150 series petrol performance upgrades

['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?

[Ahmed Qaisar]

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

[Steve M]

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

[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.

[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

[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...

[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]

Reminds me of work I've done on bike airboxes. Do you have any pictures of this airbox modification?

Actually after removing the airbox (3 bolts, 2 hose/wire clips and 1 hose clamp) and taking a look, it is obvious. The propeller bit just clips out, and then the modifying the hole takes 10 minutes with a dremel. The entire job takes 30 minutes.

[Arien]

Reminds me of work I've done on bike airboxes. Do you have any pictures of this airbox modification?

Yes, pictures please, very interested with your findings...thanks in advance

[fridayman]

Reminds me of work I've done on bike airboxes. Do you have any pictures of this airbox modification?

[4alh]

The filter is an avoidable bottleneck, but it's impact is negligible compared to the solid plastic baffles restricting airflow. There's plenty of filter surface area to satisfy the beast. The proof can readily be experienced firsthand.

I would have thought that the air filter would be the "bottleneck"...

[4alh]

Now that my V6 Prado is out of warranty, I've started tinkering with a few bits and pieces.
My wife has the V6 RAV4, which is an absolute pocket rocket with almost the same engine power output as the Prado.
Even factoring the difference in power-to-weight ration, the Prado engine always felt like a real slug and it was as if it was constantly towing around a one ton trailer.
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.
The difference in performance is nothing short of breathtaking, and fuel economy has increased by more than half a lt/100k, if you can resist the urge to put the foot down. Where the slightest touch on the accelerate would previously send the fuel monitor full scale, now it only reaches two thirds for the same amount of throttle response.
Add to this some magnatech oil and my engine has become a silky smooth turbine that actually causes the front end to nod when it kicks down a gear.
It now lives and breathes as it should and returns 12.4lt/100km around town.
Some people will say that the propeller is there to evenly disperse the airflow in the airbox. But the answer to that is neit because the FOD trap negates that. Also, there are a series of chambers after the airfilter and MAF sensor that are designed to counter any pressure differentials and pulsing in the airflow.
So far I can't find any negatives in this mod, and best of all it's for free.

If the results of this simple mod doesn't blow your socks off, I'll buy a Hummer.

PS: Stock paper filters are fine. Don't waste your money on K&N
PPS: Also, consider taking off the engine vanity cover to dissipate heat and let cool air circulate around the intake system.

[topic97]

It depends how conservative the factory tune is. My LS3 and LSA were woefully rich and benefitted from a cold air intake and tune. Picked up some kW along the way and overall fuel consumption improved. Use all the kW and then the fuel flows. Rather rapidly with the LSA. Nothing is free.

I have never had a petrol Prado but what I see is it is a good solid engine and pretty well set up. Extractors are good and a free flow exhaust but as Andy says it will never be a sports sedan.

Yeah same on my old LS1 - got heaps of economy & power out of a maffless tune!
I could quite consistently get under 9l/100k highway driving, which was bloody good for a 330kw V8!

But apparently holden used to detune them and run them rich for the factory so that it made it easier for them to "upgrade" the engines in later models.

[geoffmc1]

Its a good idea to clean the MAF sensor everytime a new airfilter goes in

cheers
Geoff