[heliolps2]

Quote from Grandy Clay

What happened to the poster who suggested we consult some “Real” engine builders? I oversaw more than 1000 911 engine builds. Some very radical for their day. Ask Pelican rs911t who still drives a 2.8S built in ’74.

In the past week, I poled 14 builders nationwide that I consider the “best experts” (certainly not even close to all). Without exception, all agreed with my assertion.

There was brought up an additional indication supporting my contention.

Porsche changed the low oil pressure warning light switch from 0.5-0.7 bar to 0.3-0.5 bar. Their contention is that was also for ‘political’ reasons – customers were complaining to Dealers that the oil light was “flickering” at idle when hot.

While it is understandable that our Beloved Manufacturer would do these things for “customer relations” reasons, we shouldn’t overlook all the technical issues.

We have the benefit of hindsight that the Factory engineers didn’t when engineering and built our 911s. We can build a ’65, ’73, ’83, ’89 engine better today than the original. Some of that is because we are not in a manufacturing environment. In many cases (track cars) we don’t have to follow ANY regulations. Mostly we have the benefit of hindsight. We have the choice to add more oil circulation (or less). We can choose the oil pressure our engines run (1.0 to 200 psi), independent of what anyone says (not that we would choose either extreme). The point is we can build a better engine today than Porsche did originally – no fault of theirs.


SO, - - -
Let me re-state my postulate:
More oil to the cam housing is better than less. The main oil pressure needs to stay above the point where the pistons squirters open. Excess crankcase scavenging (and other tricks) that reduce the crankcase pressure are to the benefit of power.


How do we do this?

Certainly not by restricting oil flow to the cams.

The proper way is with the largest possible oil pump. Today that seems to be the 3-section GT3 pump. A close second is the (more expensive) Turbo pump. Either can be fitted to every 911 engine from ’65 (with slight mod).

I haven’t surveyed the availability of current cam profiles with center-oiling. I suspect that this is an easy mod (Porsche did it with SCRS). This allows both center-oiling and spray-bar oiling.


Please let’s have some other info. I don’t have a problem with contrary views. In fact, I welcome them. That is how [b]I[/i] learn.

Best,
Grady