Oil Galley size question
06-07-2011, 07:14 PM
#1
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Oil Galley size question
When did Porsche increase the size of the main bearing oil galley size? does anyone know what engine castings are old style with the small galleys and which ones are new style with the larger galleys? Is running a 951 on an old block with the smaller galleys a really bad idea?
06-08-2011, 01:30 PM
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Eric,
I don’t think you find a definitive answer on this. I dug through 12 years of notes in my tool box and couldn’t find anything either. Here’s what I do know….the MY 82 & 83 motors had the smaller oil feeds to the mains. These motors also had x-drilled crank journals. Somewhere in the 83 casing process the blocks changed and went with the larger main feeds. I’ve never seen the smaller feeds on an actual MY 84 or later car but I’ve only dug that far into 2 84 motors. Since this block was installed in a 84, I think you might be okay. Also when we cleaned the block I would suspect that I would have noticed the smaller journals when I was cleaning everything out with the bore brush & compressed air. Also, if you recall when we were putting the main bearings in I was careful to point out to you the orientation of the holes in the main bearings to match the block. I suspect I would have noticed if the block holes were smaller than the bearings. That being said, I am still not positive. I also don’t think anyone will be able to tell you with a high degree of certainty if the earlier vs later blocks were stronger or weaker. I’m not sure any of us have definitive proof that the later 2.5 blocks were cast with different materials or were strengthened. Popular consensus is you shouldn’t use an pre 85 ½ for turbo applications but I believe it’s purely speculation. From all appearances, the blocks appear to be identical (outside of the oil feeds).
That being said, it seems that you were on the wrong end of either an ignorant or ambiguous seller. Here’s some observations I’ve made based on the description you received.
Original AD: Need an engine? Unassembled one FS
Freshly honed block. Ceramic coated 951 pistons with low-friction hi-tech skirt coating
The block never was advertised as a turbo or even a late model block. It was on the turbo board and advertised with 951 pistons but the seller never really said it was a turbo motor. The motor is actually from an 84 car that was cast in late 83. The interesting things is that someone knew it was NOT a turbo motor as the balance shaft covers are from a 86 turbo because of the bearing style and the turbo oil feeds. The issue with this is the covers are matched to the block and these covers have a different stamping number then the block and girdle. Maybe these were machined to match the block and the seller didn’t tell you. We won’t know until we can bolt them on and check the clearances to see if they’ll work.
Original AD:
Polished crank
At some point the crank may have been polished but based on the marring on all of the journals and the filth on the crank I do not believe it was recent. Also when I cleaned it there was a great deal of oil and debris that came out of the journals that almost resembled rubber chunks. That’s the first time I’ve seen that and why I had you send the crank out for proper polishing. The gash on the back of the crank shouldn’t be an issue and I believe I can file it down so it won’t interfere with mounting the flywheel.
Original AD:
Head has been pressure-tested, springs checked for balance, and decking has been checked. Valves received a 3-angle grind
It appears that the valves were reground and based on the receipt that a spring was replaced. At first glance I was really confused why the head was so dirty, particularly the deck. There was also a great deal of residual material from the valve seat grind as well as the typical oil coking. That’s the first time I’ve ever seen a head come back from a machine shop without at least being thrown through a decent jet wash. What really concerned me about the head is after I cleaned up the deck. I measured the head and it is .9mm’s below spec. I believe it came in @ 22.9mm’s (and should be at least 23.8) but will have to check my notes at home to be sure. That probably explains what a simple cleaning pass wasn’t done on the deck as the factory witness mark is barely visible.
I can understand your frustration at this point. A new motor build should be about anticipation of great power and reliability and not worrying how long the thing will hold together. I’ve easily bought and sold 15K plus in parts over the years here and never had an issue. Granted, I’ve been fortunate to deal with outstanding people like Ski, Rogue_Ant, blitz951, evil 944t, chilibluepepper, fast951, Landjet and a handful of other guys I trust a great deal. Unfortunately, when I purchase items I verify everything right away but since the parts were delivered about a year ago, and you didn’t really know what to look for, the inspection process did not happen and he’s didn’t specifically say it was an M44/51 block so it’s hard to dispute. I guess it really boils down to integrity. If it was one of the sellers above it wouldn’t be an issue but I’m not sure there’s much you can do at this point. We can still pull the crank to check the mains if we need to. We can talk more about it this weekend.
I don’t think you find a definitive answer on this. I dug through 12 years of notes in my tool box and couldn’t find anything either. Here’s what I do know….the MY 82 & 83 motors had the smaller oil feeds to the mains. These motors also had x-drilled crank journals. Somewhere in the 83 casing process the blocks changed and went with the larger main feeds. I’ve never seen the smaller feeds on an actual MY 84 or later car but I’ve only dug that far into 2 84 motors. Since this block was installed in a 84, I think you might be okay. Also when we cleaned the block I would suspect that I would have noticed the smaller journals when I was cleaning everything out with the bore brush & compressed air. Also, if you recall when we were putting the main bearings in I was careful to point out to you the orientation of the holes in the main bearings to match the block. I suspect I would have noticed if the block holes were smaller than the bearings. That being said, I am still not positive. I also don’t think anyone will be able to tell you with a high degree of certainty if the earlier vs later blocks were stronger or weaker. I’m not sure any of us have definitive proof that the later 2.5 blocks were cast with different materials or were strengthened. Popular consensus is you shouldn’t use an pre 85 ½ for turbo applications but I believe it’s purely speculation. From all appearances, the blocks appear to be identical (outside of the oil feeds).
That being said, it seems that you were on the wrong end of either an ignorant or ambiguous seller. Here’s some observations I’ve made based on the description you received.
Original AD: Need an engine? Unassembled one FS
Freshly honed block. Ceramic coated 951 pistons with low-friction hi-tech skirt coating
The block never was advertised as a turbo or even a late model block. It was on the turbo board and advertised with 951 pistons but the seller never really said it was a turbo motor. The motor is actually from an 84 car that was cast in late 83. The interesting things is that someone knew it was NOT a turbo motor as the balance shaft covers are from a 86 turbo because of the bearing style and the turbo oil feeds. The issue with this is the covers are matched to the block and these covers have a different stamping number then the block and girdle. Maybe these were machined to match the block and the seller didn’t tell you. We won’t know until we can bolt them on and check the clearances to see if they’ll work.
Original AD:
Polished crank
At some point the crank may have been polished but based on the marring on all of the journals and the filth on the crank I do not believe it was recent. Also when I cleaned it there was a great deal of oil and debris that came out of the journals that almost resembled rubber chunks. That’s the first time I’ve seen that and why I had you send the crank out for proper polishing. The gash on the back of the crank shouldn’t be an issue and I believe I can file it down so it won’t interfere with mounting the flywheel.
Original AD:
Head has been pressure-tested, springs checked for balance, and decking has been checked. Valves received a 3-angle grind
It appears that the valves were reground and based on the receipt that a spring was replaced. At first glance I was really confused why the head was so dirty, particularly the deck. There was also a great deal of residual material from the valve seat grind as well as the typical oil coking. That’s the first time I’ve ever seen a head come back from a machine shop without at least being thrown through a decent jet wash. What really concerned me about the head is after I cleaned up the deck. I measured the head and it is .9mm’s below spec. I believe it came in @ 22.9mm’s (and should be at least 23.8) but will have to check my notes at home to be sure. That probably explains what a simple cleaning pass wasn’t done on the deck as the factory witness mark is barely visible.
I can understand your frustration at this point. A new motor build should be about anticipation of great power and reliability and not worrying how long the thing will hold together. I’ve easily bought and sold 15K plus in parts over the years here and never had an issue. Granted, I’ve been fortunate to deal with outstanding people like Ski, Rogue_Ant, blitz951, evil 944t, chilibluepepper, fast951, Landjet and a handful of other guys I trust a great deal. Unfortunately, when I purchase items I verify everything right away but since the parts were delivered about a year ago, and you didn’t really know what to look for, the inspection process did not happen and he’s didn’t specifically say it was an M44/51 block so it’s hard to dispute. I guess it really boils down to integrity. If it was one of the sellers above it wouldn’t be an issue but I’m not sure there’s much you can do at this point. We can still pull the crank to check the mains if we need to. We can talk more about it this weekend.
06-08-2011, 07:06 PM
#3
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Thanks for the info Jeremy(and for helping me build this engine).
I am at a loss regarding how I want to proceed. The long block is all together at this point so it is frustrating to think about starting over from scratch. OTOH, I am always going to be worrying about this build. Are the oil galleys going to doom this engine to a quick failure.
I have the original block I bought for this build that I could send out to be honed and prepped. I'm just wondering if it would be easier and cheaper and faster to have this block machined for the balance shafts or if it would be easier/faster/cheaper to have the first block I bought honed. Can a machine shop machine the balance shaft areas while the engine is assembled or do we need to tear it apart? If the oil galleys are smaller AND it needs to be taken apart to be machined, I would rather just build up a proper turbo block.
I am at a loss regarding how I want to proceed. The long block is all together at this point so it is frustrating to think about starting over from scratch. OTOH, I am always going to be worrying about this build. Are the oil galleys going to doom this engine to a quick failure.
I have the original block I bought for this build that I could send out to be honed and prepped. I'm just wondering if it would be easier and cheaper and faster to have this block machined for the balance shafts or if it would be easier/faster/cheaper to have the first block I bought honed. Can a machine shop machine the balance shaft areas while the engine is assembled or do we need to tear it apart? If the oil galleys are smaller AND it needs to be taken apart to be machined, I would rather just build up a proper turbo block.
06-09-2011, 08:55 AM
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Oil galleys had 2 major changes, one in the early years (83ish) and another sometime in 87. The 87 change is not a big change but it is noticeable if you look at the blocks side by side.
Is it a big deal? Not for a street engine, and maybe not for an occasional DE. If given the choice up front I would go with the best casting you can get but since you already have the engine together I would not worry about it too much unless it’s a full track engine.
Swapping balance covers is usually a no-no – but it a couple attempts to save a n expensive block I have found that it will work sometimes. There is probably some other reason they swapped the covers – its easy enough to drill and tap covers for the turbo oil feed or to get oil from a different source.
BTW – the very early engines have different oil pump to crank seals diameters and the AOS holes are smaller.
Is it a big deal? Not for a street engine, and maybe not for an occasional DE. If given the choice up front I would go with the best casting you can get but since you already have the engine together I would not worry about it too much unless it’s a full track engine.
Swapping balance covers is usually a no-no – but it a couple attempts to save a n expensive block I have found that it will work sometimes. There is probably some other reason they swapped the covers – its easy enough to drill and tap covers for the turbo oil feed or to get oil from a different source.
BTW – the very early engines have different oil pump to crank seals diameters and the AOS holes are smaller.
