Widows blown engine....diagnosed!!!
04-09-2011, 06:24 PM
#106
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Would be interesting to also check wether that cylinder was running any hotter than the rest ie different lambda.
I also run those cams in my engine, my engine does not go past 6600 rpm as there is no power to be had past this level , as I have flogged it mercilessly on the dyno , the torque is plummeting past this .
In all the years that I have watched the forums I have not heard of any of these engines dropping a valve .
What is the cost of the POrsche valves as opposed to the other ?
wonder where they are made ?
I also run those cams in my engine, my engine does not go past 6600 rpm as there is no power to be had past this level , as I have flogged it mercilessly on the dyno , the torque is plummeting past this .
In all the years that I have watched the forums I have not heard of any of these engines dropping a valve .
What is the cost of the POrsche valves as opposed to the other ?
wonder where they are made ?
04-09-2011, 07:26 PM
#107
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In December '08 a single 968 intake valve (928 105 641 06) from Porsche was $90.80. I don't even want to think what they are now.
04-09-2011, 10:35 PM
#111
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04-10-2011, 12:41 AM
#112
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Unless you're a 'Lemons' racer, I'd think any used motor would have to be gone through thoroughly & improvements made before putting it in the car... or you just enjoy swapping motors. Just sayin'.
GregBBRD, since you are frequenting this thread -would you please answer the PM's from the 'Virgin 1990' thread? Very much appreciated & thanks!
GregBBRD, since you are frequenting this thread -would you please answer the PM's from the 'Virgin 1990' thread? Very much appreciated & thanks!
04-10-2011, 01:25 AM
#113
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48 hours a ticking.....
04-10-2011, 02:41 AM
#114
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04-10-2011, 02:47 AM
#115
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04-10-2011, 06:09 PM
#117
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Sean did....all in Canada.....its the same engine he got 2nd place at the Euro-Asia race during the Edmonton Indy race! He also got rookie of the year up there!! I think he finished year end points in 2nd or 3rd overall too! All on the the stock S4 engine he got from Anderson.......
04-10-2011, 06:54 PM
#118
Three Wheelin'
I go on vacation and all kinds of 928 things happen, races won, engines blown up in interesting ways, damn. 
About those TRW valves, maybe they're not involved here but since it's been brought up, here's what I know. It's important since everyone that buys new valves will face this.
It looks like most all modern OEM replacement valves are from China and of poor quality. I broke one in 2009 after a little tuning time and it never saw high rpms. After looking at the pieces, it was obvious why it broke.
The triple groove design must have tight tolerances held during manufacture. If there is the smallest amount of excess clearance between the keepers and valve, rock will be allowed and that will fatigue and break. The amount of extra clearance required for that to happen is not very great. On a single groove that clamps the stem it doesn't matter but a triple groove, any play is fatigue inducing rock. Original Porsche valves with their engraved stems have amazingly close fits. The crappy valves are made with looser fits and they can't even get the groove spacing correct or even roundness and consistancy between grooves.
The crappy valves are marked TRWN and research showed a news story of a "joint venture" between TRW and a Chinese company that began with "N" in its name. I don't know if all valves are coming from the same plant but all OEM valves I've seen lateley look the same with the same machining methods. I've even seen failures in other brands where they used to race for many years with the same engines and suddenly a valve stem breaks out of the blue. Because of that case I suspect that even Japanese OEMs are now possibly buying the Chinese valves. If yo're buying replacement vlaves from NAPA or Worldpac, you're certainly getting the crappy valves with whatever name they're etching them with. It could be that there ore other plants and other countries but they all look the same to me.
About those TRW valves, maybe they're not involved here but since it's been brought up, here's what I know. It's important since everyone that buys new valves will face this.
It looks like most all modern OEM replacement valves are from China and of poor quality. I broke one in 2009 after a little tuning time and it never saw high rpms. After looking at the pieces, it was obvious why it broke.
The triple groove design must have tight tolerances held during manufacture. If there is the smallest amount of excess clearance between the keepers and valve, rock will be allowed and that will fatigue and break. The amount of extra clearance required for that to happen is not very great. On a single groove that clamps the stem it doesn't matter but a triple groove, any play is fatigue inducing rock. Original Porsche valves with their engraved stems have amazingly close fits. The crappy valves are made with looser fits and they can't even get the groove spacing correct or even roundness and consistancy between grooves.
The crappy valves are marked TRWN and research showed a news story of a "joint venture" between TRW and a Chinese company that began with "N" in its name. I don't know if all valves are coming from the same plant but all OEM valves I've seen lateley look the same with the same machining methods. I've even seen failures in other brands where they used to race for many years with the same engines and suddenly a valve stem breaks out of the blue. Because of that case I suspect that even Japanese OEMs are now possibly buying the Chinese valves. If yo're buying replacement vlaves from NAPA or Worldpac, you're certainly getting the crappy valves with whatever name they're etching them with. It could be that there ore other plants and other countries but they all look the same to me.
