could someone explain the benefit? I see STI radiator caps or whatever that increase cooling system pressure. What exactly does that do for you?
Radiator caps raise the boiling point of your coolant/transfer heat from the cylinder heads more efficiently. Not too needed, but nothing that wont help/hurt.
the reason people replace the radiator cap is cause the spring rate in the stock one is really low unlike the sti ones (1.3 bar). If you look at any radiator cap, STi included, you'll notice the pressure is determined by a spring. It's hard to perfectly calibrate the spring's pressure, so any radiator cap you buy will have a pressure range of plus or minus 20%. On average, the pressures tend to run on the low side. A 1.3 bar radiator cap should run between 22.6 psi and 15.0 psi for an average of 18.8 psi. A 1.4 bar radiator cap will run between 24.36 psi and 16.0 psi or an average of 20.2 psi. when your raise boost levels it affects the whole engine i.e. everything works harder. your water pump also works harder so the coolant presure also goes up. the wrx cap cant handle very high boost levels. ive actually seen coolant in the dish under where that cap goes after i drove the crap out of my car. so genya is correct. Running a higher pressure radiator cap on your cooling system helps keep the temperature down on the entire system. Raising the boiling point of the coolant is important during hot operating conditions like when running the air conditioning, while climbing hills, long road trips, bumper to bumper traffic, and high performance track or strip driving. It's especially helpful if you live in a warm climate. Also, EJ20 powered vehicles tend to experience water pump cavitation at around 6700 rpm at stock pressure. The higher-pressure rating will help reduce the risk of cavitation. so its more of a safeguard rather than a Aesthetics mod.
I don't have firsthand experience of this, but I've read that the increased pressure can cause leaks/cracks around the plastic endtanks of the stock WRX radiator.
true dat! i apologize ahead for the lengthy reply... the reason for that is increasing the pressure is a good thing when speaking of the efficiency of your cooling system, however, other things are needed to support this mod - as with many other mods - if you're putting on a high pres radiator cap, the very least you should do is buy high strength hoses for your entire cooling system. you really should go with a bigger, stronger radiator along with those though. i see too many people putting ignorant mods on their car just for the sake of modding their cars. while it can definitely be fun at the time, most of the time, they are only de-engineering ther cars. Subaru engineers know what their doing, and they certainly know the parameters that each part was designed to run efficiently in. in my opinion, short cuts aren't worth the trouble...just wait, be patient and save up for what you REALLY want and don't settle for a short fix! plus, chances are you really won't need more cooling capacity, but if you do, crucial racing makes a kit that has everything you need - hoses, water wetter, etc. just my advice. cheese
Why not put this in one of the power areas, its involved with the engine so...You cannot seriously want more sub sections on the site Otoh, its bling. Browncow raises some great points as well.
i like the STi caps though...didn't realize it actually made a difference. i thought it was just for looks too.