New designed Hyway 660 cylinder

[TreeLife]

This is an excellent thread. Subbed for the continued wealth of knowledge!

 

[GlocknStihl]

I have been sent a few of these for testing as well, but I'm more working with them with the 660 to try and get the damn port timing right.
Firstly, these cylinders are not yet available for sale.
The stock cylinders are about the 96/126/86 mark
I got a regular big bore as well and it was 97/127/87. No free porting either.
Then they sent me the revised port size big bore and it was same timing, but I told them the exhaust was pointlessly oversize, the fragile little gasket wont last 3 minutes and its all undone as soon as you bolt a muffler on that has not been modified to suit. It also free ports slightly at the bottom
They then sent me a big bore with revised port sizing and revised port timing. When I told them they had successfully made the worst timed 660 cylinder on earth they rang me to discuss. It was 86/123/90.
I told them if they could create a cylinder that has factory timing around the 98/120/80 mark, they would sell them by the truckload as they are actually very good quality.
We discussed the transfers flow etc and I said they are fine for the general market and those that want more can grind it themselves. I also told them it cant freeport so they need to keep that in mind.
All the cylinders I got had pretty much bang on .020" squish with the gasket fitted under the cylinder.
They are now going to make a cylinder with timing I asked for (or try to) and will get back to me.
Fingers crossed they can get it right

I have given the original 54 and 56mm cylinders to a mate who is learning to port to mess with and test as he cuts firewood full time.
I dont cut enough to do durability testing

I noticed the same thing with the exhaust. With the piston all the way up there is a space under the piston skirt. That's why I'm sending it to someone better than I to go through it.

Thanks for your reply too. Very interesting to see the difference.

 

[Fruecrue]

It was 86/123/90.

Pipe it.

 

[smokey7]

A intake at 90 would have to be a spitback queen and a gas guzzler. They look good but if the timing is way off they wont run too good. Ive not done too many hyways on 660s but the 357 359 350s 346s 365s 372s have all had acceptable timing similar to oem. It seems 440s and 660s have had some very odd timing numbers.

 

[Brewz]

Yeah I have a 372 big bore here from Hyway I plan to do some serious work to, and it has great timing.
I don’t know why it’s so hard for the aftermarket manufactures to get the timing on tbe 660 the same

 

[Brewz]

Pipe it.

Mind reader

 

[wcorey]

We discussed the transfers flow etc and I said they are fine for the general market and those that want more can grind it themselves.

Not sure I agree with this, by the looks of what's been pictured here (unless yours are different), the trans tunnels are poorly shaped and are in some places more likely to need material added rather than ground off.
Other than maybe an excessively high exhaust this is probably the most difficult area to rectify through machining/porting and a terrible performance killer.

...I told them the exhaust was pointlessly oversize...

Keep the bigger exhaust exit and just make the flange outside diameter a bit larger.

 

[Brewz]

Not sure I agree with this, by the looks of what's been pictured here (unless yours are different), the trans tunnels are poorly shaped and are in some places more likely to need material added rather than ground off.
Other than maybe an excessively high exhaust this is probably the most difficult area to rectify through machining/porting and a terrible performance killer.




Keep the bigger exhaust exit and just make the flange outside diameter a bit larger.

Just had a good chat with them about thectransfer direction, sent pics illustrating the direction of the OEM cylinders and explained why they are like that, then pics of theirs showing the poor directional settings of the ports.
Tried to talk them into a bit more surface area on the exhaust flange but that’s how it’s staying aparently.
Pointed out the muffler will undo it all and looks they may me developing a muffler to match the large port to be sold as a set.
I also went over the issues of free porting on tbe big bore and why it’s bad. Apparently the engineers noticed it and have corrected it.
They are working on an updated mould now with changes to intake and exhaust ports so will be interesting to see what comes back after many many hours of discussion with them.
Also asked if they can leave tbe squish band unplated and they plan to do this as well

 

[species8472]

I have been sent a few of these for testing as well, but I'm more working with them with the 660 to try and get the damn port timing right.
Firstly, these cylinders are not yet available for sale.
The stock cylinders are about the 96/126/86 mark
I got a regular big bore as well and it was 97/127/87. No free porting either.
Then they sent me the revised port size big bore and it was same timing, but I told them the exhaust was pointlessly oversize, the fragile little gasket wont last 3 minutes and its all undone as soon as you bolt a muffler on that has not been modified to suit. It also free ports slightly at the bottom
They then sent me a big bore with revised port sizing and revised port timing. When I told them they had successfully made the worst timed 660 cylinder on earth they rang me to discuss. It was 86/123/90.
I told them if they could create a cylinder that has factory timing around the 98/120/80 mark, they would sell them by the truckload as they are actually very good quality.
We discussed the transfers flow etc and I said they are fine for the general market and those that want more can grind it themselves. I also told them it cant freeport so they need to keep that in mind.
All the cylinders I got had pretty much bang on .020" squish with the gasket fitted under the cylinder.
They are now going to make a cylinder with timing I asked for (or try to) and will get back to me.
Fingers crossed they can get it right

I have given the original 54 and 56mm cylinders to a mate who is learning to port to mess with and test as he cuts firewood full time.
I dont cut enough to do durability testing

I didn't see one. only joking.

 

[GlocknStihl]

I'm posting this for Luc (LBracing).

Here we go I received one of these from Kennis , thank you man was pleasure!

First thing I noticed is how nice the plating looks , all the way to the top , no death ring at all . Surprisingly rings looks VERY nice also . Piston looks good , no casting flash . Enlarged exhaust gaskets are supplied , pretty cool . Still the same bad clips .

Now for the bad . Because ... there is , and lots of it .

First : Lots of Freeport and that’s without any machining done just a basic gasket delete . I understand them making the piston shorter to clear the case and make the kit bolt on , wich is good but as you can see the the floor of the exhaust port could easily be lifted 0.100’’ and still be below piston at bdc. I like the nice round shape of that floor and flat top to maximize blowdown tho .

Second : intake port shape is horrible . It’s crooked meaning the sides open before the center . Probably not a big issue as the port is narrow and have plating on the edge . To make it a decent shape would need to be over 92* .

Overall same big bore kit as we’ve seen in the last couple years but with a flashy pop up piston and 10$ worth of intake entrance and exhaust outlet port job .

Oh and here are some numbers in duration :
Squish : 0.024
Exhaust : 176
Tr : 110
Int: 178
Blowdown : 33

 

[GlocknStihl]

More pics

 

[smokey7]

Does he have assembled yet? Is he going to run it on s oem bottom end or a asian bottom end?

 

[Brewz]

I have told them I don't like it but they have relied that its staying and is the answer to a changing market.
I really don't like it

 

[Mastermind]

Typical of the mindset.

 

[CR888]

Some of the AM companies seem like the blind leading the blind. When you copy something from someone else & have no idea why its designed the way it is what hope do you have improving on it…

 

[Mastermind]

They need to build these at 100/120/81

They will run like a mfer, and have room for others to custom tailor.

 

[srcarr52]

They need to build these at 100/120/81

They will run like a mfer, and have room for others to custom tailor.

I’d like to see even less intake duration.

 

[stihl_head1982]

Just noticed the OP is from Cana Virginia. I came through there several years ago.
Ever hear of a place called the "Hungry Farmer" (I believe was the name of the cafe?).
Like going to grandmas and her having a buffet!
Sorry for the derail.

 

[Brewz]

Yeah I told them to aim for 100/120/80

 

[GlocknStihl]

I have told them I don't like it but they have relied that its staying and is the answer to a changing market.
I really don't like it

I told them I dont like it either. The free port alone makes it ridonkulous.

They had the correct idea, just missed the mark.