SR20DET Buyer's Guide Australia: Red Top vs Black Top, Prices, and What to Check Before Handing Over Cash

Short version: a healthy, complete SR20DET with loom, ECU and ancillaries typically sells for around $3,500-$7,000 in Australia right now, with S15 engines at the top of that range and tired unknown-history S13 red tops at the bottom. The engine itself is tough if it has been looked after, and the checks that separate a good one from a grenade take about twenty minutes with a compression tester and your hands. This guide covers which variant you actually want, what they go for here, and exactly what to check before money moves.

Which SR20DET is which

Nissan built the SR20DET across the S13, S14 and S15 Silvia platforms (plus the 180SX and a few Pulsar and Bluebird variants that are a different conversation). The ones you will see in Australian classifieds:

Red top (S13, early 180SX)

The original. Cast rocker cover painted red, T25 turbo, roughly 202hp in factory trim. Runs a distributor-less coil-on-plug setup like the rest, but with the older ECU and loom. These are the oldest engines in the pool now, which means the cheapest asking prices and the highest odds of a hard life. Nothing wrong with a good one, but assume every red top has been thrashed until proven otherwise.

Black top (late 180SX, S14, S15)

"Black top" gets used loosely for everything after the red top, which causes confusion. The late S13/180SX black top is essentially the red top with minor updates. The S14 black top brought variable cam timing on the intake side (Nissan's VTC) and a slightly different turbo, and the S14a/S15 era moved to a ball bearing turbo on the S15. The S15 version is the pick of the litter: newest, best factory turbo, and it came behind the 6-speed box in Spec R form. Expect to pay for that.

If a seller cannot tell you which chassis the engine came out of, treat it as the cheapest variant and price accordingly. Better yet, ask for the engine number and check the head casting and rocker cover style yourself.

What SR20DETs cost in Australia

Prices have climbed steadily as S-chassis values pulled every halfcut and spare engine out of the sheds. As a rough map of the current market:

• Bare long motor, unknown history: typically $2,000-$3,500. This is a gamble. Price in a rebuild.
• Complete red top or S13 black top with loom and ECU: typically $3,500-$5,000.
• S14 black top complete: typically $4,000-$5,500.
• S15 engine, complete, ideally with the 6-speed: typically $5,500-$8,000+ for the pair. Boxes alone command serious money because everyone breaks them.
• Freshly rebuilt with receipts: add whatever the receipts say, minus scepticism.

These are private-sale figures. Importers selling "low km JDM" engines charge more and the kilometre claims are unverifiable, so judge those engines on condition, not the sticker on the rocker cover.

The checklist: what to look for when buying

An SR20DET that runs in the car is worth far more than one on a pallet, because you can test it. Always push to see it running if the option exists.

Compression test, non-negotiable

Bring your own gauge. All four cylinders should be healthy and, more importantly, even. A spread of more than about 10 percent between the best and worst cylinder is your signal to walk or renegotiate hard. Low, even numbers can be rings; one dead hole is usually ringland damage from detonation, which is the classic SR failure on stock bottom ends that have been wound up on cheap tuning. If the seller refuses a compression test on an engine that is out of the car and claims it is healthy, that tells you everything.

Turbo shaft play

Pull the intake pipe off the compressor housing and grab the shaft nut. A tiny amount of in-and-out (axial) movement is normal on journal bearing T25/T28 turbos. Side-to-side (radial) play where the wheel can touch the housing is a dead turbo. Look for oil pooling in the compressor housing and check the wheel for chipped or bent blades, which mean the engine has eaten something.

Rocker arms and the top end

The SR's known weak point at high rpm is spitting rocker arms. Pull the rocker cover if the seller allows it (offer to bring a new gasket): you are looking for scored cam lobes, loose lash adjusters and any glitter in the oil sitting in the head. While you are there, check the timing chain guides. A rattly SR on cold start that quiets down is often chain tensioner wear, which is fixable but worth $100s off the price.

Oil and coolant tells

Milky residue under the oil cap or filler neck means moisture at best, head gasket at worst. Coolant that looks like rust soup means the engine sat, or was run on tap water, and the water pump and heater core are on borrowed time. Check the sump plug and oil filter for metal.

The paperwork side

Ask for the engine number and where the engine came from. In every state, an engine's identity matters when your car gets inspected after the swap, and a stolen engine can be seized with zero compensation to you. If the price is well under market and the seller is vague about origin, that is not a bargain, it is a liability. Our guide to buying safely covers the payment side; the short version is never bank-transfer a deposit to hold an engine you have not seen.

Swapping one in: the compliance reality

General info only, not legal advice: every Australian state treats an SR20DET swap into a car that did not come with one as a modification requiring engineering approval (VSCCS in NSW, VASS in VIC, a mod plate through an Approved Person in QLD, and equivalent schemes in SA, WA and elsewhere). Into an S13 or 180SX that came with one, it is a like-for-like engine change, which is far simpler but may still require notification depending on the state. Emissions-era rules mean the engine generally needs to meet the standards applicable to your car's build date. Budget for the engineer before you budget for the turbo upgrade.

Red top vs black top: which should you buy

If the engine is going in a budget drift car and you plan to run stock-ish power, buy on condition, not colour. A healthy red top beats a hammered S15 engine every day. If you are chasing 250kW-plus down the track, the newer engines give you VTC and a better starting point, but you will be replacing the turbo and supporting mods anyway, so again, condition and completeness (loom, ECU, sensors, manifolds) matter more than the variant badge. Incomplete engines bleed you dry: a missing loom, coilpacks and ECU can easily add $800-$1,500 in secondhand parts.

Still tossing up whether the SR is even the right engine for your build? Read the comparison in SR20 vs RB25 vs 1JZ: which engine should power your drift build before you commit, because the answer is not automatic.

Where to find one

Browse the current engine listings to see what SR20s are actually on the market and what sellers are asking this week, and check the S13 and S15 listings for complete cars and halfcut-sourced setups. Got a spare SR sitting on a stand from a project that went a different direction? List it free, describe it honestly with compression numbers, and it will find a home fast, because good SRs always do.