Check and make sure your bypass valve is closing. You might be losing boost here. Search the threads for related posts.

 

I'm using an AutoMeter mechanical taped into the fue pressure regulator. I do notice that at around 6500RPM at low altitude the needle will jump back and fourth verry fast (looks like an orange blur) from 15 17psi, it might be enough to confuse a electronic gauge into a false reading.

 

JumpingJackFlash

Thanks. I swapped out the bypass with a Detroit Tuned. Either way they are both closing all the way, at least when I look at them on the bench.

 

I know this post is a little old but I recently opened a thread asking about boost levels with modifications...seems like a good place to ask.

I have a port matched header and exhaust ports with a rebuilt head, ported and rebuilt SC, JCW kit, 16% pulley, DTBPV, stock JCW intake. It's an 02' MCS. I'm also running Bosch Platinum's +4...

I just installed a Glowshift gauge and it hits about 12-12.5 psi at WOT. Seems a bit low to me but the head and SC ported so I have increased the volume and the flow is much better...

 

Increased volumes will yield lower boost levels. By how much I am not sure. Boost level alone does not dictate your performance gains. Larger intakes, intake/exhaust head ports, headers, and exhaust will create less resistance, hence less boost. The overall goal is to get as much air into the engine, combust, then exit as efficiently as possible.

 

I just reread the whole thread and given your increaced flow through the head/ exahust, you are right about normal. You didnt mention an altitude and dont have your location in your profile header but, I would say if you live at or above 3000 feet you are making good boost.

Oh and welcome to the site.

 

Stock head, ddm works intake, race cam, Megan header(no cat), invidia de resonated catback. 15% pulley
12-14psi.

 

I have 17% s/c 2% crank bvh header ported s/c race cam and a couple more things I can't remember and I get 15.7

 

I know it's an old thread but I'm curious what others are boosting at . I feel my ported sc ,intake and horns are doing an amazing job. I'm hitting 19psi WITH minor belt slip too so I bet once I get correct belt ille see atleast 20psi. Mods are:
2004 with ported facelift sc and 19% pulley , ported ic horns , ported plastic boost tube , ported intake Manifold, 65mm tbody and intake, catless headers and ported flange with stock mufflers still , 380cc injectors and 1x step colder plugs. Still on stock tune and lightweight flywheel and stage 1x clutch.

other 2004 r53 is making 23psi with sprintex sc and 60mm pulley and 2% crank , tpr2r head and ns1 cam , obx 421 catless headers and nvida exhaust , Detroit tuned bpv , 550cc injectors , 65mm tbody and 3in intake and 6in velocity stack , fully ported sneedspeed intake Manifold , ported ic horn and tapped fir methanol, grs motorsport ic and remote activated ic sprayers , snow stage 2.5 methanol kit , nology hotwires and step colder plugs , lower grade thermostat and all other bolt ons possible. Tuned by adriancl.
so 19psi max on stock sc , head and cam..23psi on aftermarket sc , head and cam...

 

I have a second engine that I removed the air horns and also ported / cleaned the interior of. Never put them on my engine (06, JCW) though !!
I've been porting cylinder heads since the early 70's, so I've got a good idea what needs to be worked on. And yeah like you (MiniMan), figured that they could use some help in that area.

I also got a head and hack sawed it up to see how thick the port walls are, and where the bad areas are to stay away from. Never finished that task either. See, I live in CA. and can't even legally put a freaking vacuum gauge in my car !!! I sorta gave up on any real performance work thoughts !

Mike

 

My 05 with 15% wmw pulley, ATI dampener, Milltek exhaust hits 16 lbs of boost.

 

'04 R53 - stock ECU, CAI, 15% SC pulley, 380cc Siemens injectors, NGK 1 step colder plugs, NGK wires, Bosch mech boost gauge, stock exhaust, adriancl tune = 15 psi/boost @ 6,200 rpms.