Geo Metro 1.0L G10 engine rebuild mods for better MPG

[Gasoline Fumes]

I made my grooves with a hacksaw like this one:


And my grooves are all pointing toward the spark plugs.

[Oldgeodriver]

Will, Thanks for the reference to Total Seal. I'm in the process of putting together my G10 XFi engine and was totally dissapointed when I got my Sealed Power premium rings in today. As you indicate, they are not the gapless design so I called Total Seal. Their rings are not the same as the OEM design but should address the same concept. My Sealed Power rings are going back and I'm putting together my order for true gapless. As for using the old rings, that's a poor path to go down. The whole discussion on ring tension is mostly not a player but the problem is, as you can guess, wear.

[Wonderboy]

Thanks for posting oldgeodriver, I'm glad this thread was of use to you, and hopefully to other lurkers. Don't be shy about posting about other topics - this forum is filled with very smart and helpful people. I'm sorry your original XFi rings were worn to much to reuse. My rings and Gasoline Fumes's rings are well within spec for gap and thickness, so with the elimination of concern for less outer spring force than replacement rings, we were "cleared for takeoff" as it were for reusing the old ones. A big deterrent as you know to using totalseal rings is the price. I still don't know whether I'd go with making my own rings out of Honda rings, or buy totalseal. Could you do us a huge favor and post some closeup pics of what the ends of your totalseal rings look like when you get them?

In other news, I've been talking to aerohead about what the science behind the singh grooves and where/what angle they are placed in. He didn't have any definitive answer, but he put me on the trail of some good relevant info by telling me about a guy named Larry Widmer. He works for a super high-tech machine shop that could really be called an engine test lab. He tunes engines for HP, and specializes in Honda. There are several articles scattered about (see aforementioned link to google search of his name), but there is a very nice repository of articles, how-tos, and resources on the machine shop's site. This is a huge wealth of information even if you don't own a Honda. I know I'll be reading these for a while, looking for anything I can test out on my XFi motor to squeeze more FE out of it. Remarkable resource.

[Oldgeodriver]

I’m sure that you’ve given considerable consideration to reusing rings. You have probably thought about most, if not all of this, but if it helps, here are my concerns:

Unfortunately, since rings are not reused as a rule, published design specs would not try to address wear, but rather manufacturing tolerances. The gap thickness is set to ensure rings don’t get into an interference problem when they heat up, but I believe that this an assembly fit measurement/adjustment and not a reuse tolerance range for worn or used rings (I do believe it could be a good sanity check but it would seem to be difficult to measure in this type of overlapping end gap design). The ring thickness is normally considered as a function of ring to piston land clearance for worn pistons, usually to ensure the piston can be reused. I have seen rings with visible piston ring land contact area wear on the ring and it is easy to spot, but typically pistons wear first in this area and not the ring. There is a thin layer of chrome on the outer edge of the ring that “seats” in concert with the individual way a ring moves in the piston ring grove. The ring will form a wear pattern fit on the face of a new ring for the unique piston/ring/cylinder combination as it breaks in. Over time, this thin layer will continue to wear uniformly to the patter originally developed. While it is true that chrome rings experience less wear than other rings, this is the wear that I am most concerned with. The most favorable scenario will be to install the same ring on the same piston in the same cylinder but, at best, it will experience a reduced life.

Since part of the concern in a two ring motor is to minimize leakage (intake, compression, and combustion) with only one ring, I believe there is less risk of leakage by using new, conventional gap rings than reusing old rings with no real guarantee for a new complete seat to the cylinder; however, I am not satisfied with the compromise of using a conventional gap ring for my engine build. I am not happy with the cost difference, but in the big picture, I am seeing it as an additional $65 - $85 cost for the unique engine design that, hopfully, I will feel less pain with over time when it is running great.

On another note, in the past I’ve read about the Singh grooves head mod discussed. In my last G10 (three ring) engine build (now at >100K miles) I experienced some detonation problems that I believe this could help address. I would like to hear if anyone has seen carbon build-up problems in the groves over time and, if so, how the thickness and depth of the groves may play a role.

[drbobwoolery]

Several threads on reuse of XFI rings suggested that some had done this, what with the gapless rings being out of stock. Do you know how that worked out? My new (to me) XFI gave 150 / 190, 140/ 180, 90, 90 on compression. #3 is clearly a valve, and the head is in the shop for recutting the valve seats. Fresh 3tech valves and bolts are on their way.
Should I take the 40 psi compression jump on oiling as an indication that the compression rings are shot? They appear fine, and unless others have had trouble reusing the stock gapless rings, i plan to reuse mine with new oil rings.
Comments?
re: Singh grooves, carbon buildup seems to limit the lifespan of improvement, so I'm skipping this.