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The Radium King · 10-06-2012, 03:50 PM

here is a great diagram of all the chains, pads, ramps, tensioners and cams:

http://forums.pelicanparts.com/boxster-cayman-forum/685614-question-boxster-camshaft-swap-chain-tensioner.html

so, you can see, the crank drives the ims, the ims drives each bank of cams, and there is a chain tying intake and exhaust cams together on each bank. this chain has the ability to change tension at higher rpm ('variocam') resulting in an overlap between intake and exhaust - more air can flow, less back presure, more power.

*from what i understand*, the deviation values are the deviation between intake and exhaust. this is why they stay steady until 4000 rpm, at which point they change to a new fixed value as the cams 'roll over' to the new cam profile.

as per the attached diagram, what can cause an increase in this deviation is wear of the actuator pads (both items which porsche has updated) or a bad sensor. ims may affect deviation in that a wobble at the ims might introduce a vibration into the variocam assembly and register via the deviation sensor. worn tensioner paddlers, paddle pads or tensioners may also have the same effect.

the timing process in the diy referenced in the previous post, as stated by the author, does not affect the timing between intake and exhaust, but rather the timing of each bank relative to the ims, crank, and the other bank. timing the engine as per the diy should not affect deviation values. performing the timing in the diy will address timing issues caused by worn tensioners, paddle pads, tensioner paddlers or stretched chains, but doesn't address the problem causing the timing issue in the first place.

10-06-2012, 03:50 PM	#14
The Radium King Registered User Join Date: Apr 2010 Location: Canada Posts: 3,121	here is a great diagram of all the chains, pads, ramps, tensioners and cams: http://forums.pelicanparts.com/boxster-cayman-forum/685614-question-boxster-camshaft-swap-chain-tensioner.html so, you can see, the crank drives the ims, the ims drives each bank of cams, and there is a chain tying intake and exhaust cams together on each bank. this chain has the ability to change tension at higher rpm ('variocam') resulting in an overlap between intake and exhaust - more air can flow, less back presure, more power. from what i understand, the deviation values are the deviation between intake and exhaust. this is why they stay steady until 4000 rpm, at which point they change to a new fixed value as the cams 'roll over' to the new cam profile. as per the attached diagram, what can cause an increase in this deviation is wear of the actuator pads (both items which porsche has updated) or a bad sensor. ims may affect deviation in that a wobble at the ims might introduce a vibration into the variocam assembly and register via the deviation sensor. worn tensioner paddlers, paddle pads or tensioners may also have the same effect. the timing process in the diy referenced in the previous post, as stated by the author, does not affect the timing between intake and exhaust, but rather the timing of each bank relative to the ims, crank, and the other bank. timing the engine as per the diy should not affect deviation values. performing the timing in the diy will address timing issues caused by worn tensioners, paddle pads, tensioner paddlers or stretched chains, but doesn't address the problem causing the timing issue in the first place. Last edited by The Radium King; 10-07-2012 at 09:30 AM.