I tuned a completely standard IX FQ320 to 25 PSI on 97 RON recently. The final map I sent him away with was 23 PSI, but it behaved at 25 PSI just fine - the MAP sensor in kPa, knock and ignition timing are shown with repeated 25 PSI runs (~270kPa) in a variety of gears. FQ320 is a JDM 9, as standard it has an HKS exhaust with the stock cat, turbo inlet pipe and intercooler pipes.

I'm not worried about blowing the head off or damaging internals at this level, as long as the AFR and timing are correct. The magazines and loads of owners have put FQ360s through hard use peaking at 25 PSI with no issues I've heard of, I think 20 PSI would be a but dull.

 

Evo 9's begin at 23psi.

With the stock cat I would aim for 18-19 or so psi up top as the cat is a restriction. You would be hard pressed to hold more than that anyway with the stock induction.

 

thanks guys,

I thought the IX cat was fairly decent flowing?

If I would do the dump(o2 housing) or the cat which would you do?

 

Cat makes much more difference. O2 housing is sometimes a nightmare job and the gains are small. I wouldn't bother again.

 

Get rid of the CAT for sure, A test pipe is cheap, easy to install, and makes a really big differences in power and how much boost you can run

 

test pipe = $10,000 fine if caught in oz

I want to get a 100cpi MIL.SPEC, but I think the shipping cost will be hideous

I really need a sponsor :P hehehehe

 

With a 3" dp, megan o2 and stock cat+catback I ran/run 25 psi without issue and made 290/320tq on a land and sea dyno configured like a mustang dyno. I have since the tune added a Cobb HFC and do plan on installing a fuel pump and head studs. The problem with head studs is i may be forced to pull the head so i can port it and then i may be forced to do drop in pistons...

 

wow, thats crazy. Do they really check for stuff like that.

I already thought OZ sucks when it comes to cars, I mean all the cars here cost twice as much and the speed limits are just above walking pace, and whats with all this speed camera nonsense.

I'll never complain again when I get back to the US,

 

In MA it is something like $50k if you get caught having removed emissions controls (EVAP, Cat, ect). One of the reasons i went with the HFC, if a cop really wanted to hassle you he could check for the cat.

 

yeah crazy...

I dont mind though, happy to keep the cat and do good for the environment

 

I'm very happy with the Mil.Spec 100 CPS cat. I'm sure there's no other cat that flows better than this. With my exhaust and the jcsbanks intake mod, I'm holding a solid 20 psi at 7000 rpm with about 11 deg advance. I could probably eek out another 0.5 to 1.0 psi, but I'd probably have to pull out more timing than would make it worth it. I suspect that switching to the razorlab intake and adding an aftermarket FMIC would allow me to push up to ~22 psi at 7000 rpm. (All this on 92 octane.)

The cat will help across the RPM range as well. You'll be amazed at the improvement in daily driveability.

 

I always thought that reducing backpressure was bad for low/mid range?

 

The turbo itself always creates backpressure on the engine itself, lowering the backpressure beyond the turbo is always better.

 

May have some merit in NA motors because of the so-called scavenging effect, but in turbo motors where the turbine gets in the way of exhaust flow, its all about having the highest possible ∆P across the turbine to make use of the exhaust energy available to spin the turbine.

 

from personal experience i wouldnt run anything over 23 psi on pump. i have gotten bad gas from places and slight knock. i couldnt imagine being tuned on 24-25psi and get bad gas. but hey all cars arent the same.

28-30 psi on meth is more common