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21st February 2018, 12:26 | #11 |
Gets stuck in
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Well.. I've had the vis motor off, the one at the highest point that sits flat . And the arm inside the manifold is totality loose. Doesn't feel like its attached to anything at all.
Its completely loose and floating around inside the manifold .
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21st February 2018, 16:25 | #12 |
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As in so many other cases, you ask a question and get many varied responses!
As a good piece of advice, I suggest you pay attention to the people who have been there and done that, rather than armchair warriors giving advice from the comfort of their living rooms. You know the expression, "expert"? that is the person that have made all the errors and learned from them. But enough talk, here is some visual stuff, which normally is easier to digest. Should you be interested in some of the "science" behind it, look up my posts on the subject. https://www.youtube.com/watch?v=hPyT...eature=youtube if the manifold rattles, there is not much you can do about it, if the individual flaps, well- err flap!. Repair is possible, if you are skilled, but if I am going in there, make it simple, is always my motto. So out my flaps went, and simply put, the car went much better thereafter. But draw your own conclusions.
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21st February 2018, 20:48 | #13 | |
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Quote:
Simon
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21st February 2018, 21:03 | #14 | |
Doesn't do things by halves
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Quote:
The VIS system is designed to smooth the torque curve over the entire range of engine revs. This makes the car more relaxing and responsive to drive without having to use excessive engine speeds. This video does not address this fundamental principle. Also note that at the rev. limit the car is travelling at 103 mph. The published top speed of the 2.5 V6 automatic is 134 mph. Simon
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22nd February 2018, 09:54 | #15 | |
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Stick one of those two manifolds you have in the boot on, after as I suggested give them a good clean out with carb cleaner, then get them blew out with an air line to dry them that's quicker than letting them dry over a few days. As you know I checked the ones it the boot and they both felt nice and firm so not an hard job to change over, but remember both your Vis motors are not working. https://youtu.be/sa5jiUdAfxU Trim the flap if it is sticking https://youtu.be/gssAdwMMH0Y
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14th March 2018, 21:57 | #16 | |
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I've pulled the linkage arm back and forth on both manifolds and one feels 'free-er' but seems to not move 100% totally smoothly, the other manifold feels a bit smoother but a little heavier to shift. which one should I pick? Because how strong are the VIS motors at pulling on the arms? Do the motors have plenty of guts to them? so a little resistance wouldn't be an issue? Can I take off the bottom panel off the manifold and put some greese on the linkage? or will I encounter any problems taking it apart? ALSO.. I Think I've detached everything I need to on the old manifold, but How the *beep* do I unbolt the rear part of the manifold?
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14th March 2018, 22:09 | #17 |
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Worth his V8 in gold Last edited by kaiser; 14th March 2018 at 22:12.. |
15th March 2018, 07:33 | #18 | |
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looking at your pictures, it looks as if some of the valves were attached/working and some weren't . Did the arm still pull in and out and still feel un broken? Im worried that there might be no way of knowing if ALL the butterfly are connected to the mechanism correctly on the replacement manifold. ?
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15th March 2018, 08:21 | #19 | ||
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I'm afraid that you'll have to make that decision Gareth. We cannot possibly advise without testing the two linkages for ourselves.
Quote:
Quote:
Simon
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15th March 2018, 11:50 | #20 | |
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There must have been a reason to have it.
Quote:
If only the masters had allowed an aluminium inlet manifold. The 800 had one. From what I have read, Rover designed the KV6 on the then present F1 engine technology. The variable intake system is about getting the maximum volume of air into the cylinders at the critical time – when the inlet valves open to get the maximum power. The engineers have to seek the best torque performance over a wide rev band – especially important for road cars that operate over a wide rpm range and this is why we have a variable intake system. Cars without a variable intake manifold only have one power peak in its torque curve. Through its variable intake manifold, the KV6 has expanded its torque peaks to four – thus increasing its power torque over a good part of its rev range. A second plenum is imbedded within the inlet manifold to assist in this objective. Granted not quite a flat “power curve” but on the graph that I have seen, all four peaks are above the “single torque curve” of a non- VIS engine – naturally aspirated engines. I read that power and torque gains of up to 30% have been achieved in some engines (as much as low-boost turbocharging achieves). I guess that without a VIS system, engine designers have to make concessions that, to a point affect performance across the rev range. The engines cycle is constantly affecting the engines airflow intake as the inlet valves shut off. This pressure wave (in the intake port) then rebounds back towards the plenum, lowering the pressure in the intake port. As the piston descends, and low pressure develops in the combustion chamber, a negative wave (being below atmospheric pressure) rushes towards the inlet valves. This wave when tuned properly has the potential to ram more air into the engine and improve the power. That is if this rushing pressure wave (of air) reaches the engine at the critical time - when the inlet valves open. That is the theory of varying the intake length to match the engines requirements and pressure waves. If the incoming pressure wave “arrives” whilst the inlet valves are closed, this powerful pressure wave rebounds back up the inlet manifold towards the plenum, and the engine will only receive a portion of its potential intake. This will have a detrimental effect on the engines next cycle and those following. Development work on VIS systems showed that engines could gain more than 100% volumetric efficiencies. |
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