Metro XFI Score!
 

I found a Geo Metro engine on craigslist. I found out it was from a '91 XFI and I went to get it. I got the engine, transmission, axles, radiator, ECU, fuel tank and a bunch of various little parts. All for $100!!! I have yet to verify if it really is an XFI, but I'm happy either way for the price.

It's supposed to be a good running engine, but I haven't heard it run. I was going to rebuild my late '94 engine, but now I'm not sure. I could rebuild the XFI engine or rebuild the non-XFI engine and just stick the XFI cam in it. Anybody know if the XFI piston rings are the same as the normal engine's top rings? Or is it a special design?

They just leave one of the rings out for friction purposes I believe. If I were rebuilding an engine, I would find some Total-seal rings (better compression) to put in there, JohnnyMullet would know about the number of rings.

No, it's a different, XFi-specific piston. Not just a regular one with one ring left off.

That said, I'm not sure if it's the same ring as the non-XFi. When you find out, please post back though.

And... congrats on finding the $100 parts pile!

I would rebuild the non XFi, and then put the XFi cam w/ a +4 cam gear and ECU on it. Should do about as good as the XFi.

What, and give up the massive fuel economy benefit of the 2-ring XFi pistons???

I just read some reviews on the Total Seal rings and some people have had problems with them, while others love them. I don't think they're worth the risk. And they're not cheap either. $126 from Jegs. I got my NPR rings on eBay for $22.

I probably won't be using the XFI ECU. I'd have to basically convert the whole 1994 Metro to a 1991 and I think I'd lose the ability to use my Suzuki scan tool with the older ECU. What does the XFI ECU do differently anyway?

Taking a closer look at the engine, I see it's a '92, not '91. Which means I should be able to use the XFI ECU with my scan tool. Now I need to measure that cam. Wish me luck! :)

Do you mean measure the lift/duration?

Yep, lobe height/lift is shorter on the XFi.

Hope it turns out to be the lucky cam.

The ECU runs leaner on the XFI, and the tall gears are a big help, too. You can probably measure the cam right through the oil filler using the depth guage on a caliper, close enough for identification.

Bob: that's actually the first difference I've seen mentioned about the ECU.

Lobe height is 39.63mm. That's an XFI cam in good condition! The normal cam lobe height is almost 1mm taller.

As a bonus, I got a Daikin clutch with almost no visible wear. It still has writing on the disc. :D

I'm using the Swift 3.52 gearbox over the 3.79 XFI box.

I stumbled across this browsing through my 1993 Metro service manual.
http://i48.tinypic.com/2v8sh3s.jpg
Notice the offset ring gap.

I'll get an actual pic when I pull the pistons out.

XFI piston:
http://img.photobucket.com/albums/09.../XFIpiston.jpg

XFI piston ring:
http://img.photobucket.com/albums/09...s/XFIring1.jpg
http://img.photobucket.com/albums/09...s/XFIring2.jpg
It might be hard to tell from the pic, but the staggered gap is also angled. I haven't checked if the gap is within spec yet. If it is, I might reuse them with new oil rings. Is that a bad idea?

And another craigslist score, engine stand for $10! :D

...unlike in art, a patina like that is definitely NOT something you want.

...some soaking in MacKay's Engine Cleaner will remove that gunk, but it'll also make all "wear" clearances/tolerances get bigger.

...lastly, the "top" compression ring might be a problem, because it rides right up against the "wear ring" in the cylinder -- installing a new ring with its new, unworn, 'square' ring edge will be "crunching" up against "the rounded" wear ring in the cylinder...and could result in a broken ring. MORAL: the top ring and cylinder bore cleanup are critical to longivity.

Nice photos, thanks. Interesting detail on the gap in the ring. I take it the 2-ring pistons don't have the same style ring?

Everything will be very clean when it goes back together. :)

I'm going to hone the cylinders, is that good enough? I don't see much wear in the cylinders anyway.

My replacement rings (NPR brand) have normal flat gaps. I'll dig up some non-XFI pistons and see what the rings look like. But I'm pretty sure they're not like the XFI rings.

Thanks. If you're willing, I'd like to know more of the specs between the two pistons/rings. To determine if a simple "ring delete" is a valid modification to a non-XFi engine.

I realize it would be a lot of work for a tiny gain, even if it could be safely done (safely in terms of the wear/mechanical implications to the motor). Just noodling.

The XFi piston places its single compression ring in a slightly different location than the top ring on the normal piston. I don't know if that's significant or not. The XFi and standard top rings are the same size, but only the XFi has the special "gapless"design. I don't see why you couldn't give the standard pistons the XFi treatment. Maybe the extra/open ring groove will collect goo and keep the other rings cleaner. :)
http://img.photobucket.com/albums/09...comparison.jpg

Another view of the special gap. Same ring, just flipped for the second pic.
http://img.photobucket.com/albums/09...XFIringgap.jpg

You should see if the 2nd compression ring from the std piston fits in the groove of the XFi's piston. Don't even have to install it, just measure the ring thickness.

If it does, I'd personally have no problem ordering a set of total seal rings and only using the 2nd compression ring. I've never left piston rings off a piston in an engine before, but that's no reason not to start, right?

The XFi groove looks wider in the pic for some reason, but it's not. Top rings are 1.2mm, 2nd rings are 1.5mm (not present on XFi) and the oil rings are 2.8mm. I believe this applies to all Suzuki G10/G13 engines.

Out of curiousity, I got my old 1985 Honda Civic service manual out. They also left out the middle ring on the 1300. Same design compression ring too, angled and overlapping.

Has this been done by anybody other than Suzuki and Honda?

Rebuild them both :)

Gasoline Fumes: most excellent information & pics posted. Good stuff. Thank you! The side-by-side photo: very nice.

I wasn't aware of Honda doing it on their 1300. News to me.

And Johnny has a point: do 'em both!

EDIT: I actually owned an 85 or 86 Civic hatch, probably with the 1300 (the 1500 was the "S", right? I know mine wasn't the "S".) I'm embarrassed I don't remember the details of that car, but I only owned it a couple of months before the head gasket went and I cracked the head. Had it repaired and sold it after that. Other than my Suzukiclones, it was the only other car I had that got fantastic fuel economy. I really liked it before I blew it up.

The Civic DX Hatchback had the 1.5l along with the slightly sportier 1500S. At least in the US. And I'm not sure if the 1.3l in Canada had the single ring, there were quite a few differences between the US and Canada versions. I had an '84 Civic Wagon until rust took it away from me.

Next rebuild is a Swift GTi engine for my other '94 Metro. I have plenty of engines I can rebuild, but only two good Metro bodies.