i was wondering , when i got my FD (JDM), ( R1 with dual oil coolers ) it came with a so called ( SPEC Radiator VALVE ), Cap , on both the AST and the filler neck
they are both spring equipped 1.1 bar pressure caps , identical ,
on my FD i rebuilt the engine completely , simplified the vacuum lines ,( still SEQ. ) and of course a full hose job , ... but never gave any thought on altering the rad/ast cap setup

i know that standard , the filler neck is not a pressure cap ,

what is the advantage , disadvantage of this setup ,
should i go to :
Filler : No spring
AST : .9 bar Pressure
or leave it alone ,

btw , i have an after market water gauge ( Electrical ) tapped right into the water pump housing body ( where water exists the engine ) and i have never seen my temps go over 100C , and this while idling ( 1300 RPM ) in dead still bumper to bumper traffic traffic with next to no wind , outside temps ~35 deg in the shade .. for over 1 hour , ( at this stage my oil temp ( picked up at filter ) was also ~100C , this is the highest i have ever seen these

thx for reading

 

i heard that the 1.1bar is to high of a pressure to run on the FD, instead people have switch to .9 which is what i have. Do a search, i found some threads on it so tha is what i have a Greddy 13psi cap on the filler neck and stant 13psi on the AST.

 

I would keep the 16 lb cap. Thats what i run. The pressure is only higher when the water temp goes up. I would rather the car have a higher threshold before it starts boiling the water. Thats more dangerous then higher pressure. The fd originally had 19 psi caps. You might change the filler one to a no spring cap just in case it does go high enough it boils over into the overflow instead of the ground.

 

thx for the comments guys ,