INFO: What is CVVT?

[Keyan]

This is copied from AllData, a popular web based technician reference for all cars:

CONTINUOUS VARIABLE VALVE TIMING




DESCRIPTION




The CVVT (Continuously Variable Valve Timing) which is installed on the exhaust camshaft controls intake valve open and close timing in order to improve engine performance.

The intake valve timing is optimized by CVVT system depending on engine rpm.

This CVVT system improves fuel efficiency and reduces NOx emissions at all levels of engine speed, vehicle speed, and engine load by EGR effect because of valve over-lap optimization.

The CVVT changes the phase of the intake camshaft via oil pressure.

It changes the intake valve timing continuously.

OPERATION

• The CVVT system makes continuous intake valve timing changes based on operating conditions.
• Intake valve timing is optimized to allow the engine to produce maximum power.
• Cam angle is advanced to obtain the EGR effect and reduce pumping loss. The intake valve is closed quickly to reduce the entry of the air/fuel mixture into the intake port and improve the changing effect.
• Reduces the cam advance at idle, stabilizes combustion, and reduces engine speed.
• If a malfunction occurs, the CVVT system control is disabled and the valve timing is fixed at the fully retarded position.

The above figure shows the relative operation structures of the housing vane to the rotor vane.
If the CVVT is held a certain control angle, to hold this state, oil is replenished as much as oil leaks from the oil pump. The OCV (Oil-flow Control Valve) spool location at this time is as follows. Oil pump Advance oil chamber (Little by little open the inflow side to the advance oil chamber) -> Almost close the drain side Be sure there might be a difference in the position according to the engine running state (rpm, oil temperature, and oil pressure)


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I know the pictures are big but there is nothing really i can do about that because of the small lettering, sorry.

sticky?

[DESIGN]

Ford Zetec motors used in the contour, new cougar, and ZX2 have what they call VCT that was used in leu of egr. It made tuning using cam gears nearly impossible without a special part to overide the VCT.

On Beta 2s does this become a problem or is it striclty an RPM/ECM managed system that can be modified with a SAFC or like?

Are there any advantages to making changes on this system?

Are there any CVVT friendly mods? In other words are there any that take particuliar advantage of this system for making more power?

[Keyan]

Ford Zetec motors used in the contour, new cougar, and ZX2 have what they call VCT that was used in leu of egr. It made tuning using cam gears nearly impossible without a special part to overide the VCT.

On Beta 2s does this become a problem or is it striclty an RPM/ECM managed system that can be modified with a SAFC or like?

Are there any advantages to making changes on this system?

Are there any CVVT friendly mods? In other words are there any that take particuliar advantage of this system for making more power?

The CVVT soleniod I think is directly linked to the ECU, and the signal couldbe altered w/ a VAFC style control unit. But no control unit exists so no one has tried.

I am 90% sure the EVO 9's have a similar CVVT setup, so I am waiting for the mitsu aftermarket community to come out with a controller...

[BColeman]

Keyan, I just found this thread, and thought I'd resurrect it.

You were speaking of the similarities between the Evo 9 valve timing and the Beta CVVT.

AEM makes a product, brand new on the market, called the F/IC. It is a control like an SAFC. It controls Fuel, but it also controls Ignition, even on cars with Variable Valve Timing in the forms of MIVEC(Evo 8&9), VVT-i and VVTL-i (toyota), i-VTEC (Honda), CVT, etc. They have limited plug and play systems right now, with more due out in the very near future.

Do you think that this could be a possibility for us? When I read an article in a magazine about it, I got really excited. I was so hoping that it would be a universal system. But, they do not have a universal unit at this time.

Here's the direct link:
AEM F/IC

[Cypher]

i really don't see how it couldn't be universal. the only thing that wouldn't be would have to be the harness they supply. if i'm not mistaken i think TC is planning on offering these.

[BColeman]

Oh yes, it really just is a wiring function to be universal. But I wonder if the programming is universal too. Capable of tuning any form of variable valve timing.

[Cypher]

i don't see why not. pick it up and let us know!

[BColeman]

Yeah right, and then 'f' everything up. No thanks. My means include a new motor soon, but not in that way

[04 elantra cvvt]

Hmmm... This could get interesting. If we could get the motors to advance quicker, we could make a lot more power. Just like the V-TEC controllers for Honduhs.

[BColeman]

See, that's what I was thinking. But researching the CVVT, the systems are so different between CrookedH and those other H people, that the idea just won't work right.

Now, if there was a way to work around the Continuous part, and just have VVT, that would be great. Then we could adjust the activation of it down low in the RPM band, just like a V-Tec controller would do, and make use of that added power. But I see a hindrance in the CVVT already. It attempts to make more power at the upper band, but it's basically useless around 5800 rpm. I wish it weren't so, but the only vehicle I've seen that it didn't seem to matter on was Hayden's (struck1481) '05 boosted sedan.

Time will tell though. I'm not in a position to be a guinea pig right now. I have a feeling though that this will be bugging me to no end, and I will be making the leap to try and figure it all out. What's the worst that can happen, right? Besides a blown motor, that I intend to replace anyway.

[vladj]

well here is a link about a guy making a controller for the CVVT but im to stupid to understand it:

http://www.freepatentsonline.com/700...vt&stemming=on