to engine experts: camshaft difference from left to right
08-23-2011, 08:46 AM
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Note also that a majority of European tracks are run clockwise. This leads to differing fuel entry/mixing rates at the left-right cylinder banks.
For this reason, lift and duration are altered on the left intake lobes by just a bit.
08-23-2011, 10:22 AM
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08-23-2011, 10:32 AM
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The lobes are positioned differently by more than a bit, Bruce Anderson and Wayne Dempsey talk about the differences to differentiate right from left but they don't explain why.
08-24-2011, 05:06 PM
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It's a fairly simple one to answer.
The camshafts both rotate in the same direction (anti-clockwise at the timing chain end) with the valves on the opposite sides of the camshaft centrelines. As a result the left cam opens intake valves 1-3 by wiping the follower from the bottom edge of the pad to the top, whereas the right cam opens intake valves 4-6 by wiping the rocker from the top edge of the pad to the bottom. With the exhaust valves operated in the opposite way to the intakes, the relative centrelines of the intake & exhaust camshaft lobes have to be ground at different angles to achieve the same timing on both sides of the engine.
The camshafts both rotate in the same direction (anti-clockwise at the timing chain end) with the valves on the opposite sides of the camshaft centrelines. As a result the left cam opens intake valves 1-3 by wiping the follower from the bottom edge of the pad to the top, whereas the right cam opens intake valves 4-6 by wiping the rocker from the top edge of the pad to the bottom. With the exhaust valves operated in the opposite way to the intakes, the relative centrelines of the intake & exhaust camshaft lobes have to be ground at different angles to achieve the same timing on both sides of the engine.
08-24-2011, 06:15 PM
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It's a fairly simple one to answer.
The camshafts both rotate in the same direction (anti-clockwise at the timing chain end) with the valves on the opposite sides of the camshaft centrelines. As a result the left cam opens intake valves 1-3 by wiping the follower from the bottom edge of the pad to the top, whereas the right cam opens intake valves 4-6 by wiping the rocker from the top edge of the pad to the bottom. With the exhaust valves operated in the opposite way to the intakes, the relative centrelines of the intake & exhaust camshaft lobes have to be ground at different angles to achieve the same timing on both sides of the engine.
The camshafts both rotate in the same direction (anti-clockwise at the timing chain end) with the valves on the opposite sides of the camshaft centrelines. As a result the left cam opens intake valves 1-3 by wiping the follower from the bottom edge of the pad to the top, whereas the right cam opens intake valves 4-6 by wiping the rocker from the top edge of the pad to the bottom. With the exhaust valves operated in the opposite way to the intakes, the relative centrelines of the intake & exhaust camshaft lobes have to be ground at different angles to achieve the same timing on both sides of the engine.
I have a 1989 964 motor, 1 broken head stud all stock that needs a rebuild and I'm trying to see if I can do it myself. engine ran excellent on the track pulling 249hp at rear wheels with wong chip and headers. can I rebuild with all stock parts except for rod bolts, valve springs, head work and cams in addition to motec (does it have to be the most expensive one?) and expect close to 300hp at the wheels? my 993 varioram with wong and headers is pulling 281hp at the wheels, I have a 6 speed and short gears (144mph max speed)
Appreciate your reply!
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08-25-2011, 03:36 PM
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I have a 1989 964 motor, 1 broken head stud all stock that needs a rebuild and I'm trying to see if I can do it myself. engine ran excellent on the track pulling 249hp at rear wheels with wong chip and headers. can I rebuild with all stock parts except for rod bolts, valve springs, head work and cams in addition to motec (does it have to be the most expensive one?) and expect close to 300hp at the wheels? my 993 varioram with wong and headers is pulling 281hp at the wheels, I have a 6 speed and short gears (144mph max speed)
Appreciate your reply!
Appreciate your reply!
Yes, over 300hp at the tire is achieveable with the 9m Motec M48 or M84 +1 package.
I recommend that you start with new factory pistons & late spec cylinders (flat top & gasket), fresh narrow seat valve job with new guides, port work (without going larger), a set of Ti retainers & race springs and a pair of Sport camshafts. You can use stock rods safely up to 6800-7000rpm which in any case would be well above the peak hp of the intake system/cam combination. Good headers would be nice but not essential, the stock 964 exhaust minus cat will give the numbers you are looking for.
