Geo Metro 1.0L G10 engine rebuild mods for better MPG
 

I got a quote from Totalseal on gapless compression rings similar to the top rings that come stock on Metro XFi's. All piston ring replacement sets out there (even those labaled as "for XFi models") do not have the gapless style top ring that prevents blowby and increases compression.

These are suitable for anyone with a 74mm bore, but AFAIK that will generally apply only to those with the 3cyl G10 geo metro engine. I haven't decided if it's more worth it to me to bite the blowby with the gapped ring set that cost about half what these gapless rings are quoted as, but having gapless rings, especially in an XFi where there is only one compression ring seems pretty darned important, and unequivocally beneficial to the efficiency of any 1.0l suzukiclone motor.

Hopefully there will be enough people interested in this to get a nicer price for everyone. I've never done a group buy before, and I don't know if companies are willing to take one lump payment, then ship to individuals or what, but we can figure that all out in the mean time. I'm willing to coordinate this at no profit to myself - I just want to get gapless rings for my XFi rebuild, and help anyone who wants to do something similar. I hope to gather the orders of all interested parties by the end of the month. Please spread the word to whomever may be interested.

-Will

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.

Ooooo maybe we could rope an ecomodder out in that neck of the woods to go pick up the order so the rings only need to get shipped once (= fuel savings!) Eh? Any left coast takers? Carlos?

If I'd have gotten those Metros I was looking at (as opposed to getting jerked around by the guy), I'd have so been in on this for 2 sets. I was going to build both engines to XFi specs and sell one (or keep it as a spare if I couldn't get a decent price for it).

Alas, I am Metro-less. :(

I checked a couple of GM parts sites and found the rings. It might be a good idea to verify they are are the correct rings before ordering them. I assume "w/o LSI" would be the XFi. And I assume the price is per cylinder. I could use 7 of the "gapless" top rings....

http://www.gm-parts-dealer.com/
http://www.gmpartscheap.com/
There might be other sites too, I only checked a few.

Pistons, rings & bearings, Piston rings
Metro, w/o LSI - 1.0l
List Price : $33.00
Your Price : $26.40

Pistons, rings & bearings, Piston rings
Metro, w/LSI - 1.0l
List Price : $42.82
Your Price : $34.26

XFi decals are available too! :)

Good find Gasoline Fumes...Do you want to contact them to find out whether those are the rings we're looking for? I could do it too, I just don't want to be the second or third person to contact them within a week about the same exact thing.

GM part number for the XFi rings is 96061652. Now for the bad news, both a local GM dealer and GmPartsDirect.com have informed me that the rings have been discontinued. The dealer checked and no dealers in the US have any. :(
I don't know what you'll get if you order the rings from one of the site that still lists them.

Guys, did Suzuki use these rings in any of their engines?

What are the odds of being able to take a bigger (1mm or so) ring and filing it at a steep angle to approximate the gapless design?

If the XFi's rings are 74mm, rings from D-series engines (Honda) should work... they're 75mm pistons.

I'm not sure if it would work or not, but NPR sells Honda D series rings cheap enough that it might be worth it to try.

Will, I've got some old D-series rings still on pistons, maybe. I could send a couple to each of you if I can find them, and that way you could both work on trying to make a gapless ring from a slightly larger one?

Thinking about it, I may not have those rings. I'll have to take a look the next time I'm at my Father's house before I offer them.

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?

I get this weekend all to myself (wife and kid free, not actually to myself), so I'm going to look around at my Father's house and see if I've got any 75mm std bore rings from some old Honda pistons.

If you have a blown Honda engine laying around, it might be worth it to check it out, too. I know your one friend was having trouble, dunno what happened with that.

I would think that 1 or 2mm should be within tolerance for rings seating properly, but don't take my word for it.

Side note - Are you going to be at PAP this weekend, and should I bring anything with me?

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.

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

I think we're saying the same thing. I meant the angle shown here:
http://img.photobucket.com/albums/09...XFIringgap.jpg
I'm not sure why the angle is there. Maybe it helps combustion pressure push the ring harder against the cylinder wall?

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.

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.

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.

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.

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?

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. :mad:

O well, I'll try for tomorrow.

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.?

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.http://ecomodder.com/forum/attachmen...1&d=1266353431 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.

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.

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.

do not disable your EGR system
 

...."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

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.

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.

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.

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.

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.

Did you check Majestic Honda?

I checked their site, but I don't remember if I contacted them.
http://www.hondaautomotiveparts.com/...IN+Number+---#

I spent a long time fighting with my lathe today... But I finally got an alright solution. I visually turn it down to just over half width with a dremel stone in the lathe chuck, with the ring clamped to a bit. Then, I used a file to gently and gradually bring it down to as close to halfway as my measurement tools/eyeballs can tell me. I found that the best way to do this is to measure the overall thickness of the lap instead of each half individually.
http://i47.tinypic.com/1zgql4w.jpg

http://i45.tinypic.com/10gbcqq.jpg

http://i48.tinypic.com/308wkg8.jpg

I don't know if it's an issue, but the corner of the cut on each edge of the ring kind of sinks down a little bit from the edge due to my imperfect filing abilities, but after I looked at the stock ring, noticed there was a bevel, and added a similar bevel to mine, it seemed to fit quite well. Whaddaya guys think, I don't know how much better I could get at this with the limited machining tools I have. I don't know how important perfection is here, but something tells me some imperfect lap is better than a gap. Edit: The filing looks a little rough, but of course I plan to use a whetstone to make it nice and smooth.

Not necessary to smooth the filing, just make sure the piston and cylinder bore sides (I.D. and O.D.) of the rings are smooth with no burrs.

That filing job is a thing of beauty, I must say. It's exactly what I had in mind when I described what was going through my head for making a gapless ring a few posts back.

Let's hope they work, eh?

Not a Metro owner, but I did install the Total Seal rings on a Datsun quite a few years ago. They never gave me any problems, seated up quickly, haven't worn prematurely.

The reason they can decrease friction/increase mileage is that they can function with a lot less spring pressure- the gapless design seals well enough when cold or upon start-up that normal spring pressure isn't needed. Gas pressure takes over, though, so I don't know how much of a FE increase you will get compared to standard rings, at least if you have a long commute where cold starts have a lesser effect. They do have a reputation of maintaining good compression for a long time because of the wear pattern of the two different ring materials.

I think you will need a much more precise step in the standard ring to actually get some gapless benefit. It does need to be a gas seal, after all.

Welcome to EM, TimG! Thank you for the input. Now I'm back on the fence again. I PMed johnny mullet about this issue - hopefully he'll reply and put the last nail in this coffin.

FWIW -

It's a gas seal, sure, but I don't think it really needs precision due to the pressures involved. I think that under the combustion/compression pressures, the rings will likely "close" themselves, especially at the speeds they normally travel up and down the cylinder bore.

You also have to remember that gasses will always take the path of least resistance... combustion gasses won't like changing direction 3 or more times to get through the filed ring, so you're not likely to lose much of anything.

No ring is totally sealed, either. There's always going to be some blowby, which is part of the reason that racers use gas porting on their pistons.

More spring force does not mean more compression, when it comes to ring pressure it's not a case of more is better but a case of adequate is all you want- any more is unnecessary friction imposed on what is (IIRC) already the single highest frictional loss in the motor.

As far as I know 1991 was the only year the G10 didn't have EGR ( for the standard model at least, don't know about the XFI)

I've thought about using gapless top rings and removing the second rings as well, bu the higher cost dissuaded me (and IIRC they didn't make gapless tops in the right size at the time, about 2 yrs ago) so I just went with gapless second rings instead.

If it were me I'd try the rings you've made, just make sure the ends can't butt up against each other once operating temp is reached and make sure you're OK with the possibility of tearing back into the engine if they don't work out...

I knew a guy that raced VW Sciroccos and used the zerogap rings, he told me he had to replace the pistons every season but that he used the same rings for 3 seasons so far at that point.

I think the real benefit from using them comes once the engine gets up there in mileage. Performance/ efficiency wise you'd probably get as much benefit from anti-friction (DFL) and/or thermal barrier (ceramic) coating (the appropriate part of) pistons.

Christ-

I think the stepped gap will work just fine, if proper care is exercised regarding gaps being adequate for thermal expansion. But the gain compared to going with the Total Seals is probably closer to 25% than 75% IMHO. It is cheap and easy, and should increase FE, hard to complain about that.

I received another vote for reuse of the stock rings. Still a tough choice, but actually starting to lean toward reuse. I emailed the guy who made this site about our situation, but still no reply. There might be some value in heating up the original rings while they are open a bit wider than they are in their "relaxed" position to give them a tad more spring force. That would solve all the questions here if it actually worked. I PMed Johnny Mullet a while ago now about this, but no dice there either. I really wish he'd respond. :(