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Porting for extra performance. Real, or Placebo?

Started by Mick, May 04, 2019, 08:39:36 AM

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Mick

Read so many posts about engine porting, and I realise when this is done properly you will gain extra power / speed from your chainsaw.

Then you read about the guys who opened up their muffler / exhaust on their brand new chainsaw and it runs so much better.  This begs me to ask the question.  Taking into account that a blocked muffler will defo have a negative affect.

Does opening up the exhaust really give you extra power?  How much of this is placebo effect on the user, I mean the extra noise possibly making it sound more powerful, and actually not having any affect on the performance at all, apart from making it possibly worse.

In my opinion the stock muffler should be optimised from the factory for max performance and longevity of the saw, not to mention noise levels, and emissions = (CAT versions).

What's your take on all this?
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Marks Mowers

Fitted the "repair kit" to an MS201t, no difference in performance, advanced the timing and opened up the muffler and it was like a different saw.
No bogging down anymore and a happy customer.

Mick

Thanks Mark.

While I agree that done properly by someone with the necessary and skills for tuning these small two stroke engines, there will be an increase in performance.  It's the ones that say things like "Opened up the exhaust on my saw, now it goes like stink" etc, that's what I find slightly bemusing. Yes it's louder, and sounds like it's faster and more powerful, but is it?

Also, going back to my days racing Motocross bikes, it was always the case that anything highly tuned, built for power and speed will need constant rebuilding to keep it that way.  I guess these days technology and materials have changed so maybe they will withstand being pushed a little better.  But I still believe it's a case of, increase performance, decrease lifespan.

After all the machines should be optimised from the factory for max power + Longevity + Reliability, once you start changing things you can ad those to a sliding scale, something has to give.
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Mick

I have to revisit this topic, and ask something that's been bugging me, and it might be a tad controversial, but I'm really curious from a none tree surgeon's perspective.

What's the point?  Like most machines, if you were racing / competing with it I can understand porting tuning and trying to wring as much power out of the engine to within a mm of it's life. And talking about life, usually anything built for speed has a limited time between rebuilds.

But this is equipment used for your day job, time is costed in when you quote,  ripping through a log 5 seconds quicker and adding those cuts up = x? mins per day. 

Anyway, now I'll await the flack.  :doh:  Thoughts?
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NOMIS

Il have a stab Mick.
This situation seems to have much in common with the overall "Modification" world , be it car,truck,motorbike ...etc.
There are some very clever and innovative minds out there and if its what floats your boat then i guess you will be enthusiastic about the benefits as you see them.
More performance from the same size saw is often the most reasoned point from those who use them as a tool to make a living. The life of a pro saw is hard regardless of porting the saw so to ..some...degree I think good maintenance will help ether way.
The saw porting world is much more common in the USA and to some degree you would expect it to be with there history for "Modification" and a liking of HP.
The EPA with the emission regs is often blamed as the reason saws (and other motors) have been choked by the exhaust, carb limiter regs and many think 50:1 is a bad choice.
Iv only touched on the subject and am being as "diplomatic" as I can because there are some rather "Grumpy" threads out there on other forums.
There is more I would like to say on this subject but I will hand it back to you for now to comment . :tup:

Mick

NOMIS  Thanks for your input.   ;)

I'll give this more thought and come back, though I do wonder sometimes if having the saw set up properly in the first place is half the battle, because that alone makes one hell of a difference.

I do see and accept your point though, regarding the strive for all things = max HP.
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Allan Macpherson

Quote from: Mick on May 04, 2019, 08:39:36 AM


Does opening up the exhaust really give you extra power?  How much of this is placebo effect on the user, I mean the extra noise possibly making it sound more powerful, and actually not having any affect on the performance at all, apart from making it possibly worse.


Although when tuning an engine the exhaust along with carburation is critical to the performance as I'm sure you know, simply opening up the exhaust and doing nothing else could be very damaging.
Sick engines can be heard every day, usually attached to a silly wee hatchback.. they make a lot of noise and less power than the standard car.

In my experience nearly all factory engines, even high performance, aren't that near to the limit as manufacturers need reliability.

So I suppose as we're talking garden machinery that's often homeowner and mostly started with a piece of string the majority are in a very low state of tune and most definitely able to be tweaked but whether or not they're components would be robust enough to handle much more power is probably questionable, maybe the top makes ie. Stihl and Husky but even they're getting cheap and nasty these days.

Also as has been said the emissions problem is a major constraint on engine tuning from the makers point of view, and that's why there's scope for folk to tinker.

Just my take on it 


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