The translations for the numbered labels in the diagram are:
Engine specifications between B16A and B16B.
|Engine Type||B16A||B16B 98 Spec.R|
|Bore x Stroke||81.0x77.4mm||<- same|
at 1mm lift
|Valve Lift||IN 10.7mm, EX 9.4mm||IN 11.5mm, EX 10.5mm|
|Inlet Valve Diamter||33mm x 2mm||<- same|
|Spark Plug Type||Heat Rate #6||Heat Rate #7 platinum|
|Throttle Bore Diameter||60mm||<- same|
|Intake Manifold||Single pipe sideflow||<- same|
|Air Intake Diameter||65mm||<- same|
|Exhaust Manifold||4-to-2||<- same|
|Exhaust Pipe Diameter||48.6-50.8mm||57.2mm|
|Silencer Flow Capacity||98liter/sec||115liter/sec|
The camshaft profiles (wild cam) change from B16A 160ps to 170ps and finally to B16B are :
|Cam Profile||B16A 160ps||B16A 170ps||B16B 98R|
|Max Lift (IN/EX)||10.4/9.4||10.7/9.4||11.5/10.5|
|Open Timing (IN/EX)||BTDC 10/BBDC 40||BTDC 15/BBDC 40||BTDC 18/BBDC 45|
|Close Timing (IN/EX)||ABDC 40/ATDC 5||ABDC 45/ATDC 7||BTDC 45/ATDC 10|
Different pistons are responsible for the compression ratio increases between 160ps & 170ps B16A and the 10.8 ratio for B16B. Readily apparent is the relatively modest change in piston top between B16A 160ps and B16A 170ps for the 10.2 to 10.4 change. However, the radically different piston top for B16B is very clear from the picture. The increase in compression ratio between B16B from B16A is 0.4.
|On B16B, the inlet ports are manually ported to increase air-flow. The exhaust ports are identical to B16A.|
|B16B intake valve seats are at a different angle to B16A, 45 degrees vs 60 degrees. The intake valves are also different, being lighter and having a thinner valve stem.|
On the left are the power curves for B16A 170ps versus B16B. Note the big gain in power after 6000rpm, the VTEC switch-over point between mild and wild cam profiles. The gain at extreme high rpms is readily apparent on the curves.
Various individual specifications for B16B can teach us about the feasibility of various modifications to B16A. For eg, the throttle bore diameter for B16B is identical to B16A at 60mm. This means that enlarged throttle bodies for B16A might not be an optimal mod or that a compromise in power delivery might result, eg loss of low-end power in return for gain in high-end power. Note that B16B has identical low and mid range power as B16A.
As with B18C Spec R, the wonder of B16B is the assurance of a 15 to 25ps gain in power on a B16A provided the tuning done by Honda can be completely replicated. Nevertheless even if only a portion can be duplicated, combining with properly designed aftermarket exhaust, headers, and intake could still potentially realize this 15ps gain. B16B engine parts are available from Honda and with care, most of them can be used on B16A for good power gains.
April 1999, Wong KN, Temple of VTEC Asia.
Japanese translation, Kaz Mori, Temple of VTEC Asia.
Information source, Hyper-Rev Volume 31 'Civic & CRX #2 (re-visited)'