Jump to content
SAU Community

Aww.. Pls Help Me.. Turbo Surging Under Load.

R32-PSH77

By R32-PSH77,
in Engines & Forced Induction

 Share

Recommended Posts

R32-PSH77 Enthusiast

R32-PSH77

Posted
Posted

Hey guys, i really need a hand trying to get my car not to surge under load..

I recently installed a larger turbo to my car of a T3/T4 nature.. using an Rb25 exhaust housing bored out and steel wheels with a t4 compressor wheel 60mm blade. This setup is running on my Rb20 currently not runing a After market Ecu as im still shopping for one. it has the supporting mods. However my problem lies with Labouring/Load of the engine.

For Example. High way Driving 5th gear around 100km/h depress accelerator and slowly makes around 5psi before it start to splutter boost needle rapidly going back and forth. You can tell its suffering. its not coils.. and i hardly doubt boost cut when it happens at only just 5psi..

the same affect can be done from climbing hills in 4th.. under load.

I REALLY REALLY want to enter the QLD dyno day thats happening on the 24th of this month thats only days away.. but..

If the car is driven under load in 4th gear like they will do at a dyno im afriad it will just surge.. and not make any power.. and the car will have to be pulled of the dyno.

I guess i could miss this dyno if its not logical to try it.. or ther is no fix for this problem..

Any help would be greatly appreciated

Regards, Adam

Beer Baron Grand Master

Beer Baron

Posted
Posted

i would say it's the fuel cut. there is no such thing as 'boost cut'. it doesn't cut fuel based on boost, it does it based on airflow. so a larger turbo could be flowing the same amount of air at 5psi as a small one is at 14psi. so my solution is get a new ecu, or have the stock one re-mapped with the fuel cut removed.

blind_elk Grand Master

blind_elk

Posted
Posted

It's compressor surge - the engine simply can't ingest the increased fuel / air charge being supplied by the larger turbo.

You had better find that aftermarket ECU pretty quick if you want to impress on the dyno.

discopotato03 Grand Master

discopotato03

Posted
Posted

Usual "high flow" issues , the "turbo" sounds like it was put together by someone with no idea . Doing it with factory engine management was not a good idea because the std system only knows how to deal with standardish states of emmision tune .

Slide knows plain bearing Hi flows so talk to him , a good price for a known quantity . If you show him your turbo he can explain why its giving you grief .

Cheers .

Dale FZ1 Veteran

Dale FZ1

Posted
Posted
It's compressor surge - the engine simply can't ingest the increased fuel / air charge being supplied by the larger turbo.

You had better find that aftermarket ECU pretty quick if you want to impress on the dyno.

I agree on the point of it most likely being compressor surge.

But not with you on the new ECU.

The surge is related to the physical capacities of the engine vs compressor. Changing an ECU won't cure surge. But obviously it will give him the freedom to tune decent AFR + ignition once the surge issue is corrected. ;)

R32-PSH77 Enthusiast

R32-PSH77

Posted
  • Author
Posted

I never thought it would run Any good with the standard ecu. im currently in the market for an aftermarket ecu.. still weighing up my options. i was just hoping it to actually just make a reading so i can compare it to the dyno tuning when i finally get my aftermarket setup. i can have the turbo on as low as 7 psi.

obviously though as i thought its a Rb20 " beinge to small" to push the turbo problem.. something thats not really gonna be easy to fix. oh wells.. i'll just sit and watch.. Maybe next time i can enter.

Thanks for your help anyways guys.

Cheers, Adam

Dale FZ1 Veteran

Dale FZ1

Posted
Posted
obviously though as i thought its a Rb20 " beinge to small" to push the turbo problem.. something thats not really gonna be easy to fix.

Adam just as a point of reference, check this page: http://www.turbobygarrett.com/turbobygarre...bo_tech103.html

which gives a bit of technical info on what causes surge.

Basically, it's not the case that the engine is too small to push the turbo, rather it is too small to ingest the turbo's output once the turbo is allowed to crank up to a certain pressure ratio (ie. boost level).

And yes, once diagnosed it's not easy to fix without some $$. Ported shroud housings and BOVs can/do mask the event, but you do need to be in the ballpark first off. Sometimes not too easy when you're dealing with high flows either.

Best thing is there are some very knowledgeable traders out there with a wealth of proven high flow specs so you're not out on a limb. :P

From previous posts you should be able to tootle around with a lower boost level without coming up against the surge issue. Let us know how it works out for you.

cheers

Dale

  • 3 months later...

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

    • GoHashiriya
      R34 Skyline Sunroof Won't Tilt/Vent

      By GoHashiriya · Posted

      Actually, that's not entirely true. It's also the same motor in the 1st gen Nissan Cube but they're rare as hen's teeth.  
    • Duncan
      Unknown sound similar to BOV on positive boost with partial throttle RB26

      By Duncan · Posted

      Yeah it is always worth testing and balancing actuators out of the box, just set the pressure regulator on a compressor very low (eg 5 psi) and increase it slowly to see when they both move.....unfortunately while you may be able to adjust the length of the actuator rod to minimise any difference, the actual pressure they move from is not adjustable so you need a well matched pair. And yes, the VCAM is probably contributing; the earlier in the rev range they come on boost and the slower the revs build (I think your demo was in 5th), the more you notice it.  Driving at WOT through 1st, 2nd, 3rd etc you will probably never hear it as any shuffling starts and is over super quickly
    • Dose Pipe Sutututu
      Shoota's R33 GT-R RB30/26

      By Dose Pipe Sutututu · Posted

      oh they were with that motor, you need to remove the engine to change the spark plugs (don't have to, but it does make it easier)
    • nouveau_poor
      Unknown sound similar to BOV on positive boost with partial throttle RB26

      By nouveau_poor · Posted

      I certainly fall into the annoyed camp, but glad to hear that if it's happening at low boost then I'm not likely going to blow a turbo and end up with metal shards in my oil. Just feels like it prevents me from really driving it without hesitation and "peak" performance. Wonder if it's the VCAM, it did an impressive job of shifting the torque curve and faster spool, but maybe now it's "too fast" and there's too much air for how open the throttle is.  Based on some other threads, will also do some reading on synchronizing the actuators. They are the default actuators that come on the Garrett's and I would think they would be set the same coming from the factory, but if the turbos don't actually work exactly the same way at the same time as previously mentioned, it would be worth making sure the actuators are actuating together properly
    • GoHashiriya
      R34 Skyline Sunroof Won't Tilt/Vent

      By GoHashiriya · Posted

      I went down this rabbit hole before, ended up sourcing a motor from the UK (I'm in Japan) which also didn't function correctly. With the original motor, I disassembled it and reassembled it and it works somewhat, sometimes. What I could deduce from all my screwing around is that there is calibration of the gears on the inside of the motor and two ramps on the main gear which activate switches that operate the motor and move the sunroof either to retract into the roof or tilt. Where I got stuck was that, it seemed in my case that one or both of the switches that are activated by the ramp on the gear did not always activate and thus the motor did not move, causing it to sometimes not retract or tilt (apologies, I've forgotten which way it didn't work.).  Of course this part is discontinued at Nissan now, it's the same part in the S15 but no other models. I also contacted the manufacturer of the component for schematics - forgot the name, they're based in Gifu - but they declined to share the information due to being bound by an NDA, sadly. Looking through my pictures now, it seems I last had a crack at this in 2022. See, I so kindly wrote "open" and "close" next to the switches. If you figure it out, please do tell me. Those little switches, with the red buttons may need to be replaced.
×
×
  • Create New...