Adjusting the Vtec???????

Discussion in 'Mechanics Garage' started by troy21212, Jan 14, 2009.

  1. troy21212

    troy21212 New Member

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    Has anyone played with the Vtec on the VFR??????????????
    I want to lower the spot where the extra valves kick in down to 4000RPM from 7000RPM so I'm in the 'happy zone' for longer.
     
    Last edited: Jan 14, 2009
  2. malcster

    malcster New Member

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    the engine roars,the V-tec?I think it works fine,rippit and shuddup;dammit!!!!!!!!!!!!!!!!
     
  3. malcster

    malcster New Member

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    Somebody is an idiot
     
  4. Cyborg

    Cyborg New Member

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    I don't think the VTEC can be adjusted at the rider level...
     
  5. Phil Ceptor

    Phil Ceptor New Member

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    I think all of us who ride the sixth generation would like the vtech to hit earlier , but I do not believe their is a cheap fix. Learn to love it or buy a fifth gereration stablemate
     
  6. Yakima9

    Yakima9 New Member

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    I know some company's make aftermarket VTEC controllers for Honda CARS. Apex and Field's are two that come to mind. Found this in a discussion about VTEC controllers on a Honda forum:

    VTEC engagement on a stock car is OPTIMIZED. Do NOT f*** with it because all you are really doing is taking away power, depsite what it "feels" like

    Now that we have that cleared up...YES, i know that bringing the VTEC crossover up or down around 500 or even 1000 rpm up or down may indeed improve your power curves. Again, this is something u can only really prove if you are on a dyno and u can see the immediate results.

    So, why do you need a vtec controller? U dont, really. Unless you are using aftermarket cams, or have upped the compression, or some other internal modification that demands a shift in the VTEC x-over to again be optimized. AGAIN, something you should really be doing on the dyno, as every motor is different, not to mention weather conditions, grade of gasoiline, general condition of the motor, etc....


    Gotta imagine that same would apply to the bike. The Honda engineers didn't just guess at this stuff when they set it up.
     
  7. stoshmonster

    stoshmonster New Member

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    Troy,the answer to your question is No. You cannot simply "adjust" the VTEC down to 4000 revs to get to what you called the "happy zone". I often hear VTEC equipped VFR owners ask this question. It always amazes me that they either don't know or don't fully understand exactly what VTEC really is,or does. I know that most people seem to think it's like some kind of resettable programmable computer,much like a Power Commander where you can download different maps to change torque and power curves. It isn't. VTEC stands for Variable Valve Timing and Lift Electronic Control. I'm going to reprint an article for you,read it slowly and carefully Troy and you'll understand why Yakima9 was right when he said "The Honda engineers didn't just guess at this stuff when they set it up". The article is from the Jan/Feb 2008 edition of Honda RedRider magazine,there is no author listed. The article is titled "A VTEC Primer". "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 it's 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. Honda was the first company to offer variable valve technology with the introduction of the 1983 CBR400F with REV (Revolution-Modulated Valve Control)in the Japanese market. As the precursor to VTEC,the system delayed the opening of two of the four valves,allowing engineers to tune the two-valve low RPM power curve for torque and the four-valve high RPM power curve for horsepower. On the Intercepter,the V-4 engine runs on two valves per cylinder below 6400 RPM and then switches to four valves per cylinder,delivering significantly stronger low-end and mid-range torque while maintaining the Intercepter's impressive high-RPM power delivery. The Intercepter also features a solenoid-actuated dual-air-intake-duct design that keeps one duct closed during low-speed operation. Like the two valve/four valve system in the engine,this one duct/two duct system keeps intake velocity speed high as well. In operation,the Intercepter's camshafts act directly and continuously on one intake and one exhaust valve per cylinder. Above 6400 RPM,a special oil spool valve actuated by an electric solenoid sends oil pressure to a hydraulically actuated lifter sleeve inside the inverted buckets of the direct-actuation lifters. This positions a spring-loaded engagement pin above each valve stem of the two unopened valves. Consequently,the two previously disengaged valves now open and close together with the two direct-actuation valves,and the engine functions in a conventional four-valve manner. At all engine speeds,camshaft lift,timing,duration and overlap remain constant." So,as you can see Troy,the VTEC system is a very complicated piece of engineering. An electronic computer,controlling an electric solenoid,sending pressurized oil to a hydraulic actuater,moving a steel pin,to operate a mechanical valve-train. All this to keep intake charge speeds high so your engine's cylinders can fill as completely as possible. If you were to attempt to move the two-valve/four-valve operation engagement point down to 4000 revs,you'd kill that high intake charge velocity that the Honda engineers worked so hard to achieve,and kill your engine's power output in the process. Notice that the article says 6400,not 7000 revs. I believe it was in 2006 that Honda lowered the VTEC engagement point to 6400 revs on the engine in response to some customer criticism that it was "Too abrupt". Personally,I like the way the thing goes "Whack",and the whole bike shudders at 7 grand. And the way the low muted grumble emanating from my Two Brothers exhaust pipe changes to a piercing mechanical shriek is positively glorious! It never fails to put a S--t eating grin a mile wide on my face that you couldn't wipe off with a hammer and chisel. Imho,that rush you get from 7000 to 11800 revs is worth the wait. It's almost as much fun as the stump-pulling torque of my RC51. And that's saying alot! Hope this helps you.
     
  8. whenindoubt01

    whenindoubt01 New Member

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    Troy,
    When I want the happy zone I just keep the RPM at 7500 or more. The engine will drink the gas doing that, but it keeps Vtech surge from kicking in on a corner. If I'm just riding and taking it easy or cruising for the long haul, I keep the RPM lower than the Vtech engagement which I believe it's 6800 RPM on the 06-08 model and get a lot better gas mileage.
     
  9. malcster

    malcster New Member

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    Stoshmonster sounds right,pretty high tech stuff that Honda company puts out.They dropped their "formula 1"race team.Economic stuff.The V-tec has been well researched,7000 down to 6500rpm.If you run rad in the twisties your r's should beyond 7000 anyway.RPM=power and stability.Oh,so much more
     
  10. Hotbrakes

    Hotbrakes New Member

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    Work the gearbox like a 600 and keep it over 80mph. Shouldn't have a problem staying in the happy zone at all. You could also go -1 +2 on the sprockets.
     
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