I want to install an air - air intercooler.
What's the CFM output of the 3.9's turbocharger? I found a 276 cfm built by Radiator Speciality Company at a surplus dealer. It's 32"x11"x10", and will fit my application, but the CFM has me stumped.
There's a set 'volume' that an engine will cycle through it at a given rpm, but the mass/air density of that volume will vary depending on boost. What you need to do is pick the maximum rpm the your engine will be operating at and begin from there with the air volume calc. Here's what I did for sizing my air filter and intercooler for my engine.
Ambient temperature 80 F
Actual atmospheric pressure, 12.23 psia (pound per square inch, actual pressure for my elevation)
RPM 2500.00
Engine Displacement 239.0 CID (cubic inch displacement)
# of cylinders 4.0
cylinder CID 59.8 cubic inches displacement (CID)
Boosted Intake Vol @ RPM 172.9 cfm (actual compressed/boost cubic feet per minute going through intercooler and into the engine)
Boost pressure 25.0 psig (pounds per square inch, gauge pressure)
Turbo Inlet Volume 437.9 cfm (actual cubic feet per minute going through filter)
hey vanman......I just posted a few days ago the dimensions on my stepvan 4bt intercooler. They're in a thread 6 or 7 threads down........stepvan intercoolers. Maybe you can draw some conclusion from those.
Thanks for the reply. If it's not too much trouble would you give me a rough measurement of the intercooler on your van. I have an 86 Grumman 4bt with th 400 trans that I'm working to get more highway able. I'll eventually use a gm overdrive, but I need to go one step at a time.... The intercooler is $70. that will work this month.
Thanks again
the dims. are posted in a thread titled "Step Van Intercooler". That thread is 5-7 threads below this thread in General Discussion. They are the dimensions from the intercooler that I am running in my 72 Bronco, which came out of a P-30 Van with a ve pumped 4bt.
I have an intercooler from a Freightliner MT35. It appears to be a couple of inches taller and wider than CumminsBroncos' measurements.
32.5 at top
30 at bottom
2.5 thick
16.5 high from top to bottom mounting flanges
19 from top of ports to bottom of lower mounts
14 core height
27.5 core width
4 top of core to top of ports
30.5 outside to outside of ports.
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