Geo Metro 1.0L G10 engine rebuild mods for better MPG

[zoltanbod]

Will,Zoltan here .Do you know of any varifiable evidence as to the efficiency improvement reported using the gapless ring on the Suzuki 3 cyl.?

[Wonderboy]

Another small update:
I went back to the racing shop that did the valve job on my head (they encouraged me to come back whenever I wanted - they enjoyed talking to me about my aero mods and FE in general) and talked to a very knowledgeable guy about gapless rings. He reassured me that totalseal was the only place where gapless rings available if Gasoline Fumes' research holds true (that there are no longer any more OEM gapless XFi rings in stock from GM parts suppliers). He said that I should measure the spring force of the old rings vs. the new ones using a fishing scale or similar spring scale by seating the rings into a cylinder, then pulling on the scale. There should be a spec somewhere for the force required to move a piston - does anyone have this? I also talked to him about using the 75mm honda ring and making my own gapless ring. He said it was actually a pretty good idea, and that it would produce more spring force (= more compression?) than the stock 74mm bore rings would. I assumed this to be the case, and was only reassured. He said to do exactly what Christ advised - seat a 75mm ring into a cylinder, mark off the overlap, then add at least .007" to that to leave wiggle room for heat expansion. I asked if the large radius of the grinding stone used to remove ring material could cause any issues, but he said nope, as long as the outermost points of it were at least .007" away from the other end of the ring. I made a picture to demonstrate this. By exaggerating the scale, I hope it illustrates what I'm trying to say. I hope to try it out as soon as my experiment rings arrive.

Originally Posted by bgd73

and you geo owners. for god sakes..remove egr before doing it?

I dont think any of the 1.0l G10 engines had EGR, right? At least I'm pretty sure my xfi doesn't - out of curiosity though, how exactly would retrofitting a gapless ring affect an engine equipped with egr? I'm clueless and wouldn't mind learning.

Originally Posted by zoltanbod

Do you know of any varifiable evidence as to the efficiency improvement reported using the gapless ring on the Suzuki 3 cyl.?

I don't have any first hand accounts to give you, but I can tell you that the XFi motor only has ONE compression ring per cyl. The fact that the XFi (combined with a different ECU, a more efficient cam shape, and some body weight reduction) yielded significantly higher fuel economy than a stock 1.0l is verification enough for me that the gapless ring was used on the XFi for a reason. I assume that reason is reducing cylinder friction while reducing any blowby liable to occur using standard rings.

I couldn't tell you what kind of change you would see if you were to remove all the 2nd rings from a stock G10 and added gapless top rings, but if it resulted in an efficient gain, I'm almost certain it wouldn't be as significant as swapping the cam out and getting an advanced timing sprocket, which can both be found here.

[mwebb]

...."I dont think any of the 1.0l G10 engines had EGR, right? At least I'm pretty sure my xfi doesn't - out of curiosity though, how exactly would retrofitting a gapless ring affect an engine equipped with egr? I'm clueless and wouldn't mind learning.
"....

My 1996 g10 does have EGR

removing the EGR is a bad idea

EGR does not degrade anything and it enhances fuel economy and lowers emissions and combustion temperature at part load cruise
which is the only time it functions in a system that is operating as designed .

and
on a 1996 or newer system
it is a violation of federal law to tamper with any of the OBD2 components

[Christ]

Sent rings to your parents' house this afternoon, Will.

The only advice I can offer on how much force it should take to push the pistons up the bore would be that it's just not very much... I mean, we're talking about a few lbs of pull before it should start moving.

Having more spring pressure just prevents compression/combustion gasses from leaking around the rings moreso than rings with less spring pressure.

The Honda rings are 2 thicknesses, the thinner ones are the "upper" ring, and the thicker ones are the "lower" ring. I'm not sure which ones (if any) would match the ring land, though.

If the large ones are still slightly too small, you might try stacking two small ones in the ring land instead? That would negate having to make the gapless rings altogether, since you could "clock" the gaps at 180* to each other. I'm sure that's just one of my hare-brained ideas, though.

[Rob10_99]

The pressure the rings exert on the walls is not for sealing. I've never seen or even heard of a reason why they aren't more than 'somewhat' tight pressure against the cylinder walls.
The force that keeps the combustion in the chamber is the force itself.

The pressure generated goes behind the ring, on the inside diameter and pushes outwards, forcing the ring to the wall. Some rings have a chamfer on the inside top portion of the ring to have more surface area to accommodate for this.

[Christ]

Originally Posted by Rob10_99

The pressure the rings exert on the walls is not for sealing. I've never seen or even heard of a reason why they aren't more than 'somewhat' tight pressure against the cylinder walls.
The force that keeps the combustion in the chamber is the force itself.

The pressure generated goes behind the ring, on the inside diameter and pushes outwards, forcing the ring to the wall. Some rings have a chamfer on the inside top portion of the ring to have more surface area to accommodate for this.

The ring pressure on the cylinder walls is also necessary to create compression in the first place. The pressure that the rings exert on the cylinder walls prevents compression bleed-down, allowing the mixture to be entirely compressed in the combustion chamber, instead of allowing any part of it to escape into the crank case.

You don't hear reasons to increase spring tension because OE configs are normally sufficient, and the combustion pressure, as you noted, forces the rings out against the cylinder wall to hold the pressure and prevent blow-by.

[Wonderboy]

Originally Posted by Christ

If the large ones are still slightly too small, you might try stacking two small ones in the ring land instead? That would negate having to make the gapless rings altogether, since you could "clock" the gaps at 180* to each other. I'm sure that's just one of my hare-brained ideas, though.

Initially this sounded like a great idea, especially if the honda rings are thin enough such that two of the stack up to the thickness of one stock xfi ring. Again, I'm a beginner at this, so I'm not really in a great position to say what would work and what wouldn't, so here's the only thing I could think of that may or may not cause problems when putting two rings into one land as you call them (new term for me): If there is even a teeny gap in the top ring, carbon may build up on the lower ring just below the gap and potentially cause enough buildup to raise that side of the top ring, skewing its formerly level position and causing uneven wear on the cylinder walls. I don't know if this could or would happen, but this could actually be a brilliant inexpensive solution for people trying to find a gapless ring solution to rebuild an XFi motor...That's really what this thread is about - sourcing a cheap gapless solution. When I made the thread, I was thinking totalseal was the only remaining solution. The jury is still out.

[Christ]

Originally Posted by Wonderboy

Initially this sounded like a great idea, especially if the honda rings are thin enough such that two of the stack up to the thickness of one stock xfi ring. Again, I'm a beginner at this, so I'm not really in a great position to say what would work and what wouldn't, so here's the only thing I could think of that may or may not cause problems when putting two rings into one land as you call them (new term for me): If there is even a teeny gap in the top ring, carbon may build up on the lower ring just below the gap and potentially cause enough buildup to raise that side of the top ring, skewing its formerly level position and causing uneven wear on the cylinder walls. I don't know if this could or would happen, but this could actually be a brilliant inexpensive solution for people trying to find a gapless ring solution to rebuild an XFi motor...That's really what this thread is about - sourcing a cheap gapless solution. When I made the thread, I was thinking totalseal was the only remaining solution. The jury is still out.

I might be inclined to try it as a last resort, but not as the first attempt, for sure.

I'm not sure how well it would work, but I think before expecting any sort of performance, I'd look for a sealant that would work between the two rings and hold them together after they've been installed.

Chances are, it's a moot point, as I'm sure that two of the thinner rings stacked will be too big.

[Gasoline Fumes]

If you have an EGR, it would be bolted to the right side of the intake manifold. I believe the '92+ G10s all had it, I'm not sure about the older ones. I know the 1989-91 G13B did not have EGR outside of California.

Stacking two rings in interesting for a gapless setup, but is it better than using the non-XFi pistons as far as friction is concerned? The oil ring rails are pretty thin if a "shim" is needed. 0.47mm on my NPR set.

[Gasoline Fumes]

The 1984-87 Civic/CRX with the 1.3L engine in the US (I'm not sure about Canada/other markets) had the same ring setup as the XFi. And a 74mm bore. Rings are discontinued of course. I had 4 different parts sites tell me they're either backordered or not available. Part number 13011-PE0-663.