Chain saw with forced induction

[Coloradobum]

This is the general statement you made that has been disputed, not the feasibility of turbocharged chainsaws:

...and what context did I make that statement in? In a CHAINSAW forum in a thread named "CHAINSAW forced induction". Think maybe I was talking about turbos that would work on a CHAINSAW? Why in the world everyone keeps replying about cars is beyond me. EDIT: I went back and read my claim. Here is the very next sentence I wrote: "Adapting one to a chainsaw while keeping the weight down and keeping the engine/turbo from burning up would be a serious technical challenge".

Clearly I was NOT talking about a turbo for a frickin mack truck if I was talking about turbos you could adapt to a chainsaw. Since I have to absolutely spell it out, here it is: small turbos that would be lightweight enough and feed small enough CFM's for a chainsaw DO NOT have the cooling capability to not burn up rather quickly at WOT conditions. Car turbo arguments are a red herring brought up by OTHER people, not me.

 

[timberwolf]

No, the red herring is the whole idea of puting a turbo on a small 2 stroke naturally aspirated engine.

Why the automotive examples are brought up is because that is where the vast majority of turbos are found.

There are a bunch of reasons the idea does not work well in a chainsaw senario and they have been pointed out a number of times.

#1 there is an absolute limit where pushing more into the saw just blows more out the exhaust due to the intake/transfers being open when the exhaust is open (overlaping in valve timing in 4 stroke talk)

#2 Lack of cooling and lubrication to support the turbo, sure it could be added but there is nothing in place to work with on a chainsaw.

#3 Lack of pressurized fuel system which either is going to require rigging up a pressurized fuel injection system or running your mixture through your turbo which brings about a bunch of risks and problems that would need to be engineered around.

#4 no intercooler, heat from the exhaust is going to get fed into the intake which will work against charge density and in an air cooled 2 stroke is asking for heat problems.

#5 The back pressure the turbo develops on outflow is going to work directly against transfer flow this is going to cause acceleration problems with the engine as the back pressure must be first developed in order to spool the turbo up to develop more boost to overcome the back pressure. Likely would be best to move to reed valves as opposed to piston ported.

#6 Crank case seals are not designed for the heat and pressure that is going to be pushed into the base.

If you want to race, just put a tuned exhaust together and get on with it. That is what has been proven to work.

If you want to do work, port the dang thing, hog out the muffler and take the gains of 50% plus improved cutting speed with no additional crap hanging off the saw. Also likely can't go far past this point anyway without getting more cooling

 

[Dan_IN_MN]

:hmm3grin2orange::hmm3grin2orange::hmm3grin2orange:

A Kid with a wild thingy and some RC toy parts, done started somethin'.....LOL!!

I love this place!

Stay safe!
Dingeryote

:hmm3grin2orange:
:biggrinbounce2:

I don't know how long that little saw is going to last......I'm sure we'll find out!

 

[Coloradobum]

No, the red herring is the whole idea of puting a turbo on a small 2 stroke naturally aspirated engine.

Why the automotive examples are brought up is because that is where the vast majority of turbos are found.

There are a bunch of reasons the idea does not work well in a chainsaw senario and they have been pointed out a number of times.

#1 there is an absolute limit where pushing more into the saw just blows more out the exhaust due to the intake/transfers being open when the exhaust is open (overlaping in valve timing in 4 stroke talk)

#2 Lack of cooling and lubrication to support the turbo, sure it could be added but there is nothing in place to work with on a chainsaw.

#3 Lack of pressurized fuel system which either is going to require rigging up a pressurized fuel injection system or running your mixture through your turbo which brings about a bunch of risks and problems that would need to be engineered around.

#4 no intercooler, heat from the exhaust is going to get fed into the intake which will work against charge density and in an air cooled 2 stroke is asking for heat problems.

#5 The back pressure the turbo develops on outflow is going to work directly against transfer flow this is going to cause acceleration problems with the engine as the back pressure must be first developed in order to spool the turbo up to develop more boost to overcome the back pressure. Likely would be best to move to reed valves as opposed to piston ported.

#6 Crank case seals are not designed for the heat and pressure that is going to be pushed into the base.

If you want to race, just put a tuned exhaust together and get on with it. That is what has been proven to work.

If you want to do work, port the dang thing, hog out the muffler and take the gains of 50% plus improved cutting speed with no additional crap hanging off the saw. Also likely can't go far past this point anyway without getting more cooling

Thank you for taking the time to eloquently say what I've been trying to. I don't have quite a good as handle on chainsaw engines as you obviously do, but in many years of tinkering with quads and dirtbikes I never saw a turbo on a small air cooled 2 stroke, and I figured there must be engineering reasons. I saw lots of turbos on 4 stroke street bikes stuffed into quad frames though (Silver Lake, Michigan). Those were sweeeeeetttttt.

 

[Jonsered2095]

Has a centrifugal supercharger with an air box been considered here? Not an exhaust driven turbo.

No it blows!

 

[cwpoulan250a]

He's got the right idea, just the wrong side of the carb. A chainsaw would benefit from a supercharger, not a turbo.

I've seen guys at the hobby shop run miniature belt driven ones on their nitro r/c's with good success. It wouldn't be so hard to hook one up to a chainsaw.
You want to discuss tiny basic carburetors?

We just need you guys with machining experience to step up to the plate

Imagine the power:chainsawguy:

i can build a turbo for a saw... i have no problems with actually doing it but do you think i could run the carb on the other side of the turbo???? like run the fuel, oil and air through the turbo then into the engine??

 

[MechanicMatt]

i can build a turbo for a saw... i have no problems with actually doing it but do you think i could run the carb on the other side of the turbo???? like run the fuel, oil and air through the turbo then into the engine??

im not sure id do it on a turbo, but on a supercharger sure. Can you adapt a different carb with pressurized fuel system to the saw? when you run a turbo with a carb on a car you use a special carb designed for it, im not big on sticking the fuel through a exhaust driven turbo. good luck kid and don't let all the guys arguing scare you off, tinkering leads to invention and with out invention we would all still be stuck with axes. Stihl tinkered and he came up with the chainsaw!

 

[cwpoulan250a]

Sigh. Think maybe there's a reason they don't use turbos on chainsaws? Or mx bikes? Or ultralights? Just maybe those engineers know something? You can NOT say that because turbos work on a car engine they would work on a saw. I for one don't care to lug around a liquid cooled saw. I'd love a manufacturer to prove me wrong.

maybe the reason is that no one has done it???
i'll do it and i will do my best at it even if it fails, if it does fail 100000rpm should be a good explosion when the turbo flies apart... haha
i do know someone who has a turbo on his dirt bike and he is scared out of his pants to ride it cause it had such a sharp power band... in about 300rpm it spikes 20hp. if i can do that to a saw why not??

 

[cwpoulan250a]

:hmm3grin2orange::hmm3grin2orange::hmm3grin2orange:

A Kid with a wild thingy and some RC toy parts, done started somethin'.....LOL!!

I love this place!

Stay safe!
Dingeryote

Haha ya i never thought that my crazy idea would turn out like this
thanks to manyhobbies for putting my stuff up for me.

 

[cwpoulan250a]

i think i have the solution.......... i am just going to build a really really small turbo, using the exhaust for the turbos rotation and running the turbos out put straight into the engine block.......... here is the clever part..... then on the turbos intake side i will have the carb.... running the fuel and oil mix through the turbo will lubricate the bearing( the open side of the bearing on the intake side, the sealed part of the bearing on the exhaust side) and continue to the engine.
this will allow me to use what ever carb i want( bigger or smaller)... still have the atmospheric pressure and no depletion of fuel delivery. and i will have some psi of boost.

there an 18 year old just solved the problem you all have been scratching your heads about.

 

[Terry Syd]

My 50cc saw is already too heavy for me after an hours worth of cutting. However, an increase of power of 10-15% by only adding a few ounces would be worth it.

You can get that 10-15% by tuning the intake resonance.

Just hook up a clear plastic, reinforced hose after the carb. Tune the length (by pinching it at various lengths) to give you the desired effect at the RPM you want. Cut the hose, plug it at that length and then slip it up inside the handle.

Keeping it light, simple and reliable on a work saw.

 

[Dan_IN_MN]

Sigh. Think maybe there's a reason they don't use turbos on chainsaws? Or mx bikes? Or ultralights? Just maybe those engineers know something? You can NOT say that because turbos work on a car engine they would work on a saw. I for one don't care to lug around a liquid cooled saw. I'd love a manufacturer to prove me wrong.

Got me thinking........

Mini Rad...

Mini liquid jacket around the jug.....

Possible mini liquid pump.... maybe use thermo siphon....

Why....??

WHY NOT!

 

[dingeryote]

Got me thinking........

Mini Rad...

Mini liquid jacket around the jug.....

Possible mini liquid pump.... maybe use thermo siphon....

Why....??

WHY NOT!

Mini-rad on flywheel cover?

LOL!!!

Why? cuz' it's fun and ya can!

Stay safe!
Dingeryote

 

[bejay]

i think i have the solution.......... i am just going to build a really really small turbo, using the exhaust for the turbos rotation and running the turbos out put straight into the engine block.......... here is the clever part..... then on the turbos intake side i will have the carb.... running the fuel and oil mix through the turbo will lubricate the bearing( the open side of the bearing on the intake side, the sealed part of the bearing on the exhaust side) and continue to the engine.
this will allow me to use what ever carb i want( bigger or smaller)... still have the atmospheric pressure and no depletion of fuel delivery. and i will have some psi of boost.

there an 18 year old just solved the problem you all have been scratching your heads about.

if your serious, not sure I would try that either turbos get very hot I wouldnt be putting fuel through it. I think you have the right idea just maybe need a more efficient fan or blower maybe before the carb.

 

[cwpoulan250a]

if your serious, not sure I would try that either turbos get very hot I wouldnt be putting fuel through it. I think you have the right idea just maybe need a more efficient fan or blower maybe before the carb.

to reach a dangerous heat it would have to be under pressure and above 500f
i don't think it will exceed that
so far my plan is to fin it like a jug and set it in the path of the flywheels air out put
so there will be air going past it and it will have oil in it for lubrication
it take a lot to make ceramic bearings get hot

side not i have run ceramics in my RC race trucks and also in some of my boats
they heat up about half as much as carbide bearings

 

[Dan_IN_MN]

Might cause vapor lock

if your serious, not sure I would try that either turbos get very hot I wouldnt be putting fuel through it. I think you have the right idea just maybe need a more efficient fan or blower maybe before the carb.

The only problem that I can think of from running fuel through the turbo and the fuel getting hot would be vapor lock. It wouldn't explode because there isn't any O2 present.

Keep the ideas coming.

An open mind will learn.....What happens to a closed one?

 

[cwpoulan250a]

No, the red herring is the whole idea of puting a turbo on a small 2 stroke naturally aspirated engine.

Why the automotive examples are brought up is because that is where the vast majority of turbos are found.

There are a bunch of reasons the idea does not work well in a chainsaw senario and they have been pointed out a number of times.

#1 there is an absolute limit where pushing more into the saw just blows more out the exhaust due to the intake/transfers being open when the exhaust is open (overlaping in valve timing in 4 stroke talk)

#2 Lack of cooling and lubrication to support the turbo, sure it could be added but there is nothing in place to work with on a chainsaw.

#3 Lack of pressurized fuel system which either is going to require rigging up a pressurized fuel injection system or running your mixture through your turbo which brings about a bunch of risks and problems that would need to be engineered around.

#4 no intercooler, heat from the exhaust is going to get fed into the intake which will work against charge density and in an air cooled 2 stroke is asking for heat problems.

#5 The back pressure the turbo develops on outflow is going to work directly against transfer flow this is going to cause acceleration problems with the engine as the back pressure must be first developed in order to spool the turbo up to develop more boost to overcome the back pressure. Likely would be best to move to reed valves as opposed to piston ported.

#6 Crank case seals are not designed for the heat and pressure that is going to be pushed into the base.

If you want to race, just put a tuned exhaust together and get on with it. That is what has been proven to work.

If you want to do work, port the dang thing, hog out the muffler and take the gains of 50% plus improved cutting speed with no additional crap hanging off the saw. Also likely can't go far past this point anyway without getting more cooling

and what is wrong with trying???
new stuff is fun and tuned pipes are hard to manage
they are big and not exactly easy to keep with in the confines of the saw
my idea will fit inside the existing saw case and will hopefully work just as well as a tuned pipe
i don't mind u saying don't "waist your time" but it's people like you that really help me do incredible stuff

 

[cwpoulan250a]

im not sure id do it on a turbo, but on a supercharger sure. Can you adapt a different carb with pressurized fuel system to the saw? when you run a turbo with a carb on a car you use a special carb designed for it, im not big on sticking the fuel through a exhaust driven turbo. good luck kid and don't let all the guys arguing scare you off, tinkering leads to invention and with out invention we would all still be stuck with axes. Stihl tinkered and he came up with the chainsaw!

thanks for the positive word

if you think about it the fuel and oil in the intake side won't burn
what happens when a saw doesn't have enough compression??
it won't run because the gasses aren't compressed enough
so being that the gas and oil on the intake side of the turbo aren't under 100psi of compression it won't burn
that is just my thinking

 

[discounthunter]

i think i have the solution.......... i am just going to build a really really small turbo, using the exhaust for the turbos rotation and running the turbos out put straight into the engine block.......... here is the clever part..... then on the turbos intake side i will have the carb.... running the fuel and oil mix through the turbo will lubricate the bearing( the open side of the bearing on the intake side, the sealed part of the bearing on the exhaust side) and continue to the engine.
this will allow me to use what ever carb i want( bigger or smaller)... still have the atmospheric pressure and no depletion of fuel delivery. and i will have some psi of boost.

there an 18 year old just solved the problem you all have been scratching your heads about.

i dont see husky or stihl firing their engineers quite yet.

 

[cwpoulan250a]

i dont see husky or stihl firing their engineers quite yet.

haha
i just felt smart at the time
i wouldn't mind being able to come up with an idea that husky or stihl could use on their future saws
never know if i can come up with cool stuff and make it work i may end up working for a large company like that