hi.
how can i calculate the cfms of air that i need?do anyone have any info on this subgect?
i need a new custom made ic and all starts from the cfm.
thanks!!

 

Spend some time here:
http://www.bellintercoolers.com/pages/techFAQ.html

Its in the FAQ fwiw

 

e link.
i read it but does not mension how you determine the cfm.is it cold?
do have toinclude any eficiency factor?
do i calculate it for the max wanted boost?
how?
thanks

 

Ratings for IC's vary, there is no across the board standard, it is one of the biggest problems with knowing what you're getting. If you know what boost your going to run and you know what the IC core is rated at you can get a ballpark idea of what you need. Bell cores are rated at 10psi. If you know that you can use that as a guide to match your core. Lets say your engine flows 570CFM@10psi You could run a bell core of 3.5x11x18 that is rated at 578cfm and that will get you close. If you want more response with less resistance upsize the core a little bit run a 3.5x12x18 (go too big and it will be laggy also). Try and stay under 20" charge flow length on a street car longer than that offers little cooling benefit and is offset by weight and lag. I sized my core differently for different reasons but that would work for you. The key is knowing what pressure the CFM was rated at. Spearco will sell you a core that is rated at 1200cfm that's tiny and a person who knows what's up realizes that is a max flow, high boost rating. I would prefer a conservative 10psi rating knowing I will have both room to grow and that most cars aren't running 30psi+

~S~

 

hi Sean,
i calculate my 8000rpms cfms : 1.3litre * 8000=10400litre=>367cubic feet
so at 0 psi i have 367cfm.

i want to set max boost to 14psi and parhaps to 20psi sometimes.

at 14psi do i have : 367*2=740cfm?
or at 10psi i have : 367+367*10/14=630cfm?
or at 20psi i have : 367+367*20/14=891cfm?

am i right?
you sayed that bell uses 10psi at the charts? so i must look for 630cfm that is 10psi, for 740 that is is 14psi or for 890cfm that is 20psi?

my curent intercooler is 2.5"x10"x22" . is it too long? i think that the person who fit it have no idea of what he was doing....
anyway .now i am going to make all the setup from the biggining and a vmount from the bigining.the way i am measuring the free space , i need a core of 3.5"x12.5"x12" to fit everything nice.
this gives me 746cfm from bells chart. http://www.bellintercoolers.com/pages/aachart350.html

is it too short or too small?
do you think it is ok for my numbers?(i assume that my calculations are correct.)

any advise is apreciated.i do not want to make the same mistake twice.
thanks!!

 

You should be able to get away with a 3.5x12x18 just fine in the space you have. I wouldn't go too much smaller than that as you start to trade efficiency for flow. If you have to go smaller go with the 14" core.

~S~

 

Sean,
i do not have that space. i am planing to fit a small battery kit at the right and the air filter at the left . so the available space is about 20" with the endtanks . i assume that the inlet will be 2.5" and the outlet 2.75" so there are 14.5-13.5" left?

if the turbo have 2.5 outlet i must keep it that until ic inlet?

are the cfm corect?
thanks

 

I Have a book I that has all the mathematical calculations for ic size and just about anything else you could possibly want to calculate in designing a turbo system I will post after work if I forget please pm me