-tec rudes were what I really wanted had I purchased the boat new. Thankfully a small few didn't give up on the 2 stroke & are succeeding with them.
On motorcycles having the oil injection pump meter based on both rpm and throttle opening makes for lower oil consumption under normal street riding conditions while still supplying plenty of oil for high speed track operation. Saws are mostly run at idle or full throttle so it's less of an advantage for them. And the pump and tank add weight and bulk in a product that's very sensitive to both. So it's not likely to happen.
Fuel injecting two strokes has been problematic in the past since electronic injectors can only operate so fast. And of course on a two stroke they need to operate twice as often as a four stroke. This was (one of) the problems with Bimota's V-Due injection system. But injector tech has come a long ways since the 1990s. KTM's selling off road two strokes with FI now. Ossa had trials bikes with FI a few years back. So the tech is there. It's just got to be miniatureized for saw applications and work to 13k rpms.
The Stihl injection system was developed to work up to 16.000rpm.
Now there is oil injected or pumped where the fuel is not as the fuel is injected in the transfer ports. TPI Ktm now.
Cody
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I've seen numerous sources say there is also a temp sensor, I believe just for air temp, but people seem to argue on that and I don't have any truth to it. I would also imagine that the ignition timing is fixed so it's one less variable to control. Constantly changing timing and fuel would be difficult with so little to read off of.
Having a throttle position, and crank position sensor might allow for ignition timing to be altered but the last thing I want on a saw is multiple sensors, as that would ruin the reliability in my opinion. A sensor failing on a chainsaw like that would likely render it useless, and need to be plugged into a type of code reader to diagnose. How many sensors on Stihl's fuel injected saw? They've got quite a mess of wires under that cover from what I've seen.
I think the move to fuel injection will make modding saws easier than autotune. Aftermarket programmable electronics already exist for FI 2-smokes, and making your own simple one that works with minimal sensors would be fairly easy.
I'm honestly surprised that stihl didnt completely skip normal fuel injection and go straight to direct injection with a seperate oil pump. Imagine how much more power you could make if you didnt need to worry about your fuel all blowing out the exhaust and you could inject the fuel just before the spark when the chamber was closed. Really crazy port timing would be possible with DI.
I'm honestly surprised that stihl didnt completely skip normal fuel injection and go straight to direct injection with a seperate oil pump. Imagine how much more power you could make if you didnt need to worry about your fuel all blowing out the exhaust and you could inject the fuel just before the spark when the chamber was closed. Really crazy port timing would be possible with DI.
^^^
Sounds cool but maybe heavy and expensive.
DI requires a high pressure pump.
That system will definetly weight more than a carburetor.
Still sounds cool. A tank of fuel would go much further.
Sounds cool but maybe heavy and expensive.
DI requires a high pressure pump.
That system will definetly weight more than a carburetor.
Still sounds cool. A tank of fuel would go much further.
ferris076
ArboristSite Operative
The price for the ms500i will be between 461/462 and 661.
They are also working on a 880 replacement with Injektion
They are also working on a 880 replacement with Injektion
The Temp sensor is inside the control unit on m-tronic models.
The file attached is form a clearing saw I work with. You can see the temp during data read out (marked red) from the dealer.
