Stihl Hyde
ArboristSite Operative
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Good read ^
Racing Gas in my 357xp
- Thread starter jvpski
- Start date
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i always run 100ll i get noticably much better response and more power in the cut on my modifed 029 than i do on premium pump gas ,also i burn a quality castor based premix oil instead of the synthetic crap
TRI955
I'm the man in the box
Sounds like somebody is stuck in the 70's.....
Mac_Muz
ArboristSite Guru
I am a new guy here...
Some of you guys come close to the way I think, and others are not in line at all...
BTU is British Thermal Units and a measure of heat.
Coal has more BTU's than anything else.
Octane is another measurement that is used to delay the explosion of gasoline to reduce it to burn. Additive are added to reduce the burn time, and even it out for high compression engine that would run like a diesel setting of the air fuel mix charge before the spark did.
The primary use of octane additives are for engines that would indeed diesel due to high compression. So if you saws are in fact high compression engines, you would recieve benifits of no engine knock (ping) which eats metals like a cutting torch.
If not high compression the lower octane fuels will get you the most bang for the buck.
I agree ethenol will cut and dilute most any 2 stroke oil, and then if the dilution is bad enough the piston and bore can be damaged.
There is another reason to use hi test fuels, and that is if the EPA got their grubby little fingers into the factory specs, and created a bean counters fuel mix, where the fuel mix of AIR to FUEL is less than 14:1, which unfortunatly us all to coomon in vehicals these days, with AIR FUEL mix set to upwards of 19 to 1. (The higher figure is AIR)
Being new here, I hate to use all caps, but I do not want to confuse 2 stroke oil and fuel mix in the equation.
I do not know the compression ratio of any saws including my 242xp, and or my used new to me 359 as of today.
i would like to know the comp ratio of both.
(hopefully, I won't go down in a ball of fire either LOL)
Some of you guys come close to the way I think, and others are not in line at all...
BTU is British Thermal Units and a measure of heat.
Coal has more BTU's than anything else.
Octane is another measurement that is used to delay the explosion of gasoline to reduce it to burn. Additive are added to reduce the burn time, and even it out for high compression engine that would run like a diesel setting of the air fuel mix charge before the spark did.
The primary use of octane additives are for engines that would indeed diesel due to high compression. So if you saws are in fact high compression engines, you would recieve benifits of no engine knock (ping) which eats metals like a cutting torch.
If not high compression the lower octane fuels will get you the most bang for the buck.
I agree ethenol will cut and dilute most any 2 stroke oil, and then if the dilution is bad enough the piston and bore can be damaged.
There is another reason to use hi test fuels, and that is if the EPA got their grubby little fingers into the factory specs, and created a bean counters fuel mix, where the fuel mix of AIR to FUEL is less than 14:1, which unfortunatly us all to coomon in vehicals these days, with AIR FUEL mix set to upwards of 19 to 1. (The higher figure is AIR)
Being new here, I hate to use all caps, but I do not want to confuse 2 stroke oil and fuel mix in the equation.
I do not know the compression ratio of any saws including my 242xp, and or my used new to me 359 as of today.
i would like to know the comp ratio of both.
(hopefully, I won't go down in a ball of fire either LOL)
Termite
Time To Launch
Isn't the compression in PSI a representation of the compression ratio? My 5100 has a 150psi compression. If it was a car engine with a four inch bore it would need high octane. However, I know a smaller bore is less sensitive to detonation.
roncoinc
Official Stihl Disser
Tamworth eh ??
i hear on rt 25 in tamworth just outside of ossipeepee theres a saw shop that has good prices on chains and stuff.
know anything about it ??
Termite... Isn't the compression in PSI a representation of the compression ratio? My 5100 has a 150psi compression
just had my PS510 tested at the shop,,180 lbs !! run regular in it no problem..
Mac_Muz
ArboristSite Guru
No, what psi you have in a given engine is subjet to things, like the way the engine breaths, and what condition it is in.
What a comp ratio is, is how much volume there is that can be cramed into 1.
In theory you could use water to fill the void of space in a given combustion chamber and find out what 1 is, then use that figure to find the rest of the volume with the piston at BDC.
Pounds per square inch do not reflect comp ratio.
Not being overly familar with chain saws, I can't give a good example. On the other hand being somewhat more familar with briggs and Stratton lawnmower engine one difference from a 3 to 5 horse power engine can simply be changing out a carb.
A bigger carb with a freer flowing exhaust can increase the power alone from one horse power to another, and this is commonly done.
Nothing has changed in psi or comp ratio here in these instances. What did change is the engines abilty to breath a air to fuel mix.
The industry knows what the comp ratio is on any given engine, but may not tell a consumer what it is. Maybe saw makers say so, and I just don't know.
I can tell you a Kawii Nomad 1600 cc motorcycle has a comp ratio of 9:1 and a newer bike should have a psi reading around 185 psi warm @ WOT. The factory manual demands 91+ oct fuel, and with minor mods, you can run 87 oct fuel for a bigger, more powerfull bang for the Buck.
The simple fact is 9:1 is not considered high compression, and the EPA bean counters created a situation where they wanted 19:1 fuel mix.
The EPA has no idea that Laws of Phisics exist.
I personally have no intentions of tearing my saw down to investigate what comp ratio they have. It would be nice is saw makers would simply say so, and maybe they do, and just I don't know it.
edited as the phone rang befoe i could proof read my typo
What a comp ratio is, is how much volume there is that can be cramed into 1.
In theory you could use water to fill the void of space in a given combustion chamber and find out what 1 is, then use that figure to find the rest of the volume with the piston at BDC.
Pounds per square inch do not reflect comp ratio.
Not being overly familar with chain saws, I can't give a good example. On the other hand being somewhat more familar with briggs and Stratton lawnmower engine one difference from a 3 to 5 horse power engine can simply be changing out a carb.
A bigger carb with a freer flowing exhaust can increase the power alone from one horse power to another, and this is commonly done.
Nothing has changed in psi or comp ratio here in these instances. What did change is the engines abilty to breath a air to fuel mix.
The industry knows what the comp ratio is on any given engine, but may not tell a consumer what it is. Maybe saw makers say so, and I just don't know.
I can tell you a Kawii Nomad 1600 cc motorcycle has a comp ratio of 9:1 and a newer bike should have a psi reading around 185 psi warm @ WOT. The factory manual demands 91+ oct fuel, and with minor mods, you can run 87 oct fuel for a bigger, more powerfull bang for the Buck.
The simple fact is 9:1 is not considered high compression, and the EPA bean counters created a situation where they wanted 19:1 fuel mix.
The EPA has no idea that Laws of Phisics exist.
I personally have no intentions of tearing my saw down to investigate what comp ratio they have. It would be nice is saw makers would simply say so, and maybe they do, and just I don't know it.
edited as the phone rang befoe i could proof read my typo
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roncoinc
Official Stihl Disser
PSI has nothing to do with the way and engine "breathes"..
PSI it taken AFTER the intake is CLOSED and BEFORE the exhaust opens..
pounds per square inch IS a direct relation to the compression ratio..EG,lower compression will have lower PSI and higher compression will have more PSI.
EXAMPLE: air compressor..high PSI,high compression..
commonly done on everything from cars to saws,nothing new about that..
why would you ?? all you need to know is how many lbs of compression it has..
quit common on 4 stroke engines,,end result is a bigger jet giving more gas,,engine will take what air it needs if carb is CLOSE to size engine needs..nothing new there..
propane has more BTU than coal.
gasoline has more BTU than coal.
fuel oil #2 has more BTU than coal.
fuel oil #6 has more BTU than coal.
wood has 1/4 the BTU of coal
it wont...ethenol still has abot %66 the BTU's of MID grade gas.. ( couldnt find rating for low octane gas ).diluting is reflected only in the mix ratio.
if you want to know more,,,
1 btu = 252 calories
1btu= .293 watts
where was this going anyway ??
smaller engines and higher rpm's can help with knock sensitivity thats why you have more knock in a slow motor being lugged then one thats screaming along. quench area and squish can help reduce the instances of knock by spreading the flame front evenly across the cylinder and not having point ignition near the cylinder walls, when two flame fronts meet you have knock which damages a piston by blowing out the cooling layer of unburned fuel that insulates the piston from the flame and keeps it from melting.
The so-called bean counter ratio has more to do with making car engines more efficient when operating at cruising speed instead of running at stoichiometric ratio regardless of the need for it they can operate at up to 22:1 which saved everyone money on fuel and leaves the air cleaner as well. This cant be done on small engines because they use a stratofied charge and direct injection as well as a computer to control spark and throttle positions. The lean mix on our new saws is a result of having to meet new emissions standards and has nothing to do with EPA accountants but legislation passed and a need for new cleaner technology. It sucks but it will get better as tech gets better. The EPA also does not determine the fuel ratios used by manufacturers, those are determined by R&D engineers and test machines to see at what ratios and with what equipment emissions standards can be met. Engines ARE NOT built around a mandated fuel/air ratio set by the EPA they ARE BUILT around a set of emissions standards mandated by the EPA regardless of the fuel/ratios used.
The so-called bean counter ratio has more to do with making car engines more efficient when operating at cruising speed instead of running at stoichiometric ratio regardless of the need for it they can operate at up to 22:1 which saved everyone money on fuel and leaves the air cleaner as well. This cant be done on small engines because they use a stratofied charge and direct injection as well as a computer to control spark and throttle positions. The lean mix on our new saws is a result of having to meet new emissions standards and has nothing to do with EPA accountants but legislation passed and a need for new cleaner technology. It sucks but it will get better as tech gets better. The EPA also does not determine the fuel ratios used by manufacturers, those are determined by R&D engineers and test machines to see at what ratios and with what equipment emissions standards can be met. Engines ARE NOT built around a mandated fuel/air ratio set by the EPA they ARE BUILT around a set of emissions standards mandated by the EPA regardless of the fuel/ratios used.
super3
Addicted to ArboristSite
Yep, a few of us tested 4 dirrerent fuels at a GTG once.
pump gas
AV 100LL
VP C10
95 octane premium non ethanol
The pump gas recorded the fastest cut, all the others were 2 or 3 minutes slower per cut.
pump gas
AV 100LL
VP C10
95 octane premium non ethanol
The pump gas recorded the fastest cut, all the others were 2 or 3 minutes slower per cut.
roncoinc
Official Stihl Disser
Mac_Muz
ArboristSite Guru
Ronco, I was trying to relate that if a given engine has 150 psi warm on a comp test, that that engine doesn't have 150:1 compression ratio.
IE: My Nomad 1600 cc engine is 9:1 and warm has about 185 psi per cylinder.
IE: My Nomad 1600 cc engine is 9:1 and warm has about 185 psi per cylinder.
Henry G.
ArboristSite Guru
Were you cutting cookies off a giant Sequoia Redwood? :monkey:
roncoinc
Official Stihl Disser
OK,,i guess...
i didnt see anybody OR you say anything close to 150psi = 150:1 comp ratio..
this is a chainsaw forum,,two strokes,,it's all MAGIC here..not like 4 strokes..
we dont attempt to understand whats going on,we just accept it ..
just kidding !! LOL !!
GASoline71
Mr. Nice Guy
I use 85% Nitro Methane in all my saws.
Gary
Gary
super3
Addicted to ArboristSite
I was just being a wise ass,all the comments about higher octane robbing power and slower in the cut.Yes the pump gas was the fastest but,
You need a stop watch to see any differences,and they were small.
Henry G.
ArboristSite Guru
Higher octane gas MAY have less power especially if it was spiked with ethanol to raise the octane, due to ethanol having less BTU's than gasoline.
However, if you spike (add) toluene to increase octane, (toluene is already a component of normal gasoline, as a aromatic hydrocarbon it also has approx 15% more BTU's) to bump the fuel octane, you will not lose any power, in fact may gain some even if your saw does not have the compression requiring high octane fuel. Pure tolulene is 114 octane R+M/2 method, the method used here in the USA.
That said, I have been using a blend of 50% 91 octane pump gas, and 50% "sports blend" (75% 100 octane LL AV gas, 25% tolulene=effective octane approx 104..) to make a mix of approx 97 octane fuel that I use in my off road vehicles and saws for several years now. I have a source for this and usually get it for the same price as AV gas, around $4-5 a gallon. Runs great, tastes great, less filling. Ok, I made the last two up.
Am I "wasting" my money? Maybe. Its mine to waste. Are you wasting your money getting lap dances from some skank on Friday night when the 'ol lady aint around? Maybe. You waste your money your way, and I'll waste mine my way.
But I know this-my gas stores for months, runs great and never clogs jets.
However, if you spike (add) toluene to increase octane, (toluene is already a component of normal gasoline, as a aromatic hydrocarbon it also has approx 15% more BTU's) to bump the fuel octane, you will not lose any power, in fact may gain some even if your saw does not have the compression requiring high octane fuel. Pure tolulene is 114 octane R+M/2 method, the method used here in the USA.
That said, I have been using a blend of 50% 91 octane pump gas, and 50% "sports blend" (75% 100 octane LL AV gas, 25% tolulene=effective octane approx 104..) to make a mix of approx 97 octane fuel that I use in my off road vehicles and saws for several years now. I have a source for this and usually get it for the same price as AV gas, around $4-5 a gallon. Runs great, tastes great, less filling. Ok, I made the last two up.
Am I "wasting" my money? Maybe. Its mine to waste. Are you wasting your money getting lap dances from some skank on Friday night when the 'ol lady aint around? Maybe. You waste your money your way, and I'll waste mine my way.
But I know this-my gas stores for months, runs great and never clogs jets.
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wigglesworth
Booned
They are only stratofied in the extent that the air used to scavange the cylinder is not the same air used to make power in a car the fuel/air mixture varies from the point of ignition to the edges of the cylinder so that at the ignition point the ratio is ideal for ignition but overall the ratio is much leaner than would ordinarily be able to run well. They do this by injecting fuel directly into the combustion chamber and patterning the spray to concentrate the fuel charge near the spark plug at the time of ignition.
