Disable the vtech

Does anyone know if it is possible to disable the Vtech so that all the valves are in use all the time?

 

You might consult the wiring diagram and find out how to rewire the solenoid that enables the 2nd set of valves.

If you could power that solenoid 100% of the time, whenever the key is on, perhaps by installing a jumper from a known hot lead, it would effectively disable the VTEC and cause the 2nd set of valves to be in service all the time.

I have absolutely no idea what that may do to your motor though.

If you feel brave, try it and report back.

 

Interesting idea.....they do sell VTEC controllers for Honda/Acura cars....I wonder if they will or are going to make one for the motorcycles. Does the Power Commander give you any additional control over the VTEC engagement?

 

I have the PCIIIusb and didn't see anything in the install guide about controlling VTEC.

It was my understanding that the 2 valves at lower RPMs were for increased torque and 4 were for increased horsepower. I'd leave it alone unless you just want to burn twice as much gas to lose useful torque and gain not so useful horsepower.

I think Honda desinged the VTEC for the broad useable power band, which is what makes the VFR so much fun to ride. Who knows though, hack it and give us the dyno results, maybe it'll be sweet.

 

ooo this should be good.

 

Noise reduction, fuel economy and emissions.

Noise:
http://world.honda.com/environment/2002report/29_zisseki_01_2r03.html

Emissions:
http://world.honda.com/news/2004/2041112.html

And check pages 30 and 31 for more of the same:

http://world.honda.com/environment/...l.pdf#search="vfr vtec site:world.honda.com/"

 

wrong-o.

Putting all 4 valves to use would simply let the engine breathe more, not add more fuel! It isn't 2 to 4 fuel injectors!

Running the engine on 4 valves all the time would likely hamper the low end (say from idle to 4000RPM) just a tiny bit, but the engine would still run well. HERE's what I believe to be the problem if you try this though: The computer still thinks it runs on 2 valves below 6ish thousand, so if you lock the 4 valves on, you will likely get a SUPER LEAN run condition, and likely kill the motor due to severe engine knock. Don't know for sure, but I sure as hell ain't gonna find out on my engine. I was ballsy enough replacing the air filter with an aftermarket and putting a new exhaust on, all without changing the fuel programming,...

 

motec makes a ecm module that controls v-tec engaugement along with alot of other useful things but the price is high 2000+usd.

 

apexi makes them for honda cars too

 

Actually no, I know this one from my 98 Cobra, which did just this trick, ran on 2 valves at below 5K Rpm and above that opened up all 4.

They run on 2 V because at low RPM this actually is a more efficient configuration The offset intake causes a fuel/air swirl in the combustion chamber, giving you better combustion and power in the low RPM's however at about 5K 4v becomes more efficient. And thus on the cobra would open up all the valves to breather freely.

 

anybody got the :bsflag: smiley?

The Cobras did NOT have variable valve lift and timing. I had an 00 4.6L GT, and I KNOW MY MUSTANGS. Do not try this one on me or the group.

"The Cobra version was updated that year with a high-revving 305 hp (227 kW) dual over head cam configuration of the 4.6 L V8. The Cobra's block, cast by Teksid of Italy, was an aluminum, cross-bolted block. The heads had split intake ports and 4 valves per cylinder, and the intake ports were arguably too large for the street, but are still a favorite of modular race teams. To compensate for the relative lack of low end response associated with these kind of cylinder heads, SVT also put an intake manifold with dual runners on the Cobra, with the short runner secondaries not opening until 3250 rpm, making these early modular Cobras more responsive at low speeds."

Now then, that means that the Cobra had dual runners, which is not the same as variable valve. It means their intake system could open up or close via butterflies on the secondaries. Very few amercian vehicles have Variable Valve Timing, let alone Valve Engagement. You are, however, 100% correct about the swirl effect, but don't forget the issue of velocity. If an engine runs on 2 valves instead of 4, that means that there is one valve for intake, one valve for exhaust. This gives the engine more velocity of the air that is incoming and exiting (not so great on exiting, except for the possibilty of scavenging, a tricky thing to explain and even harder to implement) because of the nature of an engine being an air pump.

Below a certain RPM (actually, its a variable thing, but our VTEC system doesn't do variable, its FIXED), with 2 valves operational, the engine will suck/squish/bang/blow its way with higher velocities of air (and thus greater combustion mixture swirl, potentially) then if the motor was using 4 valves at this time. If it were using 4 valves at these lower RPM's, the air-fuel mixture rushing into the engine's combustion chambers would be the same quantity as a 2 valve, but the slower velocity of the mixture would not mix and atomize as well. Of course, at higher RPM's, the need for more air and fuel increases linearly, and in inverse proportion does the need for a swirl of the mixture: Its already doing well enough because of the engine's appetite for the mixture due to the RPMs. At higher RPMs, a 2 valve engine is simply wasting some of its pumping abilities on the friction of air, the principle that air will flow only so fast into the engine, and at higher RPMs, the need for more fuel and air overcomes the mixture's ability to fully enter the combustion chamber. Example, use straws to breathe. Take 2 straws, and put them in your mouth, and breathe normally. You can do it pretty easily, especially if the straws are properly sized in the first place. Now, with the straws, run in place. Very quickly your air pumps, your lungs, will need more then the 2 straws can deliver, despite your lungs abilities to pull air into the straws. Take 4 straws, and try again.

Running the engine on 4 valves all the time will soften the bottom end just a little bit, but moreso the engine will not completely burn its fuel correctly. My opinion on it is that the engine should switch to 4 valve operation much sooner, like 3-3.5K rpm, where a "KICK" would not be felt, because the engine would not be straining for fuel and air as much.

 

Ok splitting of hairs here, I'll admit technically you are correct, however in practice you're still doing exactly the same thing as the Vtech in the VFR does.

Granted the VFR does it by not opening a valve(s) and the cobra did it by closing off one of its intake runners.

However from the perspective of a air pump (or if you want to split hairs further a heat pump) this doesn't make one whit of a difference weather it is the valve, that is not being actuated or the airflow is being blocked in the manifold. Result same.

Remember the VFR Vtech really isn't variable timing.

And lets get onto the straw analogy....

you take your two straws, I'll take my 4" one we'll see who breathes easier. :biggrin:

All things being equal IE in a perfect world where valve float doesn't exist, a 2V Engine will breathe better than a 4V one will, up until a point that point which is generally about 5K rpm when valve float becomes a significant problem.

this is just simple math, a larger valve diameter will have a greater area and thusly be able to flow more air/fuel easier (allowing the engine to be more efficient.)

Hence the use of 4V per cylinder you can then ostensibly rev your engines higher without having to go to exotic, valve materials to lighten weight, and massive springs to try to close them.

But this is all moot, the reason, as stated is again that this is a more efficient configuration at low rpm and not from a intake perspective but from a fuel/air atomization perspective.