scooby_simon Posted January 30, 2005 Author Report Share Posted January 30, 2005 [ QUOTE ] Is it that theres more than one set of lobes on the cam, low and high profiles. When the car hits certain revs the cam shifts along and the higher lift lobes kick in. You have twim cams, 16vs, but 32 lobes! This is essentially two different engines in one, a beastie low down and a raving nutter up top [/ QUOTE ] Ummmm. Do we know anyone with an Exige ? Link to comment Share on other sites More sharing options...
R32North Posted January 30, 2005 Report Share Posted January 30, 2005 Mate used to own one.... owned lots of Lotus' or is it Loti !! I'll ask him! Link to comment Share on other sites More sharing options...
R32Ash Posted January 30, 2005 Report Share Posted January 30, 2005 I thought that was the Honda VTEC system though?.. not the Toyota idea? Could easily be wrong though! Link to comment Share on other sites More sharing options...
R32North Posted January 31, 2005 Report Share Posted January 31, 2005 Aye, its how the Vtec works I think but I was proposing it as a possibiity as to how the Lotus engine may work as well, eg in the same manner. Link to comment Share on other sites More sharing options...
astrosteve Posted January 31, 2005 Report Share Posted January 31, 2005 The Lotus engine is a Toyota engine, vvti works by advancing or retarding the valve timing on inlet or exhaust valves and such allowing a engine to drive "normally" under a certain rev range but to act as a "performance cam" ( higher lift, longer duration) when the revs (power) rises. Yes i think Honda were the first to use Variable Valve Timing in production vehicles. Does that make any sense? Or shall i go into Jargon mode? LOL. Link to comment Share on other sites More sharing options...
jojo Posted February 1, 2005 Report Share Posted February 1, 2005 [ QUOTE ] The Lotus engine is a Toyota engine, vvti works by advancing or retarding the valve timing on inlet or exhaust valves and such allowing a engine to drive "normally" under a certain rev range but to act as a "performance cam" ( higher lift, longer duration) when the revs (power) rises. Yes i think Honda were the first to use Variable Valve Timing in production vehicles. Does that make any sense? Or shall i go into Jargon mode? LOL. [/ QUOTE ] Makes sense to me Link to comment Share on other sites More sharing options...
Tobes49 Posted February 4, 2005 Report Share Posted February 4, 2005 Most Variable valve system only advance/retard the cam(dont change duration or lift). Rover VVC, Runs 2 inlet cams (one for cyl 1+2 another for Cyl 3+4) These have oil pressure controled eccentric end that advance/retard the inlet cam VW/AUDI uses a chain between the 2 cams and this has a tensioner unit that take slack from one side of the chain to the other to advance the inlet cam, Honda uses a camshaft with 2 different cam profiles cut into the cam and 2 followers, The mild cam is run on until the set RPM then oil pressure locks up the wild cam and it changes to the wild cam, (works on inlet and exhaust) and changes duration and lift. The new hondas have 3 stages. Toyota have just brought out a new fully variable system and never seen one so can tell you about that. Link to comment Share on other sites More sharing options...
dannymacca Posted February 4, 2005 Report Share Posted February 4, 2005 Not really too relevant to the topic but can someone explain exactly what advancing/retarding the cams is? I know the basic principle of cams operating the inlet and exhaust valves according to engine speed but im not up on what your all talking about? Link to comment Share on other sites More sharing options...
jojo Posted February 5, 2005 Report Share Posted February 5, 2005 [ QUOTE ] Not really too relevant to the topic but can someone explain exactly what advancing/retarding the cams is? I know the basic principle of cams operating the inlet and exhaust valves according to engine speed but im not up on what your all talking about? [/ QUOTE ] Basically adjusting the cams by a few degrees from the crankshaft, to allow the valves to close or open a fraction earlier to change the characteristics of the engine at different revs. Link to comment Share on other sites More sharing options...
Mutley Posted February 5, 2005 Report Share Posted February 5, 2005 A nice explanation here: http://www.autozine.org/technical_school/engine/vvt_31.htm Link to comment Share on other sites More sharing options...
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