Inside the MS362
- Thread starter blsnelling
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bitzer
******** Timber Expert
Coming, coming
I don't mean to rush ya1 You've just kept us hangin for days LOL!
After doing this would you give any creedance to the statement below. I've spent a lot of time trying to understand the theory of the strato.
"What I'm thinking is that the EPA is after controlling unburnt hydrocarbons emmisions, by the addition of extra air from the strato ports it casues a more efficient burn of the mix."
I came up with that thought after seeing the saws reaction when the strato ports were closed off after I undid the throttle linkage to them.
stihlboy
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opcorn: good job brad...... id like to see you get a spare p&c in line for a 362 and port it more aggressively, i bet you would also see better results if it had a different carb....... where is andyshine77? hmmm
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I sat and stared at this P&C for a good long while trying to decide what I wanted to do with it. In the end, I basically treated it like any other saw. The only thing the strato really does is add that extra puff of fresh air to help push out the exhaust. I also believe I can explain why WOT tuning RPMs are not that high, and why it can't be pushed as far/hard as a 361.
Look at the intake port. It's only about half the width of a normal intake. It's limited by the pockets in the piston that carry the strato charge. All fuel comes through that one small intake port. So it only stands to reason that it can't flow what a traditionally ported engine can. I was able to widen it a little, but not much. I did lower it 4°, but it would need a lot more width to do more. The intake and carb are matched accordingly. So those are bottle necks as well.
Here are the beginning and final port timing numbers.
Exhaust 103° - 100°
Transfers 131° - 124°
Intake 73° - 77°
As you can see, I raised the transfers a lot. I also widened the rear ones. Transfer flow is needed to maintain RPMs in the cut, so they had to come up considerably.
The exhaust was a little low stock, but I don't like to raise it much. I build for torque and compression is your friend.
Now for the pics.
Here's the tiny intake. You can see where the edge of the skirt rides. I went as wide as I could.
I widened the exhaust a TON. I went a full 70%, as measured along the curve. I wouldn't doubt that I widened it at least 3/8"!
I widen it at the flange as well and taper it all the way in.
I raised the tranfers a lot as well. They were really low to begin with at 131°.
On the strato ports, I only slightly widened them. I did very little to them.
Look at the intake port. It's only about half the width of a normal intake. It's limited by the pockets in the piston that carry the strato charge. All fuel comes through that one small intake port. So it only stands to reason that it can't flow what a traditionally ported engine can. I was able to widen it a little, but not much. I did lower it 4°, but it would need a lot more width to do more. The intake and carb are matched accordingly. So those are bottle necks as well.
Here are the beginning and final port timing numbers.
Exhaust 103° - 100°
Transfers 131° - 124°
Intake 73° - 77°
As you can see, I raised the transfers a lot. I also widened the rear ones. Transfer flow is needed to maintain RPMs in the cut, so they had to come up considerably.
The exhaust was a little low stock, but I don't like to raise it much. I build for torque and compression is your friend.
Now for the pics.
Here's the tiny intake. You can see where the edge of the skirt rides. I went as wide as I could.
I widened the exhaust a TON. I went a full 70%, as measured along the curve. I wouldn't doubt that I widened it at least 3/8"!
I widen it at the flange as well and taper it all the way in.
I raised the tranfers a lot as well. They were really low to begin with at 131°.
On the strato ports, I only slightly widened them. I did very little to them.
You can see the widened intake here, as well as a little flow work I did in the strato port. Again, I did very little to the strato part of the cylinder.
I'v already ported this cylinder nearly as aggressivey as I have any saw. It is what it is. I'm not interested in swapping carbs. The linkage setup is unlike anything you've seen before. If that's what you want, you need a 361. This saw responded very well to the mods and is a great running saw. The fact that a 361 is a little faster in some situations, does not affect the credibility of the 362. It's a great saw.
At work.
stihlboy
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no no no i mean to mess with the strato portion of the cyl.... if only the second butterfly had a jet spraying fuel into it only at wot
it would be ideal for a little shot of nitrous
stihlboy
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better question is wher is his saw? lol
FATGUY
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Don't forget, they were neck and neck in smaller (but still substancial) sized wood.
stihlboy
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man i wish you guys would have tested it in a 6'',8'' 10'',16'' it would show its powerband
i have all those sizes in various types of wood.............even a 3'' oak cant
I don't know what that would have shown that we didn't already show. We compared them in about 12" wood and then buried the bars.
Some of you are loosing sight of what we're doing here. I ported a 362 and compared it to a stock one. It saw 18%-26% gains. Those are respectable gains for a woods port on any saw. The ultimate question here was how does the 362 take to mods. The answer is, very well.
FATGUY
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:agree2: Absolutely, Brad, you were 100% succesful here, good job. I'm sure Blood will be thrilled.
stihlboy
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im betting in small as in 6'' that 362 would own the 361..........on a side note was the 362 8 or 7 pin? if its 8 i bet it would do real good with a 7
I always run a 7-pin on a 60cc saw. They'll pull an 8-pin but not as well. Perhaps Andy was right, and I should have left the 361 out of this. This is ultimately about how the 362 responds to mods. I was just trying to answer to question in everyone's mind.
stihlboy
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that was directed at me wasn't it
so larger wood= larger gain yes?
if so that is a very good sign indicating a great increase in torque in the mid range
stihlboy
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i thank you for that because it shows that it is not a very shabby saw.
what all is done to the 361? point being is if it were apples to apples would it be different?
brad, great work as always!
FATGUY
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I see where you're going with this but it's a bit of a moot point. A 346 would hand both of those saws there ass in 6" wood. Most of the cutting the 60 cc saws will do will be in the 10"-18" range.
