Rebuilding head as to have something like VTEC?

[Xpect]

The last few days I had something floating around in my head.

Would it be possible to rebuild a head, making new cams and valves to implement something like VTEC to our beloved E-engines?

I know VTEC is engaged with a little pin connecting the valves so the work after a wilder camspec in higher revs. i-VTEC (being a combination of traditional VTEC an e-VTEC) even has an additional feature to only use 12 Valves in low RPM regions so it saves fuel.

So what is needed is an indirect engaging of the valves, in German called "Kipphebel" or "Schlepphebel", I really don't know the english word (*), so the variable cams can be used. also an oil-line with a valve is needed to be able to activate or deactivate the wilder cams. I also have in mind the integration of i-VTEC so on the intake side two oil lines would be needed.

So entirely the whole Head has to be newly build, would this be possible for a "normal" person?

I have rather accurate plans in my head, where each camshaft has only 2 camlobes per cylinder as normal, opposed to the original VTEC with two normal lobes left and right of the wilder lobe in the middle. so 3 lobes total on them. The plan would be in low revs the normal lobe only activates one valve, in middle revs the second valve is connected to this stroke via a oilpressure activated pin and on high revs (**) additionally the wild cam engages utilizing both valves while the normal one runs pretty much free. With the double connection the need for connecting the "half" valve (which is not used on low rev) to the gear of the wilder valve isn't needed as it's already connected to the gear of the other valve, thus making it a tiny bit more easy.

But would this even be possible? To rebuild the whole head to this?

I would draw you a picture if I could, but I'm not really good at this.

(*) on a sidenote, most other engine parts I only think of the english word when trying to explain things to some mechanic friends so have to think about the german word for a while all the time

(**) where the efficiency of the normal cam stroke ceases and torque begins to drop again

[AdamB]

Anything is possible with the cash.

However! I don't see the point, when you could just use a manifold like the ACIS to give you the bottom end torque for pottering around town, and then the mid-top end torque by utilising shorter runners for the fast backroad/track action.

It would be much much cheaper, much easier to install, easier to setup, etc.

Not to mention that the 4E is of a square design engine, and the 5E is under square making power a lot sooner in the rev range than VTEC engines.

If that's what you wanted to look at doing, I would look closer to home with Toyota's VVTI system

Edited September 3, 2013 by AdamB

[Xpect]

I thought this might even be useful for turbo operated engines, where the torque drops again at a certain rev (eg in the TF35 thread at near 5500rpm) and there the wilder cam could be engaged to raise torque even more, together with a higher rev limit.

Also, an ACIS alone, even without the controlling needed, is hard to come by and is very expensive. The cheapest I've seen was 300€, I guess around 170£, and together with that I need like at least a Piggyback and the control unit. Even getting a CT9 to plop on my 4E would be cheaper I think, as the CT9 is just dropped on here in favour of bigger turbos, and the management needed is the same.

[morgey]

honda b18c4's use a similar system to the acis system anyway.

what you are on about its possible but it would be a complete redesign of the head, cams, camgears, timing belt setup. due the the system needing a pair of rocker arms the cams or valves will no longer be directly cam driven.

both toyotas 2zzge vvtLi and mitsibushis Mivec system uses the 4 big and 4 small lobes system. the 2zzge also have vvti which makes it identical to I-vtec.

e-vtec is basically vtec in reverse, you have 12 valves in use 90% of the time then when you boot it it locks in the final 4 valves, but there is no differences in cam profiles on these engines. ie no agressive cam lobe.

then easiest and least work to make a system like this would be impliment fiats multi air system. controllable oil filled tappets. you put in a really agressive cam but only half fill the tappet making it run like a normal cam at low revs, when up in the higher rpms you open a oil valve allowing the tappets to fill completely to make use of the agressive cam and continue to make power at higher rpms

[ryan lang]

Pretty sure there wouldn't be enough space in there to get extra can lobes for each valve either so you would struggle to include that into a design

[ste91]

Anything is possible with the cash.

However! I don't see the point, when you could just use a manifold like the ACIS to give you the bottom end torque for pottering around town, and then the mid-top end torque by utilising shorter runners for the fast backroad/track action.

It would be much much cheaper, much easier to install, easier to setup, etc.

Not to mention that the 4E is of a square design engine, and the 5E is under square making power a lot sooner in the rev range than VTEC engines.

If that's what you wanted to look at doing, I would look closer to home with Toyota's VVTI system

A variable inlet manifold is totally different to variable valve timing/lift, the ACIS manifold just alters the "acoustics" of the air intake to optimise air flow for high/low revs.

The idea of VTEC is that you have a low cam to retain low end torque and high cam for high end power. If you just had the low cam permanently, it would choke the high end power. If you had the high cam on permanently, you would lose low end torque, and the engine wouldn't run as smoothly, and you'd also lose MPG.

It would take a lot of R&D and engineering work to build something like as suggested in the first post, infact it would be less work to do a complete engine swap.

[ste91]

I thought this might even be useful for turbo operated engines, where the torque drops again at a certain rev (eg in the TF35 thread at near 5500rpm) and there the wilder cam could be engaged to raise torque even more, together with a higher rev limit.

The cams aren't the issue there, the turbo is the problem, the small size of the turbine housing causes a restriction.

[morgey]

The cams aren't the issue there, the turbo is the problem, the small size of the turbine housing causes a restriction.

*cough* twin charged *cough*

[5e colin]

be cheaper to fit a vtec turbo engine to a toyota

[AdamB]

A variable inlet manifold is totally different to variable valve timing/lift, the ACIS manifold just alters the "acoustics" of the air intake to optimise air flow for high/low revs.

The idea of VTEC is that you have a low cam to retain low end torque and high cam for high end power. If you just had the low cam permanently, it would choke the high end power. If you had the high cam on permanently, you would lose low end torque, and the engine wouldn't run as smoothly, and you'd also lose MPG.

It would take a lot of R&D and engineering work to build something like as suggested in the first post, infact it would be less work to do a complete engine swap.

I know this but essentially its the same thing, by altering low and high end torque ranges.