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Piston Rings

Ahh Piston Rings... I have personally struggled a lot with piston rings in my builds as everyone has a different opinion on what to do with them. There are many ways to do things. It is entirely up to you what you pick, this is just all the information I have gathered through my struggles for finding what is right.

OEM Piston Rings:

STD (78.00 mm) - PN: 12033-59S00 - Discontinued

+0.05 mm (78.50 mm) - PN: 12036-59S00 - Discontinued

+1.0 mm (79.00 mm) - PN: 12038-59S00 - Discontinued

OEM Piston Ring Sizes:

78mm bore - 1.50 mm / 0.059 in Top Ring

78mm bore - 1.50 mm / 0.059 in Second Ring

78mm bore - 2.8 mm / 0.11 in Oil Ring

***Please inspect all parts / part numbers right when you get them in the mail. I have had major issues with companies sending me parts for other RBs or just the wrong part number all together.***

Compatible Part Numbers

**These Rings are for OEM pistons, aftermarket / forged pistons come with different rings and will need to be installed according to that manufacturers instructions. I have NOT personally bought and tested all of these rings, I used the Hastings parts catalog to cross reference other brands for kit numbers.

Hastings: Kit 6240 / 2C6240

NPR: Kit SWN30092 / SWN30092

Grant: Kit P1813 / C1813

Sealed Power: Kit E697X / E697KC

Mahle: Does not make compatible

Goetze: Does not make compatible

Hastings Part Numbers and Details

**These Hastings rings are for OEM pistons, aftermarket / forged pistons come with different rings and will need to be installed according to that manufacturers instructions.

I have gone deep down the rabbit hole with this so you do not have to. Basically there are 2 common piston ring kits offered by Hastings. Kit 6240 and kit 4662. 6240 is the correct 6 cylinder RB20DET / VG20DE Hastings piston ring kit; however 4662 is the commonly sold piston ring kit. 4662 is for the CA16DE and uses the exact same rings in each cylinder they just sell the kit as a set of 4. Many parts suppliers will buy the 4 cylinder sets and repack them in as 6 cylinder sets and sell for RB20 use. There is nothing wrong with this, just be cautious as you may receive parts in open packaging and double check you received the correct number of each ring.

Another area that confused me is where the rings are installed. In a factory RB20 the top ring is a taper (with a chamfer on the inside) ring and the second ring is a barrel (square face). For the Hastings rings the top ring is a barrel ring and the second ring is a taper ring. I have called Hastings directly and this is the correct installation of their rings. Their instructions are very ambiguous and do not label the ring location properly especially if you buy a kit where the rings have been repacked.

Lastly each kit is sold in multiple different sizes and with 2 finishes. The common sizes are std (78.00 mm bore), 78.50 mm bore and 79.00 mm bore. The phosphate coated rings are dark grey in appearance and are best used for engines that have a slightly rougher bore. They wear in and seal great with a rougher bore finish. The (2C) chrome rings are harder and provide less friction. I would recommend these after a fresh bore and hone. After many phone calls with suppliers and Hastings directly, I have confirmation (confirmed in Oct 2024) that only the std bore sizes (6240 and 2C6240) are still in production. All other sizes are no longer in production! Always follow the Hastings master catalog for installation specifics and how to machine your block.

*Other manufactures may have different recommendations on install, please use what that manufacturer recommends.

Hastings Direct: 1(800) 776-1088

Single Piston Ring Dealer (Total Seal): 1(800) 874-2753

Single Cylinder Piston Ring Dealer (Summit Racing): 1(800) 230-3030

Full Kit Piston Ring Dealer (Summit Racing): 1(800) 230-3030

Hastings Phosphate Top Ring, Barrel

Note there are no markings and can be installed either direction.

Hastings Phosphate Second Ring, Taper

The dot is face up during installation.

Installation

OEM Top Ring Gap

OEM Clearance:

0.22~0.39 mm / 0.008~0.015 in

Notes:

Stamped mark facing upwards.

Hastings Rings the top ring is the barrel (square ring with no mark)

OEM Second Ring Gap

OEM Clearance:

0.19~0.45 mm / 0.007~0.018 in

Notes:

Stamped mark facing upwards.

Hastings Rings the second ring is the taper (inside chamfer with mark)

OEM Oil Ring Gap

OEM Clearance:

0.20~0.76 mm / 0.008~0.030 in

Notes:

Do not overlap the ends, the tips are butted together (vv vv).

Supertech Ring Gap (std bore)

Street Clearance:

0.350 mm / 0.0138 in

Moderate Turbo:

0.381 mm / 0.015 in

Drag:

0.430 mm / 0.017 in

Race Only:

0.510 mm / 0.020 in

Second Ring:

Multiply top ring gap by 1.25

Oil Ring:

Minimum Gap 0.381 mm / 0.015 in

Notes:

These rings are for Supertech pistons only. Will not work with other pistons.

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