B18 Engine in Phoenix, Arizona
The engine that built the Honda swap scene, now old enough that the condition of the specific unit matters more than the specification on paper.
- Family
- B18 (B-series)
- Displacement
- 1.8 L
- Configuration
- Inline-four
- Valvetrain
- DOHC, 16 valves (VTEC on B18C)
- Produced
- 1990–2001
Bore and stroke are omitted for this family: the code covers variants with different figures, and a single pair of numbers would be wrong for some of them.
The B18 powered the Acura Integra through the 1990s and is the engine most people picture when they hear "Honda swap". It came in two broadly different forms: the non-VTEC B18A and B18B fitted to base and LS Integras, and the VTEC B18C found in the GS-R and Type R.
Every B18 is now at least a quarter of a century old, and that changes the buying question. Nobody is fitting a B18 to a daily driver as a cost-saving repair any more. The people buying them either own a 1990s Integra or Civic they intend to keep, or they are building something. Both groups care much more about the condition of the specific unit than about the family specification.
Because the family is old and desirable, it is also the family where misrepresentation is most common. A "B18C Type R" is worth several times a B18B, and the difference between them is not visible in a photograph of a crate.
Why the stroke difference matters
The B18B and B18C share an 81 mm bore but not a stroke: 89 mm on the B18B against 87.2 mm on the B18C. That is why the two have almost the same displacement while behaving quite differently, and it is also why they are not the same short block.
It matters when someone offers a "B18 short block" without qualification, or when a build is planned around parts that assume one stroke and receives the other. The code settles it; the displacement figure alone does not.
Buying a twenty-five-year-old engine
Every B18 is now decades old, and that changes what diligence looks like. The specification tells you what the engine was when it left the factory. It tells you nothing about what has happened since, and on this family the gap between those two things is usually the whole story.
Treat the timing belt, water pump and seals as due regardless of what the seller says about mileage. Ask for compression and leak-down figures on the actual unit rather than the family. And on any Type R claim, ask for a photograph of the stamp in place on the engine you are buying. The price gap is wide enough to motivate misdescription, and a crate photograph proves nothing.
Vehicles built with a B18
A single vehicle line across a decade, split by trim into non-VTEC and VTEC halves.
| Vehicle | Years | Trim / body | Engine code | Market |
|---|---|---|---|---|
| Acura Integra | 1990–1993 | Base / LS / GS | B18A | USDM |
| Acura Integra | 1994–2001 | RS / LS / SE | B18B | USDM |
| Acura Integra | 1994–2001 | GS-R | B18C1 | USDM |
| Acura Integra | 1997–2001 | Type R | B18C5 | USDM |
B18 variants
Five codes covering two genuinely different engines: the non-VTEC A and B units, and the VTEC C units with their own internal hierarchy.
- B18AUSDM
- Early non-VTEC Integra. 81 mm bore, 89 mm stroke.
- B18BUSDM
- Integra LS/RS/SE non-VTEC. 81 mm bore, 89 mm stroke.
- B18C1USDM
- Integra GS-R. VTEC, 87.2 mm stroke, higher compression.
- B18C5USDM
- Integra Type R. Revised head, intake and pistons over the C1.
- B18CJDM
- Japanese-market designation covering several VTEC specifications.
Identifying a B18
- The B-series code is stamped on the front face of the block, between the engine and the radiator, on a flat machined pad. Unlike the K-series, which is stamped on the driver’s side near the starter.
- B18A and B18B are non-VTEC; B18C is VTEC and carries the VTEC solenoid and its wiring on the cylinder head.
- The B18C1 (GS-R), B18C5 (Type R) differ in head, intake, pistons and compression. A Type R claim should be checked against the stamp and the head casting, not the seller’s description.
A seller describing an engine as a particular variant is making a checkable claim. Asking for a photograph of the stamp on the actual unit is not a sign of distrust; it is the normal way this gets confirmed. The engine code guide shows where each family is stamped if you want to read the one in your own car first.
What varies between B18 units
These are the differences that decide whether two engines with the same family code are substitutes in a particular car.
- B18B and B18C use a different stroke: 89 mm and 87.2 mm respectively, so they are not the same short block despite sharing an 81 mm bore.
- VTEC and non-VTEC heads require different wiring and ECU support; fitting a VTEC head to a non-VTEC harness is additional work, not a bolt-on.
- On a vehicle this old, the condition of the unit dominates the specification. A compression and leak-down test is worth more than any claim about the variant.
- Given the age of the family, timing belt, water pump and seals should be assumed due regardless of what the seller says about mileage.
Nothing on this page confirms that a specific B18 will work in your vehicle. That takes the year, model and trim at one end and a specific unit at the other, and it happens before a price is given rather than after. What goes into that check is set out here.
Ask about a B18 for your vehicle
The code is pre-filled. Add the year, model and trim, and the variant question gets settled on our side before anything is confirmed.
Common questions
How do I tell a real B18C Type R from a GS-R engine?
Start with the stamp on the front face of the block, then check the cylinder head casting and the intake manifold, which differ between the C1 and the C5. Because the price gap is large, treat any Type R claim as unverified until the stamp is photographed in place on the engine you are actually buying: not a stock photograph.
Is a B18 still worth buying as a replacement engine?
If you own a 1990s Integra you intend to keep, yes, because the alternative is a swap with all the supporting work that implies. As a general-purpose replacement it makes less sense than it did: every unit is decades old, and the condition of the specific engine matters more than the specification on paper.
Related pages
- K20 EngineThe 2.0 K-series from the RSX, Civic Si and JDM Type R cars.
- D17 EngineThe 1.7 SOHC four from the seventh-generation Civic.
- K24 EngineThe 2.4 K-series from the Accord, CR-V, Element and TSX.
- Honda CivicThree engine families across the generations, and the trim decides.
- Honda EnginesHonda engine families, what they came in, and how fitment is confirmed.
- What Comes With a JDM EngineWhat is usually attached, what almost never is, and what to confirm in writing.
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