451 Air Box Pipe Removal

MHD & American 451

Remove the air box lid and undo the hose clamp to the throttle body with a 7mm socket.

Just left of the engine (near the engine cover clip) is a bolt that’s a bit of a pain to get to.

There is just enough room to reach in from the top with a small ratchet with a Torx30 bit attached. Remove this bolt.

Pull the crank case breather pipe off and hook it out of the way.

Lift the left side of the pipe to disengage the ball and socket joint underneath.

Slide the entire box down the back of the engine to give you access to the support beam.

Remove the 2x Torx30 bolts from the support beam and remove it from the car.

Now, with a bit of strength and a slight struggle you can lift the pipe from the car. It helps if you twist it clockwise as you move it out of the engine bay.

The right side of the pipe does need a good pull to get out and it will slightly deform the edge of the engine bay.

Don’t panic, it’s not a problem, just push it back into position with a light push from the palm of your hand.

The ridiculous pipe is now removed.

If you compare the shape of this pipe with the original, you’ll see it’s slight more swept of the 2nd bend. This was released after the replacement silicone pipe that I designed for Forge Motorsport.

My fully swept design increased power and MPG so I can only assume that smart copied the idea.

Non Turbo 2007 – 2008

Undo the jubilee clip seen in the centre of the picture. It is a 7mm hexagon head.

Remove the Torx30 bolt from below the first bend.

This Torx bolt is tricky, I would suggest using a very small ratchet and going in from the top right hand side of the bolt head or using an extension piece and going in from underneath.

Either way is tricky but you only need to remove it once. If you ever have to refit it, just use a zip tie through the hole and through the captive nut and pull it tight.

Undo the jubilee clip at the other end, again it is a 7mm hexagon bolt. Pull off the rubber pipe.

Lift the pipe from the car.

Refitting it the reverse of above.

What Are The Big Boxes Attached To It?

These are resonator boxes also called air silencers, they are designed to reduce the induction noise. Where is the fun it that? Cut them off and gaffa tape the holes up if you aren’t going to fit a silicone replacement.

Replacement

If you are replacing it with the Forge silicone hose (designed by me), just cut the old pipe into pieces. You aren’t going to be reusing it and cutting it up makes it so much easier to remove.