Geo Metro 1.0L G10 engine rebuild mods for better MPG

[Wonderboy]

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Anyone have thoughts on holding the used rings open a little wider than "relaxed" and heating them to achieve a little more outward spring force?

[Christ]

Can you measure the spring force of the XFi's OEM ring?

If you can find a way to measure how much compression is necessary to close the gap, which is almost how the XFi's rings would be installed, you can get something close to that w/ the D-series rings I sent you. You may actually find that they're very close to being the same.

The problem I see with stretching the ring and heating it is that they are bi-metal rings (almost universally, anymore) and something might react negatively to being forced into a different shape without proper tempering techniques? I'm not a metallurgist, so I can't say for sure...

[Wonderboy]

We discussed that before in this thread - it is measurable by seating it in a cylinder with a piston and pulling it with a spring scale. The argument was that brand new rings that hadn't been broken in vs. the used ones that have a nice shiny broken in edge wouldn't be a fair comparison of spring force. I can't think of a way off the top of my head to make it fair. Even if I could make it fair, there is no "spec" spring force that I've been able to find for anything let alone a G10, which leads me to believe it actually doesn't matter too much once the engine gets to operating temp. I got the heating idea form the site I linked to in my previous post. However, this person was making custom rings from one raw material, not existing rings, so your bi-metal thing puts yet another wrench into the gears here because I believe I did notice that the stock XFi rings have one metal as a "core", "wrapped" in another metal.

[Wonderboy]

It was super nice and unseasonably warm out this weekend and I was on a roll working on my car stuff, so I bit the bullet and popped my pistons back in with the new oil rings and the original XFi gapless rings. Gasoline Fumes, let us know what you end up doing. I was staring at the rings for a while trying to figure out what orientation made sense. and I ended up putting the side with the straight cut across the width of the ring facing up because it has less surface area for combustion gas to enter that crevasse than the other kind of "L" shaped crevasse on the other side of the ring. You should know what I'm talking about if you're holding an XFi ring.

[Gasoline Fumes]

Mine were installed with the thin side down, looking at the ring on the piston. Two out of three anyway, I wasn't paying attention on the first one.
Like this:
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I'll be reusing the gapless rings too. Unless some new OE XFi rings fall out of the sky and land where I can find them.

I've been concentrating on the head lately. Cleaning up the ports and adding Singh Grooves.

[Wonderboy]

I have never seen anything like that before. There is more detailed information about this idea available for people reading this. I am definitely going to give this a try. I wonder if aerohead would have anything to say as to optimizing the shape/angle of the groove(s) cut to encourage vortexes? This is a very exciting and compelling new idea for me. I'm going to have Darin change this thread name to something more appropriate since we're beyond the piston ring group buy and it kind of became a specific discussion on G10 internals.

[Wonderboy]

Originally Posted by Gasoline Fumes

Like this:
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And yes, that is how I did it as well, with the seam created on top having less surface area than the one on the bottom.

[Christ]

As far as I can tell after hours and hours of reading, the basic idea behind the Singh Groove "technology" (if you will... I won't.) is creating a "gust" situation to aid turbulence in the combustion chamber.

Optimal configuration would direct that gust force in the same direction as any swirl or turbulence which already occurs, something that is difficult to discern without being a trained engineer in such arts.

Cutting grooves in the head will lower your compression slightly. If you choose to do so, you can make up for it by milling the head, block deck, or using a thinner head gasket.

I can see a better effect occurring in higher compression builds, or HO builds which ingest larger percentages of air faster, such as turbo/supercharging.

The added effect is a more even pressure on the piston face as the burn event occurs, which, in theory, keeps the skirts from scraping the cylinder walls with as much force. You could, I suppose, create "optimized" Singh Grooves to lessen the frictional losses in the engine from skirt sliding.

[Wonderboy]

I made some Singh grooves today after reading up and concluding that at the very least, it couldn't hurt, and at most it will be an awesome mod to add to the list of effective ecomods. Unfortunately I don't have any baseline info about this engine, so I guess I'll have to compare to other XFi people, and start off driving as "normally" as possible.

Here's a picture of the whole job, then a closeup of each one from left to right.





I made a couple of minor scuffs on the existing surface between the valves on the the center one and the left one. It was impossible to make the center cut in the center chamber anywhere near perfectly vertical because dremel discs don't come big enough for me to have accomplished that, but I think it came out good enough. I also decided to round out my edges a little with a pointed stone to try to avoid a "glow plug" effect with sharp metal edges and very high temperatures. Then I used a circular wire brush disc to make it nice and smooth. I didn't manage to find out what the science was behind the angles on the other two slits, so I tried my best to make them so an imaginary line extending from them would be able to cross the area between the valves (squish area?) without touching the valve seats, but while being tangent to both valves. Here is some material I read before doing this: TeamSwift • View topic - Combustion chamber grooves=better economy?? , Somender Singh grooves in a Geo Metro!, and of course the original Singh site....which appears to have been recently hacked. I'd love to see some useless corporate site get hacked instead.

[Christ]

For corrective purposes:

The area you just cut is referred to as "squish" or "quench" area.

The rest is just considered combustion space.