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MG MGB GT V8 Factory Originals Technical - Cold air box/ram air/cowl induction system

I had the hood/bonnet off my bV8 recently to be repainted. When I took the car for a drive without it, I tried putting a bigger air cleaner on there (the 2" lowrider barely clears the Edelbrock's choke tower -- must be sickeningly restrictive) and with MORE air and COLD air the car felt like it had a new lease on life. Therefore I have decided to rig up some sort of cold air box or ram air system, and I'm going to put a fiberglass C hood on there and see if I can squeeze a 3" air cleaner element under it. The question I have is this: when you run a cold air box setup, do you make the engine bay even hotter? I mean, without such a setup you are processing several hundred CFM of hot air through the air cleaner and (disgusting as it may be) sucking it out of the engine bay that way. When you use a sealed air box drawing fresh air directly from outside the car, the hot air in the engine bay has nowhere to go ... will the thing overheat?

What I'm going to try to do is to build a dual-horn box around my air cleaner like the factory used to install on zillions and zillions of U.S. muscle cars. (If two fairly small horns could flow enough for a 440 Hemi, I think they will handle a Rover V8's air needs just fine.) Then I am going to use 4" tubing to grab air from one of the following locations:

- the rear of the hood (where you've got a bit of positive pressure) via louvers/vents, or

- the air dam (although that'd require long runs of tubing; probably not too helpful), or

- under the car (although that is not a positive pressure area, or

- through the inner wings (although I am by no means convinced that this would not affect the structural integrity of the car; plus it's not a positive pressure area; plus this entails permanently altering the vehicle).

Has anyone set up a cold air system? (The only one I've seen uses the fresh air grille just in front of the windshield -- great place to take air from, but I don't wish to give up fresh air inside the car so that's out. Also, aside from swapping out the hood, I'd sure like to keep the rest of the car stock-looking.) Would be thrilled to learn of any efforts in this regard.
Harry M. Peeters

I have installed a twin cone filter system in the high-pressure area ahead of my radiator.
It feeds two 3-inch bore hoses to my home-made twin-plenum fuel injection system.

I don’t think this modification would clear the standard width MGB suspension, although you could get away with smaller cones and pipe work, or go through the radiator mounts instead.

See my modification at: and go to “Making your own Twin Plenum”

Hope this gives you some ideas.


Nick Smallwood


If you can find a picture of the early '70's Oldsmobile 442 Ram Air W32, they used a tube setup that brought the air in from under the front bumper at either side and routed it to the carb. So your idea of using the scoop in the air dam to locate the tubes is not far fetched. I have also seen similar setups on modified race cars where they used the original headlight location for the inlet of a tube that ran to the carbs. So tubing length doesn't seem to be an issue
You are on the right track.

Bill Martin

Check out the air induction on a late model Camaro or Firebird. You may be able to run ducting under the bonnet to the grill area where you have both positive pressure and cool air. In fact you might be able to use the Camaro air filter assembly with a little luck.
Bill Young

This thread was discussed between 29/11/2000 and 09/12/2000

MG MGB GT V8 Factory Originals Technical index

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