Gas ports and the intake stroke

[englertracing]

I have a little engine with a big oil consumption problem, 80 mm bore 0.8mm top ring 1.5mm oil control.

It has lateral gas ports, it got me thinking about what happens with those gas ports during the intake stroke. I'm thinking on the intake stroke if the ring is moving to the top of the groove that it can allow oil to come through the bottom of the Ring Groove and the ring, around the back of the Ring, and right out through the gas ports. particularly if the case pressure is high and the cylinder pressure is very low. I think typically on a three ring piston that the second ring will prevent or hide this. has anyone ever run into gas ports causing issues

[Warp Speed]

I have a little engine with a big oil consumption problem, 80 mm bore 0.8mm top ring 1.5mm oil control.

I'm sorry!?!

[englertracing]

Yeah I'm using the talk to text thing, and it fired the post off a little bit early

[Warp Speed]

I have a little engine with a big oil consumption problem, 80 mm bore 0.8mm top ring 1.5mm oil control.

I'm sorry!?!

And I should add, if your having trouble, it isn't because of ring size or gas ports!

[Warp Speed]

Yeah I'm using the talk to text thing, and it fired the post off a little bit early

Lol

[englertracing]

I have a little engine with a big oil consumption problem, 80 mm bore 0.8mm top ring 1.5mm oil control.

I'm sorry!?!

And I should add, if your having trouble, it isn't because of ring size or gas ports!

well then I will add that, the case venting is less than ideal which is being addressed, my bearing clearances are freaking gigantic think four thousands, on an inch and a half Journal. That will be corrected as well, oem specifies a 1060 oil presumably too deal with whatever random clearance the engine ended up with. I'm thinking it would be a good idea to omit the gas ports from the new Pistons, and use a 2 mm Oil ring.

so you don't think that gas ports on a 2 ring piston could lead to reverse Blow by on the intake stroke

[Warp Speed]

I'm sorry!?!

And I should add, if your having trouble, it isn't because of ring size or gas ports!

well then I will add that, the case venting is less than ideal which is being addressed, my bearing clearances are freaking gigantic think four thousands, on an inch and a half Journal. That will be corrected as well, oem specifies a 1060 oil presumably too deal with whatever random clearance the engine ended up with. I'm thinking it would be a good idea to omit the gas ports from the new Pistons, and use a 2 mm Oil ring.

so you don't think that gas ports on a 2 ring piston could lead to reverse Blow by on the intake stroke

It depends on the quality and placement of the gas ports. Assuming this is all good (this is the 21st century! Lol), I certainly wouldn't think so.
2 ring deals can be challenging oil consumption wise (for very little if any gain, especially with a .8mm pack), but many do it all the time.
I would work on your oil control and venting, as you've mentioned, and make sure things are minimum gap wise on your oil ring, and radial tension with it is sufficient also.
The rest is up to bore prep.....

[gmrocket]

I'm sorry!?!

And I should add, if your having trouble, it isn't because of ring size or gas ports!

well then I will add that, the case venting is less than ideal which is being addressed, my bearing clearances are freaking gigantic think four thousands, on an inch and a half Journal. That will be corrected as well, oem specifies a 1060 oil presumably too deal with whatever random clearance the engine ended up with. I'm thinking it would be a good idea to omit the gas ports from the new Pistons, and use a 2 mm Oil ring.

so you don't think that gas ports on a 2 ring piston could lead to reverse Blow by on the intake stroke

I corrected an upper end oiling issue by putting the Napier THG second ring in the correct way ..it wasn't me who did that.

With a 2mm ultra low tension oil set , its smoked like a train

[englertracing]

It depends on the quality and placement of the gas ports. Assuming this is all good (this is the 21st century! Lol), I certainly wouldn't think so.
2 ring deals can be challenging oil consumption wise (for very little if any gain, especially with a .8mm pack), but many do it all the time.
I would work on your oil control and venting, as you've mentioned, and make sure things are minimum gap wise on your oil ring, and radial tension with it is sufficient also.
The rest is up to bore prep.....

Gas ports done at Cp... Look good, always check them for burrs,
Bore is nikasil. Done by millienium plating.

Oem is a 2 ring setup
1mm top steel ring I believe it is TiNi coated. Beveled on the inside diameter
Oil ring is 2mm, rails are 0.017" x 0.086" from what I can gather it's in the 6-8lb range

My current setup
0.8mm cp top ring chrome nitride no bevel cut.
Oil ring is 1.5mm rails 0.012" x 0.078" from what I can gather it's around 4lbs tension

I'm still thinking I'm drowning it in oil, my anemic oil ring is allowing the molasses oil by, and although it's not the top rings job, without a scraper the top ring is tasked with what would normally be handled by the scraper, and the gas ports are allowing leakage from case to cylinder during conditions where case pressure is greater than cylinder pressure. By fixing everything else maybe I can run my 1.5mm setup, but, I'd rather attack from all avenues.

If I'm already revising the pistons for other reasons do you think it would be worthwhile to change the ring package to 0.8mm 2mm?

Some pictures of a set that I never ran

IMAG2480.jpg

Something that concerns me is that it's only got 4 oil drain back holes, the other 4 are the "forced pin oilers" thinking i am going to do 8 drainback holes.

IMAG2480.jpg

8 gas ports evenly spaced, 2 above each skirt, 2 above each side of the pin

IMAG2475.jpg

IMAG2480.jpg

[englertracing]

I corrected an upper end oiling issue by putting the Napier THG second ring in the correct way ..it wasn't me who did that.

With a 2mm ultra low tension oil set , its smoked like a train

I wish I could add a THG! And leave the 1.5mm oil ring would probably work great! But I think my compression height is a little below what I can get away with.

[englertracing]

Bump