SR20DET rebuild kits: pistons, rods, bearings and studs

The SR20DET is a simple engine to build and an easy one to hurt. Most of the ones that come through here have either lifted a head gasket after a boost increase, spun a rod bearing after some track time, or picked up piston damage from a tune that ran out of fuel at the top. None of that is a design flaw. It is a 1990s factory bottom end being asked to do a job it was never sold for.

This guide covers what an SR20 rebuild kit actually needs, what our packages contain, and where the GTiR, the VET and the CA18DET differ. To be clear before you scroll: we sell parts and rebuild packages, not complete or crate engines.

The short answer

• A refresh is bearings, gaskets, seals and plugs, with the standard pistons and rods left in. That suits a healthy engine that needs sealing up.
• A forged package is CP pistons, Manley or Eagle rods, a head stud kit, a main stud kit, ACL Race Series bearings and a metal head gasket. That is the level our SR20 packages sit at.
• Oil control is the SR20 specific job. Sump baffling and a proper oil supply matter more on this engine than another 20 horsepower does.
• Head parts, cams and valve springs go in while the head is off. Pulling the head twice is the expensive way to save money.

What is in a rebuild package

The contents are set out on our Engine Rebuild Packages page: forged pistons, forged rods, a Cometic MLS or Tomei head gasket, an ARP or Mazworx head stud kit, an ARP or Mazworx main stud kit where the engine uses one, and ACL Race Series main and rod bearings. Each one is priced under the sum of its parts.

The SR20 packages are split by engine variant and then by gasket thickness, and the title spells out the combination.

For a standard SR20DET, the CP piston, Manley rod, Mazworx stud kit and 1.5mm Tomei gasket package is the high boost option, with the same build offered at 1.2mm and 1.0mm gasket thickness. If you would rather run ARP hardware and a Cometic MLS gasket, there is a CP piston, Eagle rod, ARP stud kit and 1.3mm Cometic package.

The GTiR gets its own listings, because the RNN14 engine is not the same animal. There is a GTiR package with CP pistons and Manley rods and a CP piston and Eagle rod version alongside it.

SR20VET builds are listed separately again, with CP pistons and Manley rods plus Mazworx studs at 1.0mm, 1.2mm and 1.5mm Tomei gasket thickness, or a simpler CP piston and Eagle rod package.

Choosing pistons, rods and compression

Every SR20 package runs CP pistons. We sell more of them than anything else in this engine, which means the common sizes are usually here rather than on order.

Rods come down to how you use the car. Manley rods are the ones we put into high rpm and drag builds. Eagle rods sit in a lot of quick street SR20s and are the value choice in the packages. The SR20 rod is short and the engine likes revs, so whichever you choose, the rod bolts get torqued properly and never reused. Bearing clearance and oil supply kill more SR20 bottom ends than rod choice ever has.

Gasket thickness is the compression lever in these packages. A 1.5mm Tomei gasket lowers static compression a little and opens the clearance up for a big turbo on pump fuel. The 1.0mm and 1.2mm options keep compression and response for a smaller turbo or a car that gets driven on the road. Cometic list an SR20 MLS gasket at 1.3mm in 87.5mm for an overbored block, and Tomei list 87mm metal gaskets at 1.2mm and 1.5mm. Order the bore size that matches your machining, not the stock number.

Head studs, gaskets, bearings and the small stuff

Head studs are not optional once boost goes up. ARP 102-4701 is the M11 head stud kit for the 2.0L SR20DET, and Mazworx makes its own SR20 head stud kit as part number 11001 with a matching main stud kit 11002. Both appear in our packages depending on the build. The wider range sits in ARP head studs.

Mazworx is also where the serious bottom end hardware lives: billet main caps and a billet SR20 girdle for engines making real power, plus a crank pulley bolt, a breather adapter and a water pipe fitting for a tidy engine bay. None of it is needed on a mild street build. All of it needs deciding before the block goes to the machinist.

Bearings are ACL Race Series: the 4B2960H rod set, the 5M2964H main set and the 1T2964 thrust washer set for the SR20. They are listed under ACL Race Series bearings and in the engine collection.

The small stuff adds up. NGK BKR6EIX iridium plugs come as a set of four covering the SR20DET. An ATI Super Damper is listed for the RWD SR20. Tomei make an S14 and S15 Pon Cam for people who want a bit more without going wild on the valvetrain, and Cometic head gaskets cover the SR20 and the CA18DET.

Speaking of which: the CA18DET is still well supported here. Eagle conrods are listed for it, ARP do both a standard head stud kit 202-4302 and an undercut version 202-4702, Cometic list a 1.3mm gasket at 85mm, and there are ACL main bearings, Supertech valves and stem seals and Motul service packs. If you are building the CA rather than swapping it out, the parts exist.

Cams and valvetrain vary hard by head. The GTiR collection carries Kelford solid lifter camshaft sets in several profiles plus adjustable cam gears and valve guides. The SR16VE and SR20VE range covers the VVL head with turbo and naturally aspirated profiles, beehive springs and titanium retainers. Our Kelford cam selection guide explains how to read those profiles.

Build it your way

If none of the packages match, use the Engine Builder. Pick the engine and work through pistons, rods, bearings, gaskets and studs, and it keeps the combination honest as you go. It is the right tool for a low compression SR20 built around a specific turbo, or a VE head on a DET bottom end.

The full SR20 parts catalogue has the bearings, gaskets, studs, plugs, dampers and cams in one place, and the engine hub at Engines covers the rest of the range we support.

Where NZ Performance fits

We have been doing this out of Palmerston North since 2003, and the people picking your parts race their own cars. SR20 hardware is held in New Zealand where we can, so a stud kit or a bearing set usually goes out the same or next working day.

We get asked for a complete SR20DET or an SR20 crate engine most weeks. We do not sell them. What we do sell is everything that turns your existing block, or a used import long block, into a known quantity. Our rebuild versus import guide covers that decision, and if you want the reasoning behind studs and gasket choice at high boost, read head studs, gaskets and pistons for big boost. Building a six instead? The RB rebuild kit guide runs the same way.

FAQ

What is in an SR20DET rebuild kit?

Our SR20 packages contain forged pistons, forged rods, head and main stud kits, a Tomei or Cometic head gasket and ACL Race Series bearings. The title of each package names the parts, for example CP pistons with Manley rods, Mazworx stud kits and a 1.5mm Tomei gasket. Plugs, seals, dampers and cams are listed separately.

ARP or Mazworx studs for an SR20?

Both go into our packages and both do the job. ARP 102-4701 is the M11 head stud kit most boosted SR20DETs run. Mazworx makes an SR20 head stud kit and a main stud kit, and since they also make the billet main caps and girdle, a Mazworx set keeps your hardware consistent if you are going that far.

Do I need a girdle or billet main caps?

Not on a street car at moderate boost and sensible rpm. Once the power and the revs climb, the Mazworx billet main caps and girdle are what keep the mains located. Both involve machining, so make the call before the block goes to the engineer.

Can I buy a complete SR20DET engine from NZ Performance?

No. We sell rebuild parts, packages and the Engine Builder, not complete or crate engines. The usual NZ route is rebuilding the engine you have, or a used import long block, to a spec you picked yourself.

Is the GTiR SR20 different to a normal SR20DET?

Yes. The RNN14 GTi-R was developed as a rally homologation engine with a solid lifter head and its own induction setup, so the cams and valvetrain are specific to it. We list GTiR packages and Kelford solid lifter cam sets separately for that reason. Order against the GTiR listings rather than the standard SR20DET ones.