Honda Car Forum

I understand SOMEWHAT of how VTEC works. Can someone explain how much power different it is from VTEC to NON VTEC? Say both engines are exactly the same, but one has VTEC installed. How would power differ? How much stronger would the pull be when the VTEC kicks in? What's the difference between I-VTEC and regular VTEC?Same with the cam question. How does single differ from a dual? how much power difference? (again same engine comparison)Also does single cam and dual make any changes to saving gas or being more fuel effecient?Now what is low end and high end? I hear alot of people talk about it. But still clueless. Is low end refering to torque and acceleration, and high end being horsepower and top speed? Thanks"It does not matter what it is on a Honda. It all equals slow"That's why K20a swaps in hatchs run low 11's stock huh? Imagine a fully tuned one. Single digits done easily for under 6 grand AFTER the swap. The motor runs under 8K.

It does not matter what it is on a Honda. It all equals slow

VTEC gives you the best of both worlds essentially.Four valve per cylinder engines allow better flow so they can produce more power at high RPM, also since the valves are smaller and lighter, they won't float at high RPM like two valve engines....however.At low RPMs, the flow is too great. The fuel and air need some restriction to create swirl, which mixes them better and gives you more 'low end' (ie, you're cruising in 4th and decide to punch it to get through that yellow without downshifting).Jaguar put a restrictor plate on one of the intake ports to recover some of this 'low end' power, but it led to the perception that you were being robbed of power.VTEC changes the valve timing and lift to better take advantage of the low-end and high-end characteristics of the engine and flow.Also VTEC can allow the use of higher compression pistons without the lugging (like a Harley) at low RPM, but the extra power at high RPM.However, Honda was only interested in producing horsepower numbers out of small engines by using a short stroke and a large bore for higher RPM, and as a result they still lacked the 'low end' until they put some displacement into them (1.6L up to 2.0L for the Civic).iVTEC gives multiple valve setting instead of just two, so the power band is seamless.As for single and dual cams, a single cam is lighter, but a dual cam is required for the optimum cross flow. There are some single cam four valve engines out there, but none can produce as much power (per displacement and RPM) as a dual cam engine.Torque=how much force goes to the wheels, useful for climbing hills, towing, and spinning tires. If you want the most torque, buy a tractor.Horsepower=force/time. How fast you can accelerate, how fast you can go.

vtec LIMITS the fuel and air at low rpms for economy reasons. it does not make more power than a regular valve train. a dual overhead cam is just like its stated, theres two on top of each head... little Hondas only have one head so...they are able to run 4 valves per cylinder, which creates better breathing, and more power. it does not assure more power, it is just theoretically possibleand with twice the valves there is twice the flexibility, so it will get you better low rpm efficiency and more high rpm power.low end power means right off idle, you know how that little Honda doesn't really do much till like 3500rpms, a ford inline 6 makes most of its power below 2000 rpms, so the instant you hit the gas, its on. where in the Honda you gotta drop the clutch at high rpm to get anything resembling power.have you ever seen a muscle car do a wheely? thats not the horsepower doing that, its all the torque.

If your talking B16 engines a 1600 16v DOHC compared to a 1600 16v VTEC, the difference is about 30bhp. How this is acieved at low RPM the valves only open around 60% of there total lift caperbility this inproves engine torque as there is very little valve overlap ( when Inlet and Exhaust valves are open at the same time). With conventional fixed camshaft systems they have a compromise of the valve lift, the profile of the cam is aimed at economy so when cruising its great on fuel but at all other ranges its a compromise.The VTEC system has a good low range cam profile that gives good fuel economy below around 5700rpm with most performance VTEC engines there is a extra high lift cam lobe that will extend the valve lift and increase valve overlap. At high rpm this overlap is good because as the Exhaust gases are leaving the cylinder the gases create negative force inside the cylinder pulling in the new air fuel mixture with more efficiency. This technique is known a scavanging and increases Volume Metric Efficiency. Simply put more efficiency more power.There are a number of different VTEC systems, VTEC-E is designed for economy and basically operates on 12 Valves below 2500rpm after this rpm the VTEC control solenoid energises and oil pressure is directed through the camshaft to the VTEC rocker arms locking the two rocker arms together allowing 16Valve operation. Performance VTEC's normally run DOHC and have Variable valve control on the Inlet and Exhaust camshafts 16Valve engines 4 Valves per cylinder. The camshafts have three cam lobes for the two valves Inlet and two for the Exhaust valves, the two outer cam lobes are operating below 5700rpm as mentioned and the third operates when the rockes are locked together giving high lift. Then there is i VTEC, as a rule the i VTEC system is identified by a cam variator fitted to the Inlet camshaft (VTC controller). The VTC controller is to control the camshaft phase angle at low range rpm allowing improvments in torque as there is now even greater control of the valve overlap, again this system is oil pressure controlled via the ECM.Hope this helps and isn't to much of a head mess for you.