150 series petrol performance upgrades

[BiLLz0r Advanced Member Find all posts View Profile Close BiLLz0r]

So, I pulled out the stock airbox and investigated it for possibilities.
The first thing you'll notice is that there is a fixed propeller set up near the intake opening that fits inside the fender. This propeller is designed to form a vortex so that centrifugal force within the spinning airflow that will throw water and heavier particles to the outer surface of the intake tube, with clean air passing through the smaller diameter inner tube that feeds the airbox lower cavity. You'll note there is a crude one-way rubber valve set up in the outer tube to drain any accumulated water and debris.
After removing the propeller, I ran the car in for a couple of weeks at freeway speeds in some torrential downpour conditions. There was no ingress of water at any time or under any conditions. So far so good.
Next, working on the inside of the lower airbox, I got out my dremel and removed all of the smaller diameter inlet pipe and cut away as much of the outer feeder profile as I could. Ran more tests in all sorts of environmental conditions with no increase in FOD in the airbox, filter or air intake tube.
What I am left with is just the airbox pulling air from the fender via a short, unrestricted tube.

I assume this is all removed anyway once you have a snorkel installed as all that crap is pulled out?

[fridayman Senior Member Find all posts View Profile Close fridayman]

A quick update. I did the mod and then added a K&N air filter (adding this afterwards also made a difference). I'm not sure how this is going to affect my fuel consumption yet - the first tank with just the airbox mod was about the same as normal, maybe 0.2l/100 higher. It definitely goes better though! Would I do it again? Without any hesitation. It's made me wonder about the exhaust now...

[4alh Lurker Find all posts View Profile Close 4alh]

Some very, very quick images Pt1

Guys, my Airbox is already modded so I didn't want to remove it again, but here's some photos with the box in situ.
Prado Airbox 0.jpg
Shows position of air intake vents in driver’s side wheel arch.
Prado Airbox 1.jpg
Yellow arrows indicate clamps (4X) to undo and hose clamp to loosen prior to removing the Airbox Lid. Don’t try and pull of the manifold inlet hose now, it will come off more easily when the lid is free.
(For information only, the red arrow indicates the position of the Tabs you’ll to press down with a screwdriver to prise the right angled cowl off AFTER you remove the Airbox Body from the engine bay. This so you can get at the fan.)
Prado Airbox 2.jpg
Close up of Tabs you’ll need to depress by sliding your screwdriver in here after you remove the Airbox Body.
Prado Airbox 3.jpg
Undo the bayonet fitting on the underside of the clip with long nose pliers. This will allow you to move the Airbox Lid out of the way without stressing the wire harness. Alternatively, unplug the connector.
Undo this bolt.
Move the Airbox Lid out of the way and undo the two bolts inside the Airbox Body at the base. The Airbox Body can now be lifted out.
Prado Airbox 4.jpg
On the air inlet pipe that goes inside the mudguard, depress those Tabs shown in Prado Airbox 2.jpg and remove the right angled cowl.
You’ll see this Fan inside the air inlet pipe. Place a screwdriver at the weld points and pop the Fan out.
Replace right angled cowl.
Prado Airbox 5.jpg
This shows the original configuration of the Outer tube (Red), Inner tube (Yellow), and Fan.
Use a Dremel or similar to cut along the Red lines and remove all of the Inner and Outer tubes.
Clean up any loose material and swarf.
Prado Airbox 6.jpg
Finished product. Replace in engine bay, install three bolts and reconnect wiring clip. Refit Airfilter and Airbox Lid.
Another mod I highly recommend is removing the Vanity Cover which traps heat around the intake manifolds. A cooler system means denser air is being sucked into the fuel enriched mixture.
The Vanity Cover does nothing but make the engine bay look pretty to the non-mechanical eye.
To remove, simple lift at front and pull towards you. It’s only mounted on rubber hinges.
See Prado Vanity Cover 1.jpg to Prado Vanity Cover 4.jpg
See PT2

[4alh Lurker Find all posts View Profile Close 4alh]

Some very, very quick images Pt2



The only reason you'll use more fuel is because you won't be able to restrain your right foot.

[Steve M Addicted PP Member Find all posts View Profile Close Steve M]

Forget that question. Didn't realise there were more pages

[Ahmed Qaisar Lurker Find all posts View Profile Close Ahmed Qaisar]

Hi this is a great thread. Can you tell me if the improved air flow made a difference to the gear shifting ?

['Dan' Senior Member Find all posts View Profile Close 'Dan']

Thanks for this, exactly what I was looking for.

What are the extra chambers on the intake pipe for? From the airbox to the throttle body, Resonance?