the coolant circulating therein the top wall 236 of the tunnel 206 does not have a feature corresponding to the projection 140 of the embodiment of fig4 a portion 250 of the cold air 248 is directed toward the opening 252 and drives cold air 254 through the air passage 238 along the second side 234 of the radiator 228 the cold air 254 contacts the second side 234 of the radiator 228 and absorbs heat from the radiator 228 further cooling the coolant circulating therein as can be seen the circulation of cold air 254 is in the same direction as that of the cold air 248 referring now to fig7 a 7c a number of possible positions are contemplated for the radiator 128 referring to fig7 a the radiator 128 a is installed in the position shown in fig4 at a forward portion of the tunnel 106 generally forwardly of the track 122 the radiator 128 a is spaced apart from the front wall 130 and an air passage 138 a is formed therebetween referring to fig7 b the radiator 128 b is installed along the top wall 136 of the tunnel 106 generally above the track 122 the radiator 128 b is spaced apart from the top wall 136 and an air passage 138 b is formed therebetween referring to fig7 c the radiator 128 c is installed at a rearward portion.