Air filters on a 4BD1T

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Originally Posted by rar110

Does that mean the original is ok? What was used on NPR trucks?

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A healthy 4BD1T with aftermarket turbo and the fuel screw backed out is running at 25-30psi, much higher air demand over a stock unit.

Mmmm. It’s complicated. I disabled the actuator years ago. So regularly would peak out at 30psi. Removed the inner filter - still triggered the blockage alert. Elongated the inlet to filter housing by welding a 3” pipe across the curve - still trigger the alert.

Quote:

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Originally Posted by rar110

Mmmm. It’s complicated. I disabled the actuator years ago. So regularly would peak out at 30psi. Removed the inner filter - still triggered the blockage alert. Elongated the inlet to filter housing by welding a 3” pipe across the curve - still trigger the alert.

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That doesn't sound complicated at all.....the blockage alert triggers when vacuum increases past accepatble limits between two points?

Forgive me if I'm off here as I don't own one, on the surface it would seem airflow is insufficient in all cases.

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Originally Posted by rar110

Does that mean the original is ok? What was used on NPR trucks?

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This is an NPR59 (Factory turbo) air filter next to the Landy air filter.
If you want to look up the specs, the element is a Baldwin PA2712.

https://www.aulro.com/mobile-gallery...9ada245126.jpg

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Originally Posted by Fubar

I have seen some commentary around removing the inner filter on the standard air cleaner as it is restrictive on a healthy turbo'd Isuzu.

Is this a thing or is it based on gut feel assumptions. Idon't feel comfortable removing it if it was deemed necessary by the developers and would look at other air cleaner options that have enough flow (max 500cfmish) with good filtration.

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I removed mine and noticed a gain of 2-3 psi with the journal bearing garret.

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BTW if anyone has the brackets or pics on how the standard air cleaner mounts I'd be very appreciative of either. I had considered leaving the Td5 air box on but I'm not a fan of it & I think the physicals will be prohibitive.

Jason

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Here it is in situ, it uses the top 2 flywheel housing bolts.

Attachment 143782

Apart from providing a degree of backup if the primary filter is damaged, it is also intended to prevent dirt entry to the clean side when the primary is changed. Other than the fact that filters become more efficient (at filtering) as they get dirtier, dirt entry to the clean side during filter changes is a major cause of wear and is why overservicing air filters is a bad thing. Which is why we have vacuum restriction gauges and dont change or clean filters just because they look dirty.
I removed my secondary after weighing up the trade off between restriction and extra protection, knowing that I dont remove the primary unless the restrictor trips.

I will put it back in for a dusty trip, where frequent servicing of the primary may be likely.