Hello,

I'm trying to figure out how much CFM I need to pull through a big block Chrysler Summit 4-core radiator (radiator link) to keep a street/strip 440 cool. Is there a formula to use (ex: engine HP to BTUs)? I read a good rule of thumb is to have fan(s) that can pull 2500cfm for an 8-cylinder (how to choose an electric fan). I was looking at this shroud and fan combo from summit racing (kit link). However, it advertises only 1500cfm, which may not get the job done. I am trying to help my dad; it is his car.

The car is a 1967 Plymouth Satellite with a street/strip 440, Indy EZ440 heads, .530/.232@050, 10.8 comp, 22 degrees initial/37 total timing (we are in Colorado and he uses race gas), auto, 4.10s, flowkooler pump, 160 thermostat, factory fan shroud with a flex-a-lite fan (no viscous clutch installed; but he has one that could be used). It is an original big block car, so it has the larger radiator core support opening. The trans cooling lines are going into an external cooler and then into the radiator. I am not sure why the guy who built the car went that route; but I may try to bypass the trans oil lines going into the radiator. That might help. I also need to check that the radiator cap fits the radiator neck correctly and the pulley sizes. The car overheats (230+) in traffic, but runs around 190 or so cruising down the road. I believe the issue is airflow.

Questions/comments/concerns/thoughts?

Thank you in advance.