Variocam engagement abrupt
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From: North bay area
That drove me nuts for a while (03)... It still bugs me because I'm often cruising at 3200 or thereabouts in 6th on the freeway, so I can feel it all the time. I wish I could "move" the activation point 300 RPM north !!! I'd probably never feel it then.... It's always when crusing at light throttle that it's noticeable...
Three Wheelin'
Joined: Nov 2002
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From: north vancouver
Ah - so that's what I'm feeling. New owner here and sometimes, only somtimes I get a little on-off feel. I hadn't really noted what revs I was at - I'll feel that out soon. Wasn't bothering me too much, but since a buddy of mine just had a catastrophic IMS failure in his 2003, I am hyper sensitive to every little thing!
What oil did you switch from? Or is this just a ploy to get 1999Porsche911's goat? FWIW - I'm going with 5W50 Mobil1 when I do my first oil change...soon. 
Originally Posted by UCrazyKid
normal for me too in an '02. became smoother when i switched to 5W-40 oil.
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From: North bay area
Yeah, that is why I just laid down $3400 smackaroos for a 4 years, 100K miles, 0 deductible, dealer sponsored extended warranty when mine expired last month ! Not cheap, but cheaper than a new motor someday and peace of mind until I can afford a used 997 with GT3 aerokit ;-)
I read somewhere that since variocam + uses engine oil for actuation, thicker oil like 15-50 or 20-50 was not recommended by the factory. I think 10-40 mobil one is IT... so it makes sense that 5W-40 would make it even smoother... It's an odd thing though, my previous 987 also has variocam I think and I could not feel this... I wonder if the 997 does it too !!
Another glitch of the 996 to my eyes, is the sometimes abrupt clutch operation (pressing or releasing). It's not me, I've driven nothing but clutch smoothly all my life, but now and then it feels like I am shocking the drivetrain on the 996 when I press or release the clutch pedal, a little "doink", I think it is related to the above, it might be when I release the clutch and the RPMs land on the variocam activation "rpm range". Just a guess... The car checked out everytime I mentioned this to a dealer or mechanic !
I read somewhere that since variocam + uses engine oil for actuation, thicker oil like 15-50 or 20-50 was not recommended by the factory. I think 10-40 mobil one is IT... so it makes sense that 5W-40 would make it even smoother... It's an odd thing though, my previous 987 also has variocam I think and I could not feel this... I wonder if the 997 does it too !!
Another glitch of the 996 to my eyes, is the sometimes abrupt clutch operation (pressing or releasing). It's not me, I've driven nothing but clutch smoothly all my life, but now and then it feels like I am shocking the drivetrain on the 996 when I press or release the clutch pedal, a little "doink", I think it is related to the above, it might be when I release the clutch and the RPMs land on the variocam activation "rpm range". Just a guess... The car checked out everytime I mentioned this to a dealer or mechanic !
Race Car
Joined: Apr 2004
Posts: 4,159
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From: Chicagoland
Originally Posted by jasper
Ah - so that's what I'm feeling. New owner here and sometimes, only somtimes I get a little on-off feel. I hadn't really noted what revs I was at - I'll feel that out soon. Wasn't bothering me too much, but since a buddy of mine just had a catastrophic IMS failure in his 2003, I am hyper sensitive to every little thing!
What oil did you switch from? Or is this just a ploy to get 1999Porsche911's goat? FWIW - I'm going with 5W50 Mobil1 when I do my first oil change...soon.
What oil did you switch from? Or is this just a ploy to get 1999Porsche911's goat? FWIW - I'm going with 5W50 Mobil1 when I do my first oil change...soon.
I believe he ment he switched from 0W40 to a higher viscosity. In most cases (all that I have seen) the timing change is much smoother going with a higher viscosity oil. Smoother as measured by feel and Porsche Tester by Porsche Technician plotting timing changes. I run 15W50 and cannot feel the changover and can cruise at the changover speed all day, nice and smoothly.
Banned
Joined: Jan 2004
Posts: 3,473
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From: Pacific Northwest
now is the heavier oil making things better cuz it supposedly smooths it out or is the "abruptness" , which it really is not abrupt, the natural function/design result of porsche engineering?
not sure why people are insinuating that smoother is better inthis case
not sure why people are insinuating that smoother is better inthis case
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From: MN
I'm not sure how thicker oil will smooth out the cam shift (good or bad Ben). There really isn't any magic going on. There is an on/off (not variable) switch that changes which cam lobes are used. You have two sets of lobes, a taller center as I recall with a shorter lobe on each side. You might be able to zoom in on the picture in the X51 thread and see them. I think the valves have to be being lifted by one or the other. I don't think there is an in-between.
When we put the 3.6L in my 1999 race car the computer didn't have the ability to shift the cams so we just put a switch on the dash and did it manually. Later I added an RPM switch it do it. We shifted them at 2500 which worked fine. The car runs great on the high rpm lobes except at idle.
Not sure why I wrote this. Just trivia I guess.
Jim
When we put the 3.6L in my 1999 race car the computer didn't have the ability to shift the cams so we just put a switch on the dash and did it manually. Later I added an RPM switch it do it. We shifted them at 2500 which worked fine. The car runs great on the high rpm lobes except at idle.
Not sure why I wrote this. Just trivia I guess.
Jim
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Joined: Jan 2004
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From: Pacific Northwest
The thing is, it's funny how there are similarities between VTEC and variocam (essentially same tech, no?)
except the VTEC doesn't have this "Abruptness" so it must be better - how about them apples rennlist?
except the VTEC doesn't have this "Abruptness" so it must be better - how about them apples rennlist?