How many VVT stages and when?

[chimchim]

How many VVT (variable valve) stages are on the Mazda3s engine (and 3i) and what are the RPM change over points?

(and what's redline?)

 

[Dre]

I don't know how many stages there are but I can feel it at 4,500RPM.

 

[eting_pro5]

3i doesn't have VVT

 

[Dre]

Oops. Didn't even see the "i" in his post. Disregard my answer then.

 

[wongpres]

How many VVT (variable valve) stages are on the Mazda3s engine (and 3i) and what are the RPM change over points?

(and what's redline?)

Theory first:

There are 2 types of variable valve timing: cam changing & cam phasing. Cam changing will literally switch to another cam at a certain rpm whereas cam phasing varies the timing across all rpm's. Both systems have pros and cons. Not surprisingly, the best systems are those that incorporate BOTH cam changing and cam phasing (Acura TSX's engine is an example that uses both).

So what does the Mazda3 have:

1.6l (not available in N. America): cam phasing
2.0l: nothing
2.3l: cam phasing

So the answer to your question, there are no change-over points in cam phasing because it's changing all the time.

The rev limiter comes in around 7100rpm.

 

[Kooldino]

How does the phasing work? Does it "slide" the cam profile around on the fly?

 

[PERRY323]

heres a really interesting article, i linked the page 3 because it talk about the VVT but you can read the whole article.... easy and clear to understand

http://auto.howstuffworks.com/camshaft3.htm

 

[wongpres]

How does the phasing work? Does it "slide" the cam profile around on the fly?

I learned this engine info (and a lot of car info in general) from this excellent website:

http://autozine.kyul.net/technical_school/tech_index.htm

 

[eting_pro5]

excellent info, thanks wongpres and perry

 

[BinaryRotary]

3i doesn't have VVT

Not true, all of Mazda's engines except for the rotary use a VVT system.

 

[PERRY323]

Not true, all of Mazda's engines except for the rotary use a VVT system.

actually, eting_pro5 is RIGHT and you are Wrong binaryrotary....

VVT is a very rare and new thing on mazda engines...yep, they were a little late!

and the new 2.0L, excet from sharing some parts with the 2.3L, is NOT VVT

 

[chimchim]

Well, I'm interested in the 3s anyways. I guess I assumed VVT was Mazda version of Honda's VTEC... which meant a cam profile change.

If it truly is a continuously variable cam phase, then disregard my original post. And if so, this is nice... and I'm guessing probably contributes to the nice smooth power curve the Mz3 has.

 

[Newf]

actually wongpres is right.

 

[enry]

I wish all our engines were VVT...

 

[eting_pro5]

I LOVE BEING RIGHT!!!