View Poll Results: would you like to see the 993 and 997 style hybrid body panels (page 12, 13) copied ?
yes, would like to see lightweight copies sold by GT Racing or other vendor.
76
61.29%
sounds cool, but not interested in doing this type of update.
48
38.71%
Voters: 124. You may not vote on this poll
a few upgrades for the 968....
10-19-2012, 02:26 PM
#256
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When comparing factory belts to oem belts, I found the factory belts to be more pliable and less rigid. I wonder if these places sell are the same factory spec? My feeling is, just like tires, Porsche has it's own specification for belts which is only available thru a dealer.
I wonder if your belts would last 4-5 yrs like the factory belts. You put a lot more miles in a shorter time compared to most other 968 owners.
I wonder if your belts would last 4-5 yrs like the factory belts. You put a lot more miles in a shorter time compared to most other 968 owners.
10-19-2012, 09:52 PM
#257
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but add -- that i do something that's absolutely horrendous for belts. i often sit at truck stops and rest areas with the car idling, yapping on the phone and posting on P&C and elsewhere. not exactly good. so you can add a lot....idling is A LOT MORE abuse to these belts than normal.
10-19-2012, 10:48 PM
#258
Bannana Shine
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Is it possible that idling is harder on the belts than rapid RPM changes (blipping the throttle for downshifts, etc)? Remember, every time you rapidly change RPM, the crankshaft pulley is transferring acceleration to the belt at a 90 degree angle through the teeth, which then must transfer acceleration to the camshaft pulley or balance shaft pulleys back through the teeth again at a 90 degree angle, accelerating/decelerating the mass of the entire shaft (or in the case of the camshaft, the intake as well, via the chain) using nothing more than a few millimeters of neoprene. I'm impressed that the system even works.
I'd feel so much better if these cars just had chains.
I'd feel so much better if these cars just had chains.
10-19-2012, 10:57 PM
#259
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i could easily tack on 25~40 % more mileage on these belts due to idling.
i had 116 K miles on my original 944 S timing belt when i blew the engine up (i put 99 K miles on that car).
the engine blew (halloween 1994) due to driving it about 8 k miles with an oil leak and not checking.....
i was working long hours and commuting 1 hour and 10 minutes each morning and afternoon to a job 70 miles from Austin, TX.
i was dating this supermodel at the time and just kept forgetting to check the oel.
i had 116 K miles on my original 944 S timing belt when i blew the engine up (i put 99 K miles on that car).
the engine blew (halloween 1994) due to driving it about 8 k miles with an oil leak and not checking.....
i was working long hours and commuting 1 hour and 10 minutes each morning and afternoon to a job 70 miles from Austin, TX.
i was dating this supermodel at the time and just kept forgetting to check the oel.
10-20-2012, 05:05 PM
#261
Burning Brakes
10-20-2012, 05:28 PM
#262
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This is what happens while idling:
"Drehzahl" means "number of revolutions". "OT-Signal" is the marker for the top dead center, so every pink line marks one revolution.
"Drehzahl" means "number of revolutions". "OT-Signal" is the marker for the top dead center, so every pink line marks one revolution.
10-20-2012, 05:56 PM
#263
What's that a measurement from? If direct RPMS, then according to that, the flywheel and full rotating mass of the engine would be snapping back and forth between 825 and 865 RPMs within a split second...
10-21-2012, 01:02 AM
#265
Bannana Shine
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That graph looks drastic because you have the scale set to 820 to 870 RPM. It's varying within a range of about 25 RPM per revolution, which is about a 3% variation in speed, which doesn't seem like a terribly large load for the teeth to absorb, although it is very rapid.
10-21-2012, 06:59 PM
#266
Burning Brakes
I don't understand what that graph is trying to show. First of all, what's on the x axis? And assuming rpms are being displayed on the y axis, it shows that the rpms vary from about 824 to 864 at idle, which sounds like the typical 968 "hunt" (it's quite a bit less than the variation most of us see on the tach, actually). But when you're actually driving the car, the rpms vary from idle to redline, a range of nearly 6000 rpm. So if the thesis is that rpm variation at idle is putting significant strain on the belts, the graph demonstrates this to be false, at least from the standpoint of rpm variation. Am I missing something?
10-21-2012, 08:33 PM
#267
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belt speed variation and flutter.
i'll bet both of these trail off rapidly past 2,000 rpm.
then there's the 968 lawn mower effect added to bad motor mounts.... i'd be willing to wage
that my bad motor mounts aren't helping in my efforts to be stingy (by not doing anything
for the oem motor) before installing the V8.
i'll bet both of these trail off rapidly past 2,000 rpm.
then there's the 968 lawn mower effect added to bad motor mounts.... i'd be willing to wage
that my bad motor mounts aren't helping in my efforts to be stingy (by not doing anything
for the oem motor) before installing the V8.
10-22-2012, 07:15 AM
#268
Again, what is it a measurement *from*? I know what it is claimed to be a measurement *of*, but it looks like a handheld tach was put on one of the idlers or something else that spins about 70 times between the pink peaks.
