Do 928's have matching numbers?
01-05-2007, 04:58 AM
#16
928 Barrister
Rennlist Member
Rennlist Member
The 911s are different if I recall correctly. My 914/6 has a specific engine case number unique to that car and that model. An original six engine case is worth more and the original numbered case matched the car. This should be listed on the cardex which is available from the factory. What was done with 928s is beyond me and, hey.....I couldn't care less. But my original six....now that's another story. Unfortunately, for me, some Jerk hotrodder PO installed a 2.7L POS CIS 911 engine in my six and I searched all over the place for the original case, but couldn't find it. 
Then I blew up another original six case. Now I have another original six case based 2.0L engine, but it is never going to match the car. More But that original six case/engine will likely never see more than the 600 or so miles that are on it now, despite what is REALLY inside of it and invisible. 
Then I blew up another original six case. Now I have another original six case based 2.0L engine, but it is never going to match the car. More But that original six case/engine will likely never see more than the 600 or so miles that are on it now, despite what is REALLY inside of it and invisible.
01-05-2007, 12:20 PM
#17
Addict
Rennlist Member
Rennlist Member
VIN, engine, gearbox etc numbering is interesting mess. Nothing which points to which body some part went doesn't exists unless factory has secret list what they are not sharing even in build sheets bought from them. This doesn't mean its not possible to say what engine belongs to a car with pretty good certainty. There are several clues in all major parts which can be used to determine this.
VIN is sort of easy. ROW bodies have ZZZ VIN on top of fender or shorter old style number close to plus terminal in engine bay depending on MY.
US model ZZZ VIN in same location as ROW. What I'm not absolutely sure is if 13th digit in US car fender is same as in ROW or US model. If 13th on ZZZ VIN in fender is same as in plate under window it means its possible to tell if body is ROW or US model even though rest of the VIN is same ZZZ as in ROWs. This would be interesting to know. In case US fender VIN is same as window it means factory didn't want to stamp check digit and safety equpment info into wing for some reason while they actually knew from the star where body was heading. If this is the case reason might be digits 4 through 6 in US VIN as they tell what kind of seatbelts and possible airbags were installed. Factory might have wanted to deside this only at last moment on production line and thus only include this info in window plate.
Old US models have similar short chassis number ar early ROW car except there is one digit change to tells the marked body was meant for.
Some late model ROWs do have this piece under window also. This is somewhat worrysome even as in some countries its possible to get owners name, address etc. details from DMV with VIN. So owner isn't totappy protected even when plates are removed in car shows for example.
Third place for VIN in US model is build month sticker at the door. This is stricly for cosumer protection as its easy to see from sticker how long ago new car was made. This makes selling over year model more difficult. In ROW markets consumer had very little possibility to see how long some car had stayed in warehouse before it was registered. I suspect this to be reason why sometimes even printed information contains mistakes like '92 MY S4 etc. Car was registered in '92 calendar year and owner consideres it to be '92 car while it could have been made years ago.
Both ROW and US cars should have build sticker in drunk and/or service book dince '81 MY IIRR. It lists VIN, engine and gearbox type plus options. In some cases some or virtually all options are missing from the list.
In '80-82 MY ROW cars VIN also tells if car is 4.5L or S model. This and '88 MY ROW Club Sport is only models where VIN tells more than model year, market for which car was build for and its serial number within sequence of cars build for that market during that MY. In all other models, it's build sticker which really says what engine and gearbox type available during that MY car was made with.
Sticker engine type should match whats in engine bay. In row '86 S 32V case also option code will tell if car has 32V engine same way as it does say in '88-89 Club Sport, '88 SE and '89 GT that stronger than standard engine option was selected. Unfortunately sticker doesn't say actual engine serial number or at least none i have ever heard of says it. So there isn't sure way of saying if particular engine was installed in production line or not if engine serial happens to be close enough to the original.
In engine block there is at least four different numbers which can be used to give some glue what it is. Engine number on top of block is obvious. It contains type number, MY and serial number within that type and MY. Type number in turn tells always if engine is meant for automatic or manual gearbox. In many cases if engine is replaced under warranty replacement engine has automatic type even though car its installed is manual. This is especially good indicator if GTS engine is correct one as so many were changed under warranty.
Engine model year must match to VIN model year for it to be original. There can be two exceptions for this. Those early '93 MY US GTS and early '94 MY US GTS with option code 718 that are in reality previous MY models might have '92 and '93 engine codes and still be original. I think its likely that factory didn't change engine and gearbox codes for these cars.
Engines sequence number should also be in the zone for it to be realistic. If cars VIN is early its impossible for it to have high sequance number within that MY. Doesn't make sense. This doesn't mean sequence number follows VIN sequence. If they are same its virtually real jackpot in lottery as there were many more engines made than bodies. I suspect also that there were at least few different ways of numbering engines used in different MY's. In some years it seems those meant for manual cars got numbers 0001-4999 and those meant for automatics got 5000-9999 IIRR. This doesn't mean all 5000 for each types were made. In reality there were only maybe 3000 at most done for one engine type in best years in mid eigties. Some years can have sequences where both automatic and manual engines shared single sequence even though type number was different. Its hard to say for sure as factory documentation is so messed up.
One way of telling if stamped number is correct or not is to look how block looks like where its been stamped. In early blocks area was raw unmachined casting which is very difficult to replicate afterwards. So if early '78 MY car has wrong block this will almost definitelly give it away even though number is changed and looks ok. I don't know when factory started to machine this part of the block but suspect it to be when S models arrived and required new casting moulds. There might be intermediate years in '80-82 MY when both versions were done side by side.
In later MY block machining is done in a way that its possible to see if numbers are stamped on top of factory finish or not. Or at least factory machining is difficult to replicate without machining entire top of the block in one pass as direction machining is done leaves marks to top surface. These lines should curve into same direction at entire block top and number stamping area must be at exact same height as other parts of top of block. Reason why early blocks have this raw casting is that stamping area is lower down than top of the block IIRR.
Besides actual engine number, block also has casting number at front end on passanger side. It must make sense compared to stamped number on top. If not, there is obviously something wrong. Some early S4 can be different as there has been reports of older style 32V blocks being used in them. This must mean only first few jundred blocks as those early S4 engine I have seen weren't these while they did have piston oil squirters for example. Casting number is virtually impossible to see under cam gear and covers so its difficult to use to determine if block is genuine or not unless enough stuff is removed out of the way.
During block manufacture upper and lower half is stamped as they must not be mixed between blocks. To prevent this factory put stamp on both halfs close to oil filter location. At first this was running three number series and letter X. In early eighties it was changed to four running numbers. Halves must obviously match each other but there is other way of using this number also. Since its running, it means next higher number was assigned to next block which went through part of the manufaturing process where number was stamped until number 9999, after which sequence started over. This was early on in production before it was know what exacly engine would become. Presuming factory used one single sequence to all blocks they did this means that in theory at least its possible to say when blocks was basic machining was done if there is enough information about these numbers and how they relate to other numbers in block. When there is enough information about these it can be determined if info is good or not. This could be especially useful in determing if someone tries to make earlier block look like GTS block. So few late blocks were made that number is only little over 1/4 of the one round of sequence. If all GTS blocks have this number in 2500 to 6000 range for example I think its unlikely that questionable block with number 9000 would actually be GTS block even though stamping on top would indicate this. There are other ways of telling if block is GTS or not but this is probably easiest without dismantling bellhousing. That is of course if such half number range can be identified.
Other good point in block half numbering is that I think all numbers are stamped directly to raw casting surface like in early MY engines. If surface looks different than raw casting around it, number isn't likely original. Would need to more data than about dozen blocks to be able to say for sure if this is the case.
Fourth point which can say if engine is original for the car is block casting week which is inside bellhousing behind flywheel little above crank. It should obviosly be realistic. Block can't be younger than when car was made according to door sticker. Casting week do not have to be inside those weeks when cars were made for particular MY but I would expect it to be at least somewhere close and would be suspicious and check other numbers more carefully if block week is more than few years older than month when car was put together.
Gearbox type, year and sequence within that year is stamped to casing in similar way as engine type on top of engine. Its type must also match build sticker as does MY. 12 for LSD after gearbox type in '78-89 MY should correspond to 220 in option sticker. Sequence do not match VIN sequence any more often than engine number. It seems area where number is stamped was left raw casting in early boxes but machined to be little more level surface in later years. If surface looks machined it doesn't mean number is changed unless box is early one and it can be determined when factory changed their style on stamping them.
Other number in gearbox casing is casting week. It should match rest of the car same way as engine casting week. Possibly similar rules of only few years older casting week than stamped number of completion month is acceptable without more close study.
All of the above should obviously match to each other and what car is like. If VIN says car is '78 MY there really shouldn't be GTS rear bumber in it if its sold as totally original.
All features up to details like simple buttons in dash can be traced to certain MY range and fully original car shouldn't have anything which doesn't fit the profile. To most owners it doesn't matter one bit if some casting is original or not as long as it works. But I for example would check them all if I was buying any 928 stricly for investment. One with all numbers in the zone is according to unwritten rules of collector car market much more valuable than one where they don't match.
Hope above clear some of the mysteries of 928 body and part stampings.
VIN is sort of easy. ROW bodies have ZZZ VIN on top of fender or shorter old style number close to plus terminal in engine bay depending on MY.
US model ZZZ VIN in same location as ROW. What I'm not absolutely sure is if 13th digit in US car fender is same as in ROW or US model. If 13th on ZZZ VIN in fender is same as in plate under window it means its possible to tell if body is ROW or US model even though rest of the VIN is same ZZZ as in ROWs. This would be interesting to know. In case US fender VIN is same as window it means factory didn't want to stamp check digit and safety equpment info into wing for some reason while they actually knew from the star where body was heading. If this is the case reason might be digits 4 through 6 in US VIN as they tell what kind of seatbelts and possible airbags were installed. Factory might have wanted to deside this only at last moment on production line and thus only include this info in window plate.
Old US models have similar short chassis number ar early ROW car except there is one digit change to tells the marked body was meant for.
Some late model ROWs do have this piece under window also. This is somewhat worrysome even as in some countries its possible to get owners name, address etc. details from DMV with VIN. So owner isn't totappy protected even when plates are removed in car shows for example.
Third place for VIN in US model is build month sticker at the door. This is stricly for cosumer protection as its easy to see from sticker how long ago new car was made. This makes selling over year model more difficult. In ROW markets consumer had very little possibility to see how long some car had stayed in warehouse before it was registered. I suspect this to be reason why sometimes even printed information contains mistakes like '92 MY S4 etc. Car was registered in '92 calendar year and owner consideres it to be '92 car while it could have been made years ago.
Both ROW and US cars should have build sticker in drunk and/or service book dince '81 MY IIRR. It lists VIN, engine and gearbox type plus options. In some cases some or virtually all options are missing from the list.
In '80-82 MY ROW cars VIN also tells if car is 4.5L or S model. This and '88 MY ROW Club Sport is only models where VIN tells more than model year, market for which car was build for and its serial number within sequence of cars build for that market during that MY. In all other models, it's build sticker which really says what engine and gearbox type available during that MY car was made with.
Sticker engine type should match whats in engine bay. In row '86 S 32V case also option code will tell if car has 32V engine same way as it does say in '88-89 Club Sport, '88 SE and '89 GT that stronger than standard engine option was selected. Unfortunately sticker doesn't say actual engine serial number or at least none i have ever heard of says it. So there isn't sure way of saying if particular engine was installed in production line or not if engine serial happens to be close enough to the original.
In engine block there is at least four different numbers which can be used to give some glue what it is. Engine number on top of block is obvious. It contains type number, MY and serial number within that type and MY. Type number in turn tells always if engine is meant for automatic or manual gearbox. In many cases if engine is replaced under warranty replacement engine has automatic type even though car its installed is manual. This is especially good indicator if GTS engine is correct one as so many were changed under warranty.
Engine model year must match to VIN model year for it to be original. There can be two exceptions for this. Those early '93 MY US GTS and early '94 MY US GTS with option code 718 that are in reality previous MY models might have '92 and '93 engine codes and still be original. I think its likely that factory didn't change engine and gearbox codes for these cars.
Engines sequence number should also be in the zone for it to be realistic. If cars VIN is early its impossible for it to have high sequance number within that MY. Doesn't make sense. This doesn't mean sequence number follows VIN sequence. If they are same its virtually real jackpot in lottery as there were many more engines made than bodies. I suspect also that there were at least few different ways of numbering engines used in different MY's. In some years it seems those meant for manual cars got numbers 0001-4999 and those meant for automatics got 5000-9999 IIRR. This doesn't mean all 5000 for each types were made. In reality there were only maybe 3000 at most done for one engine type in best years in mid eigties. Some years can have sequences where both automatic and manual engines shared single sequence even though type number was different. Its hard to say for sure as factory documentation is so messed up.
One way of telling if stamped number is correct or not is to look how block looks like where its been stamped. In early blocks area was raw unmachined casting which is very difficult to replicate afterwards. So if early '78 MY car has wrong block this will almost definitelly give it away even though number is changed and looks ok. I don't know when factory started to machine this part of the block but suspect it to be when S models arrived and required new casting moulds. There might be intermediate years in '80-82 MY when both versions were done side by side.
In later MY block machining is done in a way that its possible to see if numbers are stamped on top of factory finish or not. Or at least factory machining is difficult to replicate without machining entire top of the block in one pass as direction machining is done leaves marks to top surface. These lines should curve into same direction at entire block top and number stamping area must be at exact same height as other parts of top of block. Reason why early blocks have this raw casting is that stamping area is lower down than top of the block IIRR.
Besides actual engine number, block also has casting number at front end on passanger side. It must make sense compared to stamped number on top. If not, there is obviously something wrong. Some early S4 can be different as there has been reports of older style 32V blocks being used in them. This must mean only first few jundred blocks as those early S4 engine I have seen weren't these while they did have piston oil squirters for example. Casting number is virtually impossible to see under cam gear and covers so its difficult to use to determine if block is genuine or not unless enough stuff is removed out of the way.
During block manufacture upper and lower half is stamped as they must not be mixed between blocks. To prevent this factory put stamp on both halfs close to oil filter location. At first this was running three number series and letter X. In early eighties it was changed to four running numbers. Halves must obviously match each other but there is other way of using this number also. Since its running, it means next higher number was assigned to next block which went through part of the manufaturing process where number was stamped until number 9999, after which sequence started over. This was early on in production before it was know what exacly engine would become. Presuming factory used one single sequence to all blocks they did this means that in theory at least its possible to say when blocks was basic machining was done if there is enough information about these numbers and how they relate to other numbers in block. When there is enough information about these it can be determined if info is good or not. This could be especially useful in determing if someone tries to make earlier block look like GTS block. So few late blocks were made that number is only little over 1/4 of the one round of sequence. If all GTS blocks have this number in 2500 to 6000 range for example I think its unlikely that questionable block with number 9000 would actually be GTS block even though stamping on top would indicate this. There are other ways of telling if block is GTS or not but this is probably easiest without dismantling bellhousing. That is of course if such half number range can be identified.
Other good point in block half numbering is that I think all numbers are stamped directly to raw casting surface like in early MY engines. If surface looks different than raw casting around it, number isn't likely original. Would need to more data than about dozen blocks to be able to say for sure if this is the case.
Fourth point which can say if engine is original for the car is block casting week which is inside bellhousing behind flywheel little above crank. It should obviosly be realistic. Block can't be younger than when car was made according to door sticker. Casting week do not have to be inside those weeks when cars were made for particular MY but I would expect it to be at least somewhere close and would be suspicious and check other numbers more carefully if block week is more than few years older than month when car was put together.
Gearbox type, year and sequence within that year is stamped to casing in similar way as engine type on top of engine. Its type must also match build sticker as does MY. 12 for LSD after gearbox type in '78-89 MY should correspond to 220 in option sticker. Sequence do not match VIN sequence any more often than engine number. It seems area where number is stamped was left raw casting in early boxes but machined to be little more level surface in later years. If surface looks machined it doesn't mean number is changed unless box is early one and it can be determined when factory changed their style on stamping them.
Other number in gearbox casing is casting week. It should match rest of the car same way as engine casting week. Possibly similar rules of only few years older casting week than stamped number of completion month is acceptable without more close study.
All of the above should obviously match to each other and what car is like. If VIN says car is '78 MY there really shouldn't be GTS rear bumber in it if its sold as totally original.
All features up to details like simple buttons in dash can be traced to certain MY range and fully original car shouldn't have anything which doesn't fit the profile. To most owners it doesn't matter one bit if some casting is original or not as long as it works. But I for example would check them all if I was buying any 928 stricly for investment. One with all numbers in the zone is according to unwritten rules of collector car market much more valuable than one where they don't match.Hope above clear some of the mysteries of 928 body and part stampings.
01-05-2007, 10:31 PM
#18
Instructor
Fantastic reading. Thanks for your Knowledge. Now I've learnt some more.
Cheers,
Glenn
'81 928
VIN WPOZZZ92ZBS800579
Engine # 8015318
Model 927501 928 RHD
Delivered Australia N.S.W (C23) (73 in total) 10/November/1981
Built 01/May/1981
1st Registered January 1982 ( I also know who to)
Opions 249,261,282,418,423,650
Exterior R4R4
Interior DX
Cheers,
Glenn
'81 928
VIN WPOZZZ92ZBS800579
Engine # 8015318
Model 927501 928 RHD
Delivered Australia N.S.W (C23) (73 in total) 10/November/1981
Built 01/May/1981
1st Registered January 1982 ( I also know who to)
Opions 249,261,282,418,423,650
Exterior R4R4
Interior DX
