Geo Metro 1.0L G10 engine rebuild mods for better MPG

[Gasoline Fumes]

Originally Posted by Wonderboy

So maybe we're thinking the quoted price from totalseal was a bit steep? I wouldn't mind taking a crack at making my own gapless rings with a vise and some fancy filing work if I had some junk rings to try it out on. Anyone got old 75-77mm rings to mail to me? What is the likelihood of this working if the filing job were to be flawless? Would a 75-77mm ring still make a perfectly circular compression seal in a 74mm bore if it were made gapless down to 74mm?

It's worth a shot, but I don't think it will be easy to accurately remove 0.6mm from each side of the ring by hand. I wouldn't try for the angle, just a straight step. And you probably wouldn't want chrome-plated rings like the OE Zuk/Metro top rings.

I'm getting more and more tempted to reuse my old XFi compression rings with new oil rings. The gaps meet the standards for reusing in the service manual.

[Christ]

Originally Posted by Gasoline Fumes

It's worth a shot, but I don't think it will be easy to accurately remove 0.6mm from each side of the ring by hand. I wouldn't try for the angle, just a straight step. And you probably wouldn't want chrome-plated rings like the OE Zuk/Metro top rings.

I'm getting more and more tempted to reuse my old XFi compression rings with new oil rings. The gaps meet the standards for reusing in the service manual.

Then there's no reason to not reuse them.

I was thinking that he could put the ring in the bore, allowing each end to overlap the other, then mark the overlap with a skerple (sharpie), remove the ring from the bore again, and then flat-file the ring on one side from the top down, and on the other side from the bottom up, so that you end up with (instead of an angle) a lap joint when the gap is closed. I wouldn't try for anything over a 76mm ring, though, because you'll probably end up with side clearance issues.

[Gasoline Fumes]

Originally Posted by Christ

Then there's no reason to not reuse them.

I'm just a little concerned that they could have lost some of their tension.

Originally Posted by Christ

I was thinking that he could put the ring in the bore, allowing each end to overlap the other, then mark the overlap with a skerple (sharpie), remove the ring from the bore again, and then flat-file the ring on one side from the top down, and on the other side from the bottom up, so that you end up with (instead of an angle) a lap joint when the gap is closed. I wouldn't try for anything over a 76mm ring, though, because you'll probably end up with side clearance issues.

I think we're saying the same thing. I meant the angle shown here:

I'm not sure why the angle is there. Maybe it helps combustion pressure push the ring harder against the cylinder wall?

[Christ]

It's likely just there "because it is". I can't see any reason that it would be better than a standard lap joint. Any pressure applied would be opposed by the other side of the ring gap, so while pushing one side out and down, it would be forcing the other side of the gap in the opposite direction, in and up, creating a bigger leak between the cylinder wall and compression ring.

I'm not saying that actually happens, but it does wreck the theory that the rings are pushing out because of the angle.

[Wonderboy]

I talked to my father (pretty knowledgeable guy) about reusing the rings, and he was against it because the new rings have a noticeably stronger spring force when compressed than the old ones... according to him this is more important than the gap being spec. I really don't know either way as I'm new to this. I have no way of knowing and weighing the dis/advantages of having a new strong ring vs. an old gapless ring that still has a spec. gap. One thought is that it would be really interesting for one of us to use the old, and one use the new and dyno both of them right after break-in...just a wild possibility.


As for accurately removing .6mm - I'm not daunted. There are a lot of great tools at my parents' house including a metal lathe - I was thinking maybe I could use the metal lathe "backwards" by putting an extra fine grit stone from a dremel into the chuck and mounting a ring firmly where a bit would go, then using the measurement gauge to dig down to half the thickness of a ring. This may be more accurate than filing manually.

[Christ]

Originally Posted by Wonderboy

I talked to my father (pretty knowledgeable guy) about reusing the rings, and he was against it because the new rings have a noticeably stronger spring force when compressed than the old ones... according to him this is more important than the gap being spec. I really don't know either way as I'm new to this. I have no way of knowing and weighing the dis/advantages of having a new strong ring vs. an old gapless ring that still has a spec. gap. One thought is that it would be really interesting for one of us to use the old, and one use the new and dyno both of them right after break-in...just a wild possibility.


As for accurately removing .6mm - I'm not daunted. There are a lot of great tools at my parents' house including a metal lathe - I was thinking maybe I could use the metal lathe "backwards" by putting an extra fine grit stone from a dremel into the chuck and mounting a ring firmly where a bit would go, then using the measurement gauge to dig down to half the thickness of a ring. This may be more accurate than filing manually.

He's pretty well correct. Spring force matters because no matter what the ring split gap is, if you don't have enough pressure to keep the ring seated against the cylinder, you've got a huge leak anyway. Ideal would be best spring force with an accurate/closed gap.

As with any spring-like object, the more compression applied, the stronger the spring force would be. That said, a used 76mm ring would still provide plenty of force against the cylinder, and may even drag a bit until it's worn in.

A digital caliper will tell you if you've removed .6mm, the problem will be removing half the thickness of the ring on each side, not removing material into the circumference.

Mark the ring, wrap it with some electrical tape, and try to sand/grind it as flat as possible to half the original thickness, then flip it over and make a matching side. You'll need to go further than .6mm, to account for expansion from heat and movement from loading.

[Gasoline Fumes]

Originally Posted by Wonderboy

I talked to my father (pretty knowledgeable guy) about reusing the rings, and he was against it because the new rings have a noticeably stronger spring force when compressed than the old ones... according to him this is more important than the gap being spec. I really don't know either way as I'm new to this. I have no way of knowing and weighing the dis/advantages of having a new strong ring vs. an old gapless ring that still has a spec. gap. One thought is that it would be really interesting for one of us to use the old, and one use the new and dyno both of them right after break-in...just a wild possibility.

I can't feel much difference between my old rings and the new NPR rings. Dyno time is way out of my budget, but I'll do a compression check no matter what rings I end up using.

[Wonderboy]

Originally Posted by Gasoline Fumes

but I'll do a compression check no matter what rings I end up using.

That sounds like a way better and more reasonable idea if we end up seeking separate routes for top ring replacement. The dyno was just a wild idea in case anyone lurking here happens to have access to one and wants to donate some time for the cause Anything is possible! - I think saw someone here who had access to MIT's wind tunnel.

An update: Christ is mailing me some old Civic rings for me to try my hand at converting them to 74mm gapless G10 rings. Hopefully I'll be able to get on that later this week or this weekend.

[bgd73]

Originally Posted by TOOSTUBBORN2FAIL

this is something i will be doing with my neon as well, also from total seal, as recommended by a professional road racer and inside source from chrysler.

Benifits for my 3 ring set up is almost 100 percent seal from the top ring, allowing lower ring tension on the secondary ring, allowing more power (and efficiency), and less friction.

ggpless is for small four strokes, leaving oe compression alone (gaskets, stock heads)

a neon of all vibrating crazy hemi sized sucking inline fours is making for an explosively short lifed engine. Just helping out here,
I built a bit of every engine..
I do not know as I would even put it on a 600 cc two stroke. Stuff starts getting much bigger in the 1.8L+ fours
that is a serious move. and you geo owners. for god sakes..remove egr before doing it?

[Christ]

Will -

I was going to send them out today, but it was "Prez day". Post office was closed, and I walked down there with nearly 100lbs of other stuff I need to ship strapped to my back, as well.

O well, I'll try for tomorrow.