Jump to content
SAU Community

A Couple Of Niggling Rb26 Questions,very Laggy...

groper

By groper,
in Engines & Forced Induction

 Share

Recommended Posts

groper Explorer

groper

Posted
Posted

ok, just a couple quickies in relation to a modded r33 gtr... its running pfc, stock turbos with steel wheels @19psi, stock bovs and a bigger apexi intercooler... car was already modded when purchased recently so i dont know exactly how its all been done. also, im not sure if the setup is working as best as it could be... the car makes good power when turbos are spooled but lags more than i believe it should after a gear change at WOT. i have a suspision that the tubos stall (or surge?) when the throttle shuts when shifting, as i hear a `ptrrrrrrr' (slowing down) then spool up all over again, then feel the accel again...shouldnt they already be spooled and whine almost immediately?

1. how is boost controlled (by what mechanism ie. bleed valve etc) on a stock rb26? could there be room for better response with the $22 boost controller...

2. what does compressor surge sound like? Is it like a 'ptrrrrrrr' sound im getting?...(not just the ptshhhhhh of the bov) and how can i fix? BOV issues maybe?

id love to eliminate some of this lag, any suggestions?

groper Explorer

groper

Posted
  • Author
Posted
Groper,

What RPM are these laggy WOT gear changes occurring at ?

flat bikkies mate, it does it even at 7000prm+... only time i can keep them spooled is if i dont shut the throttle completely, like when accel full boost, back off a LITTLE for a sec (small bov sneeze) then foot back down again in same gear. i get what id call `normal lag` to recompress all the intake plumbing but at least i can hear the whine almost immeditately telling me they didnt spool down...

if i back off COMPLETElY in same gear fully boosted for a sec, (take right foot OFF) same prrrrrrr sound, and the turbos slow right down, when put foot down again, i can hear them spool all the way up again and i get my very laggy problem...

is this normal?

groper Explorer

groper

Posted
  • Author
Posted (edited)

yep, but perhaps they open too late maybe, or not capable to release/flow enough volume perhaps?

i thought it might be the bov`s, but read on here some people reckon they get less lag without bov`s at all. or block them off???

failing that, i think it might be the boost controller not closing the wastegate quickly enough after a gear shift? how is the wastegete(s) controlled on a 33GTR? new car, im learning still...

what you think???

Edited by groper
  • 4 years later...
SiR_RB Grand Master

SiR_RB

Posted
Posted

I'm getting the same problem with my car lately on Hi boost @18ish psi,

Running -7 turbos, and greedy profec b spec 2 boost controller. Never had a problem with lag/flat spot between high rpm gear changes but lately it's started

Even tried turning my gain and set gain down still no luck, car doesn't even chirp 2nds anymore cos of this delay,

Anyone know what may be the problem?

Ps. It doesn't do it on low boost @14psi

Room42 Proficient

Room42

Posted
Posted

If the throttle is closed at revs this is what happens... open bov means the turbo will gently slow down. Closed bov means the turbo will rapidly slow down... there is more to it but this is the basic scenario

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

    • GTSBoy
      R34 GTR running rich and noisy turbo coincidence

      By GTSBoy · Posted

      Put a fuel pressure gauge on it. Replace the turbos. Probably completely separate issues.
    • Dose Pipe Sutututu
      R34 GTR running rich and noisy turbo coincidence

      By Dose Pipe Sutututu · Posted

      CAS maybe?
    • silviaz
      Recomended Coolant For Gt T R34

      By silviaz · Posted

      What copper washer do you guys use on the bleeder bolts? The existing one I have I had no idea where to find it in a local store, I did buy some online but that are only 1mm thick whereas my old one is 2mm+ thick and when I put the new washer out and squeeze the top radiator hose I can hear a bit of air but not with the old one. Does this matter? The new one doesn't leak, but the inner diameter is a bit loose whereas the old one threads on the bolt.
    • donut_kng
      R34 GTR running rich and noisy turbo coincidence

      By donut_kng · Posted

      Howdy all, after being out a few weeks ago on a spirited drive in my GTR I have 2 issues that oddly have appeared at the same time. Whilst accelerating quickly through the gears all of a sudden i’ve lost power at the top of third gear (below redline around 6000rpm) for no obvious reason.    From that point onwards the car has been running rich on idle, won’t really rev under load without a ton of black smoke and the odd backfire, and dying as a pull up to a set of lights unless I keep the revs up around 1500rpm. In addition when shutting down the car that same night (I was 10 minutes from home) I noticed one of the turbos was significantly noisy on wind down when shutting off the engine. After letting the car cool down overnight it starts up fine, although once it gets to temp the revs start to creep up and down, the exhaust is darker than it should be and it also sounds like it’s running rich (fat note) I’ve put a new set of plugs in it - no change, the old plugs all seemed OK with two of them being somewhat richer/fueled up than the other 3 with 1 being borderline. I’ve smoked tested the intake system via the front of the Turbos, found a split vacuum hose going to the factory boost gauge sender, which I have since replaced.  Also found another leak on the gasket coming off the rear turbo outlet, have also replaced this. After fixing both of these leaks - still have the running rich issue. I’ve also tried another pair of AFM’s - no change here After pulling off the front turbo intake pipes, there is obvious shaft play in the front turbo, which now hisses loudly on light revvs although I can’t see why this would make the car run funny even under idle. I’m curious to know why it’s running rich before I potentially replace/rebuild turbos. The car is completely stock <50,000kms  other than an exhaust. Oil and coolant are all clear. I haven’t bothered with coil packs as it looks like they won’t be the issue due to condition of the plugs. Any help appreciated as I cry myself to sleep!
    • Rezz
      R34 4 door side skirt identification

      By Rezz · Posted

      No probs at all. I used to love trying to dig up obscure info for those in need where possible going back 20+ years on SAU.  I did have another look and couldn't come up with any closer match. I'm leaning towards those skirts in your first pic are custom fitments, cut down/extended or from another car entirely and modded to fit an R34 sedan. I would've thought someone in Japan had them and taken a photo at some stage over the last 2 decades but there's nothing. Someone out there must know surely.
×
×
  • Create New...