Two Hole Mod and MCAI

[BullittSV6]

I've had sooo many questions regarding the 2 Hole Mod and since I took some pics I though I would make up this thread.

What you'll need:

• Cutting utensils (saw, dremel, hole saw, a drill)
• Sandpaper or file
• Philllips head screw driver (large tip)
• Flat headed screwdriver
• Monaro Cold Air Induction Shroud (MCAI - Holden part number 92096849)
• 90mm diameter PVC pipe (about 5 inches will do)
• Something to trace with (a nail will do)
• Adhesive
• OPTIONAL: Open flame (BBQ is best)
• OPTIONAL: Jars of different widths
• OPTIONAL: Spray paint

Time

About a day

Method

Step 1 - Extract the airbox

Use your flathead screw driver to take the pin out of the plastic rivets holding your radiator shroud in place and remove it. Then use your phillips head screw driver and remove the three screws holding your air box lix and pull the air box lid to the side. You can remove the lid using a spanner but I can't remember what size so I won't post it, but it makes life easier. Now remove your air filter (while your at it maybe give it a clean too!). To remove the air box give it a good pull. There's 3 rubber grommets holding it to the engine bay and a good pull will dislodge those easy. No tools required. Your restrictive 90 degree duct will come out too. Keep it in a spare parts box and forget about it.





Step 2 - Make your second hole in the air box

Get hold of your 90 mm PVC pipe and trace the outline on the front of your air box. It will need to be on the passenger side of the air box because there's no room of the drivers side where the primary hole is already. If you are afraid of operating on your own air box stop now and get a spare! Now cut the hole. You can use a dremel or hole saw or you can use a drill because the plastic is quite soft. I found an extra pair of hands "handy" at this point. I ended up using a vice, the plastic will hold its shape. Now you'll need to file it back so its smooth and round. Use your PVC pipe trial fitting as you go until it fits. I left a bit of give in mine so I could move it back and forth and so it still had a little give.









Step 3 - Modify the MCAI

This is the most tedious part. What you'll need to do now is get a hold of your MCAI and fit it back into the car with the air box. It won't fit first time due to the coolant pipe so as a start cut along the red lines shown below. After this do another trial fit and make more cuts as required. In the end your MCAI and air box should fit nice and snug so you can get your air box lid and radiator shroud back on without having to force to coolant pipe to one side or similar.

(NB The cuts for the coolant pipe were made the weekend after I did this so further pics won't show these cuts)











Step 4 - Make your second hole in the MCAI

Once your happy with how its all sitting, keep the MCAI and airbox in position and trace the outline of the new air box hole on the MCAI. Now remove the MCAI and repeat the cutting and filing process you used on the air box, so trialling with the 90 mm pipe. Once its all hunky dory, stick the MCAI and air box back in the engine bay and do a trial fit with your 90 mm pipe. It should look a little like below.





Step 5 - Cut the 90mm PVC pipe to size

At this point you can also put a flange on your pipe like I did. What I did was fire up the BBQ and using a series of jars, heated up the side of the pipe I wanted facing the incoming air and pushed it against a jar bottom and repeated this until I got the desired flange and dipped it in a buacket of cold water to set the shape. Now you need to cut your PVC pipe down to size. Basically leave a bit of clearance between your PVC pipe and the coolant pipe (about 1 cm) and at the rear of the pipe mark out the edge of the air box along the 90 mm pipe and do some more cutting . At You can also paint your pipe black to match its surroundings.





Step 6 - Assembly

Once your spay paint has DRIED COMPLETELY (or else you end up with a mess) place your MCAI, Airbox and PVC pipe in desired position. Use an adhesive like loctite or stikaflex and spread it around the rear of the pipe, sealing the airbox. (WARNING: don't use blue loctite like I did first time. It won't set! In the end I used clear loctite and that set in moments.) Once sealed, wipe off any excess and put your air box lid back on along with your radiator shroud and away you go.







Results

First of all remember this is a cheap mod so don't expect to be Vin Diesel and blow off the competition. Once the ECU realises "hey I can breathe now!" you'll hear a bit of induction roar under WOT. It sound slike a muffled growl, best heard with the windows down. You MAY feel a slight imporvement in low down power, however as I said don't expect a surge of VTEC like power guys.

Enjoy!

[ruggj]

nice guide good job

[-Jonno-]

nice guide mate. jus follwed it step by step and modded mine jus then.

Thanks for the great write up

[jasevt]

I just did this but instead i put the hole in the left hand side of box, and rough i know but i used a spray can lid instead of pvc lol worked and sounds alright to when you punch it!

[Changa]

Why do you even need the pipe? Its not like it goes out through engine bay so as to suck in cold air, can you just cut another hole in the box? Wouldn't it have the same effect?

[BullittSV6]

Why do you even need the pipe? Its not like it goes out through engine bay so as to suck in cold air, can you just cut another hole in the box? Wouldn't it have the same effect?

If you don't use the MCAI, then no you don't need the second pipe. Simple as that.

If you do use the MCAI, the second pipe helps to keep it together and provides a direct path for the air to go into the air box. Otherwise you will get cooler air escaping to the engine bay and warmer air coming into the airbox.

[thebulk]

Question - do you keep the original air intake pipe up to the radiator cover? I was thinking of doing this mod but thought if I kept the original pipe and only had the 2nd hole drawing from behind the light that I would get better performance rather than having both drawing from the same area behind the light - More like adding to the intake rather than changing it.....

[BullittSV6]

Question - do you keep the original air intake pipe up to the radiator cover? I was thinking of doing this mod but thought if I kept the original pipe and only had the 2nd hole drawing from behind the light that I would get better performance rather than having both drawing from the same area behind the light - More like adding to the intake rather than changing it.....

As in Step 1, leave the original pipe out. With a 90 degree angle its too restrictive. If you use the MCAI with a second hole, you draw air from both the radiator cover AND from behind the headlight anyway, but with no bends you will get better flow.

[Smitty]

good job....

end result is a little different on earlier VT/VX

[thebulk]

How much does the MCAI cost?

[BullittSV6]

How much does the MCAI cost?

$21 from your local Holden dealer

[jiffy]

I did this today on my VY clubsport. Piece of cake and because it already has a good CAI, no need for the monaro one... so it literally cost me only a bit of paint and pipe I had lying around, and some time.

I didn't notice a difference at first, but when I went for a drive on my own, I realised I hadn't noticed anything cos I had the kids in the car (driving gently). Anything past half throttle and it was well and truly noticeable (in noise, not performance)

[GUS009]

great write-up mate gonna do this on the weekend. got a vy also, so already got the shroud you bewty!

[dubekot]

Thanks for the write up BullittSV6, just finished doing this to my SV6. Im not the most mechanically minded but have successfully done it following these instructions took me 5 hours haha.
Just a tip, I found that tin snips worked well for cutting the MCAI shroud up.
After going for a drive, i can definitely feel some more pick up, not to sure about top end.

For the $30 it cost me, im pretty happy with the outcome.

Cheers, Luke

[red_rocket]

If you don't use the MCAI, then no you don't need the second pipe. Simple as that.

If you do use the MCAI, the second pipe helps to keep it together and provides a direct path for the air to go into the air box. Otherwise you will get cooler air escaping to the engine bay and warmer air coming into the airbox.

If i don't use the mcai and just have the second hole in the airbox will i need to replace the original 90 degree duct?

[kcpwns]

hey mate great write up thanks helped heapppsss

[matsv6]

If i don't use the mcai and just have the second hole in the airbox will i need to replace the original 90 degree duct?

id like to know the answer to this question aswell. anybody?

[BullittSV6]

I would leave it off. You should get more air into your engine. Don't quote me though...

[MerlinSS]

nice write up there BullittSV6

i did take my 90 degree elbow off my 5.7 airbox there is a more grow with it but then again theres not much room down there for a custom CAI

[mark b]

I have 04 Vz Sv6 stock plus K&N Filter......after a 2 hole mod and oil change I definitely noticed a small but noticeable increase in throttle response. When putting foot down hard on accelerator ( e.g. fast take off or fast overtaking ) there is definitely a small but noticeable increase in the sound quality - like an extra low note is now available at times.

Great mod, fairly easy, cheap and quick. The only thing that I recommend is to keep the top half of the stock 90 degree elbow, glue it to its original position ( bottom of the radiator shroud ) and reshape the end so that it directs airflow towards the second smaller pvc pipe inlet on the right while driving. ( Actually another recommendation that I haven't tried yet is to use sheet metal to build a 'fence' to stop hot air from the engine bay entering the air inlet while at the traffic lights etc. - similar to a heat shield for a pod filter....any ideas would be great. )

[MerlinSS]

i got mine costed me 31 bucks orderd from Garry Warren Holden near me now have to find a hole cutter

[BAM BAM 11]

Thanks for the heads up on the Vz mod guys just done my vz one tonner and am very happy :^)

[ryan101]

quick question, did it effect fuel usage worse or better doing this mod?

[BAM BAM 11]

With the mod i did on my vz I went from about 12.48 per 100 down to about 10.2 per 100 ks ,thats what the computer says anyway hope this helps :^)

[soop]

What else did you change?