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why lotus.. why

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I'll agree on the fagility front - the ones I worked on at Delphi were useless, mainly becuase of the jigs used to assemle them and amazingly NOT the assembly team. These types basically acted like a slipping clutch with a spring - the more revs the more load occured on the cam shaft wheel which retarded the cam timing and allows the inlet valve to open earlier on the intake and the exhaust likewise. Not to say all VVT systems are fragile - except the ones I worked with were :)

More components you introduce into the system the more things there are to go wrong, these were quite complex pieces of engineering which didnt help - totally dumb system as well....just relied on pure mechanics / physics.

The really interesting stuff was being shipped in when I left which was an ECU controlled system where the cam lift times etc were totally monitored and adjusted accordingly - like with injectors the result is better efficiency and fuel economy / emmissions which has to mean more power at the end of the day.

VVT's were the single think making the site money when I was there - pumps/fuel rails and so on were just being made as a sweetener to customers (hyundai/renault/ford/kia etc) to buy these products - thats about 200 people in employment and a few million squid of machinery just to get customers to look at the product.....if they didn't work that well I'd be scratching my head for reasons why they'd make such an effort over them :P

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the natural physics kind of work against you in these systems. the ones under computer control can cushion/hide the natural physical properties, but for guys working to upgrade their engines, the software has to be rewritten to suit the changes, which means up to a month in downtime in a programming/retesting loop. pet rocks didn't work and people still bought them because of frilly packaging. penis enlarger machines don't work either but there are whole industires dependant on those sales to pay their employees and feed their families.

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Yes but once again Teigan you have asserted they don't work but have made no justification of it.

Are you trying to argue that the additional weight involved in making the system is not sufficiently offset by power gains? Or some other point?

I don't care whether it works or not! I have read a very convincing argument as to why it ought to work (shifting the peak of the torque curve up the rev range) but you as yet stiill haven't offered and argued reason for your asssertions...


"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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okay. i get the message. what's being done today was available to make 15 years ago. the inventor tried to pitch the technique to all the major auto manufacturers. the test cars were vintage fords and chevys. of course it had measurable improvement in performance, otherwise why spend the money to write the patent. however the performance gain can be obtained in an infinite variety of ways, some of which are more cost effective and less calamity prone. it was evaluated and tested by the auto makers then, and even when the patent wasn't renewed ;meaning free access to the technology, the automakers didn't see fit to implement. then years later, sudden interest. makes me wonder. i bet the inventor is kicking himself for letting what he thought was a useless patent slide. but vvt is a major trend and will hamper better techniques of engine management getting developed, thanks to a consumer populace eager to jump on the vvt bandwagon. even worse, you are beta-testing their experiments for them and still getting the bill. to conclude, i wouldn't want vvt in my car unless i was assured i wasn't paying extra for it.

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penis enlarger machines don't work either but there are whole industires dependant on those sales to pay their employees and feed their families.


Damn! More money wasted.

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


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I think the point is that most of these types of technology can give benefits but are more often used to disguise poor basic design. For example, fuel injection was (and sometimes still is) touted as a great thing but, for the driver at least, it offers now gain over properly set-up carburettors and may give less power. VVT can overcome compromises in the valve timing and profiles but also saves the manufacturere the effort of finding a good compromise in the first place.

Think of all those threads where we have decried the use of computers to control steering, brakes and traction control. Yet these add-ons are all marketed as things you cannot live without. Remember those Japanese cars in the 80's which were covered in acronyms for electronic goodies like 4-wheel steering, electronic dampers and moving aerofoils and were still crap to drive when a Lotus used springs, normal dampers and carbs to give driving joy to hundreds because it was engineered properly? I think that's Teigan's point. However, VVT must do something or it wouldn't be needed for hybrids. In fact, a hybrid should not be in such need of it as a normal engine as the electric motor should give the low-speed torque.

I agree with Teigan that the end result is what you should pay your money for, not the features under the bonet that you can't feel or just deal with poor engineering.

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


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