Drilled Crank Thoughts...
01-12-2008, 01:22 AM
#316
Three Wheelin'
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silly rules........, it'd be nice if you could just drop anything in there and have at it!!!
yes, the parts are looking good.......AND BRIGHT!!
--Russ
Last edited by largecar379; 12-14-2008 at 02:27 AM.
01-12-2008, 11:52 AM
#317
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I sure as hell hope that these guys are breaking Transmissions from doing evil-keneevil jumps over the apex curbs
The over 500ft/lbs of torque with sticky 335's on a race track had something to do with it....
02-10-2008, 12:44 AM
#318
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Jeez, not to reopen a segment of the discussion that should be long dead, but here's the deal on my two 4.7 engine failures. The first one was based on a Euro S core that Mark A. sold me. I used the rods that came with it, and matched the caps just the way you're supposed to. The engine had over 100K miles on it when I got it, so I don't think the alignment of the caps was much of an issue. It was rebearinged and reringed. The second engine was an overbore of my stock 4.5 block. NONE of the parts were brought over from the first failed engine except the heads. None. Zero.
Neither engine had an Accusump. Neither was cross drilled. Neither was taken over 6000 rpm.
The first engine was on a car with Goodyear slicks, on Portland International (which has a several rather long sweepers, three to the right, one to the left). It had about 500 miles on it before the "big" day, and was not being driven at the limit when it scattered.
The second engine failed when I was using street tires, so the side loads were considerably less than what I experienced at Portland. There were no prolonged sweepers either (Lewistown, MT, which is a point and squirt course). This engine was far stronger than the first, probably because the first was a reringed elderly block and the second was bored to fit the pistons perfectly. It, too, had been broken in on the street for several hundred miles.
The first engine ejected oil all over the place. I think this was caused by relatively unseated rings (blowby) and the unexpected consequences of the oil scraper keeping more oil in the sump. I had ejected about a quart when the engine scattered. The second engine ejected NO oil. I had added two breather hoses to the housing beneath the oil fill housing, and had routed those two and the stock breather hose into a catch can, which was found to be dry during the post mortem.
I think that Kevin's statements about the bearing caps being misaligned are just so much bullcrap. As stated above, they had been installed precisely that way for a long time. All I did was slip new bearing under them. No way to make a mistake.
The "fitting issues" I encountered with the scraper should NEVER have happened. They simply didn't fit and had to be trimmed in a number of places to make them fit. That said, I don't think it contributed to the engine failure in any substantive way, though it didn't prevent it either.
Like all of you, I wish I could get inside Kibort's engine and see why it hasn't scattered by now, too. Short of that, however, the new engine will have all the discussed methodology to protect the 2/6 rod bearings, including Chevy-drilling (in case my foot is too heavy or my tach incorrect), my improved breather to keep the oil in the case (it cost about twenty dollars and it works), a dry sump to eliminate slosh-induced cavitation and to mitigate aeration, and an Accusump to put a safety net under all of it. And I'm going to look at an MSD ignition so I can program a soft rev limiter.
And I'll drive it like I stole it.
Dave
Neither engine had an Accusump. Neither was cross drilled. Neither was taken over 6000 rpm.
The first engine was on a car with Goodyear slicks, on Portland International (which has a several rather long sweepers, three to the right, one to the left). It had about 500 miles on it before the "big" day, and was not being driven at the limit when it scattered.
The second engine failed when I was using street tires, so the side loads were considerably less than what I experienced at Portland. There were no prolonged sweepers either (Lewistown, MT, which is a point and squirt course). This engine was far stronger than the first, probably because the first was a reringed elderly block and the second was bored to fit the pistons perfectly. It, too, had been broken in on the street for several hundred miles.
The first engine ejected oil all over the place. I think this was caused by relatively unseated rings (blowby) and the unexpected consequences of the oil scraper keeping more oil in the sump. I had ejected about a quart when the engine scattered. The second engine ejected NO oil. I had added two breather hoses to the housing beneath the oil fill housing, and had routed those two and the stock breather hose into a catch can, which was found to be dry during the post mortem.
I think that Kevin's statements about the bearing caps being misaligned are just so much bullcrap. As stated above, they had been installed precisely that way for a long time. All I did was slip new bearing under them. No way to make a mistake.
The "fitting issues" I encountered with the scraper should NEVER have happened. They simply didn't fit and had to be trimmed in a number of places to make them fit. That said, I don't think it contributed to the engine failure in any substantive way, though it didn't prevent it either.
Like all of you, I wish I could get inside Kibort's engine and see why it hasn't scattered by now, too. Short of that, however, the new engine will have all the discussed methodology to protect the 2/6 rod bearings, including Chevy-drilling (in case my foot is too heavy or my tach incorrect), my improved breather to keep the oil in the case (it cost about twenty dollars and it works), a dry sump to eliminate slosh-induced cavitation and to mitigate aeration, and an Accusump to put a safety net under all of it. And I'm going to look at an MSD ignition so I can program a soft rev limiter.
And I'll drive it like I stole it.
Dave
02-10-2008, 08:58 AM
#319
Three Wheelin'
Dave, thanks for the post. This thread has been a cluster but it's great to hear about your experiences.
One thing that I wonder about is the eccentricity, or lack of, in Porsche rod bearings. I've measured them and IIRC there's no thickness change at all between the center and parting line. There must be some squeezing of the rod journal when the rod has to pull down the heavy piston at higher rpms and if the bearings are a tighter clearance in the first place, well then the bearing could pinch the journal. Whether that's a big problem or yet another detail, I don't know.
I personally like to have as much eccentricity as possible as well as more clearance than might be thought ideal. Sure the oil pressure will be low at idle but I've seen looser clearance bearings survive some tough conditions.
One thing that I wonder about is the eccentricity, or lack of, in Porsche rod bearings. I've measured them and IIRC there's no thickness change at all between the center and parting line. There must be some squeezing of the rod journal when the rod has to pull down the heavy piston at higher rpms and if the bearings are a tighter clearance in the first place, well then the bearing could pinch the journal. Whether that's a big problem or yet another detail, I don't know.
I personally like to have as much eccentricity as possible as well as more clearance than might be thought ideal. Sure the oil pressure will be low at idle but I've seen looser clearance bearings survive some tough conditions.
02-10-2008, 02:02 PM
#320
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remember, we have raced 5 engines now on the track with no issues.
the first one was the 84, with 175000miles on it and quite a bit of track and race time. then it was the 5 liter 85 bock with euro stuff, then it was the holbert car, then it was scots 4.5, which raced quite a bit, before putting the euro 4.7 (which was pulled shortly after for a headgasket not being tightened) then , his 5 liter euro motor which lasted the season as well. And, all at some of the most demanding tracks around, including Laguna, Sears and Thunderhill.
Sears and thunderhill both have 80mph "U" turn sweepers.
So, my guess it has to do with driving style, Amsoil with either its protective qualities at high temps, or anti-foaming characteristics, or all the knocking of wood i do. Ive always wondered if shift style at the upper rev levels can induce shock loads differently. Ive seen a lot of incar footage of different drivers. Its interesting the range of shift styles. some do a "speed-shift" type of timing, while others seem to bang the gears a little abruptly. I dont know if it has anything to do with it. I wonder if banging off the rev limeter can induce some of these types of forces. (which im doing more of, knowing i have a replacement engine coming
) Heck, maybe it is just a "Luck" thing! 
I bet when the holbert engine comes out, we wont see anything other than a stock S4 bottom end. I hope im wrong, as that would be cool to find a substantial design change that allows one of the hardest and most frequently raced, 928s in history, to live the longest and with all stock components.
91 race days / 6 full race seasons, and 30,000 of street driving, is certainly worth looking at closer.
Mk
the first one was the 84, with 175000miles on it and quite a bit of track and race time. then it was the 5 liter 85 bock with euro stuff, then it was the holbert car, then it was scots 4.5, which raced quite a bit, before putting the euro 4.7 (which was pulled shortly after for a headgasket not being tightened) then , his 5 liter euro motor which lasted the season as well. And, all at some of the most demanding tracks around, including Laguna, Sears and Thunderhill.
Sears and thunderhill both have 80mph "U" turn sweepers.
So, my guess it has to do with driving style, Amsoil with either its protective qualities at high temps, or anti-foaming characteristics, or all the knocking of wood i do. Ive always wondered if shift style at the upper rev levels can induce shock loads differently. Ive seen a lot of incar footage of different drivers. Its interesting the range of shift styles. some do a "speed-shift" type of timing, while others seem to bang the gears a little abruptly. I dont know if it has anything to do with it. I wonder if banging off the rev limeter can induce some of these types of forces. (which im doing more of, knowing i have a replacement engine coming
) Heck, maybe it is just a "Luck" thing! I bet when the holbert engine comes out, we wont see anything other than a stock S4 bottom end. I hope im wrong, as that would be cool to find a substantial design change that allows one of the hardest and most frequently raced, 928s in history, to live the longest and with all stock components.
91 race days / 6 full race seasons, and 30,000 of street driving, is certainly worth looking at closer.
Mk
Jeez, not to reopen a segment of the discussion that should be long dead, but here's the deal on my two 4.7 engine failures. The first one was based on a Euro S core that Mark A. sold me. I used the rods that came with it, and matched the caps just the way you're supposed to. The engine had over 100K miles on it when I got it, so I don't think the alignment of the caps was much of an issue. It was rebearinged and reringed. The second engine was an overbore of my stock 4.5 block. NONE of the parts were brought over from the first failed engine except the heads. None. Zero.
Neither engine had an Accusump. Neither was cross drilled. Neither was taken over 6000 rpm.
The first engine was on a car with Goodyear slicks, on Portland International (which has a several rather long sweepers, three to the right, one to the left). It had about 500 miles on it before the "big" day, and was not being driven at the limit when it scattered.
The second engine failed when I was using street tires, so the side loads were considerably less than what I experienced at Portland. There were no prolonged sweepers either (Lewistown, MT, which is a point and squirt course). This engine was far stronger than the first, probably because the first was a reringed elderly block and the second was bored to fit the pistons perfectly. It, too, had been broken in on the street for several hundred miles.
The first engine ejected oil all over the place. I think this was caused by relatively unseated rings (blowby) and the unexpected consequences of the oil scraper keeping more oil in the sump. I had ejected about a quart when the engine scattered. The second engine ejected NO oil. I had added two breather hoses to the housing beneath the oil fill housing, and had routed those two and the stock breather hose into a catch can, which was found to be dry during the post mortem.
I think that Kevin's statements about the bearing caps being misaligned are just so much bullcrap. As stated above, they had been installed precisely that way for a long time. All I did was slip new bearing under them. No way to make a mistake.
The "fitting issues" I encountered with the scraper should NEVER have happened. They simply didn't fit and had to be trimmed in a number of places to make them fit. That said, I don't think it contributed to the engine failure in any substantive way, though it didn't prevent it either.
Like all of you, I wish I could get inside Kibort's engine and see why it hasn't scattered by now, too. Short of that, however, the new engine will have all the discussed methodology to protect the 2/6 rod bearings, including Chevy-drilling (in case my foot is too heavy or my tach incorrect), my improved breather to keep the oil in the case (it cost about twenty dollars and it works), a dry sump to eliminate slosh-induced cavitation and to mitigate aeration, and an Accusump to put a safety net under all of it. And I'm going to look at an MSD ignition so I can program a soft rev limiter.
And I'll drive it like I stole it.
Dave
Neither engine had an Accusump. Neither was cross drilled. Neither was taken over 6000 rpm.
The first engine was on a car with Goodyear slicks, on Portland International (which has a several rather long sweepers, three to the right, one to the left). It had about 500 miles on it before the "big" day, and was not being driven at the limit when it scattered.
The second engine failed when I was using street tires, so the side loads were considerably less than what I experienced at Portland. There were no prolonged sweepers either (Lewistown, MT, which is a point and squirt course). This engine was far stronger than the first, probably because the first was a reringed elderly block and the second was bored to fit the pistons perfectly. It, too, had been broken in on the street for several hundred miles.
The first engine ejected oil all over the place. I think this was caused by relatively unseated rings (blowby) and the unexpected consequences of the oil scraper keeping more oil in the sump. I had ejected about a quart when the engine scattered. The second engine ejected NO oil. I had added two breather hoses to the housing beneath the oil fill housing, and had routed those two and the stock breather hose into a catch can, which was found to be dry during the post mortem.
I think that Kevin's statements about the bearing caps being misaligned are just so much bullcrap. As stated above, they had been installed precisely that way for a long time. All I did was slip new bearing under them. No way to make a mistake.
The "fitting issues" I encountered with the scraper should NEVER have happened. They simply didn't fit and had to be trimmed in a number of places to make them fit. That said, I don't think it contributed to the engine failure in any substantive way, though it didn't prevent it either.
Like all of you, I wish I could get inside Kibort's engine and see why it hasn't scattered by now, too. Short of that, however, the new engine will have all the discussed methodology to protect the 2/6 rod bearings, including Chevy-drilling (in case my foot is too heavy or my tach incorrect), my improved breather to keep the oil in the case (it cost about twenty dollars and it works), a dry sump to eliminate slosh-induced cavitation and to mitigate aeration, and an Accusump to put a safety net under all of it. And I'm going to look at an MSD ignition so I can program a soft rev limiter.
And I'll drive it like I stole it.
Dave
02-10-2008, 04:28 PM
#321
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If you find numbers match pair which isn't correct first thing to check is do you have two rods which has same number. If not and upper and lower half were never mixed with another rod then you have found real problem. Outside differences on cast non machined surfaces around joining surface do not mean anything.
Its obviously good to measure rods before they are installed no matter if they are used or new. AFAIK so far no one has come forward with wrong shape on matching number Porsche pair. Until you find such pair you can forget whole thing. Its not explanation to oiling problems we are seeing.
02-10-2008, 11:23 PM
#322
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02-11-2008, 05:08 AM
#324
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sitting on the sideline reading this , can someone tell how to change the odd post from being presented across the screen , requiring me to scroll left & right to read it , bloody annoying !!!!
02-11-2008, 06:11 AM
#325
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Its not a problem, its feature caused by manufacturing process. Find one Porsche rod where numbers match and measurements are off. Surely there has to be some manufacturing errors but cast or forged pieces where raw unmachined surfaces do not align 100% is not indication of anything. Casting and forging moulds wear and unmachined pieces are not exactly same size. Bolt holes can be drilled little off center but this doesn't matter as final machining is done while rod is bolted together. In finished rod all those surfaces that matter are correct. Part may not look very pretty but who cares as long as measurements are correct. Factory certainly didn't and why would they as it doesn't affect anything.
02-11-2008, 06:16 AM
#326
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Can't do anything about it. Picture width forces text width to be too wide. Only way is to resize pics to enough narrow width. Thats why there are quidelines on max size of pics allowed. Its somewhat difficult to make software which would enforce these limits. So its up to individual poster to make sure size is correct.
02-11-2008, 09:20 AM
#327
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I don't know why I'm jumping in, but...
When resizing a rod's big end, material shaved off the mating surfaces, the rod is put back together and the hole recut. Or that's how I understand it. I'd expect that's the way they are made too. It's not the outside that needs to line up, it's the inside. You "fingerprint" the rod and cap by matching the machining marks on the inside, not the outside.
The outside not lining up doesn't look good, but I don't think it matters as long as the inside lines up.
When resizing a rod's big end, material shaved off the mating surfaces, the rod is put back together and the hole recut. Or that's how I understand it. I'd expect that's the way they are made too. It's not the outside that needs to line up, it's the inside. You "fingerprint" the rod and cap by matching the machining marks on the inside, not the outside.
The outside not lining up doesn't look good, but I don't think it matters as long as the inside lines up.
02-11-2008, 09:21 AM
#328
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Anyway, prove me wrong someone. Find an example of a properly matched rod and cap with the correct dimensions as Erkka says that deviates like the one that failed in Dave's motor. Jim said he had a bunch -- ok, I will play the fool -- show me your cards. I've shown mine.
02-11-2008, 10:30 AM
#329
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I think the rod on the right is mismatched as well. Look at all of the examples. The #'s on the cap are upside down, the example on the right isn't. I think there is a chance that the exaple on the right is 161 and 191.
02-11-2008, 10:39 AM
#330
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I have access to around 50 rods. More than half of these are early style parts where surface is much more rough than in GTS period parts. Eventually I will check what I can find. Most of them are oiled and stored away. There are also many more urgent things to do in garage.