Quote:
Originally Posted by SixDegrees
Better throttle response but you need to ensure you are drawing cold air only, sitting unprotected in the engine bay will draw warm air.
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Lots of info about this on the forced induction pages. The general concensus so far is:
- The stock air box is adequate for a standard car. There is nothing to be gained from changing the stock filter or air box when stock (running 8-10 PSI boost)
- When running a tune (circa 12-15 psi boost) the stock air box becomes a constraint. Ultimately this isn't good for the turbos as they need to work harder to hit boost targets. Harder working turbos also results in higher AITs (Air Intake Temps) which ultimately compromise the power of the tune.
- To improve air flow a high flow panel filter (Helene or BMC) can be used in conjunction with some air scoops fitted in the grill. This solution is still not adequate for high boost tunes (14-15 psi) though.
- A high boost tune really needs a more free flowing intake (AFe, BMS single or a dual cone setup - little difference between these, except for price). These however come with the price of drawing in hot air from the engine bay. There are some Cold Air Intakes on the market, but these are still quite unsophisticated, except for the GruppeM intake which costs over £1000.
- The general opinion is that higher AITs are not as significant on a forced induction car (compared to naturally aspirated) because the intercooler reduces the air temp significantly before it enters the combustion chamber.
- Recent tests have shown that AITs when using the stock airbox on a high boost tune (13-15 psi) are similar to AITs when using an free flowing intake sucking in hot air from the engine bay. These are both slightly higher than stock and therefore compromise performance slightly.
All of the info above led me to make the following decision for my intake. I am running JB3 (upto 15 psi boost). I therefore needed a free flowing intake, not necessarily for the purpose of lowering AITs (as the intercooler takes care of most of the increased temps) but to reduce stress on the turbos. I want them to hit boost targets as easily as possible, this can only be achieved without the stock air box. I decided to get a BMS single cone setup for $95 / £50. In an attempt to reduce AITs as much as possible I have ordered some RPI scoops (from CA Automotive) which I think will displace some of the hot air under the engine bay in an attempt to reduce AITs. The next route would be to invest in a larger intercooler which will reduce AITs back to stock levels when running a high boost tune. Ultimately though, I think this is more necessary when dealing with high ambient temps, which in the UK we don't have too much to be concerned about.
Hope that is of some use. Ben