nickk47

Okay, so for 3rd gens you can lower the boost to 7psi by unplugging some precontrol solenoids and stuff.
For 2nd gens, how can you lower factory boost? Get a manual boost controller?

KhanArtisT

iTrader: (2)

You cannot lower boost with a boost controller, common misconception. You can lower boost by porting the wastegate. If you search for Aaron Cake on google his website has a good writeup on it.

Minnionator

nope. they are ball or needle valves and resrict flow to the wastegate, most times simply installing a MBC will raise the boost even if its fully open.


port the WG, or put a more restrictive intake or exhaust on.

KompressorLOgic

iTrader: (6)

yes, the factory wg is set arond 5.5 psi. if iy our exhuast and intake are too free flowing it will creep potentially much higher then that. So porting of the waste gate is required to return boost to stock levels.

Now if your tring to run even less then stock boost, if you remove hte cclip on the waste gate and take the arm off u can drive around with the waste gate open all the time, and u should make a bit less boost than stock and spool slowly.( if maybe breaking in a motor or somethin u might want that)

nickk47

Will driving around with waste gate open all the time cause any bad things on the car? And is spooling slow good if I just want lower boost levels?
Is this the only way of lowering boost? There's gotta be some other way to get the boost level lower...

RotaryRocket88

iTrader: (7)

Porting the wastegate means enlarging the opening so when the flap opens it flows exhaust more efficiently. The stock wastegate spring is still a 5.5PSI spring, so it will fully open when it sees 5.5PSI. It will open gradually as pressure rises, so it's not a simple on-off switch. If you're trying to reduce max boost below 5.5PSI, you'll have to change the wastegate actuator/spring to something weaker. You'll be on your own fabricating something like this. Boost controllers simply reduce the pressure that the wastegate actuator sees, so it will open at a higher intake pressure level.

Honestly, why would you want to reduce max boost to below stock levels? It's not like 5.5PSI (S4) or 7.5PSI (S5) are anywhere near taxing the fuel system. Mazda designed it to last.

nickk47

Hmm, well actually I changed my mind, I won't be lowering boost lower than stock, but I am wanting to keep it at stock.