Drilled Crank Thoughts...
#407
![Default](https://rennlist.com/forums/images/icons/icon1.gif)
One practical inquiry presents itself:
What drilling and oil supply paths are used in the Cayenne GTS V8? It is the closest modern Porsche engine to that which you are building. Porsche has done a tremendous amount of research into air entrainment since the 928 (read the patents).
It has recently been learned that the most official but non-official works involvement in a racing 928 engine "... was no more than fine-tuned after chosen from a set of high power output specimen in Weissach."*
This is in line with John's suggestion.
* THE MAXMORITZ SEMI WORKS 928 GTR
Porsche´s Racing Department never officially entered or prepared a racing 928 for a pure works entry. Only once Porsche decided to make it obvious to the 911 enthusiasts that they usually tended to underrate the racing genes of the 928: So Porsche "arranged" this 928GTR to compete with the then dominant 911(993GTR) on the race track. In order not to offend sensibilities of their traditional 911/993GTR customers by officially challenging them with an outright Works-928GTR, PORSCHE asked MAX-MORITZ-RACING, their long time private racing partner from next-door-Reutlingen to enter this 928GTR Cup as a semi-works car. http://www.porsche928.net/history/strosek_928cup.html So it didn´t come as a surprise, that the drivers were: Bernd Mayländer, Manuel Reuter (Porsche Works Pilots), also Harm Lagaaij (then Head of Porsche´s Design Studio). Vittorio Strosek sponsored MM with his Lightweight-Body-Parts and racing exhaust. The car was officially entered by PORSCHE-CLUB-SCHWABEN. Homologation minimum weight had to be, and actually is 1370 kg. (more infos: „PORSCHE SCENE -Germany- 12/2006 „Frisch aufgelegt: Stroseks Design Klassiker“ and 911&PORSCHE WORLD -GB- May/June 1994 „928 Cup Racer“ ) Lagaaij reports, that the car was very competitive and able to hold most 993GTR down, although the engine was no more than fine-tuned after chosen from a set of high power output specimen in Weissach. In the last race of the season at Hockenheim a crank-bearing ran dry. As the car was supposed to race in 1995 as well, she was made ready to continue her successful competition in the 1995 season. A fresh engine was installed, selected from the same lot of high output engines and tuned as before. But in 1995 Porsche´s 928-production came to an end and the car consequently was no more raced in the new season. The late Max Moritz himself then had her join his collection of historic cars. She has never been put on the road again until after his death, when the family sold the car in October 2004 -with only 24500 km on the clock. (Porsche-Weissach is the only documented owner).
#408
Addict
Rennlist Member
Rennlist
Site Sponsor
Rennlist Member
Rennlist
Site Sponsor
![Default](https://rennlist.com/forums/images/icons/icon1.gif)
OK .."The Cayenne's V8 engines are pure Porsche. These 4.5-liter V8s have all the latest high-tech systems and materials, including a unique dry-sump lubrication system that allows uninterrupted oiling at extreme angles of operation, either off road or at high lateral gs on pavement. " Looks like they fixed it
![Smilie](https://rennlist.com/forums/images/smilies/smile.gif)
#409
Under the Lift
Lifetime Rennlist
Member
Lifetime Rennlist
Member
![Default](https://rennlist.com/forums/images/icons/icon1.gif)
Here are some relevant and irrelevant documents about the 928 Cup cars:
http://www.norcal928.org/928cup/
#410
Addict
Rennlist Member
Rennlist
Site Sponsor
Rennlist Member
Rennlist
Site Sponsor
![Default](https://rennlist.com/forums/images/icons/icon1.gif)
Bill thanks for posting that I had not seen those for a long time. Confirms the need to restrict the oiling to the heads for high RPM use... also the advantage of adding some alloy plates to direct oil returns into the sump.
#411
Rennlist Member
#412
![Default](https://rennlist.com/forums/images/icons/icon1.gif)
I'm not sure where you are going with this. The 928 Cup cars used modifed engines: cams, forged pistons, oiling changes.
Here are some relevant and irrelevant documents about the 928 Cup cars:
http://www.norcal928.org/928cup/
Here are some relevant and irrelevant documents about the 928 Cup cars:
http://www.norcal928.org/928cup/
Pretty interesting reading. Looks like some of the more subtle points are/were being missed.
Prof. Flegl from Porsche mentions reducing the oil volume in the sump. God knows they played around with that. It ostensibly looks like this is a typo when looking at punkt 7. but I think it isn't. The oil volume is reduced in the heads by restricting oil pressure/volume. That raises the normal amount of oil present in the sump during operation. That means the oil level in the sump needs to be reduced, not left higher as some sort of imagined advantage. Little differences mean a lot in this engine. Many other engines do benefit from increased volume in the sump as a result of oil restriction to the head at high rpms. The BMW M10, for example. Not so with the 928. Punkt 8. deals with the blowby problem aggravated by a high volume of oil returning from the head. Separate problem but related. This was conclusively shown in Louie's video.
I noticed during the cross research that the Porsche 928 article on Wikipedia mentions nothing about the GKN rods. They were very proud of that and it is quite a significant event in the history of powdered metal rod use. Hint hint.
Anyway, where I was going is that the cranks were not modified by re- or alternate-drilling. This was in a wet-sumped car that would presumably have the best tweaks they knew of without installing newer technology. Compare the oiling/drilling pattern of the two bed-plate based motors (928/Cayenne GTS) and see if there are differences. I brought up the comparison because Stan is planning on running a dry sump as with the Cayenne. Comparison of the engineering is the first place to start -- that's what I do and it works.
#413
Under the Lift
Lifetime Rennlist
Member
Lifetime Rennlist
Member
![Default](https://rennlist.com/forums/images/icons/icon1.gif)
Agree there is no indication of drilling. Also, one note indicates that rods were stock. I can't read the German magazine article - it seems to be about a different racing effort.
#414
![Default](https://rennlist.com/forums/images/icons/icon1.gif)
I'm not sure where you are going with this. The 928 Cup cars used modifed engines: cams, forged pistons, oiling changes.
Here are some relevant and irrelevant documents about the 928 Cup cars:
http://www.norcal928.org/928cup/
Here are some relevant and irrelevant documents about the 928 Cup cars:
http://www.norcal928.org/928cup/
#415
Addict
Rennlist Member
Rennlist Member
![Default](https://rennlist.com/forums/images/icons/icon1.gif)
Here are some relevant and irrelevant documents about the 928 Cup cars:
http://www.norcal928.org/928cup/
http://www.norcal928.org/928cup/
At least threaded pin holding it in place has same part number as pin used in 928 and 968 heads. For some reason 968 has same coil spring and ball setup as 928's. Maybe due to Variocam needing more than 3 bar to work.
#416
Rennlist Sponsor
Rennlist
Site Sponsor
Rennlist
Site Sponsor
![Default](https://rennlist.com/forums/images/icons/icon1.gif)
Cup specs document mentions 944 head 3 bar oil pressure limit. Does this mean 944 107 139 00 pressure relief Valve? If yes, is it direct fit to 928 4 valve head? Relief valve costs close to $200 each but maybe it would be worth it to buy some extra protection for oiling system.
At least threaded pin holding it in place has same part number as pin used in 928 and 968 heads. For some reason 968 has same coil spring and ball setup as 928's. Maybe due to Variocam needing more than 3 bar to work.
At least threaded pin holding it in place has same part number as pin used in 928 and 968 heads. For some reason 968 has same coil spring and ball setup as 928's. Maybe due to Variocam needing more than 3 bar to work.
https://www.928gt.com/p-1774-oil-che...-pressure.aspx
__________________
David Roberts
2010 Jaguar XKR Coupe - 510HP Stock - Liquid Silver Metallic
928 Owners Club Co-Founder
Rennlist 928 Forum Main Sponsor
www.928gt.com
928 Specialists on Facebook - 928Specialists
Sharks in the Mountains on Facebook - 928SITM
David Roberts
2010 Jaguar XKR Coupe - 510HP Stock - Liquid Silver Metallic
928 Owners Club Co-Founder
Rennlist 928 Forum Main Sponsor
www.928gt.com
928 Specialists on Facebook - 928Specialists
Sharks in the Mountains on Facebook - 928SITM
![](http://www.928gt.com/images/928Specialists-COVER3-928GTcom.png)
#417
Addict
Rennlist Member
Rennlist Member
#418
![Default](https://rennlist.com/forums/images/icons/icon1.gif)
Cup specs document mentions 944 head 3 bar oil pressure limit. Does this mean 944 107 139 00 pressure relief Valve? If yes, is it direct fit to 928 4 valve head? Relief valve costs close to $200 each but maybe it would be worth it to buy some extra protection for oiling system.
At least threaded pin holding it in place has same part number as pin used in 928 and 968 heads. For some reason 968 has same coil spring and ball setup as 928's. Maybe due to Variocam needing more than 3 bar to work.
At least threaded pin holding it in place has same part number as pin used in 928 and 968 heads. For some reason 968 has same coil spring and ball setup as 928's. Maybe due to Variocam needing more than 3 bar to work.
In the case of the Variocam, I think the higher pressure is to shrink entrained air to the point where the fluid approaches ideal characteristics. They want the mechanism to operate in parallel. Entrained or trapped air in one chamber but not another will affect the order and force of actuation -- just like if you have air in one brake line circuit but none in another.
Note that the patent will try to reveal as little as possible about problems so you must read between the lines.
Here is a relevant quotation from a Porsche patent:
Originally Posted by United States Patent 6742486 Device for adjusting the rotation angle of the camshaft of an internal combustion engine in relation to a drive wheel
However, this does not always ensure that the locking of the adjusting unit is released first before the rotor is changed into an adjusting position by the pressure chambers or hydraulic chambers constructed in the adjusting unit. As a result, operating conditions may occur in which the adjusting unit does not operate in a reliable manner.
German Patent Document DE 198 25 287 A1 shows a camshaft adjuster in the case of which the pressure oil feeding to the working chambers is controlled by way of the locking element provided in the camshaft adjuster. As a result of the change of the locking element to the unlocked position, the locking element opens up a pressure duct and the working chambers constructed in the camshaft adjuster are isochronously acted upon by pressure oil by way of ducts leading to the chambers.
It is therefore an object of the invention to improve a system of the above-mentioned type such that starting noises during the activation of the camshaft adjuster are prevented or reduced and the useful life or the functionality of the locking unit is increased.
German Patent Document DE 198 25 287 A1 shows a camshaft adjuster in the case of which the pressure oil feeding to the working chambers is controlled by way of the locking element provided in the camshaft adjuster. As a result of the change of the locking element to the unlocked position, the locking element opens up a pressure duct and the working chambers constructed in the camshaft adjuster are isochronously acted upon by pressure oil by way of ducts leading to the chambers.
It is therefore an object of the invention to improve a system of the above-mentioned type such that starting noises during the activation of the camshaft adjuster are prevented or reduced and the useful life or the functionality of the locking unit is increased.
![Smilie](https://rennlist.com/forums/images/smilies/smile.gif)
#420
![Default](https://rennlist.com/forums/images/icons/icon1.gif)
So, up to a point, higher pressure will mean that more oil is collecting in the head waiting for drainback to the sump. This drainback is often hindered by sustained lateral G forces.
The other function of the Porsche 944 and 928 restrictor valve is to retain oil in the galley so that initial startup is working with a primed system.
The pressure relief valve at the pump and the internal design of the lifters themselves helps ward against pump-up of the hydraulic lifters at high rpm. This is a related issue.