VVT questions: Help a brother out

1719 Views 11 Replies 7 Participants Last post by ToyotaDealer, Feb 20, 2007

hal9000

Discussion Starter · Jan 19, 2007

OK, admittedly I'm not a toyota owner, but I'm still a gear head and we all need help once in a while.

I'm trying to find somebody who is intimately familiar with Toyota's VVT system who can help me with some technical questions. I'm in the process of building a Mercedes 2.3-16 into street/track toy, and I think that there's a good possibility that I can reverse engineer the VVT system onto my older engine.

The engine is a 2.3L inline 4 cylinder with a cosworth designed 16 valve DOHC head. The cams are chain driven. I got the idea when I noticed that many of the new generation inline 4s that Toyota, chevy, ford, and nissan have developed over the last few years bear a remarkable similarity in design and specifications to the venerable Cosworth engine that I have. My reasoning here is that despite its age, my engine has what is still a very modern design which could concievably benefit both in term of HP and efficiency from variable valve timing.... besides, it sounds like a fun waste of time to try it.

Anyway, IF the early toyota VVT systems weren't computer controlled, but relied on something simple like rpm to determine the timing, and IF the timing mechanism is carried completely on the cam gear, then I think I have a good chance of success. What I need is somebody who can give a detailed description of the system, and maybe provide some detailed pictures of the mechanism.

So what d'yall say? Can anyone help a brother out?

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timebuilder

· #2 · Jan 19, 2007 (Edited)

In the 1960's, I often saw a mechanical valve timing device advertised in Hot Rod magazine. I believe it was called the "Vari-Cam."

[edit] Found something on it.

Go here:

http://www.jalopyjournal.com/forum/archive/index.php/t-84631.html

and scroll down to a post by a guy called "Scotch."

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hal9000

Discussion Starter · #3 · Jan 20, 2007

Interesting.... not exactly what I need for my purposes, but it's a good history lesson anyway.

I believe that Porsche does the same as was mentioned in that other thread and changes the cam timing by changing the length of the timing chain between the cam gears.

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hal9000

Discussion Starter · #4 · Jan 24, 2007

No one? Somebody's gotta know a little bit about the cam timing system in these engines.....

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wantin150

· #5 · Feb 3, 2007

http://en.wikipedia.org/wiki/VVT-i

http://en.wikipedia.org/wiki/Variable_valve_timing

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

http://www.answers.com/topic/vvt-i

Help any?

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Komodo

· #6 · Feb 5, 2007

Nissan uses what you are looking for on the VQ engines I believe.

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hal9000

Discussion Starter · #7 · Feb 7, 2007

Wantin,
Thanks for the links, but I've seen most of them already. At this point I'm really trying to move beyond general descriptions and get into the specifics for the toyota engine so that I can determine if it's worth my time to pursue the project, switch vehicles, or just give up.

What I really need is somebody who is either very familiar with the VVT system in the Toyota engines, somebody who has access to the manufacturers detail drawings, or somebody who has access to a partially disassembled engine and who can photograph or describe the parts in detail for me.

I haven't looked at the Nissan system in detail yet. But that's simply because when I read the general description of how it worked, it didn't sound as if it would be easily compatible with my engine. Maybe I should re-check though.

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hack6500

· #8 · Feb 7, 2007

sounds like a very interesting project!

there is 2005 1GR-FE 6cyl 4.0L VVT-i being tore down by a fellow tacoma owner.
i would like to see what my actual components look like, i bet we could ask him to take some pictures of this system.

i just do not know if this would be helpful for your needs.

the "-i" in VVT-i are what types of elctronics, servo controllers??

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wantin150

· #9 · Feb 7, 2007

hal9000 said:
Wantin,
Thanks for the links, but I've seen most of them already. At this point I'm really trying to move beyond general descriptions and get into the specifics for the toyota engine so that I can determine if it's worth my time to pursue the project, switch vehicles, or just give up.

What I really need is somebody who is either very familiar with the VVT system in the Toyota engines, somebody who has access to the manufacturers detail drawings, or somebody who has access to a partially disassembled engine and who can photograph or describe the parts in detail for me.

I haven't looked at the Nissan system in detail yet. But that's simply because when I read the general description of how it worked, it didn't sound as if it would be easily compatible with my engine. Maybe I should re-check though.

I kind of figured you had already researched those links. I didn't read all the way through them, just posted for what they were worth. Good luck in your quest.

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hal9000

Discussion Starter · #10 · Feb 7, 2007

Hack,
I think that the -i does stand for some kind of electronic interface, but not being a toyota guy myself I'm not 100% on that. What I'm hoping for is that the newest generation system which doesn't have any electronic interface to control the cam timing will be carried primarily on the cam gear or timing chain tensioner assemblies. As long as the system is a hydraulic/oil pressure system that is on one of these two parts, then I'm pretty sure that I can do the conversion. by having a set of custom timing gears or an adapter or two built. (and custom cams of course)

For anybody curious, the reason that I'm interested in this is that variable valve timing adds around 25-35% hp to the engines that it's added to. My cosworth engine was discontinued before VVT technology became popular, but most of the newer generation twincam engines being made by various manufacturers are near exact copies of my engine. So the potential for reaping the benefits of this are pretty good as long as I can make the parts fit.

My cossie engine produces 185 bhp stock. It would be great to bump that up to 225 or 230 though.....

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Mistabullet

· #11 · Feb 12, 2007

Hope this helps, that is if you haven't seen it already: http://www.youtube.com/watch?v=9A6S1NUjg_A

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ToyotaDealer

· #12 · Feb 20, 2007

the part you're looking for is known as the Camshaft Timing Pulley to the VVT(i) systems. it IS an oil pressure activated part.. this much is true and would work with your application. however where you run into trouble is the valve that operates that oil pressure activation, it is controlled by an electrical source, determined by the toyota ECU.

this part is known as a Camshaft Timing Oil Control Valve, toyota parts prefix 11101J (in say a Celica GTS for example)

mechanically you can make it work.. electronically it'd be a tough job. i suppose you MAY be able to wire something up based off of engine RPM, like a window switch for a nitrous kit that operates a valve.. but truthfully i think you're spending more money here than it's worth.

good luck!

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