Originally Posted by Temple of VTEC Asia

The Amazing 3-stage VTEC EK3



For the EK-generation Civics, development on the D15B engine finally culminated in the now famous 3-stage VTEC D15B. This engine is used on the current generation EK3 VTi and Ferio Vi. 3-Stage VTEC D15B is a wonder engine in that Honda took the technologies of the VTEC-E and VTEC-D15B engines and merged them into one single engine. This implementation, already covered elsewhere in TOVA, allowed Honda to give us an engine that is both economical and powerful. So, who says we can't have our cake and eat it too ?

EK3s with manual transmission have final drives of 4.058 with 1st & 2nd gear ratios of 3.250 and 1.782 respectively. Manual Ek3s have been clocked to do the standing 100kmh dash in low-9s, faster in fact than an automatic transmission EG9 or EK4 B16A Civic.

The automatic EK3 is also the model to benefit from Honda's next greatest invention after VTEC; the new wonder-CVT MULTIMATIC (MMT) transmission. MMT's most powerful strength is the flexibility of a CVT gearbox coupled with the ability to work the high 130ps power of the 3-stage VTEC D15B engine. On smaller displacement engines below 2.0l, the use of an automatic transmission with its high power loss and slippage often meant a big compromise in performance. But the Multimatic transmission changed all that. It uses a continous range of gear ratios from 2.466 to 0.449 with a final drive of 5.809. This allows MMT to use the highest possible gear ratio to suit the current engine rpm which in turn guarantees the best acceleration at all time giving the MMT EK3 an extremely preppy performance. The MMT EK3 easily surprises unsuspecting passengers with its very good torque at all sensible speeds, often leading them to think the engine is larger in capacity - 1.8l or even 2.0l !



The 3-stage VTEC D15B represents the pinnacle of development on the D15B engine. From the same configuration as the previous generation VTEC D15B; 1493cc SOHC PGM-Fi but now with the 3-stage VTEC system; it generates the same 130ps at a higher 7000rpm with a max torque of 14.2kgm at 5300rpm. The amazing thing is that now it also offers an incredible 30km/l mileage ! In the flesh, the 3-stage VTEC D15B is a sleeper. The valve cover does not have any 'VTEC' wording and only the sharp eyed will recognize the engine as VTEC by noting the VTEC switches (yes, two of them) located on top of the intake runners and the high 7200rpm red-line of the tach. The 3-stage VTEC engine runs in 12-valve mode up to around 3000rpm. In this range, running in ideal conditions will activate the 'lean-burn' mode, where air-fuel ratios as high as 20:1 can be used to take advantage of the intake swirl induced by the 12-valve operation. This lean-burn mode is what makes the 30km/l mileage (for constant 60kmh speed) possible. A green 'ECONO' LED lights up on the dash when lean-burn mode is engaged.

From around 3000rpm up to about 6000rpm, the first VTEC actuator switch engages and the previously inactive intake valve now goes into operation. The engine now runs in 16-valve mode behaves just like any of Honda's highly spec'ed 16valve PGM-Fi engines. After 6000rpm the second VTEC actuator switch engages the wild cam/rocker arm pair for the intake valves. This switches the engine into the wild-cam mode where it goes bonkers delivering 130ps at 7000rpm. With the proper driving style, one can actually enjoy mileage as high as 16 or 18km/l in town driving while at the same time frequently indulging in VTEC-inspired sprints to overtake slower vehicles.

Used with the Multimatic transmission, the EK3 can frequently shock vehicles with larger capacity engines, literally leaving the arrogant tail-gaters for dead when accelerating from medium speeds. When WOT is engaged, engine revs immediately shoots up, with Multimatic maintaining the appropriate gear ratio to keep the car at about the same speed. When engine revs finally peaks at 7200rpm, Multimatic would have engaged the highest possible gear ratio for the speed the car is travelling at. 7200rpm is now maintained as the car picks up speed and it is the gear ratio which will be continously varied according to the car's speed. Thus Multimatic guarantees the highest possible acceleration from any suitable starting speed (typically from 50kmh onwards) and maintains this condition right up to the car's artificial, soft speed limiter at around 180kph.