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why lotus.. why


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As I hear lotus is working on completely replacing the camshaft with electrical actuators as well :D

slade

"It's called a fire hydrant. Firemen like to stick their hose in it, and eventually squirt water from it."

Owner of 86 TE HCI, and 55 Chevy. Stare at broken down TR7

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Another rumour was that the Lotus V8 was designed to allow VVT. Obviously they didn't bother given the basic one had to be detuned anyway!

Neal

May: DON'T hit it with a hammer!

Clarkson: Why?

May: Cause it's the tool of a pikey.

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Guest teigan

VVT is just a transition technology that makes hybrid fuel vehicles possible without power fluctuations. all automakers were forced to start experimenting with it and practice for the future when it will be a necessity, not an option. stupid consumers are being fooled by the marketting departments who sell VVT as a feature or improvement. we shouldn't even be having this discussion as it just shows our ignorance as a public.

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Another rumour was that the Lotus V8 was designed to allow VVT.  Obviously they didn't bother given the basic one had to be detuned anyway!

Neal

<{POST_SNAPBACK}>

How was it detuned?

'03.5 Final Edition Esprit ~ 5.7lbs/hp

mildly modded - 430rwhp, 353rwtq

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VVT is just a transition technology that makes hybrid fuel vehicles possible without power fluctuations.  all automakers were forced to start experimenting with it and practice for the future when it will be a necessity, not an option.  stupid consumers are being fooled by the marketting departments who sell VVT as a feature or improvement.  we shouldn't even be having this discussion as it just shows our ignorance as a public.

<{POST_SNAPBACK}>

Then I'm as ignorant as pudding. I thought varable valve timing originally came into the market so an old engne design, from Alfa Romeo, could meet emissions laws while still giving decent performance. Then Honda used it to give reletively decent torque and big specific power and BMW did the same. Then BMW took things a step further to use the valves as the throttles for improved economy.

Having said all that, the turbo Esprits have enought torque and enough power to not really need VVT. As turbo engines have low copression ratios emissions should not be too bad so why add the complication?

S4 Elan, Elan +2S, Federal-spec, World Championship Edition S2 Esprit #42, S1 Elise, Excel SE

 

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VVT was actually invented here in america, in a hobby garage. the guy was experimenting with his old chevys and thought it was interesting, although there were drawbacks. it sat dormant for about 15 years, and the patent was never renewed. all the auto makers knew about it, and there really wasn't a reason to go to it, until recently when many governments insisted on companies developing hybrid vehicles. suddenly it's a feature. they determined long ago that the performance gains were not signifigant in themselves. nothing has improved today from the original experiments. there is just more incentive to learn it.

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Which goverments insisted on the development of hybrids?

<{POST_SNAPBACK}>

in our country it was more of a condition for continued subsidies and in some cases bail out money. japan actually set a deadline for every carmaker to have a hybrid in their line. i'll have to check on other countries, but i know the scandanavians are intent on electrics and hybrids. volvo and saab both have shown hybrid prototypes.

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What a load of old twaddle. VVT = Hybrid??? Where did that one come from??

Have you ever designed/built/worked on an engine?

Have you ever researched into cam profiles? Know anything about valve timing overlap and the reasons for it? or ever tried varying cam timings using vernier cam pulleys to see how the characteristics of an engine change, from low down torque to high end power and the compromises that have to be made to acheive an overall balance??

It is my opinion that wherever you got this information from Teigan, next time take it with a very big pinch of salt.

Yes it does improve emissions as it allows engines to be more efficient during a much greater spread of its operating speeds, yes it does improve performance and fuel consumption, it comes in various forms, from simple mechanical systems to much more highly advanced electronically controlled systems which constantly alter the settings depending on what is required of the engine at any one time.

Like many other technologies in the motor industries, these systems take time to research, develop, test and implement on a mass scale and within the budgets available at any given time.

Also if VVT technlogy is only government and emissions driven......... Why is it being used in motorsport???

Im sure Mr Schumacher would rather he had good old fashioned fixed timing and save the weight of all those complex and heavier bits and bobs that make up his VVT system.

Or has he been sold a load off bull and is obviously as stupid and ignorant as the rest of us???? :D:lol:

p.s. Isnt discussion what this forum is all about?? :lol::):( :( <_<

Edited by Simon350S

Chunky Lover

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you make it sound as if i'm calling it a government conspiracy. if you read carefully i'm calling it a marketing ploy that the public has fallen for. nobody likes to admit they are a victim, which may explain your disgust, but i'm just stating the facts. and yes i design/build/engineer stock cars as a hobby, so i'm not giving you second hand information. trying to discredit the messenger is very desperate rhetoric indeed. it's a logical fallacy inflicted by yourself on yourself. just admit you've been duped by the marketing machine and move on.

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you make it sound as if i'm calling it a government conspiracy.  if you read carefully i'm calling it a marketing ploy that the public has fallen for.  nobody likes to admit they are a victim, which may explain your disgust, but i'm just stating the facts.  and yes i design/build/engineer stock cars as a hobby, so i'm not giving you second hand information.  trying to discredit the messenger is very desperate rhetoric indeed.  it's a logical fallacy inflicted by yourself on yourself.  just admit you've been duped by the marketing machine and move on.

<{POST_SNAPBACK}>

:D Altering cam profiles alter/shifts power curves and affects emissions as well. So how is this a marketing poly?

'03.5 Final Edition Esprit ~ 5.7lbs/hp

mildly modded - 430rwhp, 353rwtq

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because the manufacturers are experimenting on you, and thier advertising/marketing department is successfully selling the experiment as an added value or feature. if you read carefully there's nothing dependant in my message about emissions. i don't read any car magazines[full of adverts and conflict of interest], which is the reason i have a better perspective than most. i'm not trying to sound less dumb than you. in fact i swapped my brain for two twiglets and a sheena easton record back in the eighties. i can't remember why. so lets not let this deteriorate into small men correcting eachother's spelling and grammar in a sad attempt to save face.

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What???

Prior to my Esprit I came from the world of kit cars, unsurprisingly a replica Lotus 7. Fitted with a good old fashioned Fiat/Lancia 2l twin cam.

Obviously tuning raised its never ending head and I learnt a great lot about the basics of 4 stroke engines. None of this pissing around with battling the ECM!

Basically once you've optimised an engine for maximum volumetric efficiency, the only way to get more power (short of enlarging the volume or forced induction) is to shift the torque higher in the rev range.

I think I've posted this link before, and it is heavy going, but worthwhile:

http://www.seight.com/torque.html

For those who can't be arsed, the jist is lbft mean nothing. What makes a car fast is lbft at high rpm.

Which bring us neatly around to VVT. It's the camshafts which actuate the valves and hence have an direct bearing on the lbft curve. But it's a one way street. For a fixed camshaft you can have lots of torque in the midrange, less bhp, but very drivable. Or lots of torque in the high range, plently of bhp but it's like a damp squib in the midrange so you have to rev the nuts off it.

VVT gives you the best of both worlds. Low-mid rpm and the camshaft is 'moved' further from the valves. Hence less lift and duration - ideal for maximising the torque in such conditions. But once you gun it with high rpm the camshaft is shifted closer to maximise the lift and duration. Hence you get the maximum torque at high rpm too, which means more bhp...

Neal

May: DON'T hit it with a hammer!

Clarkson: Why?

May: Cause it's the tool of a pikey.

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Like Neal, I enjoyed those days too, changing cams; stock, mild, hot street, track, full race, etc etc ad infinitem. Those wilder cams, when pottering around the pits, stank so much due to unburnt fuel passing through the exhaust they'd blow an emissions test in the next state.

In the early days of emission control we had pretty crude systems of retarded ignitions, recirculating exhaust gases, major changes to cam profiles and lobe angles, carbs (an old device where a container of fuel leaked it slowly into the engine) leaned off so much the exhaust colour was grey and what most people didn't like a serious drop in power.

Then came electronic fuel injection and the engineers found better control over meeting those mandated emission requirements. A bit of the old power was restored. The manufacturers then accelerated engine development with multiple valves, lower component drag, optimum bore:stroke ratios and VVT. Some VVTs simply rotating the cams and changing the centre lobe angles but not the "grind" but others like Honda and BM really delivering the goods.

Emissions met and power not just restored but exceeded. Honda's normally aspirated S2000 has 120bhp/litre! Its a reliable, emission clean, everyday car with a power spec racers 30 years ago would have cut their right arm off for.

These are exciting days for the internal combustion engine. I doubt its in its final hooray even though hybrids, fuel cells, etc are coming.

DanR

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I think you need to snap back to reality Teigan. Your comments are not just annoying but also rather insulting.

Everything else that has been posted here is of a constructive nature and very informative to those that may be interested. If you're just here to be rude i would rather you didn't comment in the first place.

People are on here for help and advice and friendly chat, not to be insulted.

Chunky Lover

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my comments are neutral. if you are insulted, then that is a reflection of yourself. and contrary to popular belief, i get no entertainment from seeing people angry. in fact it is an inconvenience having to decifer what the emotionally charged person is actually trying to communicate. if you find me one mass produced hybrid vehicle that doesn't rely on vvt to operate, i'll apologise. otherwise your only gripe with me is that you see me as a pompous ass. this could be viewed as discrimination against a minority group. we have to use special toilets you know.

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OK Teigan... I've only just come in on this thread and am utterly un-offended one way or the other. However, at no point in this thread have you actually posited any form of actual logical argument as to WHY VVT is a white elephant...

You have said much about why it's some form of marketing coup etc - I don't care one way or the other - there's no Vic20 in my car :P

However you have made no mechanical / engineering justification as to why VVT DOESNT provide the goods whereas there HAS been some what to me seem well reasoned and argued explanations of why VVT WOULD do what it says on the tin. (Eg Torque / RPM etc)

So..... WHY doesn't it do it? ...and NOT because they need them for hybrid cars - that's utterly irrelevant.

Why doesnt VVT offer more power?

"When I was a kid I used to pray every night for a new bicycle. Then I realised that the Lord doesn't work that way so I stole one and asked him to forgive me."

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I think what Teigan is saying is that companies were forced into using VVT systems in order to comply with emmision and fuel regulations in sort of the same way as carbs were replaced using fuel injectors but have marketed it as a 'new' feature and at an increased cost to the customer when really it was inevitable they had to utilise the technology - as with injectors.

I think I'm right in saying my mates FTO was sold with this (called a MIVEC) as an upgrade in comparison to the standard direct drive camshaft variant engine in the different model of the same car. Fine, technically this is an upgrade as the MIVEC chuffs out more power as the engine can react and adjust the cam timing (similar way as an engine ECU adjust the injectors).

I'm not an expert, not disagreeing with anyone - simply trying to help prevent an argument :P

VVT was also used in early aircraft design way back when piston engines were used to experiment with prop driven aircrafts's performance at high and low level altitudes (always a problem esp with warplanes), was hoped this would replace and overcome the power losses by using superchargers but wasn't overly employed if I remember correctly - possibly due to the added number of parts and complexity.

I used to build these when I worked for Delphi Diesel systems :P

Sadly an even worse place to work than where I am now ! :)

facebook = jon.himself@hotmail.co.uk

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Thats not the point

I dont care less whether they felt forced or compelled to introduce VVT

Teigan has argued that its crap / doesnt DO what it is reported to

I am asking him to justify that claim

PS Likewise - who cares if ppl have an argument about this - it's a public debate thats the point :P

"When I was a kid I used to pray every night for a new bicycle. Then I realised that the Lord doesn't work that way so I stole one and asked him to forgive me."

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i get cars donated by sponsors, and many of them today have vvt whether i want it or not. the problem is that the vvt kicks in and out at a predictable but not always convenient time. a driver must completely change his driving style and cannot alter his driving style for specific conditions. my biggest complaint about vvt is the increased size/weight/fragility. i've broken a lot of these just in testing and the cars went to the crusher. i haven't been lucky enough to play with the bmw system as someone has rought up already. that has a smooth vvt curve instead of an on/off. i'm presuming with the right software, that could be tweaked to be almost undetectable. it isn't logical to say vvt is a proven performance product because it is used in pro racing. these guys are heavily sponsored, and they'll use what the sponsors tell them to. there is a huge conflict of interest when you ask the people involved if they like the technologies. conversely, i sometimes get in colossal trouble for stating the obvious. while the people i'm trying to help are under a emperor's new vvt syndrome, and prefer to trust the car magazines who are entirely dependant upon advertising money and freebies from the automakers.

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I think you'll find that there's SO much money in F1 that they are all there purely to win because of it!

...and Who sponsors Ferrari that would have a vested interest in pushing VVT? I shall ask my friend as an F1 insider who has worked both for Ferrari building F1 engines in Italy and now has been head hunted by Williams (I SO want to marry this girl!)

"When I was a kid I used to pray every night for a new bicycle. Then I realised that the Lord doesn't work that way so I stole one and asked him to forgive me."

------------------------------

ribbon200.gifG-Car Owner and Proud! ribbon200.gif

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