Honda Prelude 1993 Service Manual page 45

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In g€noral, it would be ideal if the high rpm performance of a racing engine and the low rpm pertormance ot a standard

passenger car engine could be combined in a single engine. This would result in a maximum performanc€ engine with a

wid6 power band. Two of the major differences between racing engines and standard engines are the timing ot the in-

take/6xhaust valves and the degree of valve lift. Racing engines hsve longer intake/exhaust timing and a higher valve lift

than standard engines, The Honda Variable Valve Timing and Valve Lift Electronic Control System takes this into ac-

count, Wh€n valve actuation is set for low rpm timing and lift, low rpm torque is better than in a standard engine. Whon

valve actuation is then switched lor high rpm timing and lift, output improves to the level given by a racing engine. Until

now. tew variable valve timing systems have been commercialized, In those that have, only the time that both vatves 8re

open (intake/exhaust overlap) could be changed. Honda's system is the first in the world in which both the valve timing

and the degree of valve litt can be changed as needed, making it the most advanced valve train mechanism available.

'TDC = Top Dead Center

*BDC = Bottom Dead Center

O = Ootimum Characteristic

The engine is equipped with two valve timing and valve lift settings which change according to driving conditions.

RPM switch ovgr

Racing Engine

Standard Engine

Valve Timing

(exhsust/intake)

Low rpm Torque

ldling stability

Troubleshooting