nioyil dagmarah starlete
Karlyn Hemmerling
nverdict all the Honda cars have vtec in forza 5 and the 2.0L vvt engine conversion is the k20 engine im sure from the current 8th gen type r fn2 model and as for people in the forum saying its just vvt no cause vtec comes in many variants ie I VTEC-DVTEC-HYPER VTEC- VTEC TURBO-3STAGE VTEC AND AVTEC ALL DIFFRENT STYLES and all come into play at different rpm at the end of the day the amount of awards Honda won for vtec tells me it aint just basic vvt and also first company to break the 100 hp per liter mark in engines all down to a little thing called vtec (yes im a huge Honda fan incase you were wondering)
Apart from the Japanese market-only Honda CBR400F Super Four HYPER VTEC>, introduced in 1983, the first worldwide implementation of VTEC technology in a motorcycle occurred with the introduction of Honda's VFR800 sportbike in 2002. At low RPM, one of the two intake valves is only allowed to open a very small amount, increasing the fuel/air atomization in the cylinder and thus allowing a leaner mixture to be used. As the engine's speed increases, both valves are needed to supply sufficient mixture. A sliding pin, which is pressured by oil, as in the regular VTEC, is used to connect both valves together and allows the full opening of the second valve, and little extra power is produced but with a smoothing-out of the torque curve.
Well thats for the automotive type of vtec, the motorcycle is much simpler, all it does is slide a pin in and out which stops or starts one of the valves from opening. The vtec in the auto has different profiles so you can get a different set of cam profiles when the pin slides in or out.
Exactly......if you notice in the video, there are two modes. The first has the outer cam lobes actuating the valves, both of which are opening, with one having a smaller opening than the other. At higher rpm rates, the sliding pin locks both valves to the center lobe, which creates a larger, equal opening on both valves. This is the more complex system used in their cars.
I'll bet the new VFR (if it exists) will have cage-type VTEC, which would be okay except for the complexity of valve adjustments. Personally, I'd rather see direct injection and variable intake runner length.
I know the video in not "just like" the VTEC on the VFR, I was just trying to maybe shine some light on how it works, not everyone knows what VTEC does and how it works. That is why I listed a basic description on how it works. I was not trying to insult anyone. I was just trying to help out!
One of the 2002 Interceptor design team's goal was simple: make more power without changing the balanced character that made the Interceptor name legendary. Adding displacement to the 781cc V-4 engine would have upset the bike's balance of size and weight. Classic power enhancement approaches would have marred that balance as well. Instead, engineers chose a more elegant solution: Honda's VTEC valve train. Basically, VTEC gives the 2002 Interceptor engine the torque of a two-valve cylinder-head design at lower engine speeds, plus the high-rpm performance of a four-valve head.
Honda pioneered several systems to optimize valve timing across the rev range. Though it was never sold in America, the 1983 CBR400F REV used a two-valve/four-valve system, similar in principle, but differing in detail from the new Interceptor's.
At engine speeds below 7000 rpm, the Interceptor's camshafts open only one intake and one exhaust valve per cylinder. Above 7000 rpm, cams open both intake valves and both exhaust valves for each cylinder.
Cams always act on one intake and one exhaust valve per cylinder. Diagonally opposed in the cylinder, these direct-actuation valves use shim-under-bucket valve actuation, allowing 16,000-mile maintenance intervals. The two remaining valves, which open after 7000 rpm, use shimless buckets. Camshaft lift, timing, duration and overlap remain constant at all engine speeds; only the number of valves in use varies.
Plenty of details had to be worked out before the new engine was ready for production. Honda engineers optimized ignition timing and fuel-injection mapping to smooth the two-valve-to-four-valve transition. The Interceptor also features a solenoid-actuated dual-air-intake-duct design that keeps one duct closed during low-speed operation.
I'm really surprised their isn't more info on this. With 6 years of engines now, and so many people that complain about it, I can't believe no one has experimented with this. I know it would require modifications to the fuel input, but their are plenty of people that have the equipment to do that.
Better yet, how about a handlebar selector, performance vs. economy mode. Though I'm not sure if the low end would be better or worse with the vtec disabled. That's probably where the issue is, low end may actually get worse with both valves opening.
Dunno. My 83 VF750F, 84 VF1000F and my 85 VF1000R all used 4 valves per cylinder all the time and performance was fine across all rpm ranges, though they were carbed if that makes a difference. Fuel mileage was ok - around 42 mpg, a little lower with the 1000R. With my VFR I can't complain about the VTEC, but I have only ridden it about 300 miles.
This would only work if the oil pressure at lower RPMs was sufficant enough to mechanically engage the pins in the VTEC valve buckets. If the oil pressure isn't high enough, it won't work and that's why nobody has really tired it yet. Nobody want's to potentially damage their engine with half-engaged pins...
There has been some experimentation in this regard. A year or so ago someone had a thread about their efforts to disable/enable VTEC all the time. They were able to get some success IIRC but ultimately, it results in a degradation of performance. With 4 valves opening you lose some low end - with 2 valves only you lose some high end. I honestly don't know why people are trying to modify a VTEC powerplant to make it non-VTEC. Their time would be better spent getting another bike or swapping out the powerplant - maybe a 5th Gen with the Torocharger - that make more sense to me...
That's what 'they' said, when it was first introduced. In fact, this is not borne out by dyno evidence. The VTec motor produces more power (due to revving a little higher than the 5th Gen), but the torque at lower revs is nothing like a v-twin. That's because the VTec was developed to meet noise and emissions standards, not to produce more torque at low revs. Running one intake valve per cylinder makes the intake noise lower (as does not having gear-driven cams). The greater intake velocity and new 12-hole injectors also mean that the engine can be tuned a little leaner.
Update; I've converted to a SOHC D16A right now and the mechanic (dad's cousin, so I know I can trust him) said I just need some suspension and brake upgrades/fixes and I can slap a SOHC vtec head on there :D
From what I understand, the accepted answer is not completely true. You do not need a dual cam setup to run vtec. I believe your civic has a stock d series engine which is a single cam most, likely a d16 (if you have a d15 it is more complicated).
VTEC is a variable valve timing system which is engaged at higher RMPs so you get better performance when you need it and don't burn extra gas and risk wear on your engine riding around at lower RPMs.
Civics are probably the most commonly modified hondas this question has been asked a million times, luckily that means there is a good amount of information on it. The first google search I found returned this. but there are many more some write ups even have detailed step by step picture tutorials.
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