Jump to content
SAU Community

Recommended Posts

Hi guys. I have a 33 with 55000km.

mods include:

-fmic

-3inch exhaust turbo back

-bleed valve

-high flow t28 turbo (ball bearing, steel wheeled)

-k&n pod.

Heres my problem. Ever since installing the high flow turbo i bought from a guy on SAU it over boosts and spikes to 16 or 17psi.. which causes fuel cut because the afm is maxing out. A tuner told me that there is too much flow from my exhaust and need to put back my standard dump pipe. Another ive noticed also is my waste-gate (the valve that opens) is stuck open about 3mm when the car isnt even running!.. its meant to be tight shut.. (im thinking the centre of my turbo is different to that of a stock 33 one and i am using an actuator from a 33.. thus causing the constant opening).

so my question is.. why's it over boosting pretty much..any thoughts guys. Please?

Link to comment
https://www.sau.com.au/forums/topic/277953-rb25-has-me-all-confused/
Share on other sites

You can never have too flow away from the turbo.

If the wastegate is partially open, that should reduce the max boost, because some of the exhaust gas is by-passing the turbine wheel (which is how the controller limits boost). You could have the wrong wastegate controller - actuator arm too long.

Do you have an aftermarket boost controller? Where does the wastegate controller get its boost signal from?

a highflow of a t28? are you sure?

a t28 is typically a tiny turbocharger, the GTR twin turbos are t28s

so if you have a GTR single (from one of the twin) on your GTST, even hiflowed its tiny

do you have pics of the housing?

A couple of things to maybe look for.

If the wastegate is open just a tiny little bit, the turbo could still make boost but it may take a lot longer to build up... If the gate doesn't open at all from the 3mm e.g it is fused for whatever reason in that spot, could that cause the overboost as the turbine is copping a lot more vented exhaust gas than needed?

Is the diaphram in the actuator still in tact or is it damaged? I had a damaged actuator on one turbo that was supposed to run 10psi and spiked up to 14. Maybe get ur hands on another actuator and test that?

I have also heard of lesser quality high flow turbo's not being able to vent the exhaust gas through the wastegate (coz it's too small) enough even when it is working properly also causing overboost. Not entirely sure how correct that could be but I have heard. I have read when running higher boost through a high flowed stock turbo sometimes it doesnt hurt to enlarge the gate and flap over it.

If u have an adjustable actuator rod, try adjusting that also to see if it makes any difference.

Just a couple of things to try out, start at the cheapest and work ur way up lol.

mate make shure your auctuator is bolted on corectly and that if you loosen the 2 bolts that support the auctuator try and move it that little bit that it needs to close......

and turn down your boost controller.. or bypass it

I thought turbos on series 2 r33's are t28s? well its a standard 33 thats high flowed bought from a guy on here ans receipts showed it cost 1500 bucks done by mcg in melb. About the "never have too much flow'.. i think ur actuator works on sum sort of back pressure so u always need sum. Anyway, one guy said the wastegate is bonded to the housing.. no, just stuck open a bit but able to move from that point. i think the right thing to do would be try out another actuator or shorten it some how. I worked out the arm is about 2-3mm too long :banana:;) .. the boost controller is aftermarket one from ebay.. it was one that sau guys loved but only 30 bucks.. turbosmart or sumthing like that...

thanx heaps guys

I thought turbos on series 2 r33's are t28s? well its a standard 33 thats high flowed bought from a guy on here ans receipts showed it cost 1500 bucks done by mcg in melb. About the "never have too much flow'.. i think ur actuator works on sum sort of back pressure so u always need sum. Anyway, one guy said the wastegate is bonded to the housing.. no, just stuck open a bit but able to move from that point. i think the right thing to do would be try out another actuator or shorten it some how. I worked out the arm is about 2-3mm too long :P:) .. the boost controller is aftermarket one from ebay.. it was one that sau guys loved but only 30 bucks.. turbosmart or sumthing like that...

thanx heaps guys.. got sum fotos below. ps the high flowed one is obviously on the right

post-61475-1246878772_thumb.jpg

post-61475-1246878937_thumb.jpg

Edited by sparco33

had the same problem with my BB high flow on my 33. tried to set it to 12 psi and wanted to go to 17 psi no matter what i did. had split dump so go a 3" single dump, still did it. took it off and opened up the waste gate from 24mm to 28 mm to get better flow, still did it. cryed myself to sleep until my tuner said that sometimes the 2j's need a reducing plate in the exhaust to control boost spikes. so tried it . put a plate just before the cat (on the flange between two gaskets)with a 2 1/2" hole in it and it worked, boost only went to 11psi at top end. i put it down to not enough back pressure and the gasses were finding it easier to go out the exhaust wheel instead of the waste gate flap. another problem can the car is running to rich, this will also cause the same problem

had the same problem with my BB high flow on my 33. tried to set it to 12 psi and wanted to go to 17 psi no matter what i did. had split dump so go a 3" single dump, still did it. took it off and opened up the waste gate from 24mm to 28 mm to get better flow, still did it. cryed myself to sleep until my tuner said that sometimes the 2j's need a reducing plate in the exhaust to control boost spikes. so tried it . put a plate just before the cat (on the flange between two gaskets)with a 2 1/2" hole in it and it worked, boost only went to 11psi at top end. i put it down to not enough back pressure and the gasses were finding it easier to go out the exhaust wheel instead of the waste gate flap. another problem can the car is running to rich, this will also cause the same problem

got it in 1 this is what will happen when u pump up perssure in a hight flow you either put in a reducer plate or weld up wastegate and mount one externaly its simple air flow dynamicy stuff (uhh hu) the air will go the easiest path and your wastegate cant flow that much check that they machined out the wastegate port and fiteed a lager flap. i hate high flows tsk tsk you can get a plain bearing garrett for not much more and they can be low mounted to i got a 3576 bb unit running same boost as a mates "fully sick hi flo" and i leave him behind while layin marks cost a bit more but i know what i would rather

Edited by sick_skidz

yeh, wouldn't put one in now without the supporting mods. i run it on stock injectors for about 5 months but now have the bigger injectors and PFC. was 307rwhp with stock injectors and now 355rwhp @15psi with skids too :)

Sparco33. You can always bend the actuator arm to effectively shorten it. A bit ghetto, but it should work. Putting in an exhaust restrictor may indeed work, but it's treating a symptom that the small exhaust housing combined with small wastegate can't flow enough efficiently.

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

    • Hi guys, Making some space/cleaning up. A whole heap of random OEM R33 GTR parts and other random bits and bobs. I will update this thread as I go. Parts are located in Moorebank NSW 2170. Pickup preferred but will post at buyers expense. Prices are negotiable. If they don’t sell it will go in the bin. Item 1: BOV return pipe. $40 Item 2: RB26 cam gears. $20 Item 3: R33 GTR torque split, oil temp, boost centre gauge. $100 Item 4: RB26 fuel rail x 2. $20 each Item 5: RB26 Recirc valves. $50 Item 6: OEM upper front arms. $20 Item 7: Royal Purple Max Gear 75w-140 1 quart/946 ml x 5. $50 each or 5 for $200. Item 8: OS Giken 80w-250 diff oil 1 litre. $25 Item 9 Eibach springs. ers-11-140-60-0140. $100 https://www.streetfx.com.au/eib140-60-0060-eibach-ers-140mm-length-x-60mm-id-coil-over-spring?_ga_campaignid=22235933977&_ga_adgroupid=180146800292&_ga_keyword=&_ga_device=m&_ga_target=pla-295238231169&_ga_locint=&_ga_locphy=9071723&_ga_matchtype=&_ga_network=g&_ga_device=m&_ga_placement=&_gcl_id=CjwKCAjwlt7GBhAvEiwAKal0cvkVE_hstv24cDiaICsIk1oznH9zAoJf3By6vR3Tpe7jmByqM6JFHBoCZYAQAvD_BwE&gad_source=1&gad_campaignid=22235933977&gbraid=0AAAAADPiTbo1xAuvnjIWWYnezivf-BUSY&gclid=CjwKCAjwlt7GBhAvEiwAKal0cvkVE_hstv24cDiaICsIk1oznH9zAoJf3By6vR3Tpe7jmByqM6JFHBoCZYAQAvD_BwE    
    • That's kind of what I was getting at saying you'd be here soon regarding length etc being able to add additional restriction.  My assumption (possible donkeys of you and mption) is that the length of hose to an oil cooler, and back, isn't going to be that huge of a loss. Typically you're talking about 1.5m of total length. And so far everyone in our world hasn't had issues with oil not being able to get to a cooler and back, it's more been, how the heck do we get the oil out of the head and back down to the bottom? I'd nearly hazard a guess the biggest issue people have with oil cooling and oil supply, is being able to get the heat out at the cooler itself (not enough air flow, too small of a cooler etc) Also, when people mount them wrong and make really awesome air traps so they've dramatically diminished the cooling capacity.
    • I will rebutt this and the preceding point from Dose....but without doing any calcs to demonstrate anything and without knowing that I am right or wrong. But... The flow capacity of a fluid transfer system is not limited by the smallest orifice or section of conduit in that system, unless it is drastically smaller than the rest of the system. OK, I use the word drastically perhaps with too much emphasis, but let's drill down on what I really mean. The flow capacity of the system is the result of the sum of the restrictions of the entire system. So, to make an extreme example, if you have a network with 3" pipe everywhere (and let's say a total length of only a few metres) and that 12mm ID restriction of the oil filter connection being the obvious restriction, then for any given amount of pressure available, the vast majority of all the pressure drop in the system is going to occur in the 12mm restriction. But.... increase the length of the 3" pipeline to, say 1000m, and suddenly the pipe pressure loss will likely add up to either be in the same order of magnitude, possibly even exceeding that of the 12mm restriction. Now the 12mm restriction starts to matter less. Translate this to the actual engine, actual oil cooler hose sizing, etc etc, and perhaps: The pressure loss caused by flowing through the narrow section (being the 12mm oil filter port, and perhaps any internal engine oil flow pathways associated with it) is a certain number. The pressure loss through, say, -12 hoses out to the cooler and back is negligible, but The pressure loss through -10 hoses out to the cooler, at the exact same length as the above, starts to become a decent fraction of the loss through the 12mm stuff at the filter port. Maybe even it starts to exceed it. I could actually do these calcs if I knew 1) how much oil was actually flowing in the line, 2) gave enough of a f**k to do things that I hate doing for work, voluntarily for a hypothetical discussion. Anyway - I reiterate. It's not the narrowest port that necessarily determines how much it can all flow. It is the sum. A long enough length of seemingly fat enough pipe can still cause more loss than a semmingly dominant small bore restriction.
    • To pick up what Dose is putting down. Not a lot of point running a huge hose if the motor is still restricted to the smaller size... It's only capable of flowing so much at that point...   *Waits for GTSBoy to come in and bring in the technicalities of length of pipe, and additional restriction from wall friction etc etc*
    • Hooley Dooley these things have some history! If i sell them they will need a certificate of providence to prove they have been in the hands of verified RB20 royalty! They have been stored in a plastic tub, away from sunlight and moisture. They are in mint condition. And they will stay that way, as i have sprung the money for a set of shockworks coilovers. I'm just working on getting them in at the moment, after rebushing the rear of the car, and while the subframe was out i welded in the GKtech reinforcement bracing as well.  They will get a workout at Ararat King of The Hill in November. I ran 48s on the short course there a few months ago, and i am hoping with new bushes and shocks in the rear i can launch a bit harder. There was a fair bit of axle tramp when i tried too hard off the line. a few of the corners had dips mid way which also made the car feel a bit unsettled, hopefully this will help there too.   
×
×
  • Create New...