361 Shootout

[Trigger-Time]

Slick idea!

Likely would not even need to glue them they should seal on them selves.

If you could put a screen over the whole works to help shead the larger stuff it would help too. Filtration for milling is one area where I like the husky design over the stihls as the stihls plug up fast.

For screen, was thinking about pantie hose.

What I would really like to do is make a PVC intake pipe about
16" tall. Then I could make it take a small engine or automotive filter.
But then would have to brace it up for support. But the 2 filter deal
will be enough I think.


TT

 

[blsnelling]

If you could put a screen over the whole works to help shead the larger stuff it would help too. Filtration for milling is one area where I like the husky design over the stihls as the stihls plug up fast.

Outerwears are awesome for that.

 

[timberwolf]

Finnished the mufflers up.

 

[parrisw]

Finnished the mufflers up.

I love the muffler hanger!!

 

[timberwolf]

Some work on the next 361.

Plugged the hole in the bottom of the intake, always wondered what this hole was for, best I could figgure it was a drain to keep fuel from making a puddle in the boot causing a stumble on acceleration.

Roughed in the upper transfers, a little wider than the other saw, but kept them low, Still need to clean the corners of the front transfer a bit.

 

[timberwolf]

Here is some rough in work on the moddified intake flange.

Can just make out where the old passage was before being pluged with a 3/32 aluminium filler rod.

 

[mtngun]

Nice work, TW.

 

[timberwolf]

Couple pics from the inside of the intake, not a lot of piston skirt width to work with but can grab about 1mm on each side and have extended the durration a little but gained a fair bit of area by re-shaping. Also because the carb and rest of intake will be able to flow a good bit more than stock the base can be filled quickly so alot of intake duration is not needed.

 

[Outlaw5.0]

What did you use to fill the hole?.

 

[timberwolf]

3/32 aluminium filler rod with a skim of JB.

 

[Terry Syd]

Looks like you may have slightly enlarged and smoothed some of the areas in the piston. I've always wondered about how much the piston affects the flow. Have you been able to detect a difference in flow by reworking the piston a bit?

 

[timberwolf]

Yes, took off some of the rough edges on the piston. Would be a really good experiment to flow the whole saw case and transfers to see how much flow could be improved with piston work alone.

 

[mtngun]

Impressive amount of sweep back on those upper transfers.

 

[Thorcw]

Hey I know I asked on the 440-460 build but how do you do the ceramic coating (im guessing like powdercoating) and were do you get the stuff at?

 

[Terry Syd]

From the earlier picture where Brian roughed in the rear transfer port -

http://www.arboristsite.com/attachment.php?attachmentid=160800&d=1291590345

It looks like he has now worked that swep backed area (changed the angle of discharge) to make the port wider in order to pick up more area of flow. The jug is starting to look more like a motorcycle cylinder with those wide transfer ports.

 

[timberwolf]

The jug is starting to look more like a motorcycle cylinder with those wide transfer ports.

Yes, looking to get a little more RPM with this 361, maybe not quite as much torque. Wait till I get to the BB, have a couple ideas for that one that I have not tried before.

The ceramic sprays on as a wet emuslsion and is baked which I think activates some polymer binders to hold the ceramic dust together. Coating is not as good as with pistons I have sent out to be coated (some fuels will eat at it), but a fraction of the price.

 

[timberwolf]

Exhaust side

Port is offset to one side more due to the lower ring end pin location.

 

[Trigger-Time]

Exhaust side

Port is offset to one side more due to the lower ring end pin location.

Outside of cylinder, looks as if exhaust port center is in line with casting marks
on outside of cylinder, if it is.
Does the port angle from inside to outside of cylinder?

Or does exhaust blow out left to right or other way around?

Port walls look very, very smooth!

It sounds right in my head, if you know what I mean.


TT

 

[Terry Syd]

Nice looking port, too bad about the ring end. Do you think it will have an effect on symetry of flow?

I suppose after you have run it a bit you can check the carbon patterns and then make a decision about keeping the lower ring.

Looking back on your original computer simulations I noticed that the curves were essentially the same except that they gained in amplitude. Are those curves still valid with your decision to increase the transfer area on this new jug? If not, if you get a chance to run another simulation with the increased transfer area, I'd like to see how it affects the curve.

 

[timberwolf]

I have moved the second ring end before though there is almost nowhere to put it that it does not hit ports and I have run them without for racing, but as this is still a full on work saw...

The exhaust does head out a bit right to left looking at the back as the saw is held. I don't really think this makes any huge difference on scavenging, at least I have not noticed.

Here are the lower transfers, tool makers ink which I was using to mark height all over everything.