Power Commander and Vtec

I have a few questions about the power commander that many people seem to be adding to their bikes. It seems to me like on this bike the Vtec should kick in a little earlier. I know the vtec works by switching the engine from 2 valves/ cylinder to 4 valves per cylinder at about 7000 RPM's. As I understand it, a 2 valves per cylinder engine makes more power at low RPM's but a 4 valves/ cylinder engine makes more at high RPM's. The power would look like this:



the change over should happen when the red and green lines cross, but instead they happen like this:



Which causes the jump in power (the blue line). It SHOULD look like this:



What I want to know is whether the power commander can be used to change the Vtec engagement point. If not is there a way to do this? I know it is possible on my car (not a honda: it is a toyota with a knock-off version of v-tec)
If not, can the lower range be tuned so it revs quicker and behaves more like the upper range so that the change over isn't so abrupt, using the power commander? My old bike was a cbr,and it had the really quick revving, insane power, like this bike has once vtec kicks in, and I liked that it was available earlier on my old bike.

PS: I may be totally wrong on how the vtec effects the power of the bike. this is just how I understand it at this point.

 

I don't think you can change the Vtech transition to lower RPM unless you can hack in the ECU and reprogram. Might want to get the PCV and autotune so you can program on the fly.

 

Alright, I'm no expert (only owned one for less than a week) but keep in mind that that power curve will be representative of a single throttle opening, pretty much guaranteed to be wide open. One thing I've noticed during my time on the bike is that at less than wide open throttle the VTEC transition is actually very smooth, and that with very little throttle the bike actually loses a bit of power after transition. I'd hazard a guess that if the transition were lowered to where you've indicated it would be silky smooth at full throttle and provide maximum power, but during more mild riding you'd experience an annoying loss of power every time you transitioned. And since the transition would be less than halfway to redline, you'd experience it a lot.

If that makes sense I'd certainly prefer a kick in the pants.

 

I agree with what you are saying in theory but there are reasons why I don't want what you propose. I prefer to cruise on the highway not in Vtec mode as it is smoother and I get better fuel efficiency. Then when I want to git er done, I crank er up over 7k and kapow I'm off like a scalded cat. It's like having two different motors.

If you don't like the transition, there are plenty of 5th gen bikes out there.

 

the 5th gen really doesn't do anything for me. It's starting to look dated. I like the digital display, the undertail exhaust etc. With the power commander, can I tune the lower range more aggressively so it behaves more like a normal sport bike? Because screw efficiency, I WANT POWER!!!

By the way, Do the later model 6th gens (after they made the update) have the same vtec engagement point?

 

No the later versions engage sooner that the early versions by about 500 rpm I believe. I've had two of the early versions and now an 07. I prefer the way the 07 runs.

I agree that the 5th gen styling certainly says 90's and I prefer the 6th gen for appearance but I wish I had the 5th gen motor again.

 

If you're willing to give up a little on the top end, you could consider changing your sprockets and chain. Down 2 up 1 (or more) would probably give you a helluva lot more "grunt" at those lower RPM's. Of course, you'd need a speedo healer too. But something to think about.

 

what if I change ECU to that of a newer interceptor?

06 Honda VFR800 VFR 800 Interceptor CDI ECU ECM Igniter Tested | eBay

 

No it can't. The Power Commander controls the electronic fuel delivery to the engine.

The Variable Valve Timing and Lift Electronic Control (VTEC) is a purely mechanical system that has absolutely nothing at all to do with electronic fuel delivery.

(Okay technically the spool valve solenoid is switched on electronically and the slide pins do get a hydraulic assist from high pressure engine oil for all you tech geeks out there. :lol

Yes,it can be done manually. The question then is why the heck do you want to kill the intake air speed at low RPM's?

Yes,that's what the Power Commander is for.

As delivered from the factory these bikes have to meet strict government emissions standards,which means that they're tuned so lean that they buck and snatch and fall all over themselves at lower RPM's. The Power Commander (with a properly tuned map for your particular bike) will smooth all of that out.

Keep in mind that you won't be gaining much power because these bikes are not in a particularly high state of tune to begin with. In other words the VFR ain't no CBR,so don't expect it to be.

The later model '06 to '09 bikes used an ECU with different programming that helped to smooth out the VTEC transition. According to the post below it's possible to use that later model ECU on the earlier model '02 to '05 bikes but you also have to use the higher flow rate fuel injectors that are used on the '06 to '09 bikes as well to make it all work properly.

Yes my friend you are.

The VTEC only controls how the engine breathes and not how fuel is electronically delivered to it.

You said you wanted more low RPM power and that was exactly what Honda was trying to give the VFR800 with the VTEC engine. In reality though all Honda managed to do was to make the engine a bit heavier and a little more complex because in the end it didn't really produce all that much more power than the engine it replaced.

 

First off, thank you.

Once I pass 7000 RPMs It pulls way harder than my cbr. It just baffles me how they could make the midrange (5k-7k) Worse than the cbr.

So I think I want the power commander. Do I need the autotune? Its expensive. shouldn't somebody else already have a decent tune for my bike? for mods it has a leo vince catback and that's it.