Stihl 046/460 D Jug. Are there benefits using it on a 460, or better using it on a Hybrid?

[MustangMike]

OK, just my 2 cents, or opinion, or whatever!!!

In theory, the round chamber should be more efficient, but the D chamber is worth about 10 psi all else being equal.

I think all the 046 D jugs were Mahle, and generally had good port timing, which makes them both better stock and easier to port.

My two best running ported 460s both have 046 D jugs.

The three best running hybrids I have seen all were running 046 D jugs.

Now keep in mind that 046 D jugs are rare compared to other 046/460 jugs.

So, I'm a fan of the 046 D jug, even if it does not make any sense! I'll take one any time I can!

 

[mdavlee]

Best running ones I've done were round chambers. For a stock saw I can see the draw to it. Ported not enough difference if any.

 

[RI Chevy]

Cool. Thanks for the responses guys. Good info. [emoji106]

 

[wigglesworth]

The good early cylinders had a lot less blowdown than the later ones. I've seen em with as little as 14 degrees blowdown, and they were always the stronger of the stock 046's.

A lot less to grind out too if you were porting one.

There's a lot of talk in the two stroke tuners handbook on combustion chamber shapes. If I recall, optimal was around 50% squish area. With the D-chambers, they are dang close.

I'd take a D-chamber over the hemi everytime.


It's been a while since I read the two stroke handbook though, so I could be off....

 

[wigglesworth]

Here is a link to the book. If your monkeying with two strokes and haven't read this book, your a monkey yourself.

http://www.amrca.com/tech/tuners.pdf

 

[mdavlee]

50% is pretty close if I remember right. I never figured a D chamber or round chamber for area.

 

[Keith Gandy]

The D-shaped combustion chamber saw is a better runner stock, especially when you have the good early carburetor and the 1309 ignition. Those components were all designed in concert on the early 046s to make a strong running stock saw.

If you're sending it to a builder, then it doesn't matter at all and the round combustion chamber jug is the better choice.

I agree. My buddy has a 1st yr 046 that only has a gasket delete thats a really strong runner stock

 

[drf256]

Dallas has both a hemi and D chambered 046. I believe he says that they run neck and neck.

OK, just my 2 cents, or opinion, or whatever!!!

In theory, the round chamber should be more efficient, but the D chamber is worth about 10 psi all else being equal.

I think all the 046 D jugs were Mahle, and generally had good port timing, which makes them both better stock and easier to port.

My two best running ported 460s both have 046 D jugs.

The three best running hybrids I have seen all were running 046 D jugs.

Now keep in mind that 046 D jugs are rare compared to other 046/460 jugs.

So, I'm a fan of the 046 D jug, even if it does not make any sense! I'll take one any time I can!

You have that unicorn 460 jug Mike. Best I've ever seen.

Let me know if you ever want to give that one up. The jug looks factory ported. The intake is huge and near the edges of the skirts from the factory. It's a hemi.

The band may be less than 50% stock on the hemi, but it grows when you cut it.

 

[MustangMike]

Al, I would love to see if you could make that jug run stronger than the excellent 460 (w/046-D jug) you did for me. As you recall, the 460 jug you like came off that saw. I think we should check the port timing on it just to see if it needs any mods.

I have an abundance of 046/460s right now (5 + 1/2), and will likely come into more in the spring, so we should be able to work something out.

How does your 046-D jug look, still think it was a great stroke of luck coming into that one!

 

[Keith Gandy]

Al, I would love to see if you could make that jug run stronger than the excellent 460 (w/046-D jug) you did for me. As you recall, the 460 jug you like came off that saw. I think we should check the port timing on it just to see if it needs any mods.

I have an abundance of 046/460s right now (5 + 1/2), and will likely come into more in the spring, so we should be able to work something out.

How does your 046-D jug look, still think it was a great stroke of luck coming into that one!

Id love to get the 1st year 046 from my buddy John but it was his Uncles so he isnt parting with it. It has a bowbar on it

 

[blsnelling]

There are a lot of myths that float around about D-chambered cylinders. I believe the same is true about non-decomp 066 jugs, as well as perhaps K&S jugs. IMHO, it's not the chamber shape that makes the difference. It's the port timing. Additionally, IIRC, it's only the first year 046 cylinders that had that optimal port timing. These early cylinders had extremely short blowdown. That's what makes them run. Myself? I'd rather have the round chamber and put the proper port timing on it.

BTW, I have a very first production month 046. My late father bought it new. It is a VERY strong running saw!

 

[Deets066]

There are a lot of myths that float around about D-chambered cylinders. I believe the same is true about non-decomp 066 jugs, as well as perhaps K&S jugs. IMHO, it's not the chamber shape that makes the difference. It's the port timing. Additionally, IIRC, it's only the first year 046 cylinders that had that optimal port timing. These early cylinders had extremely short blowdown. That's what makes them run. Myself? I'd rather have the round chamber and put the proper port timing on it.

BTW, I have a very first production month 046. My late father bought it new. It is a VERY strong running saw!

Still building hybrids Brad?

 

[blsnelling]

Still building hybrids Brad?

I haven't ported but maybe a couple saws in the last 6-9 months.

 

[2stroke800]

Soo, random question.. i dont know much about hybrid builds. But could someone make a 441c/460 hybrid still using the mtronic from the 441c on the 460 top end? Sorry for the hijack but i was just thinking out loud.. haha!

 

[RI Chevy]

Good question. No worries here. [emoji106]

 

[RI Chevy]

I think 441CM is a quad port. May flow better than the 460.

 

[Deets066]

441 is quads right?

Transfer would be different

 

[MustangMike]

That is a definite no, but I'm not sure about a 461 jug on a 441? Never had a 441 apart, but they are both quad port saws.

 

[wigglesworth]

There are a lot of myths that float around about D-chambered cylinders. I believe the same is true about non-decomp 066 jugs, as well as perhaps K&S jugs. IMHO, it's not the chamber shape that makes the difference. It's the port timing. Additionally, IIRC, it's only the first year 046 cylinders that had that optimal port timing. These early cylinders had extremely short blowdown. That's what makes them run. Myself? I'd rather have the round chamber and put the proper port timing on it.

BTW, I have a very first production month 046. My late father bought it new. It is a VERY strong running saw!

I agree it's the port timing that makes the most difference. It just so happens most of them better ported jugs are the early D-shape 46 jugs, non-decomp 66 jugs and the KS branded 044 jugs.

Again, that's in total stock form (which is how I like my work saws, I'm a weirdo I know).

Still one can't count out the R&D in the tuners handbook...

 

[Chainsaw Jim]

I agree it's the port timing that makes the most difference. It just so happens most of them better ported jugs are the early D-shape 46 jugs, non-decomp 66 jugs and the KS branded 044 jugs.

Again, that's in total stock form (which is how I like my work saws, I'm a weirdo I know).

Still one can't count out the R&D in the tuners handbook...

Well if the factory changes port timing on the same model upgrading it to a magnum or super then I don't consider that stock, I consider it a mass produced ported saw.