Jump to content
SAU Community

Boost Maxes Out At 9psi

diamondjo

By diamondjo,
in Engines & Forced Induction

 Share

Recommended Posts

diamondjo Collaborator

diamondjo

Posted
Posted

So I installed a Turbosmart Boost Tee today along with a boost gauge and according to the gauge I always max out around 9psi and this is the weird part: even with the stock solenoid. The Tee (according to the gauge) makes absolutely no difference - even wound out all the way! Something is very wrong wrong here.

I always ran 12psi on my previous Skyline with a Turbotech controller and really didn't have any problems getting to this pressure.

The only real difference between the old and new cars is that my current one is more heavily modified that my old one (3" turbo back, hiflo cat, fmic, pod, bov versus just the pod on my old one).

Does the fact that the engine breathes easier somehow mean I can't make as much boost? Or perhaps there's something wrong with my gauge. The gauge is responsive and smooth, but I'm not sure I trust it.

Anyone have any ideas?

Link to comment
https://www.sau.com.au/forums/topic/317519-boost-maxes-out-at-9psi/
Share on other sites
diamondjo Collaborator

diamondjo

Posted
  • Author
Posted

Sleep on it, they say, and the answer will come. Now I'm not a mechanic, this only comes from thinking about the physics of the problem - please someone who knows what they're talking about put me right if this isn't the case. Now I know this is modding 101, but please bear with me because this is my first foray into proper mods.

The FMIC and all that extra piping has (for argument's sake only) doubled the volume that needs to be filled with air before the intake plenum. This means that it takes twice as much air to reach the same pressure as it once did and the turbo has to work twice as hard to get there. There's probably nothing wrong with my gauge, tee or anything else, I'm simply getting to the limit of what my little snail can puff.

Is this the case? And if so, if it was considered "safe" to run my virtually stock skyline at 12psi, I'm assuming I've got to wind this figure down somewhat for the modded one?

Pal Veteran

Pal

Posted
Posted

cooler piping and FMIC will not make much difference to your boost, and if it does it will increase . take the bleed valve out and plumb straight from the intake pipe to the actuator, should be under 9psi with that. that will test your gauges to see if they are ok. make sure you are winding the screw the right direction, i think it has to be wound in to increase boost

diamondjo Collaborator

diamondjo

Posted
  • Author
Posted
You are using an aftermarket boost gauge yes?

Yeah an aftermarket gauge. Can't remember the brand name but it's from Supercheap. Can't afford an electronic controller yet - having just bought the new car and getting some mods so I needed a gauge (any gauge) quick smart. I wouldn't have expected the gauge to be more than a fraction of a PSI out regardless of the cost - but I'm really wondering whether or not to trust it. As I mentioned though, the readings are smooth and consistent - it's not like it wiggles up to the line or anything.

It's hooked into the pressure line to the stock gauge via a T-Piece.

To be honest, the car "feels" faster when I unwind the tap - but you know how reliable feelings are when measuring power increase :(

What bothers me is that even with the tap FULLY unwound, it makes no difference to pressure. Tonight I'll try winding it all the way in to see if the readings come out lower - as they should.

diamondjo Collaborator

diamondjo

Posted
  • Author
Posted (edited)
cooler piping and FMIC will not make much difference to your boost, and if it does it will increase . take the bleed valve out and plumb straight from the intake pipe to the actuator, should be under 9psi with that. that will test your gauges to see if they are ok. make sure you are winding the screw the right direction, i think it has to be wound in to increase boost

I'm pretty sure I followed everything correctly, with the arrow pointing towards the turbo-housing (and hence the wastegate actuator) and I was turning the tap in the direction of "Boost+". I can't help but think I've done something wrong though as (apart from the very occasional hunting at idle) everything else about the engine in terms of smoothness and response seem fine.

Edit: I think the idle problem is the AFM. It only happens when cold and only very occassionally. A light tap of the throttle always sorts it out.

Edited by diamondjo
diamondjo Collaborator

diamondjo

Posted
  • Author
Posted

Okay, this is weird... tightening the controller right up has no effect either! Tomorrow I will try reversing it in case I have it backwards, but I'm almost certain I don't! Also, checking under the bonnet, things look a bit different to my last skyline. For one thing, I can actually see the waste gate actuator and it almost looks as if the hose from the solonoid comes from a T-piece on the main line goes somewhere else entirely. It was getting dark when I did this, so I couldn't see exactly what was going on, but I'll draw a diagram:

b4p5V.gif

It was also hard to see exactly where everything went because of the rubber conduit. I'll take some actual pics tomorrow and try to find out where everything goes.

HoWiE_Au Collaborator

HoWiE_Au

Posted
Posted

Hi there mate yeah mine was maxing out at 9 too awhile ago it didnt matter how i installed it , Then i had it trying to boost to infinity or untill the turbo shit itself. Remove it and ground out the the boost solenoid wire im on about 10psi or so now and my stock turbo is happy ( lol for awhile anyway ) give it a crack you can only stuff it :(.

RBceffy25 Rising Star

RBceffy25

Posted
Posted

Ok mate read the following carefully and study it.

As far as I understand one line/hose must go from actuator to tee and the other line/hose from either compressor housing of turbo or turbo outlet pipe (the pipe that goes between the turbo and intercooler). As far as I remember (and I have installed about 4 different makes and brands of boost controllers) it must be before it goes through the intercooler as a minor pressure drop will occur through the intercooler giving inaccurate boost and false readings.

Also you I think you have leave the factory boost solenoid connected or your ecu/AFM wont like it which could be why it wont allow you to make more boost due to the AFM not seeing correct boost levels in correspondence to what the ecu thinks it should be seeing from the standard boost solenoid. I know it sound like a contradiction but trust me it actually makes sense because when you install an aftermarket boost controller it runs independently without being directly linked to the ecu, AFM etc.... leave it plugged in to the loom but cap off the ports.

By the way save your money and get an electronic boost gauge with its own solenoid etc as I have also used various cheap mechanical boost gauges and they are too inaccurate for a conclusive boost reading. I even went through 2 identical 'Speco'(supercheap) gauges on my own car and both read differently running on an identical engine/car setup (I assume this is what you are using).

By the way your idle issue is your IAC valve. Here is the link you want http://www.skylinesaustralia.com/forums/Di...0&start=160. It’s easy as and it works.

While you’re at it though I recommend you also remove you AFM and pod and clean your pod and get a can of CRC MAF/AFM cleaner. It also works nicely.

I hope all this helps you in some way.

RBceffy25 Rising Star

RBceffy25

Posted
Posted
Nice write up ceffy, Do you know much about stalling after the Bov kicks in?, It feels like it gulps in a shitload of air and it doesnt like it.

Thanks mate, much appreciated.

Ok firstly, I assume what your saying is that when you make boost or start making boost and then back off the throttle (which initiates the BOV because the boost needs somewhere to go when the butterfly in the throttle body slams shut) your engine is stalling. Is this correct? (i'll explain more on this later)

Also please explain what you mean by "It feels like it gulps in a shitload of air and it doesn’t like it"

Next question.

What type of BOV are you using? Is it the standard unmodified plumb-back unit or have you swapped it for an aftermarket item?

And if its aftermarket, is it venting to atmosphere or still plumb-back?

Depending on your answer, it may have something to do with what i started to explain in the brackets in the first paragraph.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing


  • Similar Content

  • Latest Posts

    • djr81
      R32 update from 1990's spec.

      By djr81 · Posted

      New CAS just turned up from NZ Wiring. Looks like a nice bit of gear.  So, yeah. Triggered, bro. Realised I may as well do the cam belt while mucking about with it so will order one of them.
    • MBS206
      Duncan's V37.......race car?

      By MBS206 · Posted

      Even more fun, leave all the ADAS stuff plugged in, but in different locations, hopefully avoid any codes!   And honestly, all these new cars with their weird electronics. Pull all the electronics out Duncan, and just shove an aftermarket ECU and if needed a trans controller in, along with a PDM. Make it run basic but race car styled!
    • Duncan
      Duncan's V37.......race car?

      By Duncan · Posted

      To follow up a question from earlier too since I had the front bar off again (fking!) This is what is between the bumper and the drivers side wheel And this is the navigator side, only one thing but its a biggy! So basically....no putting coolers in the wheel arches without a lot of moving other stuff. Assuming I move to properly race prepping this car I'll take that job on and see how the computers respond to removing a whole bunch of ADAS modules
    • Duncan
      Duncan's V37.......race car?

      By Duncan · Posted

      So I prepped the car for another track day on Wednesday (will be interesting to see coolant temps post flushing out and the larger reservoir, with a forecast of 3-14 being 20o cooler than last time I took it out). Couple of things to mention; since I am just driving the car and not taking a support vehicle, I took the rear seats out and just loaded the back up Team Trackday style. Look at all that space! To cover off removing the rear seat....it is weird (note the hybrid is probably different because it wouldn't have folding rear seats) Basically, you remove the lower seat base, very similar to a r series but it is a clip that pulls forward to release the base rather than it being bolted down. Easy Then, you need to remove the side section of the rear seat on each side. There is a 14mm head nut at the bottom of the side piece, the it slides upwards off a hook at the top to release; you also need to unhook the seatbelt from the loop at the top. Then the centre piece is weird. You need to release/fold the seats forward with the tab in the boot on each side From there, there are 2,x12mm headed bolts holding the rear of each seat to the folding bracket, under the trim between the rear seat and the boot (4x christmas tree clips there, they suck). The seat is out but you can see where the bolts attach to the bracket
    • RP1421
      S15 Spec R

      By RP1421 · Posted

      As discussed in the previous post, the bushes in the 110 needed replacing. I took this opportunity to replace the castor bushes, the front lower control arm, lower the car and get the alignment dialled in with new tyres. I took it down to Alignment Motorsports on the GC to get this work done and also get more out of the Shockworks as I felt like I wasn't getting the full use out of them.  To cut a very long story short, it ended up being the case the passenger side castor arm wouldn't accept the brand new bush as the sleeve had worn badly enough to the point you could push the new bush in by hand and completely through. Trying a pair of TRD bushes didn't fix the issue either (I had originally gone with Hardrace bushes). We needed to urgently source another castor arm, and thankfully this was sourced and the guys at the shop worked on my car until 7pm on a Saturday to get everything done. The car rides a lot nicer now with the suspension dialled in properly. Lowered the car a little as well to suit the lower profile front tyres, and just bring the car down generally. Eternally thankful for the guys down at the shop to get the car sorted, we both pulled big favours from our contacts to get it done on the Saturday.  Also plugged in the new Stedi foglights into the S15, and even from a quick test in the garage I'm keen to see how they look out on the road. I had some concerns about the length of the LED body and whether it'd fit in the foglight housing but it's fine.  I've got a small window coming up next month where I'll likely get a little paint work done on the 110 to remove the rear wing, add a boot wing and roof wing, get the side skirt fixed up and colour match the little panel on the tail lights so that I can install some badges that I've kept in storage. I'm also tempted to put in a new pair of headlights on the 110.  Until then, here's some more pictures from Easter this year. 
×
×
  • Create New...