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Old 11-19-2008, 04:13 AM   #1 (permalink)
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vvt for engine that dosnt have it?

of course its possible to create and program VVT of our own but if Im starting on an engine that dosnt have it how would I manage to create it? where do I start?

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Old 11-19-2008, 04:48 AM   #2 (permalink)
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you start with understanding Variable Valve Timing. They don't use flywheel weights to adjust it like old school governors. Last I checked it was controlled electronically by a happy little computer. If your engine doesn't have it, you can't add it without significant effort, more than it would be worth. Electronic solenoid controlled valves are superior to standard mechanical cam controlled valves, but it's not as simple as adding solenoids and removing camshafts.


...or is it...?

Start by understanding valve theory; ie valve overlap, length, lobe profile (how fast it opens and closes). Presumably you could use the values given for you motor. You don't need a timing belt anymore, or camshafts, so the need for ample amounts of oil in the head are reduced, if not almost eliminated. We'll start simple first, so lets ignore the oil issue.

Where were we? Oh right, no camshafts. Okay, you have an empty head, just valves on springs. Time to rig up some solenoids. You know the timing of the valve, so you'll need to time that to the crankshaft's rotations. Simple method? EDIS trigger wheel on the crankshaft pulley. Quite common thing for custom ecu installs. Trigger wheel spins, optical eye sees the rotation, computer interprets degrees into timing, solenoid triggers, valve opens and closes. Simple enough right?

Now I know someone out there is going to say "What about the electrical load on the motor now? It takes quite a bit of energy to open a valve, I can't even push them open by hand!" Yeah, I can't either. Good thing they make lighter springs. But if that fails, the valve drops, engine explodes, game over. Aha! says the wise man, use a two stage solenoid! Oh wait, if the power goes off, the solenoid won't hold the valve up, down she goes.... Dang. Looks like a strong titanium spring may be our best bet. Back to figuring out electrical load for the valves CONSTANTLY opening.

Not as easy as it sounds. Not for the weak at mechanical and electrical understanding.

Oh yeah, another random thought: Valves can crash 2 ways: up and down. You release the solenoid to fast and the valve slams shut, possibly weakening the head, maybe even snap it off. So now we have to open and close the valve using variable power input the to the solenoid.


Hope that helps you some, gives you ideas. I'm thinking since you're asking this question that you're not currently capable of undergoing this task. It sounds awesome, and I think I'd like to find an old single cyl motor and try this out, maybe as a senior design project. I have the understanding, but not the skillset yet to attempt this.

Someday.
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Old 11-19-2008, 08:42 AM   #3 (permalink)
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You could rip off an vvt system from another car and rig it to your own. This would involve a lot of machining work and electronics and programming. It would be a huge job, but it could be done if you had the time and money.

I have seen another simpler (still not simple) system that used a mechanical system instead of electronic. It used weights that would alter cam timing based ONLY on engine rpm. As the camshaft spun faster, the weights (which are on springs) pulled and advanced cam timing. This is a bit less useful as it doesn't incorporate engine load, but is probably a lot easier to implement.
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Old 11-19-2008, 02:44 PM   #4 (permalink)
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thing I love about Hyundai's are that parts are interchangeable, so im not worried about finding parts for the job kinda just worried about the ecu business see I have other plans for the engine too.

when getting into car modification I learned that a turbocharger dose not increase economy at all... soon after VVT was introduced to me.
I believe with VVT and a higher air flow power to weight ratio goes flying but without burning double the gas. get higher power with better miles I think its depending on the engines exhaust power, and the turbo itself.
small engines cant spool up turbos at around 1-2.5k rpm wich means its like running without a turbo, no jackrabit start. VVT helps controll the amount of airflow needed meaning there should not be any air flow restrictions played by it. better airfilter are shown to increase the mpg and Horse Power, so as long as the turbo spools a little to make Intake manifold Vacume to be at 0 we would be good.
now you might be thinking that without a turbo only with a Wide open throttle can we reach 0 with is right but its not like gunning the engine.
throttle position is still lower but you are getting better air flow without the extra need for more fuel once it goes over the 0 then you are boosting and using more fuel.
tho engines do create more horse power when they are leaner they still explode when they are lean too.

and with VIT I think it would be even better.

if you remember what a turbos function is for, it was made to use the waisted power coming out of the exhaust to spin a fan that increases intake air flow.

this exhaust power is in ever gas powered vehicle and I think it should be used and not waisted because it is being created.

if I get a factory made ecu for the VVT engine it wont understand the turbo airflow.
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Old 11-19-2008, 03:31 PM   #5 (permalink)
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Quote:
Originally Posted by Frank Lee View Post
I thought of doing that with OHV engines... but there must be a reason why it hasn't been done already.
I have been reading over the last 10 years where several schemes have been tried, I don't know of anything ready for 'prime time', but you can bet the first place it would show up is in Formula 1 race engines. I once read the fast acting actuators where the key. Perhaps that wouldn't be an issue in a low rpm high FE engine application? Just think, the only limitation to your valve timing map would be mechanical interferences

edit: I found a link where this has been talked about
http://www.halfbakery.com/idea/Camless_20engine

Last edited by metromizer; 11-19-2008 at 05:33 PM..
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Old 11-20-2008, 09:37 AM   #6 (permalink)
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the idea behind the vvt on the civic vx is to keep half the intake valves closed at lower rpm, so that intake port is not being used, toyota does this by adding a butterfly valve to the intake port in the intake manifold to close off that runner, as long as your head doesn't combine the intake ports inside of the head you could retrofit this to your current engine with just a new intake manifold and there are a fair number of people out there who have made their own intake manifolds so they could add after market carburators to engines that were fuel injected, or independent throttle bodies, all kinds of stuff like that.

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