Jump to content
SAU Community

Recommended Posts

Im in need of a few ideas guys...

Ive get an R33 GTST S1.5

HKS 2535

Turbo Back Exhaust

Blitz Spec S Boost Controller

PFC

Z32 AFM

580cc Injectors

Trust Front Mount Cooler

Nismo Fuel Pump

Now, im trying to run more boost, about 17-18psi and as soon as it is turned up more than 14psi it wont hold boost anymore, it will hit 17psi then drop of straight away to 12psi...

The items that have been checked are, Exhaust, intake, Blowoffvalve, AFM and tried various boost controllers but nothing seems to work.

My mechanic seems to think it may be the turbo on its last legs...

Any ideas???

The car has run perfectly on 14psi and i am only experiencing trouble now that i am turning up the boost...

Cheers

Link to comment
https://www.sau.com.au/forums/topic/105352-hks2535-not-holding-boost/
Share on other sites

possibly waste gate creep aswell.On a few of the xr6 turbo's I have worked on, the waste gate is to small to support high boost aplications ( standard is 6 psi ) what happens is the boost wil spike as you mention. a common mod on thr standard xr6 turbo is to enlarge the waste gate to increase its flow and hold a consistant boost pressure. Typhoon turbo chargers now have a different rear housing so it hasnt been an issue with them.

exhaust was dropped on dyno with no difference, i should have mentioned the wastegate actuator is a standard nissan one... but shouldnt the boost controller hold the boost?

It was making about 200 rwkw on his dyno at 14psi, then after a quick tune and 16psi 220rwkw but the more boost that was wound into it the less it would hold.

Previously it made 244rwkw on 14psi with quite a bit of advance and held boost well with no boost coontroller on a different dyno but i have been told that it is probably a fudged figure...

cubes, this is corect, but x amount of air should = y amount of boost, i dont think it is a problems with impellor or trubine side of the turbo, more its boost control systems, ie, bov or waste gate. It doesnt matter if a turbo gets more air, it should if specified correctly hold the same boost, say x + more air = y boost still

if its the stock actuator then the boost controller must work very very hard to maintain stable pressure, ie if the actuator is a 5psi item and your trying to dial in 18psi then the boost controller will have an absolute fit trying to maintain pressure in and out. change to a larger rated actuator, 1 bar should be fine

the psi difference between the actuator or ext gate spring and the boost controller should be as minimal as possible to give the boost controller the best chance of accurate control, the larger the pressure difference the harder the controller has to work (like in your case it can't keep up well enough)

I think ill give it a go with the actuator, maybe a garret or HKS type actuator, as when it was originally installed not long ago after a quick inspection by a very reputable tuner i was told the turbo was fine... thing is if i had no boost controller before and it was holding 14psi, why would it need and better one now? I think he may have regualted boost by bending the actuator arm on the stock nissan item...

YOU BENT THE ARM ! Dude big no no, puts way to mush pre load on the diaphram of the actuator, im not surprised it doesnt hold boost if you have done this, becomes way to hard for any boost conrtol system to evectivly modulate the boost pressure if this is the case

I think that is what has been done, as it has had no boost controller on it and was running 14psi from a stock nissan actuator... Is there any other way to regulate the boost without a boost controller?

I hope it is a simple problem as the actuator and i dont need a new turbo!

[200]

If its making the power then dialing in more boost will only be dropping off in to surge resulting in v.hot air + boost drop. :D

-----

A decent boost curve learning EBC may help. The manual type elec. boost controllers only allow the selection of a set duty cycle through out the rpm.

In order to squeeze every little bit out of it you really need a learning elec. boost controller such as the Blitz SBC-id or AVCR where you dial in 15psi and the ebc learns at various rpm points what duty cycle is required to hold such a boost level.

The decent ebc won't fix a turbo that is too small for the power goal.

Drop the same turbo on a little rb20det and you will find it will hold 17psi without issue, yet still make the same power. :D

At the end of the day tune to 230-240rwkw as this is pretty much the max you will get out of the turbo depending on engine condition and how high/low the dyno reads.

Disregard the boost being run unless you are not achieving the max considered power achievable.

[200]

If its making the power then dialing in more boost will only be dropping off in to surge. :D

-----

A decent boost curve learning EBC may help. The manual type elec. boost controllers only allow the selection of a set duty cycle through out the rpm. What you really need is an elec. boost controller such as the Blitz SBC-id or AVCR where you dial in 15psi then the ebc learns at various rpm points what duty cycle is required to hold such a boost level.

The decent ebc won't fix a turbo that is too small for the power goal.

Drop the same turbo on a little rb20det and you will find it will hold 17psi without issue, yet still make the same power. :D

I have the EBC installed at the moment and it wont hold the boost, and another member has almost exactly the same setup as me and runs 20ish psi with no probs... im not looking for more peak power, just more midrange...

thats a good point, you say 200 at 14 and 220 at 16, theory generally says 10 per 1 psi, it would be intweresting to see the inlet temp difference at this point and again at where you feel that you are having problems.although that being said, i was in china last yr and witnessed with my own eyes the cryo bottle set up being used in a high powered lancer evo 7, it had approx 600hp but when talking to the mechanic and engine builder about the bottle, they dont use it ! what happens is the air becomes so cold in the inlet that ice begins to form, damaging spark plugs and diluting the octane rating of the high strung fuel they were using causing a few monumental blow ups !. cold is good, freezing cold is not good !

its the actuator, get rid of the nissan one

i have a very similar setup to yours but i have the hks actuator.

I have no boost controller and the spring in the actuator holds a min of 1 bar.

Mine peaks at 15psi at 3200 rpm and holds to redline where it dips to 14psi at 6500rpm.

I have no doubts this turbo can run 1.2 bar all day long, i just need bigger injectors...

I dunno, the car has been running perfect since it was on 14psi... only in hot weather did it run less boost which is expected... Since having it done it has been on a couple of dynos just for dyno days etc and didnt pull anywhere near the 244rwkw it had... it doesnt bother me at all as i know it is just a number but the difference between 244 and 200rwkw with an untouched car leads me to believe there may be something wrong with the turbo...

Reflex, thats is exactly what mine did before i would the boost up, would sometimes peak at 15 then hold 14psi to redline... what sort of power did yours make??

its all very confusing but i appreciate all your help guys!

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


  • Similar Content

  • Latest Posts

    • Stock ECU (or more accurately stock tune) absolutely refuses to go over 10psi and behaves like you have seen. The Nistune is the same if it is the stock tune. If the Nistune chip has been tuned, the resulting tune could be literally anything for any combination of parts. The Nistune just makes the stock ECU Tunable.
    • So stock ECU does not like anything above 10 psi?  That Nistune one is just for "try" if it will be any different, I know it need to be tune for that. I know but YOU may know about these problem but i/we dont. They few little Skylines here let alone people who know anything about tham so that is why iam asking here  
    • So now we have a radiator with no attachments whatsoever. It lifts up with a particularly tight spot between the drivers side air box mount and the lower radiator outlet, but if you've got this far you will sort that too. This is the lower mounts with the rad out so you can see where the rubber bushes go, it is a straight shot upwards Done! Assembly is the reverse of disassembly, with blood less likely to be shed.
    • Right, onto the second last trick. The Air Con condenser is mounted to the front of the radiator and stays in the car when the radiator is removed. There are 2x 10mm headed self tappers holding the top of the condenser to the radiator, remove those The bottom of the condenser is attached to the radiator with clips. You need to lift the condenser out of those clips and clear (up, then forward). f**ked if  could work out how to do that last bit with the front bumper on. I hope you can, and you share the trick.  Bumper removal probably deserves its own thread one day once I've recovered the will to live, but basically you need to remove the wheels, front inner guard liners (clips and 10mm headed bolts), the self tapper between the guard and the bumper at the rearmost point of the bumper (same as an R32 that bit), any remaining clips at the top/front of the grill, an absolute bastard design with a plate that holds the top of the bumper above the headlight each side (only 1 bolt which is tricky to get to, but the plate catches 2 places on the bumper and must be removed....carefully!) and push clips between the bumper and guard under the headlight. If you've done all that you will be faced with wiring for the fog lights on both sides and in ADM Q50 RS at least, 4 nasty tight plugs on the driver's side for the ADAS stuff. So, the clips at the bottom look like this on drivers side (looking from the front) And on the passenger side (also from the front), you can see this one is already out Clearance on both of these are super tight; the condenser needs to move up but the upper rad support mount prevents that, and the radiator can't move down far because it is (rubber) mounted. Once you achieve the impossible and drop the condenser off those mounts so it does not stop the rad moving, you are good to go
    • OK, next the shroud needs to come off and there are a couple of tricks. Firstly, there is a loom from near the passenger side headlight to the fans, coolant temp sensor etc and there is no plug to undo.  In my case I was OK to leave the shroud on top of the engine so I just undid the passenger side fan plug and about 10 of the clips which gave enough free wire to put it aside. The fan plugs were super tight, the trick I used was a small falt screwdriver to push down on the release tab, then a larger flat screwdriver to lever the plug out of the fan unit....be careful with how much force you apply! If you need to remove the shroud altogether for some reason you will have to deal with all the plugs (tight) and clips (brittle)....good luck. I removed all of the clips and replaced them with cable ties that I will just cut next time. Also, in the Red Sport / 400R at least, the intake heat exchanger reservoir hose is bolted to the shroud in 2 places with 10mm headed bolts; so remove them (the hose stays in the car; no need to undo it at the t fittings down at the radiator lower mount. Once you've dealt with the HX hose and the wiring loom, there are 3x 10mm headed self tappers holding the top of the shroud to the radiator; remove those.   The shroud then lifts out of the bottom mounts where it sits on the radiator, up and onto the engine out of the way. Simples
×
×
  • Create New...