Honda’s Reason for VTEC Explained

Discussion in '6th Generation 2002-2013' started by stewartj239, Dec 28, 2007.

  1. stewartj239

    stewartj239 Member

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    In the Jan / Feb 2008 issue of Honda’s RedRider magazine is an article that discusses the purpose of VTEC. Here is an excerpt from that article:

    “The goal of VTEC is to keep the air / fuel charge moving at a high velocity – in the neighborhood of 350 to 450 feet per second – on its way to filling the cylinder. The faster the charge moves, the more air / fuel gets stuffed into the cylinder – and that means more power. In a four-valve head, high charge speeds are easy to maintain at high rpm because as the piston moves down rapidly it pulls the mixture into the cylinder quickly. But at lower engine speeds the charge velocity drops and therefore the cylinder doesn’t fill as efficiently. By eliminating the operation of two of the four valves (one intake, one exhaust) at lower engine speeds, VTEC ‘narrows’ the path to the cylinder; this keeps intake charge velocity high, ensuring crisp throttle response and ample low-rpm power…………….”
     
  2. DAN-SLO

    DAN-SLO New Member

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    The fuel injected 16-valve block now has a form of 'variable valve control' which Honda calls Hyper V-Tec. While the name suggests this works like the system used on their cars - where inlet and exhaust valve timing is varied with rpm - it uses a different approach. It uses just two of the four valves in each cylinder at low rpm. This speed up the gas flow which increases torque.

    At about 7,000rpm a servo opens an oilway, and the pressure pushes a pin into the gap between the valve stem and the tappet on the two unused valves. The next time the cam lobe pushes on the tappet it opens the valves, and from here to the redline all 4 valves operate normally. This way peak power maintained, while torque is noticeably improved at lower revs.
     
  3. Gears

    Gears New Member

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    All that sounds good...so why doesn't it made more power than a 5th gen. engine? Don't flame me for knocking the v-tec, I have an 04, but I'd give anything to have an 01 engine in my bike.
     
  4. grayflare

    grayflare New Member

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    Honda isnt looking for more power out of this engine yet, they are just improving what is already there and making it more useable. Mayby when they make a 7th gen they will increase to 1000cc and those who want more power will finally get it.
     
  5. chesthing

    chesthing New Member

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  6. grayflare

    grayflare New Member

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  7. chesthing

    chesthing New Member

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    Ok, just one more question - if vtec improved the 5th gen motor, why doesnt any other motorcycle use it?
     
  8. junktionfet

    junktionfet New Member

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    Someone posted a dyno chart on VFRD which shows the VTEC motor ('06 anyway) has a power and torque advantage across the entire RPM band than the 5th gen motor. I saved it and could repost it, but I don't know if the original poster at VFRD would get mad.

    The problem with magazines and reviewers that "poo-poo" on the VTEC VFR is not with the bike--it's with the biased nature of the reviewers. In their pigeon-holed world of motorcycling, the VFR had gears to drive the camshafts, and reliable sidedraft carbs to feed the cylinders. And that's that. Power was turbine-smooth, it did 3,000 horsepower and as much torque as a Cummins turbodiesel. Somehow...

    Bah... I tune out reviewers that spout their opinion like that as if it's fact. It reminds me of watching Aaron Brown on CNN. I don't want his freakin opinion, just tell me the news and go away. :D

    Hook up a gas analyzer on a dynamometer and tell me which bike is more toxic for the environment and the people around you. :smile:
     
  9. stewartj239

    stewartj239 Member

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    From what I've read, the 6th Gen motor does make more power, but that power gain is offset by wider internal gear ratios for gears 3-6. It is for this reason that I went +2 on my rear sprocket to bring the gear ratios back down. Here is a link to the article that discusses this.

    http://www.motorcyclistonline.com/escape/motorcycles/146_0204_revamped_honda_interceptor/
     
  10. stewartj239

    stewartj239 Member

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    Actually, this is not Honda's first bike that uses a VTEC type system. The CBR400F employed a similar type system. In addition, there are at least two other motorcycle manufacturers that currently produce models that have a VTEC - like system. I think that with the manufacturers coming under more and more scrutiny for emissions and fuel economy, you will see more of this type of technology evolve. Like it or not, I think motorcycle technology will only get more complex going forward - much like what has happened with the automobile industry.
     
  11. jasonsmith

    jasonsmith Member

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    Ya! What he said! :caked:
     
  12. chesthing

    chesthing New Member

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    which two? I'm not arguing, I'm honestly curious.
     
  13. grayflare

    grayflare New Member

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    Well Im pretty sure Honda has a patent on it so if some one else wanted to use it they would not be able to copy it without coming up with somethig similar but different unless they want to come under attack by Hondas team of lawyers.

    Also as stated above you will see more technology make the step from auto to motorcycle because of emissions, both good and bad. Like in the dirt bike world 2-stroke motorcycles are almost out of date, some mfg.s dont even make them anymore. No one would have believed 6-7 years ago that a 4-stroke motor would even compete let alone take the market. Now all MX and SX racers race 4-strokes. Guess what else, now off-road bikes are starting to get fuel injection, not new for car or street bike but it is for off-road. It is all about "cleaning up the air" or "emissions", and this is just the start, trickle down technology is here and as soon as they can get the tech to work and fit on bikes it will come.
     
  14. stewartj239

    stewartj239 Member

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    Yes, no problem. The first one is Kawasaki. They have it in the 2008 Concours 14. The other one is Yamaha, they are looking to use it in the new V-Max.

    Here is a link to an article that talks about VTEC - like technology as being the future for sport bike engines.

    http://www.motorcycledaily.com/07february06_cams.htm

    To sum it up, here is an excerpt from this article: "Of course, we all know that the inevitable march forward will eventually lead to lighter, smaller, cheaper parts, and so it is only a matter of time before we see modern variable camshaft technology applied to sportbikes."
     
  15. chesthing

    chesthing New Member

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    Honda cars and Kawasaki's Concours use a variable valve timing system, which is smooth and unnoticeable. The VFR is the only vehicle I know of that has the step going from 2 to 4 valves - I doubt this vtec design is in any danger of being copied.
     
  16. goinphaster

    goinphaster New Member

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    Actually VTEC has been used on bikes for many years in Japan. Most of their 400cc bikes have it now, but it's been going on for awhile. I lived their for two years and have seen many different types of bikes over there, and most of them have stuff on them long before we see it here in the states. as for why the dyno charts display more power torque on the 6th gen than the 5th; the dyno does not measure acceleration. everyone loves the response of the 5th gen, and most hate the response of the 6th. narrower head pipes, the catalytic converter, eco friendly ignition maps (read: EPA) and wider spaced gearing have all robbed the 6th gen of what it could be. I have to stress the ignition maps because everyone wonders why the 6th gen does not get huge gains with a power commander. if the ignition map sucks, a power commander can only do so much.....
     
  17. stewartj239

    stewartj239 Member

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    I agree with you on that. Honda's version of VTEC is either on or off as opposed to being constant. I think that they've done a good job with it though. I have an '07 and I can say that it is silky smooth when it kicks in. It can kick in mid-corner and it does not upset the bike in any way. It just pulls very, very hard. However, I can't speak for the earlier 6th Gens as I haven't ridden them.

    However, the current VTEC implementation is immature, but you have to give Honda credit for pioneering this technology in the US market. They've been using it here since 2002 and have continually tweaked it. That is 7 model years! The other manufacturers are now just coming out with their own versions (even though they are more advanced). I imagine that the 7th Gen will have a much more sophisticated system.

    Lastly, here is another quote from the current RedRider magazine: "Honda has made no secret of the fact that the Interceptor is a rolling showcase of the company's substantial technical prowess." With that said, new innovation will more than likely continue to make it's way to the Interceptor. You could call it a guinea pig, but if you like high tech stuff, then the Interceptor is the bike to have. It has been this way since 1990. It will continue to evolve.
     
  18. stewartj239

    stewartj239 Member

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    I think it is important for people to realize that VTEC technology is not a "Honda Interceptor 6th Gen" thing. It is an industry wide technology which until now has mainly been confined to the automobile industry, but yet is not entirely new to the motorcycle industry as Honda has been "tinkering" with it for 25 years. It is just now starting to emerge in our industry.

    All the reason why I believe that a gearing change is the best way to make the 6th Gen feel more lively. I think their biggest mistake was widening the gear ratios for the touring crowd. Stock gearing (internal and final) is way too high.
     
  19. goinphaster

    goinphaster New Member

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    Bah humbug! rolling showcase my butt. when you strip the fairings almost everything can be matched up to a 5th gen. VEtc? they changed out the heads, but left the bottom end the same. If I want technical prowress I'll go for a ride on my 1995 RVF400- it has stuff on it that most liter bikes just got last generation! The only reason I got a VFR is because A: it has hard bags B: it's comfortable for me C: I got it cheap. If it were so technologically advanced why don't they update it every time like the CBR's? Red Rider is a propaganda tool.
     
  20. junktionfet

    junktionfet New Member

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    Maybe that just means the 5th gen was a rolling showcase. If it ain't broke, then just fix it a little bit? Hahaha

    I'm just trying to be an optimist. :tongue:
     
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