V-Tec Advantage - Or Not

[BiKenG]

Can anyone point me to a comparison of V-Tec and pre V-Tec power/torque curves? To be a worthwhile comparison they would have to be from the same dyno on the same day with both bikes. I'm interested in quantifying the exact advantage V-tec provides.

[Baileyrock]

Hey Ken,

All the vtec did was add a glitch in the smoothness of the normally seamless power of a 5th gen, still a blast to ride though.

If you are refering to the 8th gen 800, I here there are much smoother then the 6th gen version.

[Skids]

You are correct Bailey....from my test ride of the new 800 when it first came out, the engine felt as close to a 5th Gen as I think it could ever get. 5th Gen is still the best engine of the 2 from a riding perspective imo. But I've never seen want the OP wants.

[Dutchy]

Et voila!

[Cogswell]

If I'm reading the chart correctly (please correct me if I'm wrong), the VTEC motor produces less, (or at best matches) the HP and torque of the 5th gen motor all the way to about 9,000 rpm. I spend the vast majority of my riding below that. IMO disappointing given the extra complexity and cost of incorporating the technology.

[RobF]

Et voila!

Nice pull, Dutchy! I am sure this has been hammered to death in older threads, but I always assumed the VTEC was a regulatory gambit -- a way for Honda to meet emissions requirements at the certification engine speed (3K-5K?), and yet still hit their desired peak HP goals. If that's the case, then we're never going to see the rationale for VTEC in an HP/torque chart because one of the chief parameters against which Honda optimized (emissions) isn't on that chart. As riders, we attempt to fix the issue with Power Commanders and wonder why Honda can't figure this out. As a practical matter, a Power Commander functions as an end-run around emissions regulations that Honda simply can't duck as a large manufacturer (cf the massive VW brouhaha last year), but that we (and Dynojet) can as a smallish number of enthusiasts that legislators and regulators choose (for the time being) to ignore.

[3dcycle]

that's what it looks like to me, simple solution though, shift down twist wrist. problem solved.

I agree though you would think that since 86 they could have got this to put out a little more power. in 20+ years they could not up the horse power by more than 7

[Dutchy]

The chart is from the respected german mag Das Motorrad.

The explanation is the more relaxed legislation on noise and polution in the olden days....

When I eventually returned to the Netherlands after 7 years abroad and went to get my LeMans a set of Dutch plates, it failed the regulations. If not for the tester being a mc nut himself, I would have been forced to fit more restrictive mufflers.....

[Skids]

Et voila!

Nice pull, Dutchy! I am sure this has been hammered to death in older threads, but I always assumed the VTEC was a regulatory gambit -- a way for Honda to meet emissions requirements at the certification engine speed (3K-5K?), and yet still hit their desired peak HP goals. If that's the case, then we're never going to see the rationale for VTEC in an HP/torque chart because one of the chief parameters against which Honda optimized (emissions) isn't on that chart. As riders, we attempt to fix the issue with Power Commanders and wonder why Honda can't figure this out. As a practical matter, a Power Commander functions as an end-run around emissions regulations that Honda simply can't duck as a large manufacturer (cf the massive VW brouhaha last year), but that we (and Dynojet) can as a smallish number of enthusiasts that legislators and regulators choose (for the time being) to ignore.

Nail/head!

Nice find Dutchy.

[Dutchy]

I scanned that yeeaaaaaaars ago from the actual mag :-)

[Shinigami]

Those of you who are ducking under the radar with PC's and the like on street bikes might want to get caught up with recent developments. EPA is about to double down on this.

[Cogswell]

Not surprising I suppose. All they have to do is read bike forums to know that it's quite common for owners to disable, remove or alter emissions related components. Where I live, bikes are not inspected nor emissions tested, so just about anything goes. That will probably catch up with us some day.

[Switchblade]

"The purpose of the VTEC system on the Interceptor, of course, is a broadening of the power curve. Operation on two valves per cylinder at lower rpm levels increases power and torque, while operation on four valves per cylinder at higher rpm levels increases horsepower and torque. Most engines must be tuned to compromise power at one (or both) extremes of the rpm range. With VTEC, the Interceptor does not have to accept this compromise. "

[Switchblade]

[BiKenG]

Thanks for the chart Dutchy, just what I wanted.

My reason for asking is because I have always believed that the V-Tec addition was a complete waste of time and although that chart confirms this to me, it's not a total slam dunk. The V-Tec engine certainly lags behind in the mid range torque, but that catches up and carries on making more power at the top end of the rev range, that area we never normally make use of.

So one could say then the V-Tec system does marginally broaden the spread of power, although with that mid range loss I'd say it is of very questionable merit, especially as I have no doubt, they could have achieved that higher top end without resorting to the unnecessary complexity of V-Tec.

So why do they do it? Because they can. Historically, V-tec was developed for cars and used oil pressure to push a pin into a rocker arm that then provided higher lift. A simplistic form of variable valve timing and it worked quite well on the larger engines of cars, although there are now far, far better systems in use that can provide finer control over the timing. Even on bikes this has been achieved to great effect with Ducati's new DVT system. But that has a slightly different purpose. Rather than needing to make more power and/or torque, they need to calm down the valve overlap at low speed or a big high power twin shakes itself to pieces at low revs. By softening the valve timing, the engine runs MUCH better at low rpm. Try a Multistrada with and without DVT if you want to feel the effect yourself.

But Honda developed V-Tec many years ago and to be honest they've fallen into a rut with it and don't want to give it up. Even worse, the translation to smaller bike engines was never very successful, as evidenced by the chart Dutchy kindly provided. There's a lot of additional mechanical complexity which adds the potential for failures and significantly increases servicing costs. And all for what? Well, not a lot really and nothing that couldn't be obtained by other simpler and cheaper means. Let's face it, if it really was any good, they would use it on other machines.

It's hard to escape the fact that V-Tec on the VFR is a albatross that should be eliminated from the engine. In truth there was nothing wrong with the Gen 5 engine. It can make all the power they would want it to, around about 100hp is the design goal. Could that be increased, sure, but it's not really needed. Having said that, why not make it full RC45 spec as that pulls like a train AND has a better top end. No doubt they'd need a cat now, but I don't believe there's anything fundamentally wrong with that engine that some updated electronics wouldn't sort (for emissions etc, not adding stupid and unnecessary power modes).

The trouble is, motorcycle manufacturers have fallen into the same trap as so many manufacturers of other types of product. They have to keep updating and changing and fail to see that in so many cases they're making it worse. But it's the general buying public who force them into this position by continually demanding change, even when something is basically already perfect at what it does. I have even read on this forum critical comments about the 8th gen, saying it's a rehashed old engine and frame design. Well both may have been designed some years ago, but what precisely would a more 'modern' version do? The engine does everything that is required of it. It is a paragon of smooth usable power (ignoring V-tec), better than many other more modern designs with a similar aim. Handling? What more do you want, let alone need. The very first VFR750 was able to achieve a third place in an international race, ridden by Ron Haslam at Donnington against the very best riders in the world on their world championship machines - I watched him do it. And the handling has certainly not got worse over the years. Change just for the sake of change is not to be desired. As the old saying goes, if it ain't broke, don't try and fix it. As far as I'm concerned, Honda tried to fix the unbroken VFR800, and broke it.

I don't mean to annoy those of you with a V-tec, but you have to ask yourselves the question, wouldn't it actually be a better bike without V-Tec. You know it would. Sadly, if you want a new bike, Honda have given you no other option.

[PairOfAces]

It's like my wife is fat and she never stops Bitching ! Why don't I leave her ? Because I Love her and I'm so stupid I don't know anything else ?

[Switchblade]

It's like my wife is fat and she never stops Bitching ! Why don't I leave her ? Because I Love her and I'm so stupid I don't know anything else ?

+1 This topic has been covered a dozen times and the out come is always the same, if do not like the concept of VTEC don't buy it .

[dgordon]

Fwiw, I love mine. :-) Vtec that is. For such a maligned model of VFR they seem to be extremely reliable. Mine is great, and this is from a prior 5th gen owner. :-)

[InterceptorPR]

Vtec is annoying, but nowhere bad enough for me to choose another bike. I love the VFR.

[deltaboxii]

I couldn't decide if I liked it or not so I bought one of each!

[LEGEND]

For me maybe its miles on the engine or familiarity with the bike but the vtec transition is not a problem for me. The low end snatchiness is problematic but not enough for me to make any changes in nearly 7 years ownership. Instead I enjoy the overall competence of the machine. I did try a vtec with a PC installed but really didn't feel a huge improvement. Made me realize riding the thing is more fun than picking nits and piling on with the negative non vtec owners. Way too many bikes on the market to fixate on the perceived shortcomings of one model.

[Skids]

Thanks for the chart Dutchy, just what I wanted.

My reason for asking is because I have always believed that the V-Tec addition was a complete waste of time and although that chart confirms this to me, it's not a total slam dunk. The V-Tec engine certainly lags behind in the mid range torque, but that catches up and carries on making more power at the top end of the rev range, that area we never normally make use of.

So one could say then the V-Tec system does marginally broaden the spread of power, although with that mid range loss I'd say it is of very questionable merit, especially as I have no doubt, they could have achieved that higher top end without resorting to the unnecessary complexity of V-Tec.

So why do they do it? Because they can. Historically, V-tec was developed for cars and used oil pressure to push a pin into a rocker arm that then provided higher lift. A simplistic form of variable valve timing and it worked quite well on the larger engines of cars, although there are now far, far better systems in use that can provide finer control over the timing. Even on bikes this has been achieved to great effect with Ducati's new DVT system. But that has a slightly different purpose. Rather than needing to make more power and/or torque, they need to calm down the valve overlap at low speed or a big high power twin shakes itself to pieces at low revs. By softening the valve timing, the engine runs MUCH better at low rpm. Try a Multistrada with and without DVT if you want to feel the effect yourself.

But Honda developed V-Tec many years ago and to be honest they've fallen into a rut with it and don't want to give it up. Even worse, the translation to smaller bike engines was never very successful, as evidenced by the chart Dutchy kindly provided. There's a lot of additional mechanical complexity which adds the potential for failures and significantly increases servicing costs. And all for what? Well, not a lot really and nothing that couldn't be obtained by other simpler and cheaper means. Let's face it, if it really was any good, they would use it on other machines.

It's hard to escape the fact that V-Tec on the VFR is a albatross that should be eliminated from the engine. In truth there was nothing wrong with the Gen 5 engine. It can make all the power they would want it to, around about 100hp is the design goal. Could that be increased, sure, but it's not really needed. Having said that, why not make it full RC45 spec as that pulls like a train AND has a better top end. No doubt they'd need a cat now, but I don't believe there's anything fundamentally wrong with that engine that some updated electronics wouldn't sort (for emissions etc, not adding stupid and unnecessary power modes).

The trouble is, motorcycle manufacturers have fallen into the same trap as so many manufacturers of other types of product. They have to keep updating and changing and fail to see that in so many cases they're making it worse. But it's the general buying public who force them into this position by continually demanding change, even when something is basically already perfect at what it does. I have even read on this forum critical comments about the 8th gen, saying it's a rehashed old engine and frame design. Well both may have been designed some years ago, but what precisely would a more 'modern' version do? The engine does everything that is required of it. It is a paragon of smooth usable power (ignoring V-tec), better than many other more modern designs with a similar aim. Handling? What more do you want, let alone need. The very first VFR750 was able to achieve a third place in an international race, ridden by Ron Haslam at Donnington against the very best riders in the world on their world championship machines - I watched him do it. And the handling has certainly not got worse over the years. Change just for the sake of change is not to be desired. As the old saying goes, if it ain't broke, don't try and fix it. As far as I'm concerned, Honda tried to fix the unbroken VFR800, and broke it.

I don't mean to annoy those of you with a V-tec, but you have to ask yourselves the question, wouldn't it actually be a better bike without V-Tec. You know it would. Sadly, if you want a new bike, Honda have given you no other option.

Ken yr wrong. Rob got it right in post #6. Honda introduced the VTEC to enable the VFR to pass international emissions legislation. Simple as that. The Gen 5 would have failed and the costs to get it through would have been astronomical when they had VTEC sat on the shelf as a technology waiting to go.

I do agree though that there should be other ways around it by now; it adds weight & complication which is not needed nor does it do much if anything for the rider.

[dogman]

Not to mention the pain in the ass job of checking the vtec clearances.

[BiKenG]

Ken yr wrong. Rob got it right in post #6. Honda introduced the VTEC to enable the VFR to pass international emissions legislation. Simple as that. The Gen 5 would have failed and the costs to get it through would have been astronomical when they had VTEC sat on the shelf as a technology waiting to go.

Nope. I am 99% sure that is not correct. I may not actually have any inside information on this, but having worked for Honda I have a pretty good idea how they think and they do love to hang on to any special technology they have developed. As for needing it to pass emissions. Nah, I don't believe that. There's nothing wrong with the pre V-tec engine that requires this additional technology to comply and that couldn't be done with electronics. It is a very well designed engine after all. When introduced on the VFR, all the hype was about spread of power, no mention of emissions which I believe have nothing to do with it.

V-tec is a worthless technology. As I said, if it's so good, they'd use it on other bikes. They don't because it provides nothing that cannot be obtained by other better means. But Honda see it as their unique technology and don't want to be seen to give up on it.

As for the 6th Gen VFR, I am not knocking the bike, nor those that choose to buy and ride one. I'm not saying it's a bad choice. My complaint is levelled solely at Honda for forcing customers down this route, unnecessarily and just for their own reasons that have nothing to do with good bike design. This is not a rant, just an interesting technical discussion. I don't care whether Honda continue with V-Tec or not, even if I disagree with their choice. I'm not interested in any VFR as standard. I like my 1200 eVo4 conversion and my 800 will similarly fit my requirements. I don't need Honda to produce any new V4 just to suit me, that's not what I'm saying. In fact, I didn't even start this topic to argue against V-tec. All I actually wanted was some power comparison data for my own interest and I had no intention to ruffle anyone's feathers. My apologies if I have.

[ggathagan]

I can't remember the source, but I was under the impression that the main reason was noise levels, not emissions; that the whine from the gear drive would fail pending changes in EPA noise standards.