Subaru Engine Rebuild, How to Set Piston Ring Gap

[@Mike_44]

Very technical work. It’s really inspiring watching your videos.. Hopefully one day I can build such a motor. Keep up the great work.

[@SWSpeedCo]

Thank you!!

[@Mike_44]

@@SWSpeedCo Finally brought the OXT home. Body is in great shape, a few scuffs, scratches here and there, and most importantly, no rust on the undercarriage, but she does have 210K miles. However, seems to be running just fine.. but a closer inspection reveals oil leaks in several areas/lines/gaskets, etc.. I got my work cut out, would like to do a full engine overhaul and get rid of that hideous AEM cold air intake it brought. Car shut off when I was backing up on my driveway right after an hour drive. I wonder what that could be. But it turned on right away. Will put it back to stock as much as possible. Striving for a clean modified look but as stock as possible, kind of what you have done with yours. I’m very excited! 😎🤟🏻

[@SWSpeedCo]

Love to hear it!! Good luck with the project

[@Mike_44]

@@SWSpeedCo Thanks, I will refer to some of your videos for guidance.

[@unleavenedkaraiteplus3412]

Because aluminum expands more than cast iron or steel is the reason for tighter ring gaps. Bores get bigger with heat.

[@GaryBarner-l6e]

One of the best videos I have ever seen thank you

[@GaryBarner-l6e]

I'm rebuilding a 2014 fb25 2.5 engine and black side skirts were gone but had no Grove at top of cylinder so ordered new pistons and rings. Handed the cylinders and thought I should check the ring gap found 9 thousand gap 😢 started looking at videos and found yours SO THANK YOU FOR YOUR VIDEO I will find the specs for my engine tomorrow and GET ER DONE thanks

[@SWSpeedCo]

Thank you, glad I could help!!

[@mendozachild135]

Thanks for this video helped out a lot I'm in the process of learning more and more on ej motors!!

[@SWSpeedCo]

Glad to here it, they are very interesting engines, and there it lots to learn

[@rocketboyz1004]

Amazing video

[@John-rw9bv]

great video, nicely done :)

[@aliasalias1460]

Aluminum expands up to 2x as much as cast does

[@Darkmatternightstorm]

So what's the proper size for oil ring? Or ideal? You only mentioned top and 2nd ring thanks

[@SWSpeedCo]

Usually the oil rings don't need to be touched, they are really hard to get an accurate reading on with a feeler guage since they are so thin but If I remember correctly ideal would be between 0.013 and 0.015

[@ericdonson8069]

So how’s this motor running now

[@SWSpeedCo]

It's been holding up good, I have probably 30k + miles on it and I'm making 400 whp, shooting for 450whp shortly. Thanks for watching!

[@Boxers_or_Bust]

Do you have any issues with the scratches from the rings?

[@SWSpeedCo]

No issues, the engine now has around 20k miles and it's still going strong

[@mamz6270]

@ 3:40 "aluminum dosent expand as much as........" that is not correct, aluminum expansion is like 2x or 3x

[@SWSpeedCo]

You know what you are right. I was thinking backwards, the block expands more ant that is why you need to run a tighter ring gap because when it expands the ring gap will open up.

[@2007Account]

As for the ring gap values, why did you choose such a low value? According to the calculation data provided by JE, the gap should be greater

[@SWSpeedCo]

I talked to a local shop that specializes in subarus, who did the machine work on the block. They told me that JE gives those numbers because there is alot of room for error so they are not responsible if you engine blows up. The .015 and .018 is what they told me to gap it to, oem ring gap spec is .011 so it's even smaller

[@2007Account]

congratulations friend for your videos! I have a confused neophyte question, are the ring gap measurements expressed in mm or in inches?

[@SWSpeedCo]

Thanks!! The ring gap is measured in inches

[@2007Account]

Ok friend, I would also like to ask you what tolerance did you use between piston and cylinder wall?

[@SWSpeedCo]

I had a shop do the machine work so I think it is whatever the manufacturer recommends

[@silverispro8573]

What size pistons are you using I’m trying to figure out ring gap for my 99.75 Manley pistons

[@SWSpeedCo]

I got 99.75 je pistons, outfront motorsports told me that .015 for the top ring and .018 for the bottom ring are safe ring gaps for around 20 psi to 25 psi. Probably need a larger ring gap for 30 psi and up.

[@silverispro8573]

@@SWSpeedCo I’m trying to run anywhere from 25 to 30psi but I’m not using a torque plate

[@SWSpeedCo]

The torque plate shouldn't affect ring gap too much, its more for machining the block. I would call the shop that did the machine work and ask them what they would recommend for that kind of boost pressure

[@silverispro8573]

@@SWSpeedCo the machine shop I brought my engine to bore out doesn’t know anything about engine building they just know how to machine blocks. I used the instructions that came with the pistons and after calculating both the top and second ring is supposed to be .023. Is the second ring supposed to be a tad bit larger than the top ring?

[@SWSpeedCo]

Yes the second ring is supposed to be a little larger than the top. As far as the ring gap calculations you can run those numbers they are just sort of loose for safety purposes and you may burn a little bit more oil, but if you might me running 30 psi it probably wouldn't be a bad idea to be on the safe side as far as ring gap goes.

[@stasethridge6619]

😬 you’re supposed to grind both sides of the rings evenly, not just one end of the ring

[@SWSpeedCo]

No just one side, reason being is If you grind both sides you won't know if your grinding it square.

[@stasethridge6619]

That’s why you’re supposed to have a ring gap file wheel. Meant to gap both sides at the same time

[@SWSpeedCo]

I guess in that case yes you can grind both sides but that's the way my machine shop told me to do it