The race department at Porsche® determined the amount of air needed to cool their race engines, without wasting excess energy. The 911R, 906, ST, and RSRs (through the 3.0 model) all utilized the 250 mm fan and smaller diameter housing.
In fact, the 1978 and 79 model 911SC's used the smaller fan for the engines too< a good source for the smaller fan needed for this application
Our precision cast and machined fan housing replicates the original part perfectly. Cast in long lasting aluminum and coated to mimic the original magnesium finish, this is one of the pieces needed to complete your competition Porsche engine, or hot street sports purpose 911.
NOTE: Use of this smaller diameter casting will require the companion strap clamp and use of the race version shrouding, also available from us.