What are the original 968 camshaft specifications??
02-14-2002, 04:43 PM
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What are the original 968 camshaft specifications??
What are the oiginal 968 camshaft specifications? Valve lift, duration etc.
I have read that the Variocam retards the intake cam by 7.5 degrees between 1500rpm-5500rpm, this it correct right?
Any facts would be appreciated.
Eirik Kvello-Aune
<a href="http://www.diateam.no/porsche" target="_blank">www.diateam.no/porsche</a>
I have read that the Variocam retards the intake cam by 7.5 degrees between 1500rpm-5500rpm, this it correct right?
Any facts would be appreciated.
Eirik Kvello-Aune
<a href="http://www.diateam.no/porsche" target="_blank">www.diateam.no/porsche</a>
02-14-2002, 09:04 PM
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[quote]Originally posted by PorscheG96:
<strong>No, Variocam advances the timing 15 degrees on the intake camshaft so that there's more overlap between 1500 and 5500 RPM. I'm looking for lift and duration.</strong><hr></blockquote>If you advance the intake timing this means it will open sooner and close sooner compared to the exhaust cycle. This means there will be LESS overlap, which is what you want at lower rpm.
<strong>No, Variocam advances the timing 15 degrees on the intake camshaft so that there's more overlap between 1500 and 5500 RPM. I'm looking for lift and duration.</strong><hr></blockquote>If you advance the intake timing this means it will open sooner and close sooner compared to the exhaust cycle. This means there will be LESS overlap, which is what you want at lower rpm.
02-14-2002, 09:15 PM
#4
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Ehhh...the intake stroke is right after the exhaust stroke, so if the intake valve opens sooner its gonna be open partly at the same time as the exhaust valve...that's overlap if you ask me. 
Looks like from what I said before that there's less overlap at low RPM's [below 1500] and more between 1500 and 5500.
Looks like from what I said before that there's less overlap at low RPM's [below 1500] and more between 1500 and 5500.
02-14-2002, 09:48 PM
#5
Race Director
Take a look at the camshaft diagrams on my website to see how the cam-timing works: <a href="http://members.rennlist.com/951_racerx" target="_blank">951 RacerX website.</a>Advancing the intake makes it run into the exhaust stroke, increasing overlap.
So when is it then that the VarioCam is activated? Is it from 1500-5500rpm when there's 15-degrees advance on the intake? Or is it from idle-1500 and 5500rpm+ ? I'm trying to figure out what kind of timing I'll get if I disconnect the VarioCam signal. Thanks - danno
So when is it then that the VarioCam is activated? Is it from 1500-5500rpm when there's 15-degrees advance on the intake? Or is it from idle-1500 and 5500rpm+ ? I'm trying to figure out what kind of timing I'll get if I disconnect the VarioCam signal. Thanks - danno
02-14-2002, 09:56 PM
#6
Race Car
The intake timing is advanced between 1500 and 5500 RPM...in other words, you're getting 15 degrees overlap mostly through the midrange. Thanks for the clear-up Danno, I thought I had it right. 
02-15-2002, 01:50 AM
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[quote]Originally posted by PorscheG96:
<strong>Ehhh...the intake stroke is right after the exhaust stroke, so if the intake valve opens sooner its gonna be open partly at the same time as the exhaust valve...that's overlap if you ask me.</strong><hr></blockquote>Yeah, you are correct of course. It was late in the day and my head wasn't thinking correctly. Now that I've had a few <img src="graemlins/drink.gif" border="0" alt="[cherrsagai]" /> I can think more clearly.
<strong>Ehhh...the intake stroke is right after the exhaust stroke, so if the intake valve opens sooner its gonna be open partly at the same time as the exhaust valve...that's overlap if you ask me.</strong><hr></blockquote>Yeah, you are correct of course. It was late in the day and my head wasn't thinking correctly. Now that I've had a few <img src="graemlins/drink.gif" border="0" alt="[cherrsagai]" /> I can think more clearly.