I recently finished a fibreglass cover for the alternator (http://mearcat.blogspot.com/2017/11/alternator-cover-and-cooling.html) to protect it from debris and water as it is mounted partially in the wheel arch. Approximately half of the alternator is in the engine bay however I was concerned that because the alternator cover is sealed (no ventilation holes), the other end of the alternator would not be able to draw in any fresh air for cooling. Note : Alternators with internal fans such as this one draw in air from either end of the alternator and the air is pushed out radially.
Getting fresh air for the alternator is not a problem as there is big gap above the intercooler core end tank, as indicated by this 25mm conduit that I placed through the grille area.
The plan was to make a small duct to pick up air from the grille and route it to the alternator cover via a factory hole directly above the alternator cover. This hole has a diameter of 25mm and it seemed that it would be a reasonable size for a small cooling duct, although I actually had no figures to back up that thought.
To form the shape of the base of the duct I used the same procedure as the alternator cover, by taping up the inner guard and laying some fibreglass over the top.
I used half of a 35mm diameter steel tube (which is close to the same cross-sectional area as the 25mm hole) and laid some fibreglass in the pipe to get the semi-circle shape for the straight pieces of the duct.
I superglued some small lengths of the semi-circle pieces to the duct base and used some modelling clay to create the shape of the bends between the straight sections. I then made a mold of the entire duct and after more fibreglassing work, the duct was finished. The duct is held in place by an M5 bolt at the front and a small length of tube that presses into the 25mm hole at the back end.
I unfortunately forgot about the bolt used to hold the alternator cover in place so I had to fibreglass in a small semi-circle notch in the duct to clear the bolt, rather than do the whole plug and mold again with a re-route around that bolt head.
The front of the duct picks up air from the gap between the headlight and front mount intercooler end tank.
I also made a short tube and fibreglassed it into the alternator cover so that the air from the back of the duct feeds directly to the rear part of the alternator.
The plan was to make a small duct to pick up air from the grille and route it to the alternator cover via a factory hole directly above the alternator cover. This hole has a diameter of 25mm and it seemed that it would be a reasonable size for a small cooling duct, although I actually had no figures to back up that thought.
To form the shape of the base of the duct I used the same procedure as the alternator cover, by taping up the inner guard and laying some fibreglass over the top.
I used half of a 35mm diameter steel tube (which is close to the same cross-sectional area as the 25mm hole) and laid some fibreglass in the pipe to get the semi-circle shape for the straight pieces of the duct.
I superglued some small lengths of the semi-circle pieces to the duct base and used some modelling clay to create the shape of the bends between the straight sections. I then made a mold of the entire duct and after more fibreglassing work, the duct was finished. The duct is held in place by an M5 bolt at the front and a small length of tube that presses into the 25mm hole at the back end.
I unfortunately forgot about the bolt used to hold the alternator cover in place so I had to fibreglass in a small semi-circle notch in the duct to clear the bolt, rather than do the whole plug and mold again with a re-route around that bolt head.
The front of the duct picks up air from the gap between the headlight and front mount intercooler end tank.
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