Drilled Crank Thoughts...
02-11-2008, 11:40 AM
#331
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Its by far easiest and cheapest way to achieve correct result every time. Same system was used in engine block upper and lower halfs, 4 valve cylinder head cam bridges and in 944 block balance shaft covers for example.
Thats correct. Glyco isn't talking but that doesn't prove anything either.
Was this just marketing strategy so that 928 wouldn't step on to 911 toes or did Porsche know there is some basic design flaw in 928 engine which they couldn't fix at the time? Either because they didn't know how to fix it or it would require so large redesign that it would be cost prohitive.
I think it was you that commented about the silence that enveloped the discussion when engineers at a subcontractor to Porsche were asked about bearings (?).
Remember that Porsche actively threatened race teams that wanted to campaign the 928. The threat was that they would receive no further support at all. A powerful means to keep people quiet and/or persuade them not to continue with what they wanted to do. And it worked.
02-11-2008, 12:37 PM
#332
Possibly separate from that, the story I got whether or not true, is that the porsche bearings are the same as the glyco bearings, but they are all tested for clearance, and glyco gets the rejects that are too tight. This was an explanation by a porsche dealer parts guy of a previous point made here by greg brown about the glyco/porsche rod bearings.
02-11-2008, 12:48 PM
#333
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02-11-2008, 01:11 PM
#334
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Its called a scope and there are plenty around. I'm sure someone here would gladly lend you one if it would put this question to rest. And for the sake of full disclosure, are you sponored by Amsoil in any way?
02-11-2008, 01:14 PM
#335
Ah.
02-11-2008, 01:35 PM
#336
Road Warrior
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Its by far easiest and cheapest way to achieve correct result every time. Same system was used in engine block upper and lower halfs, 4 valve cylinder head cam bridges and in 944 block balance shaft covers for example.
Thats correct. Glyco isn't talking but that doesn't prove anything either.
Was this just marketing strategy so that 928 wouldn't step on to 911 toes or did Porsche know there is some basic design flaw in 928 engine which they couldn't fix at the time? Either because they didn't know how to fix it or it would require so large redesign that it would be cost prohitive.
Thats correct. Glyco isn't talking but that doesn't prove anything either.
Was this just marketing strategy so that 928 wouldn't step on to 911 toes or did Porsche know there is some basic design flaw in 928 engine which they couldn't fix at the time? Either because they didn't know how to fix it or it would require so large redesign that it would be cost prohitive.
good question... prolly a bit of both based on what I've gathered. also the 928 was a GT car, not a real trackster from the get go. except for the club sport version, I don't recall any other real competition 928 orinted effort by the docs in the motherland. I think the 911 is still the crowing glory, as I suspect the cayman could run circles around a gt3 if it had the same HP, which for some funny reason it doesn't...
maybe we're just all retarded for trying to make a racecar out of a cruiser when the factory clearly supports the 911 platform for racing?
02-11-2008, 03:48 PM
#337
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actually, redline is the only one appreciating my efforts. 
mk
mk
02-27-2008, 12:16 AM
#338
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Wow - how did I miss this thread??
So am I to assume my 79 track car after more than 15 years (four owners) of track use. On the original engine with no rod bearing failure...that my motor was not assembled by Gerhard "slippery hands" Wolfgang?
Or maybe my engine wasn’t assembled on a Friday?
Question for mtcarrera (might have been covered in the thread) – were you using an accusump?
Or maybe my engine wasn’t assembled on a Friday?
Question for mtcarrera (might have been covered in the thread) – were you using an accusump?
02-27-2008, 08:45 AM
#339
Three Wheelin'
What does the Maybach engine have to do with anything? That's an anomoly, those aren't counterweights on the crank but main bearing journals. The largest diameter of the crank IS the main bearing journal, it's freakishly large and makes a Buick 455 look reasonable. It must have had some unholy surface speed at the bearing.
02-29-2008, 09:41 AM
#341
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As to what the original thickness was -- I suggest looking at the 2.0 Audi engine in the 924 with the 50 degree tilt -- about 1.5mm to 2mm.
That is just silly.
02-29-2008, 09:50 AM
#342
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I guess I will be easy on you since you haven't read the whole thread. My rejoinder would be the same as that for Mark: I will be impressed with the 15 year, four-owner racing history of your wet-sumped engine when it survives one race with sustained [read consistent] 7000rpm shifts.
My shift points have always been closer to 6k than 7k.
At least you have moved the discussion away from your theory on the misaligned rod caps....
02-29-2008, 09:54 AM
#343
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I can only assume the 944 engine has the same problem, so why did they only screw up the #2 cap?
Back to the discussion!
Last edited by hacker-pschorr; 02-29-2008 at 10:28 AM. Reason: forgot stick pokey smiley :-)
02-29-2008, 10:32 AM
#344
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Kevin,
Maybe this was covered, 471 posts later a re-cap (no pun intended) might be in order.
Assuming your theory on the rod cap is on the money, what is the solution other than tearing apart a few motors to find a "perfect" set?
Maybe this was covered, 471 posts later a re-cap (no pun intended) might be in order.
Assuming your theory on the rod cap is on the money, what is the solution other than tearing apart a few motors to find a "perfect" set?
02-29-2008, 10:43 AM
#345
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Think again. Since the 1930s it has been known that aerated oil does not behave as an ideal fluid. The higher the rpms, the higher the mass separation of the physical states. That is central to a discussion on drilled cranks regardless of whether it is understood.
Wonderful. The rpm level I chose is one to surely evoke the problem with aeration in an unprepared engine. The wet-sump engine is otherwise capable of sustained 7200 rpm operation -- that is what the Dutch Stallion Team's was run at last season until the timing belt broke.
Well, there isn't much more to say -- one person that called me a fool for the theory and claimed to have many counterexamples has yet to take the effort to produce even one. I am thinking reflexivity. No?
Ordnungswahne I think it is called -- or some deviant derivation -- that matched serial numbers are sancrosanct and are a signal to turn off your brain.
Wonderful. The rpm level I chose is one to surely evoke the problem with aeration in an unprepared engine. The wet-sump engine is otherwise capable of sustained 7200 rpm operation -- that is what the Dutch Stallion Team's was run at last season until the timing belt broke.
Well, there isn't much more to say -- one person that called me a fool for the theory and claimed to have many counterexamples has yet to take the effort to produce even one. I am thinking reflexivity. No?
Ordnungswahne I think it is called -- or some deviant derivation -- that matched serial numbers are sancrosanct and are a signal to turn off your brain.
Developing a motor to shift reliably at 6-6.5k does not create the requirement of developing a motor shift reliably at 7k.