dreamer1uk

Hey guys,

I have a question or maybe questions regarding performance engine builds and setups.

When you guys are planning motor build ups and deciding on what intakes to use, heads and so forth, how do you decide on what parts to use when it comes down to the CFM on the given heads and intakes?

How much CFM is too much CFM for a build? How do you know how much CFM you would need for your specific build?

Is there such thing as too much free flowing air that could lead into lean running conditions?

I hope my questions make sense

Thanks in advance for taking the time to read and answer the above!

tinman

Ok, here goes....
Yes to part of the question, you can most certainly get heads that will flow more air than your engine can use. An example could be a TFS head with 225cc intake ports on a 302 thats stock other wise.
There have been entire books written on this subject.
Look up writings by Vizard on this ...

dreamer1uk

Hi,

Thanks for the response and ill look up those books after work

I forgot to ask, if the engine is receiving more air than it can use, will that cause a lean running condition? Im going to assume yes. Or would you recomend hooking up a DVOM to the o2 sensor and checking the voltage of the 02 sensor, seeing if its too lean?

uedlose

no matter how big the head is the engine it self is only gone to ingest as much air as the bore and stroke will allow without a power adder. just cuz it is a big head it will not make it go lean. Now if you move lots of air and not the proper amount of fuel then yes it can go lean. now add a S/C or Turbo or N2O and that changes everything very fast. Remember a engine is nothing more then a air pump the more air that goes in the more power it will make and the more fuel you will need. Port velocity and lots of other things can come into play also and don't get hung up on CFM. Victor Jr heads they claim can make 500 hp NA and they flow like 280 on the intake so while the big CFM is very tempting and can be made to work you will need to build the rest of the engine to work with the big heads. But like said 225 afr are not gone to work the best on a stock 302. There is also a site some where on the net I have seen that tells you the CFM required to make said HP