[Mutant138]

There is an issue with some precleaners being too restrictive for the 5th gen and any engine really.

I imagine it's about understanding what kinds of CFM's the ECU is expecting or physically how much oxygen it needs to go bang?

Anyone running a Sy-Klone? I was told there is a model that is okay for the 4.0 and was apparently confirmed with Sy-Klone themselves to be safe.

Backwoods Overland is selling the 9001, "airflow from 100 to 275 CFM (2.83 to 7.79 m3/min) which fits a 4-inch inlet. Adaptation parts are available for other inlet sizes. Sy‑Klone’s patented technology ejects dirt and debris before it reaches the filter housing. Maintenance-free as no dirt is collected within the unit."

Any alternatives?

ARB snorkel has helped cut down the AZ dust. Not enough tho. Filter is still getting pretty dirty.

[Mutant138]

Sy-Klone 9001 Snorkel Pre-filter Pre-Cleaner Air filter – BACKWOODS OVERLAND

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[Space King]

I don't know anything about that particular product or it's maker... what I do know is that 100-275 CFM is not enough airflow to support a 4.0 liter engine. Sure, it'll run. However it'd get a little asthmatic in the upper RPMs.

[Mutant138]

Originally Posted by Space King

I don't know anything about that particular product or it's maker... what I do know is that 100-275 CFM is not enough airflow to support a 4.0 liter engine. Sure, it'll run. However it'd get a little asthmatic in the upper RPMs.

Suppose it would be good to know the stock numbers for airflow on the 4.0

It's also my understanding that being alittle restrictive is the trade off for longevity. I just don't want to do more harm then good.

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[rdruss]

If my math is right it appears that a 4 liter at 2000 rpm would be 282 cfm.

[Space King]

Originally Posted by rdruss

If my math is right it appears that a 4 liter at 2000 rpm would be 282 cfm.

I'm not sure what formula you're using... but this is how I got there:

CFM = (CID x RPM x VE)/3456

4.0 liters comes out to ~244.1 cubic inches. The 4Runner's engine max RPM is 6,000. And I'll make a guess and peg Volumetric Efficiency at around 85%. So let's do the math...

(244.1 x 6000 x .85)/3456 = 360 CFM

So you'd need 360 CFM at wide open throttle at 85% VE. At 2,000 RPM you'd only need about 120 CFM. So the 275 CFM unit the OP was talking about would cruise around OK, but starve the engine at higher RPMs. Running around with an air filter that can't flow sufficient CFM... produces nearly identical symptoms to a clogged air filter.

[Spinnukur]

Honestly, avoid Backwoods Overland at all costs. I ordered the Sy-Klone 9001 Snorkel Pre-filter Pre-Cleaner Air filter before my last brief TDY. Came back, nothing. No shipping confirmation email, and Nick (The owner) will not return calls or emails.

Disputed the transaction with Chase this morning.

Unfortunate

[83Mule]

Model 9001R flows 350 CFM and has 4'' inlet...........use the sizing and flow page on their website and you can support up to 14ooCFM.

[mrblah]

Originally Posted by Mutant138

There is an issue with some precleaners being too restrictive for the 5th gen and any engine really.

I imagine it's about understanding what kinds of CFM's the ECU is expecting or physically how much oxygen it needs to go bang?

Anyone running a Sy-Klone? I was told there is a model that is okay for the 4.0 and was apparently confirmed with Sy-Klone themselves to be safe.

Backwoods Overland is selling the 9001, "airflow from 100 to 275 CFM (2.83 to 7.79 m3/min) which fits a 4-inch inlet. Adaptation parts are available for other inlet sizes. Sy‑Klone’s patented technology ejects dirt and debris before it reaches the filter housing. Maintenance-free as no dirt is collected within the unit."

Any alternatives?

ARB snorkel has helped cut down the AZ dust. Not enough tho. Filter is still getting pretty dirty.

bringing back your post from the dead.

I ended up getting a engineaire version on amazon, cheaper than the sy-clone and a larger CFM range. Works like a charm.

Amazon.com: Engineaire 4" Precleaners Composite 150-465 cfm: Automotive