How fast is a vtec engine

If the engine is running at 4, RPM, the valves are opening and closing 2, times every minute. So when the intake valve opens right at the top of the intake stroke, the piston is not able to get the air moving into the cylinder in a fraction of time available.

The result is that at higher RPM ranges, what you need is the intake valve to open before the intake stroke, this way the piston starts moving down in the intake stroke, and the valve is open, moving the air freely into the cylinder during a complete intake stroke.

If you want maximum engine performance at low and high speeds, you need to open and close the valves differently for each speed. Without i-VTEC technology, you would have a problem. In some cases, it can even make it harder to start the engine. Now, what the i-VTEC technology does is that Honda engines work effectively by having multiple camshafts. Through these efforts the team satisfied the requirement for timing-belt load while achieving its output objective.

Output across the full rev range was increased by widening the diameter of the intake valve from the conventional DOHC engine from 30 mm to 33 mm. Also, the team adopted valve timing and lift settings that were comparable to Honda racing engines in order to enhance volumetric efficiency.

The improved output resulting from that technique actually served to improve performance at high speeds. Additionally, measures were taken to reduce intake resistance. At last, the goal was reached, with a full horsepower at 7, rpm and a redline of 8, This permitted the intake valve to close early, drastically improving the engine's volumetric efficiency.

Since the engine now had higher efficiency at low speeds of operation, a broader torque band could be realized. The implementation of new materials was certainly a factor in the successful application of these technologies.

For example, since the VTEC engine's three cam followers must be positioned in a single bore, the camshaft offers relatively limited cam width. Therefore, the shaft must be designed to withstand high surface pressures. To achieve this, the team developed a new camshaft of cast steel. The shaft was made of new high-carbon, high-chrome cast steel alloy, which was given a combination of heat and surface treatments.

As a result the unit's extreme rigidity increased its critical surface pressure by as much as 40 percent. The VTEC engine parts used around the head. Each part was made lighter and more rigid in order to increase output and withstand greater loads at high engine speeds. The exhaust valve, too, employed a newly developed material made of a nickel-based, extremely heat-resistant steel combined with molybdenum, titanium, and tungsten. Accordingly, its heat resistance was increased by 30 percent.

Moreover, the larger diameter of the valve's umbrella section and its reduced stem thickness produced a drop in weight of nearly 20 percent. These ideas and effort gradually shaped a reliable VTEC engine. The VTEC engine had finally revealed its complete performance profile.

However, the success of D-development only meant the start of a critical phase. In order to ensure absolute reliability in mass production and introduce the engine to the market with confidence, the team had to guarantee the functions of all mechanisms and parts.

In addition to a significant responsibility for product reliability, the team had special expectations regarding the VTEC engine. Said Kajitani, "We all shared the determination to apply these technologies to every Honda model. The team's view of it was that VTEC technology shouldn't be limited to the Integra alone but further improved it could be adapted to Honda's future model developments.

As such, the initial specification would have to meet customer expectations. In fact, the team had gone through a repeated process of trial and error designed to eliminate all possible problems, however minor they might have been.

Actually, at the onset of engine development their greatest concern was the assurance of engine functions. They knew how difficult it would be to guarantee a complex switching mechanism. For example, the selector pin had a thickness of only 10 mm, so its operation was affected by wear of just several microns.

Yes and no; it depends on how you drive. Galaxy Buds 2 Best Movies on Netflix. Engine basics Gasoline-powered engines require four things to generate horsepower: Air, fuel, compression, and spark. The below video explains what we just talked about start at about 49 seconds. The best iPhone apps November How to use Google Maps. The degree V sitting behind Ginther was a thing of intricate beauty, with a dozen vertical intake trumpets, 48 valves, and tiny pistons oscillating through 1.

Main and rod bearings were fitted with needle rollers to minimize friction. An elaborate aluminum casting contained the cylinder block and a six-speed transaxle. Power peaked at 12, rpm with horses, and this 1.

Driver Dan Gurney estimated that the Honda V enjoyed a hp advantage over the field. Some 20 years after that first F1 win, Honda dominated the premier car-racing series. Honda was on a roll when the team responsible for inventing VTEC began work in on a roadgoing, high-output powerplant.

Engineer Ikuo Kajitani headed the effort. He concluded that the best way to meet these ambitious goals was a mechanism capable of adjusting valve timing on the fly. One profile would be optimized for low rpm, the other for high rpm. More than Honda engineers pondered design possibilities for three months. The team concluded early that some 30 new technologies would be required to meet performance and durability goals.

Early tests were problematic. An experimental engine with a narrower-than-normal angle between its intake and exhaust valves in pursuit of more low-rpm torque snapped valve springs and the timing belt at peak rpm. At low rpm, two outboard lobes operated one pair of valves through rocker arms. When more-aggressive valve timing was desired to optimize high-rpm performance, the third cam lobe centered between each pair of valves came into play.

Inside the middle rocker arm, mm 0. The changes in oil pressure were commanded by an electronic controller monitoring various operating parameters such as rpm, throttle position, and coolant temperature. Even though the concept was sound, making 30 new technologies work demanded fastidious attention to detail.