Quote:
Originally Posted by aaronng
Sorry took me a bit of time to reply.
Anyway CAI is generally fairly bad for low-rpm power and throttle response, that's a given. As for Short Ram Intake, I actually 'used' this configuration previously mostly due to the same reasoning as you have, yet still noticed slight lag at lower rpm. I think most people I talked to find some small lags even using SRI and pod filter compared with stock airbox and filter. Obviously high RPM is much better.
I agree wholeheartedly that the diameter of the pipe can wreak havoc with the Intake Air's Velocity at Low RPM (when negative vacuum pressure is relatively unexhibited compared to Higher Air Volume Intake at Higher RPM). Just as more Aggressive Cams on both Intake and Exhaust side actually doesn't get more power sometimes, as air velocity going through the engine becomes affected negatively.
Or the Throttle Body size might affects power at diff RPMs.
EDIT: Or the Exhaust diameter is too large so the venturi 'gas extraction velocity' effect or whatever you call it means low rpm power is lost with larger diameter exhausts. This is the real explanation that debuncts the common false-belief that back-pressure in exhaust system is needed for low-rpm power, btw.
I don't think most SRI's or even CAI's have bigger or much bigger piping diameter though that's the thing. I just don't understand why low RPM power can be robbed if my SRI piping diameter is the same (in fact, I used completely stock piping actually).
Although I just remember that people having Asthma is adviced to breathe through a paper bag instead to relieve their symptoms. Perhaps this could be related to low rpm power somewhat?
I've also heard that Panel Filters in general straighten airflow so it is probably better for low RPM application, whereas in high RPM perhaps the extra volume of air from a pod filter will be more beneficial? Also the APEXi Filter funnel cone design means the airflow into the piping is straightened as well despite the pod design so that has to be a great thing.
As for Comptech Icebox vs Stock Airbox, I don't know if its relevant but some people say that air flow is actually more turbulent if the piping is too smooth, due to air drag at the edges. I've heard same thing with Aerodynamics on a car's paint being too smooth and actually inducing drag. So perhaps the Comptech being smoother might be relevant?
As for the Heat Shield being warm or not and thus affecting intake air temp, I think since the heat from the engine builds up on one side of the heat shield, but then it needs to transfer to the intake air on the other side via Radiant heating only, as long as the air on the intake side isn't stagnant, which it never is, then the amount of heat transferred through the 'shield' to the intake air that the engine breathes in must be very minimal. That is EVEN if the heat shield is hot. I mean I don't think there's so much difference between a well insulated, clark rubber layered or carbon fibre shield versus a heat absorbing aluminium one, to be honest! Its not exactly direct heat transfer... :O
