Possible GTS prototype engine
06-26-2010, 03:05 AM
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Possible GTS prototype engine
Large file warning: http://tiny.cc/vv9jl
It appears that there is a good possibility that the GTS sump and block castings are substantially different from earlier engines. The engine shown could possibly be (stress possibly) the referred to select high output engines at Weissach used in the GTR during 1994/1995. Perhaps tuning included replacing the heads with 4v editions.
It appears that there is a good possibility that the GTS sump and block castings are substantially different from earlier engines. The engine shown could possibly be (stress possibly) the referred to select high output engines at Weissach used in the GTR during 1994/1995. Perhaps tuning included replacing the heads with 4v editions.
Last edited by Kevin Johnson; 06-26-2010 at 10:13 AM. Reason: tiny url
06-26-2010, 08:13 AM
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It occured to me that it might be an early engine as well. This is why I loaded the picture into my drawing program to correct the scaling.
I then methodically went through the small and handed variations in the major bed plate fastener locations with respect to the major axis of the crankshaft. I have all these measurements from years ago. Those at the third main line up very well while others did not. I then used this calibration of the scaling to check the dimensions of other components.
I found very good agreement with some. For example, I have a meter long vernier caliper and checked the distance between the oil pan fasteners. I have measured many, many engines by hand and know that large distances like this are where you discover scaling errors. There was very good agreement with the actual pan and the drawing.
~~~~~~~~~~~~~~
Digression:
When I first started making the parts I would have commercial scans made of my patterns on very high end equipment, involving an hours drive each way. I trusted that the technology would be dead on. Instead, I found significant error requiring correction factors. Many people would not reveal this type of information publically because it would make it easier for a competitor to save the probably tens of thousands of dollars of my time and wasted materials it took to learn.
When I was in chemical sales and talked to many hundreds of different businesses across the western United States, I listened to many tales of competitors deliberately giving disinformation. In the case of Eucalyptus growers treating their harvest with improper colored glycerine techniques this would ruin a seasons work. I am sorry but I cannot help thinking about the families of the owners and workers affected by this.
~~~~~~~~~~~~~~
Having good agreement on a major dimension like this, I then proceeded to methodically measure many components of the engine and compare those measurements to actual components on the core that I have here.
I have commented in the text on the picture about timeline difficulties with certain design elements and the bulk of this indicates a time period contemporary with the GTS. For example, there was a long expanse of time during which the sump cover attachment points were not drilled. Then the factory started drilling them again for the GTS tray.
Lastly, I have a great deal of experience in comparing automotive parts. Cognitively, humans will often attend to the similarities of parts particularly if they really want them to be the same and gloss over differences in parts. Later on, when they try to actually use the part, reality intervenes and some dimension or another will be wrong. Famously, on the Rennlist, I did this exact error when I was comparing 928 rods to 944 rods. Many people enjoyed calling that error out. I am human with more than my share of fallibilities.
So, check my work. Examine the dimensions. Compare them to actual GTS parts. I have never had GTS parts in my possesion before. As you can see, I voraciously look for data anywhere I can find it.
I then methodically went through the small and handed variations in the major bed plate fastener locations with respect to the major axis of the crankshaft. I have all these measurements from years ago. Those at the third main line up very well while others did not. I then used this calibration of the scaling to check the dimensions of other components.
I found very good agreement with some. For example, I have a meter long vernier caliper and checked the distance between the oil pan fasteners. I have measured many, many engines by hand and know that large distances like this are where you discover scaling errors. There was very good agreement with the actual pan and the drawing.
~~~~~~~~~~~~~~
Digression:
When I first started making the parts I would have commercial scans made of my patterns on very high end equipment, involving an hours drive each way. I trusted that the technology would be dead on. Instead, I found significant error requiring correction factors. Many people would not reveal this type of information publically because it would make it easier for a competitor to save the probably tens of thousands of dollars of my time and wasted materials it took to learn.
When I was in chemical sales and talked to many hundreds of different businesses across the western United States, I listened to many tales of competitors deliberately giving disinformation. In the case of Eucalyptus growers treating their harvest with improper colored glycerine techniques this would ruin a seasons work. I am sorry but I cannot help thinking about the families of the owners and workers affected by this.
~~~~~~~~~~~~~~
Having good agreement on a major dimension like this, I then proceeded to methodically measure many components of the engine and compare those measurements to actual components on the core that I have here.
I have commented in the text on the picture about timeline difficulties with certain design elements and the bulk of this indicates a time period contemporary with the GTS. For example, there was a long expanse of time during which the sump cover attachment points were not drilled. Then the factory started drilling them again for the GTS tray.
Lastly, I have a great deal of experience in comparing automotive parts. Cognitively, humans will often attend to the similarities of parts particularly if they really want them to be the same and gloss over differences in parts. Later on, when they try to actually use the part, reality intervenes and some dimension or another will be wrong. Famously, on the Rennlist, I did this exact error when I was comparing 928 rods to 944 rods. Many people enjoyed calling that error out. I am human with more than my share of fallibilities.
So, check my work. Examine the dimensions. Compare them to actual GTS parts. I have never had GTS parts in my possesion before. As you can see, I voraciously look for data anywhere I can find it.
06-26-2010, 04:33 PM
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No need to look any further than cylinder heads and intake system. They are clearly early ('83 MY ROW S or earlier) 16V engine parts. It doesn't matter at all what bottom end dimensions are. Its 95mm or 97mm bore and 78.9mm stroke engine. Same picture has been used in early MY factory literature. End of discussion.
06-26-2010, 06:26 PM
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No need to look any further than cylinder heads and intake system. They are clearly early ('83 MY ROW S or earlier) 16V engine parts. It doesn't matter at all what bottom end dimensions are. Its 95mm or 97mm bore and 78.9mm stroke engine. Same picture has been used in early MY factory literature. End of discussion.
Here is a picture from the factory floor in 1977 of the pan casting. Next to it is a 1981 pan. If you look closely you can see that the end of the front rib pattern is shorter in the 1981 pan. This suggests that the measurements are accurate -- there is a 20mm difference in the depth of the floor.
http://www.crank-scrapers.com/1977%2...sus%201981.jpg
Now we proceed to another image from 1977 on the factory floor and we can compare it to the front of MK's S4 block -- the bedplates appear to be the same height.
http://www.crank-scrapers.com/1977%2...0bedplates.jpg
So, now it appears that at least some of the unique elements found in the GTS engine were present in 1977.
Does anyone know whether the windows were used in any other block but the GTS?
Does anyone have a GTS block that they could measure the bedplate height on?
06-26-2010, 06:42 PM
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Does anyone have a GTS block that they could measure the bedplate height on?
06-26-2010, 06:59 PM
#7
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Girdle is 80mm thick, cast in the 49th week of 1990.
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06-26-2010, 07:01 PM
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06-26-2010, 07:13 PM
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That is really interesting.
Some more questions:
1) Does your block have the "windows" or sort of rounded triangular passages between bays on the upper portions of the web above the mains?
2) Is it possible for you to measure the OD (swept OD) of the counterweights? I often have people do this by placing a straight edge on a flat portion of the counterweight and extend it over the snout. Then you can get the radius by measuring to the center of the snout.
3) Can you measure the depth of your sump? I placed a straight edge spanning the flanges and measured down to the floor right next to the pickup depression. On my 1981 pan it is ~117mm.
Thanks!
Some more questions:
1) Does your block have the "windows" or sort of rounded triangular passages between bays on the upper portions of the web above the mains?
2) Is it possible for you to measure the OD (swept OD) of the counterweights? I often have people do this by placing a straight edge on a flat portion of the counterweight and extend it over the snout. Then you can get the radius by measuring to the center of the snout.
3) Can you measure the depth of your sump? I placed a straight edge spanning the flanges and measured down to the floor right next to the pickup depression. On my 1981 pan it is ~117mm.
Thanks!
06-26-2010, 07:50 PM
#10
Race Director
great thread
there are so many small "running changes" to the 928 engine along the years that basically nobody outside of germany knows why they did it......some are obviously bad like the torque tube problem and change of the oil sump.....clearly these were cost saving measures to reduce production costs...but it killed engines later...
Back to the picture...it looks different to me...why is the deep part of the wetsump sideways.....clearly it is NOT a full front view of standard oil pan.....
there are so many small "running changes" to the 928 engine along the years that basically nobody outside of germany knows why they did it......some are obviously bad like the torque tube problem and change of the oil sump.....clearly these were cost saving measures to reduce production costs...but it killed engines later...
Back to the picture...it looks different to me...why is the deep part of the wetsump sideways.....clearly it is NOT a full front view of standard oil pan.....
06-26-2010, 08:33 PM
#11
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1) Does your block have the "windows" or sort of rounded triangular passages between bays on the upper portions of the web above the mains?
2) Is it possible for you to measure the OD (swept OD) of the counterweights? I often have people do this by placing a straight edge on a flat portion of the counterweight and extend it over the snout. Then you can get the radius by measuring to the center of the snout.
3) Can you measure the depth of your sump? I placed a straight edge spanning the flanges and measured down to the floor right next to the pickup depression. On my 1981 pan it is ~117mm.
93GTS block, front and back:
1: Here are shots of the upper portions of the webs- don't see anything other than the round passages that are line-bored from the rear of the block:
2) Is it possible for you to measure the OD (swept OD) of the counterweights? I often have people do this by placing a straight edge on a flat portion of the counterweight and extend it over the snout. Then you can get the radius by measuring to the center of the snout.
2. So with the caveats that A) I don't have a straight edge long enough to do this on the front of the crank, B) there's probably some axial play in the pilot bearings, and C) My caliper sucks, here's the comparo of a '91GT crank and my '93 GTS crank:
91 GT: (2* (93.03 mm - (0.5* 14.84 mm)) = 171.22 mm counterweight diameter
93 GTS: (2* (93.75 mm - (0.5* 14.91 mm)) = 172.59 mm counterweight diameter
3. 3) Can you measure the depth of your sump? I placed a straight edge spanning the flanges and measured down to the floor right next to the pickup depression. On my 1981 pan it is ~117mm.
3. The GTS pan is attached to the the 91GT block which is now a stroker. Greg had to weld the holes in the pan from where the #2 rod shrapnel ventilated it.
I do have the 91GT pan, which (with the caveat of using a non-straight straight edge is 120 mm to the center of the bump under the pickup. 120.6 mm to the depression around the bump.
(Ignore the fact that it's drilled for a GTS baffle, we were going to use it on the stroker then decided to use the GTS pan for the sake of a little GTS DNA....)
2) Is it possible for you to measure the OD (swept OD) of the counterweights? I often have people do this by placing a straight edge on a flat portion of the counterweight and extend it over the snout. Then you can get the radius by measuring to the center of the snout.
3) Can you measure the depth of your sump? I placed a straight edge spanning the flanges and measured down to the floor right next to the pickup depression. On my 1981 pan it is ~117mm.
93GTS block, front and back:
1: Here are shots of the upper portions of the webs- don't see anything other than the round passages that are line-bored from the rear of the block:
2) Is it possible for you to measure the OD (swept OD) of the counterweights? I often have people do this by placing a straight edge on a flat portion of the counterweight and extend it over the snout. Then you can get the radius by measuring to the center of the snout.
2. So with the caveats that A) I don't have a straight edge long enough to do this on the front of the crank, B) there's probably some axial play in the pilot bearings, and C) My caliper sucks, here's the comparo of a '91GT crank and my '93 GTS crank:
91 GT: (2* (93.03 mm - (0.5* 14.84 mm)) = 171.22 mm counterweight diameter
93 GTS: (2* (93.75 mm - (0.5* 14.91 mm)) = 172.59 mm counterweight diameter
3. 3) Can you measure the depth of your sump? I placed a straight edge spanning the flanges and measured down to the floor right next to the pickup depression. On my 1981 pan it is ~117mm.
3. The GTS pan is attached to the the 91GT block which is now a stroker. Greg had to weld the holes in the pan from where the #2 rod shrapnel ventilated it.
I do have the 91GT pan, which (with the caveat of using a non-straight straight edge is 120 mm to the center of the bump under the pickup. 120.6 mm to the depression around the bump.
(Ignore the fact that it's drilled for a GTS baffle, we were going to use it on the stroker then decided to use the GTS pan for the sake of a little GTS DNA....)
06-26-2010, 09:05 PM
#12
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There isn't anything special in GTS block other than those three holes and their surroundings just to make block little bit stronger around the holes. All other measurements are basically same within manufacturing tolerances. For example GTS oil pan is exact same part as was used in late S4/GT.
Kevin, you are reading way too much from blown out engine drawing which probably comes from marketing material and isn't even meant to be accurate description of real engine dimensions. Your latest crusade is even sillier than idea of rod lower end being installed wrong way round.
06-26-2010, 09:26 PM
#13
Race Director
Left side shows back of the pan and right side shows front section. Its just to show how different pan is in front to back direction.
There isn't anything special in GTS block other than those three holes and their surroundings just to make block little bit stronger around the holes. All other measurements are basically same within manufacturing tolerances. For example GTS oil pan is exact same part as was used in late S4/GT.
Kevin, you are reading way too much from blown out engine drawing which probably comes from marketing material and isn't even meant to be accurate description of real engine dimensions. Your latest crusade is even sillier than idea of rod lower end being installed wrong way round.
There isn't anything special in GTS block other than those three holes and their surroundings just to make block little bit stronger around the holes. All other measurements are basically same within manufacturing tolerances. For example GTS oil pan is exact same part as was used in late S4/GT.
Kevin, you are reading way too much from blown out engine drawing which probably comes from marketing material and isn't even meant to be accurate description of real engine dimensions. Your latest crusade is even sillier than idea of rod lower end being installed wrong way round.
