[QUOTE]Originally posted by djohnston
[B]

You may be referring to the way both the ITR and the Integra GS-R have a dual-stage VTEC system, in that there's a switch to the high RPM cam at 4400 RPM, then a change in the intake runner length at 5600 RPM.

 

You all should be looking forward to an eventual changeover from a 12 volt electric system to a 42 volt system (like those used in Europe). Not only does this mean great stereo systems that need much less current, but continuously variable timing. Because 42 volt systems have so much more electrical potential, they are able to control all of the valves independently through solenoids which means you have a continuous optimization of your fuel air mixture/quantity throughout the entire RPM band. Better yet, this elliminates the need for cam shafts all together reducing the weight of engines meaning better gas mileage and performance. I think some of the new Mercedes coming out in the next few years will have a system like this implemented. I cannot wait!

Nix

 

[QUOTE]Originally posted by Kraziken
[B]I haven't experienced it, but from what it would appear to me, it should feel like a more linear acceleration, not like the on/off feeling from normal VTEC.

If I understand correctly, the Valves will "adjust" thru out the whole RPM range to allow for more air/fuel.

 

[QUOTE]Originally posted by Nixlimited
[B]You all should be looking forward to an eventual changeover from a 12 volt electric system to a 42 volt system (like those used in Europe). Not only does this mean great stereo systems that need much less current, but continuously variable timing. Because 42 volt systems have so much more electrical potential, they are able to control all of the valves independently through solenoids which means you have a continuous optimization of your fuel air mixture/quantity throughout the entire RPM band. Better yet, this elliminates the need for cam shafts all together reducing the weight of engines meaning better gas mileage and performance.

 

Intrepid -

As far as I know, this technology has been in use in indy cars for years, but I might not be correct. Check it out. I think ultimately this system will be pretty stable and really have some great pay-offs.

Nix

 

[QUOTE]Originally posted by Nixlimited
[B]Intrepid -

 

INDY cars (aka Indy Retirement League) use vlave springs and are rev limited to 10-11,000 rpm. CART (the real open wheel series in the US) also uses valve springs but are allowed to rev to whatever each manufacturer thinks will last the whole race. Nobody officially knows how high they rev, but the best guess is in the 16,000 RPM range.

If I remember correctly, the problem with soleniods operating the valves was that they are simply too loud, snaping open and closed is very different that following a gently sloping cam profile.

 

Would the S benefit from a dual stage VTEC?

 

I got the impression that the S has a 3 stage v-tec, from the Quicktime video on the Honda website.

http://www.hondacars.com/models/s2000/engineering.html

If you click on the video it explains the v-tec. In the video, it says the engine has two "low" rpm lobes and one "high" rpm lobe. I thought it was low mid high, but does anyone know why they have two low rpm lobes?

Mazda has now incoporated the Valve technology in the Miata, but the power output is kind of disappointing compared to the Honda engines. If I'm not mistaken, Hondas patent on the technology expired, and now other companies are using it.

Anyway, here is a quote from Mazda's website on the Miata engine;

"1.8-liter DOHC 16-valve 4-cylinder engine w/VVT
The Miata's powerful DOHC engine incorporates Variable Valve Timing (VVT) technology. This system continuously adjusts the timing of the intake valves to maximize power at all engine speeds, while reducing fuel consumption and exhaust emissions. "

They still haven't been able to match Honda's efficiency in the VTEC system. I would think Mazda could get more power out of a 1.8l, and the Celica's engines usuable RPM range is high so it is very limited. By the time you get to the power, you have to shift.

 

[QUOTE]Originally posted by Kraziken
[B]I got the impression that the S has a 3 stage v-tec, from the Quicktime video on the Honda website.

http://www.hondacars.com/models/s2000/engineering.html

If you click on the video it explains the v-tec.