Technique! This is how it works VTEC
Posted on 27-10-2015 at 22:02 by mauritsh – 71 Comments”
Everyone has heard of it, but how does that VTEC system from Honda?
Introduction
The whole idea behind VTEC (Variable Valve Timing and Lift Electronic Control) variable valve timing. That way it can be ensured that the motorkarakter (or, as our eastern neighbours so beautiful to say: Laufkultur) can be changed. Why? Because the engine in that case, at low revs economical and clean can be, to reach higher rpm brightens to the gas to hang and relatively more power to generate. That may indeed be also, for example, with turbo’s, but there are disadvantages. See this extended special.
VTEC is a system to variable valve timing as possible and in a mechanical way, namely through the use of different rocker arms on the camshafts. Who already begins to become dizzy: please read this article through and you’re completely up to date.
The basic principle
Although Honda multiple versions on the system has been developed, we highlight, for the purpose of simplicity, in this article only the basic principle. The below image (via) shows very schematically how VTEC works. Click for LARGE.
On the left of the picture you can see the ‘normal’ situation at low speeds. The two outer cams (egg-cases) controlling each inlet valve, two inlet valves per cylinder. The middle lobe is clearly larger and sharper shape, but may not yet play a role if the gas is not seriously pressed.
Happens and increases the speed, then gives the ECU a signal to a hydraulic system. By means of oil pressure is a pin by the tumblers was stuck. Now it becomes interesting, because that means that the ‘hot’ cam, the now of the two cowardly tabs takes over. This is somewhat exaggerated defined, but it covers the cargo. The moment the hot cam is approached is indeed what fans mean by VTEC that inkickt, then you know that.
That hot cam is higher and sharper, so the valve goes further and longer open and shows consequently a larger amount of the combustible mixture -of air and vaporized gasoline. This causes the output of the engine up. As soon as the speed drops as the throttle is lifted or because there is a gear up switch, take the small tabs in the back. Thus, consumption and emissions (and output) down again. Voilà.
Application in cars
Smaller turboblokjes (with a displacement of pak ‘m beet one liter) nowadays have relatively high specific capacities of around 100 hp per litre. It is precisely in that market can have VTEC added benefits and thus combines Honda the technique with turbos to get the maximum out of it.
Exciting is of course only for Type-R models and the already legendary S2000. The latter had an atmospheric engine with a cylinder capacity of two litres on board, with a maximum power of around 240(!!) hp. The S2000 was already 16 years ago, was introduced, but these are still values to be mouth-watering. Emissiegeneuzel aside, indeed.
To decide
Perhaps (but hopefully not) a bit of an admission of weakness, but this article is intended only as a brief explanation of the basic principle. If it were so simple in each other stuck as I have defined, the technique is not even worth of discussing are worth. Additions and suggestions plempt you just in the comments.