Here’s a thought. 372 or anything else you don’t mind drilling holes in.

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John Stryker said:
Your mod will lower the intake air pressure, and make less horsepower. It might also lower fuel consumption, since you will have to tune it leaner to match the lower air intake volume.
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im sorry, but that makes no f-ing sense at all. this is not a turbocharged engine, there is no positive intake pressure. if anything it may reduce VACUUM (negative pressure) in the airbox, and allow MORE air to enter the engine.
 
cus_deluxe said:
im sorry, but that makes no f-ing sense at all. this is not a turbocharged engine, there is no positive intake pressure. if anything it may reduce VACUUM (negative pressure) in the airbox, and allow MORE air to enter the engine.
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At full throttle, the air coming off the flywheel is shoved into the air box. I'm no engineer, but it would behoove engineers to keep positive pressure in the air box from the flywheel air to keep from junk entering the air box through other openings.

I know on my Stihl saws, there are centrifugal separators that keeps most of the junk out of the air box, but allows air from the flywheel to pressurize the air box. I'm guessing this isn't true on all saws.

So really, it depends on the saw whether or not cutting extra holes in the air box is a good or bad idea.
 
EchoRomeoCharlie said:
At full throttle, the air coming off the flywheel is shoved into the air box. I'm no engineer, but it would behoove engineers to keep positive pressure in the air box from the flywheel air to keep from junk entering the air box through other openings.

I know on my Stihl saws, there are centrifugal separators that keeps most of the junk out of the air box, but allows air from the flywheel to pressurize the air box. I'm guessing this isn't true on all saws.

So really, it depends on the saw whether or not cutting extra holes in the air box is a good or bad idea.
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When I decided to put holes in a 372 cover what led me to do that was with the cover off it would four stroke, with the cover on it wold not. Which made no sense to me. But in that specific situation maybe Echo Romeo is right. Why else would it four stroke with the cover off but not when its on?????
 
chipper1 said:
Where's the video then, we're gonna need a comparison of before and after if you can get it.
Here's the saw in the picture, it pulls a longer chain well also, could have taken the rakers down a bit.
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I don't think we're on the same page. When I said, "with juice" I meant it's ported. You've seen at least one of the videos already. The 2065 is a cylinder slut and gets changed around quite often.
 
EchoRomeoCharlie said:
At full throttle, the air coming off the flywheel is shoved into the air box. I'm no engineer, but it would behoove engineers to keep positive pressure in the air box from the flywheel air to keep from junk entering the air box through other openings.

I know on my Stihl saws, there are centrifugal separators that keeps most of the junk out of the air box, but allows air from the flywheel to pressurize the air box. I'm guessing this isn't true on all saws.

So really, it depends on the saw whether or not cutting extra holes in the air box is a good or bad idea.
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yes, the air injection feature directs air to the air box, supposedly relatively clean air. my point is that there is a vacuum developed inside the air filter/intake tract from the engine running. that vacuum would far outweigh any kind of positive pressure generated by air injection.
 
cus_deluxe said:
yes, the air injection feature directs air to the air box, supposedly relatively clean air. my point is that there is a vacuum developed inside the air filter/intake tract from the engine running. that vacuum would far outweigh any kind of positive pressure generated by air injection.
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Got data to prove that or is that an assumption?
 
lol, no i dont have data. are you unfamiliar with how diaphragm carburetors work? they operate using vacuum to draw fuel. if there was positive pressure, it would not pull fuel.
airboxes on saws are certainly not airtight, so any meager pressure generated by flywheel action would be leaking out just as fast. read the factory literature. its not about pressurizing the airbox, its about using the centrifugal action of the flywheel to sling out the larger particles and collect air from as close as possible to the flywheel.
 
cus_deluxe said:
lol, no i dont have data. are you unfamiliar with how diaphragm carburetors work? they operate using vacuum to draw fuel. if there was positive pressure, it would not pull fuel.
airboxes on saws are certainly not airtight, so any meager pressure generated by flywheel action would be leaking out just as fast. read the factory literature. its not about pressurizing the airbox, its about using the centrifugal action of the flywheel to sling out the larger particles and collect air from as close as possible to the flywheel.
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I am familiar with how a carb works. Yes, the fuel is drawn into the throat of the carb via a vacuum, however, that vacuum only exists in the throat of the carb via the 'Venturi effect'. It does not create a vacuum in the entire housing.

Proof of this is the fact that a carb engine can be turbocharged. Effectively causing a positive pressure in the intake, yet, the fuel still flows via that same vacuum created in the throat of the carb.

You're correct, the saw is not going to create a ton of positive pressure in the housing, however, any positive pressure is better than a vacuum as a vacuum would suck in more dust and debris causing faster clogging of any filter media. If the flywheel is providing more air than the engine can consume, there will be positive pressure. What I don't 100% know, is how much air the flywheel provides, and a how much air the engine is consuming. One could figure out the air consumption of the engine fairly easily, however, figuring out the airflow of the flywheel is a much more difficult venture. Without both numbers we're purely speculating. My guess would be that there is sufficient airflow form the flywheel to provide more than enough air to the engine, thereby causing a small amount of positive pressure. If this is true, providing more holes for the pressure to escape is detrimental to the saws performance.
 
this has gone on a crazy tangent. i was originally responding to a guy that said you would lose power by drilling holes in ur top cover. which is f-ing stupid. i seriously doubt any significant positive pressure exists in any airbox on any saw at any rpm. i seriously doubt you could produce enough positive pressure to impact the amount of air delivered to the carburetor.
 
EchoRomeoCharlie said:
My guess would be that there is sufficient airflow form the flywheel to provide more than enough air to the engine, thereby causing a small amount of positive pressure. If this is true, providing more holes for the pressure to escape is detrimental to the saws performance.
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agree to disagree man, thats just something i cant get on board with. what about saws without air injection? are you telling me that all else being equal, the presence of air injection, which according to your train of thought (and that of the person i originally responded to), will increase power?? if so you should let husqvarna know. they invented that **** 30+ years ago and theyd probably like to advertise an increase in power.
 
I just sometimes ....if somethings not vroom vroom. Might wanna drill a few holes grind this sand that. I think that husqchirna deserved it. If decides to cut some wood might patch its wounds.:..probably not. Probably Probably cut a few more.
 
Lol I thought this might happen. U guys get way to serious n analytical about it. Which is good. Piece of **** still ain’t cutting ...but need all the advice I can get. Kim jung oon....do you know how these saws work..???? Some...though are using really big words I don’t understand. Just a dummy that drilled up old used up top cover on a wasted Chinee chainsow. I bet my fortune cookie says “this will not end well”. Damn u china how many more douchy cars n bikes are there?
 
My step-brother and I once put holes in bottom of step-fathers Chris-Craft. Didn't do anything but get us both grounded and added work around the house. Lucky we didn't get an azz beating.
 

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