FAQ- Cold air/short ram intakes

[ZeForce]

are u sure its cross-sectional area and not just diameter?

if u have a 70mm diameter t/b u need to have a diameter 25% bigger ?

a 25% bigger diameter would mean a 90mm pipe

or do u mean

u take a cross-section of the pipe then work out the area of the cross section (area of a circle), then work out 25% bigger ?

so the area of a 70mm diameter circle is 38.5cm2

so 25% bigger is 48cms2

an 80mm diameter pipe has a cross-sectional aream of 50cms2.

so if u do mean cross-sectional, whats the point u r only going 1cm bigger in diameter?

70mm is just shy of 3" so y not just go 3.5 or 4" pipe?

or is it like most other things, too much is bad, too little is bad. u have to get it spot on?

The second way is correct.... Its like with most things, the biggest isnt always the best. Too big and you sacrifice intake velocity, too small and you restrict the overall flow

Remember that the actual butterfly is usually 10% smaller, in most cases.

I was refering to the cross-sectional area of the butterfly

It is a simple rule of thumb. Not all people want to spend their time to work out the E=MC2 when installing an SRI. Its ment to be a quick and cheap effective mod for a mostly stock car.

No way I am knocking about what you said, just trying to give people easy answers.

Cheers

I do agree with you, the intake is one of the most basic mods which will only give small gains and yet there are hundreds of threads on this forum about which intake is the best or people dissappointed coz they spent $500+ on an intake setup and didnt get the massive gains they were expecting. At the end of the day if u do want to design an effective intake, then it is important to have correct sizings. Intake piping, throttle body, plenum volume, runner size and lengths all need to be in proportion to each other. Optimising the size and length of the intake piping may not give u huge power gains but they can have a big impact on throttle response or the RPM at which the peak torque occurs.