Mastermind Meets The MS661 Again

[fordf150]

I'm stupid here so bear with me.

Does the floor have to be sealed or can you do as I think Chris was suggesting with a insert that stops .010 shy of the skirt? If you can do that I don't think an insert would be all that hard or expensive to have made

 

[Mastermind]

I like the idea of an insert as well. There are a few things that need to be considered though.

It really couldn't hook into the boot, and be thick enough to be solid.

The insert would have to be glued, or anchored to the floor of the port somehow. If the glue failed.....the engine would eat it.

3D printing could possibly make the insert, but can thermoset plastics be printed at this time?

 

[bryanr2]

40% I'd bet!!!! isn't that the magic numbah? you pro porters shoot for???

Some reach, Some attain.

 

[singinwoodwackr]

Not everybody has the bucks to buy the latest fad in feller bunchers.

I'd like to see a FB on a 60* slope ;p

 

[Deets066]

I'd like to see a FB on a 60* slope ;p

Only if I was uphill from it.

 

[singinwoodwackr]

I like the idea of an insert as well. There are a few things that need to be considered though.

It really couldn't hook into the boot, and be thick enough to be solid.

The insert would have to be glued, or anchored to the floor of the port somehow. If the glue failed.....the engine would eat it.

3D printing could possibly make the insert, but can thermoset plastics be printed at this time?

current 3D printing can use just about any metal...they are making 1911s out of SS at the moment.

 

[singinwoodwackr]

Only if I was uphill from it.

...and w/in reach of your machine....

 

[Mastermind]

If the insert could made from stainless......then it could be very thin.

 

[LegDeLimber]

maybe time for a little milling machine setup?
Taking a touch more out of the intake floor and some sort of counter-bore at the boot side of the intake
to accommodate some manner of a stamped insert.
But without my standing there ,holding a cylinder to roll around and get an accurate actual shape I'm likely to be way, way off with that thought.

And of course you'd need the tool & die guys to tell ya what geometry could be stamped
and done repeatably.
Then once you fit something in there, it's going to have secured in a fashion so as not to turn into
rattle/reed and shake itself to point of cracking or slapping metal fragments loose.
Something like 4 or 5 thousandths movement would slowly become a motor killer.

little bitty flecks from the impacts gets you scoring, The stress cracks eventually turn the insert into a large foreign object wedged between some fast spinning guts.
Could be that the mill work would allow a more secure epoxy shape.
get rid of some longer, tapered sections that will be more likely spots to give way eventually.
and then there is that aforementioned, molded insert when you have a place to fit it into.

 

[singinwoodwackr]

If the insert could made from stainless......then it could be very thin.

price would 'only' be $1000/per

 

[KG441c]

Randy I would like to hear you discuss how much you cut from dome/base and where the intake landed afterwards and how you determined which way you wanted to go with the intake number after you were satisfied with the squish setting? And the theory u have in mind? Also can you discuss the affects of a intake when raising and lowering and widening? Thanks

 

[KG441c]

I'd hate to have to epoxy the intake on all these 661s. I'm gonna predict that when I raise the intake floor to 78 - 80 degrees.....this engine will come alive.

I'd like to see 101/118/78 in this short stroke motor.

When you say come alive would that be rpm, torque, or both?

 

[KG441c]

Randy what is your prediction it will make on the dyno?

 

[Deets066]

 

[Chris-PA]

current 3D printing can use just about any metal...they are making 1911s out of SS at the moment.

Not with any reasonably affordable machines.

The one we have here at work can print ABS, and I think perhaps nylon with an additional bed adapter. Nylon might be suitable.

I think an insert could be retained by drilling a hole in the insert spout, and running a countersunk screw in from the outside. That way the screw could not enter the intake even if it came loose. Maybe the insert could be formed so as to hook over the intake inlet spout? I don't know what the boot looks like, but it probably fits too closely for that.

Overall a pre-made insert would be a challenge on a port that had been modified, as the shape would have to match very closely. It might be viable on a stock port. Even with a stock port, drawing it would be fun, as it is an obscure shape. I suspect filling it with epoxy and grinding it down would be the best process for low volume mods, but even that is a PITA..

 

[Ron660]

No Andrew, one is with unfinished Devcon, the next is after finishing, then next is a stock port.

The factory port ends up at 85* after machine work. That's not crazy low on a 90cc saw, but I would like to be able to cut more from the squish to get the compression a little higher. At 85*, that's as far as I will lower the jug.

Even then I can't raise the transfers quite as high as I'd like to.

So, I'm at 102/122/85 on the two jugs without epoxy.

The jug with epoxy in the intake is at 100/120/80.[/QUO

Randy what is your prediction it will make on the dyno?

I think the stock 661 dyno results will be close to factory specs just like your 461 were. Ported 661, not sure.

 

[Mastermind]

Randy I would like to hear you discuss how much you cut from dome/base and where the intake landed afterwards and how you determined which way you wanted to go with the intake number after you were satisfied with the squish setting? And the theory u have in mind? Also can you discuss the affects of a intake when raising and lowering and widening? Thanks

I tend to creep up on my final "recipe" for any new model Keith. This unit is no exception. If you will remember the first MS661 I did, I was very displeased with the measly 15% gain in cut speed I got. After reviewing my notes, and rechecking that first jug, I found that I missed my mark on the exhaust by 2°. I ended up with the exhaust port too high.

I figured that if going only 2° too high made the saw feel like it needed to be babied thru the cut to keep from losing RPM, then lowering the exhaust port below stock specs would make it have more power, and then it would be a better work saw.

With that in mind I needed to cut at least .030 from the squish to be able to lower the jug enough to make a real difference in exhaust height. That is where I got the amount I planned to take from the squish band to begin with.

I like compression......any engine builder will tell you that raising compression increases volumetric efficiency. The closer an engine is to 100% volumetric efficiency the better it will perform across the entire RPM range. By cutting .030 from the squish band, I ended up with 175psi. I really would like to see 200psi. That would mean more from the squish band.

There was a problem here though. The intake port is at 81° stock. That ain't insanely low.......the MS660 is about in the same place.

But the 064.......and some of the older flat top 066s......they have a higher intake port. They also make more power. Why is that?

Case compression.....

Primary compression is what forces the air/fuel mixture around the piston, thru the transfer ports.

If I cut more from the squish to gain more compression, I will further lower the intake, and lose case compression.

That's way I would like to be able to decrease intake duration.......and why I'm filling the intake port on this one jug. It all about R&D.

 

[KG441c]

I knew I would learn something if I could pick your mind alil!! Lol! Thank You. Very interesting and very eager to see what you have came up with. I see the motto, thinkin outside the box now! Is there a set amount in .000s that equals 1°? And also when blending the transfers how does taking too much out of the transfer effect the volumetric efficiency overall and do u look for direction of flow more importantly or both? Thanks

 

[KG441c]

Also Randy while Im pondering what you just said, Is it possible to have too much compression pushing the fresh charge in the combustion chamber and colliding with each other for a non efficient effect vs less compression? Thanks

 

[Mastermind]

Bore size, rod length, and strike will make .000 VS ° different for engine to engine. So the best thing to do is check that with a wheel at the port height you are looking at altering.

Too much primary compression can slow down the engine due to pumping loses. The same is true with too much cranking compression. This is why race saws, and work saws are so far apart on build style.