phillyfordyce

like i said, i am new and there is a few references to using the vtec 3 or 4 times per day.

what does that mean

sherwood

VTEC is the name of honda's older variable valve timing and electronic lift control system.
VTEC engages at a certain rpm and changes to a higher-rev cam profile for the valves.

this ensures that the engine is still economical in the low end but in the top end is still powerful.

generally speaking a car consumes less gas while in the first cam profile so it is better to leave it below the engaging rpm to save gas.

fastball

VTEC = Variable valve Timming with Electronic lift Control

Some form of it or another has been used in Formula 1 racing for 20 years by various manufacturers, but Honda was the first to mass produce engines with variable timming. It was first introduced on the 1989 Acura NSX super exotic. Then in 1994, on a mass scale for affordable cars, on the Honda Prelude VTEC (think Si, but faster). By the late 1990's, everyone and their brother had gotten in to variable timming (BMW's VANOS, Toyota's VVT-i, etc). And even manufacturers of engines without it got into the whole accronym marketing thing (GM's ECOTEC, Ford's DURATEC, etc.).

It works by having twice the amount of cam lobes for each valve. One for normal operation at normal speeds. The other, when you hit the gas, a computer running the engine hydraulics, shifts the cams over to large lobes for longer duration, deeper opening, and faster operation. This ultimately alters the engine's timming which produces more power and essentially, a turbo effect (without the nasty spool up and such)

Original VTEC motors (like mine), were designed to engage at a set RPM (mine's at 4800). Today's i-VTEC motors (like the Acura RSX and TSX) are infinitely variable, so VTEC can engage at any RPM, proving even more instant response when you downshift and hit the gas.

Very good system.

sherwood

vtec keeps vlaves open longer at higher rpms because the engine is sucking in air at such high speeds that it uses the momentum of the air to pull more air into the chamber, and yes, infact creates a sort of psuedo forced induction

motoguy128

Short and simple, VTEC solves the problem you often ran into when driving for example a Toyota Camry from the early 90's Great midrange, but after 5000 RPM it fell flat on it's face. VTEC allows you ot tune the engine tooperate well at low RPM's and good economy yet have good high RPM peak power when needed. It gives you the desirable flat torque curve that all engine builders strive for.

fastball

And even if you aren't tuning or modifying the engine, in completely stock form, any Honda, Toyota, or BMW motor with variable valve operation is far superior than the competition in terms of general performance and efficiency. My Prelude and the current Acura RSX and TSX have natually aspirited 4 cylinder motors with at least 200 horsepower (I believe the RSX-S is at about 210 or 220), and the S2000 is at 240. All retaining efficient fuel economy. You just can't attain those numbers with standard engine designs. BMWs straight 6 motors are routinely underrated numerically, yet they are world renowned as some of the best engines ever, in part due to their variable timming.

dubcac

No, forced induction is compressed air. It switches to larger camshaft lobes which give more valve lift and duration, which allows more air into the cylinders.

DakarM

yep not forced induction at all. psudo or no.

sirg-vtec

it means driving your car. lol

alphaxxn

it sounds like a rocket, or so my friends say.