#Custom fan shroud how to#

Alexander obtained measurements from four main points on the radiator, which included the bottom of the top tank to the bottom of the radiator core, radiator width, the water pump center pin to the radiator fins, and the layback of the radiator. Accurate measurements are crucial in keeping the overall form of the shroud nice and tight to the radiator as well as keep the unit streamlined. With the fan placement issues resolved, it was time to begin measuring for the dimensions of the fan shroud.

To complete the update, he incorporated a water pump from a 250ci Chevy to the equation. To overcome this issue he installed a cast aluminum water pump riser by Zip's, which placed the water pump and mechanical fan 5 inches higher at the front of the engine. In stock form the engine's water pump is mounted far too low for the fan to be efficient.

#Custom fan shroud how to#

The optimum depth of the shroud is when the pitch of the fan blades are showing 1/2 in and 1/2 out of the shroud.With the truck being set up to run a 327ci Chevy V-8, his first order of business was to address how to effectively run a 15-inch mechanical fan. So for my 16' fan I added 1.6' to 16' and cut my hole at 17.6'. To get the optimum hole diameter for shroud take the fan diameter and add 10% of the fan diameter. But that's where good shrouding in front of the radiator becomes inportant.Ī guy that worked large automobile and industrial radiator manufacture explained to me the design of a fan shroud. At higher speeds with enough air hitting the front of the radiator the fan isn't so important. However simply over sizing the radiator would, imo mask whatever results one observed to the above solutionsĪ shroud around the fan is mostly a low speed deal. Seems to me the first goal would be best for low vehicle speed use, and the second more ideal for high speed use, since it would present less blockage of the radiator since most shrouds reduce airflow area at some point. Is it to move air by the engines fan thru the largest area of of the radiator by the fan, or is it to make the fan move the most amount of air thru improved efficiency by good shroud design (ie a simple tight fitting ring), albeit thru a smaller area of the radiator? The 20 gauge aluminum sheet was $21.75 for a 24' x 48' piece.Īnd a little OT, I have always pondered the original concept of a fan shroud. That aluminum angle is 1/16' thick and 3/4' by 1/2'. Here’s the pictures that tell the story…. So I traded some parts with Troy and he said he’d make me a shroud if I helped. The factory 68-69 and 70-72 V-8 shrouds needed cutting to end up with a marginal shroud. Radiator Works in Northridge, Ca did that and added a aluminum tab on top to help attach a shroud. The upper hose inlet tube had to be moved outward to fit any fan shroud. I run the short Jaguar fan clutch (Hayden #2765) because of the thick radiator and 70-up taller aluminum water pump. The car still performed pretty darn good with a skimpy looking 16” fan and no shroud. So I cut 1” off each blade of a 5 blade and made a 16” fan. When we first built the motor, the Champion upper radiator hose mounted way too close to the center and hit my 18” 5 blade MP fan kit. The fan by itself just could not pull enough air without the car moving. Once in 88 degree heat I got stuck in road construction barely moving for 20 minutes. No major cooling problems, but I don’t run a fan shroud. I run distilled water and Justice Brothers Radiator Cooler (RC/22P) and Justice Brothers Cooling System Protector ( CSP/1P). Radiator looks great inside, no rust, and no measured electrolysis. I’ve put 3458 miles the motor in 1 ½ years and driven a few times 80 miles to/from Willow Springs Raceway racing 60 laps/150 miles going about 1 rpm on straights. I have a Champion 4 core 22” radiator that has performed well in my new 416 stroker small block.