Highlights of B18C Spec R compared to standard B18C (JDM 180ps)

Highlights of the B18C 96 spec.R high-output engine. While increasing durability and reliability, we also increased compression, lowered friction, and maximized air output to create and engine that can rev to 8400RPM, and create 200hp. In order to achieve this accomplishment, over 60 custom parts were created.

Translations of the numbered labels in the engine diagrams are :

  1. Camshaft - Wide-angled, high-lift, high-durability camshaft
  2. Exhaust Valve Spring - High-lift, dual-layered spring
  3. Sparkplug - High-heat-type #7 platinum plug
  4. Engine Stiffener - Aluminum die-cast, high-durability, one-piece type
  5. Crankshaft - Full-balancer, 8-weight, high-output, custom crankshaft
  6. Connecting Rod - Custom TypeR rod, high-durability, lightened
  7. Pistons - High-compression, low-friction, custom pistons
  8. Inlet Valves - Lightened inlet valves
  9. Intake Manifold - Custom tuning, single-port type.
  10. Throttle Body - 62mm wide-mouth throttle body.
  11. Inlet Valve Springs - High-lift, flat-surfaced, dual-layered spring

Engine specifications between B18C and B18C Spec R (1996 & 1998).

Engine Type B18C B18C 96 spec.R
Bore x Stroke 81.0x87.2mm <- same
Displacement 1797cc <- same
Compression 10.6 11.1
Maximum RPM 8000rpm 8400rpm
Maximum Output 180ps/7600rpm 200ps/8000rpm
Maximum Torque 17.8kg-m/6200rpm 18.5kg-m/7500rpm
Valve Timing
at "High" 1mm lift
IN Open/Close BTDC10/ABDC40 BTDC15/ABDC45
EX Open/Close BBDC40/ATDC7 BBDC45/ATDC10
Valve Lift IN 10.6mm, EX 9.4mm IN 11.5mm, EX 10.5mm
Inlet Valve Diamter 33mm x 2mm margin reduced by 0.5mm
Spark Plug Type Heat Rate #6 Heat Rate #7 platinum
Throttle Bore Diameter 60mm 62mm
Intake Manifold Dual-port Single-port
Air Intake Diameter 65mm 70mm
Exhaust Pipe Diameter 48.6-50.8mm 57.2mm
Tailpipe Diameter 50.8mm 76mm

Important tuning changes for B18C Spec R includes manual porting of the intake ports and change in intake valve seat from 60 degrees to 45 degrees. Another major change is the replacement of the intake manifold from a dual intake VVIS (Variable Volume Intake System) to the single tract intake for B18C Spec R. The original intake runners were optimized for a flat torque curve and the high-rpm runners open by a butterfly valve. This was replaced by a special ultra high-flow manifold in the B18C Spec R.

For the 98 Spec Integra Type-R, the main change to the B18C 98Spec R engine is the use of a 4-to-1 SUS-stainless exhaust manifold. B18C 98SpecR's max power is still 200ps but the max torque rpm was increased slightly and shifted down to a lower 6200rpm.

The power curves for standard B18C, B18C 96 Spec R and 98 Spec R are above. Clearly seen is the design objective for a flat torque curve for standard B18C acheived via a combination of VTEC/dual cam lobes and the VVIS dual intake manifold. For B18C 96 Spec R, the big gain in torque and power at high-rpms can be clearly seen. Comparing now the power curve for B18C 98 Spec R, the effect of the 4-in-1 headers are very unexpected as B18C 98 Spec R has higher upper-mid rpm power and lower high rpm power than B18C 96 Spec R. This is the direct opposite of the rule-of-thumb for power gains between 4-2-1 and 4-1 headers !

The changes made for B18C Spec R represents tuning by Honda on the 'standard' 180ps B18C engine and for a 20ps gain to 200ps. The greatness of this tuning is not the quantum of power gain - 20ps gain and a max power of 200ps may not be that great in absolute terms - but rather the assurance of this amount of gain provided the tunings by Honda can be completely replicated. Nevertheless even if only a portion can be duplicated, combination with properly designed aftermarket exhaust, headers, and intake (which are subjected to more leanient legal noise restrictions than stock exhaust) can still potentially realize the 20ps gain. B18C Spec R parts are available from Honda and most will swap straight into the standard B18C though some may require some machining work, eg intake valve seats on the B18C Spec R head (which is essentially a B16A head).

Copyright April 1999, Wong KN, Temple of VTEC Asia
Japanese Translation, Kaz Mori, Temple of VTEC Asia
Information Source, Hyper-Rev Volume 27 'Integra'