280ZX Stock Oil Feed Unfiltered?

[dogmeatk]

In digging into the FSM, I noticed that the oil feed line to the stock turbo is ... not filtered at all ? Is this an error or is this true? Is there any deliberate reason for this? I would think that engine contaminants are not great for turbo bearings. I would like to filter the oil feed but now I wonder about the Nissan engineers and whether they had a good reason for it. Maybe the pressure drop from the filter is more of a risk than particulates?

 

[calZ]

The oil still gets run through the filter eventually, since not all the oil goes to the same place each time through. 

[AydinZ71]

5 hours ago, dogmeatk said:

In digging into the FSM, I noticed that the oil feed line to the stock turbo is ... not filtered at all ? Is this an error or is this true? Is there any deliberate reason for this? I would think that engine contaminants are not great for turbo bearings. I would like to filter the oil feed but now I wonder about the Nissan engineers and whether they had a good reason for it. Maybe the pressure drop from the filter is more of a risk than particulates?

 

It may have been to ensure there’s as a pressure-bias towards the turbo, since as you said the filter provides back pressure. Without consistent flow, the oil will cook in the turbo bearing (especially non water-cooled oil bearings) within seconds of boosting, so momentary oil starvation to the turbo is even more sensitive than the broader engine (which operates at lower temperatures). This “cooked” oil will foul the bearing and reduce the lubricating and cooling effectiveness of oiling over time.  

 

It may also be nothing more than convenience. The turbo oil feed comes from the main oil galley where the pressure transmitter is mounted. This is an existing external tap into the galley, where the NA and turbo block are identical castings. There is the Siamese piston sleeve difference between some L28’s but that is mut regarding oiling systems. The ends of the main oil galley have plugs, but are not exposed/accessible outside the engine when assembled. 

it is a true statement that the oil eventually gets filtered through re-circulation, and I am Unaware if there are any clear issues people have experienced with the oil supply not being pre-filtered.

 

if you were to go dry-sump oil pump, the diagrams I have seen all recommend the oil be filtered prior to any use, including the turbo, so this may again have been a convenience consideration over deliberate.