Jump to content
SAU Community

Rb26, -5 Turbos, Boost Creep - Common?

black bnr32
 Share

Recommended Posts

black bnr32 Community Regular

black bnr32

Posted
Posted (edited)

Morning ladies and gents,

I'm troubleshooting some massive boost creep on my rb26 with -5s. I have not finished testing, but I am curious if others have experienced boost creep on a -5 setup. Is it common? Are we near the mechanical limits of boost control on this setup? I do not see many posts on this topic, so I suspect we are not near the limits.

Edited by black bnr32
Link to comment
https://www.sau.com.au/forums/topic/427505-rb26-5-turbos-boost-creep-common/
Share on other sites
scotty nm35 Grand Master

scotty nm35

Posted
Posted

I doubt it, you are close enough to maximum best torque anyway, perhaps 24-25psi...

Do you have split dumps or something? Any porting done in the manifold or turbo opening?

Is the top end tuned? A lack of timing and excess fuel can raise boost like that.

OoskylineoO Experienced

OoskylineoO

Posted
Posted

I doubt it, you are close enough to maximum best torque anyway, perhaps 24-25psi...

Do you have split dumps or something? Any porting done in the manifold or turbo opening?

Is the top end tuned? A lack of timing and excess fuel can raise boost like that.

^ +1 on dump set up.

Actuators will not be the cause for boost creep, you get boost creep (generally at higher RPMs) because the flow of exhaust gas entering the turbine housing can not physically exit quick enough for whatever reason, i.e, turbine housing too small/restrictive, wastegate outlet port too small/restrictive, bad dump pipes or tune.

I would be looking into the tune or dump pipes, had a mate with similar issues on his XR6 where he tried everything to fix the boost creep, turns out he overlooked the dump pipe, even with the larger port and flapper upgrade, the problem was a poorly designed dump pipe causing it, WG flap could only travel a short distance before it hit the divider. Changed his dump and fixed his problem straight up.

black bnr32 Community Regular

black bnr32

Posted
  • Author
Posted

My head, stock manifolds, turbine housings, flapper ports, and tomei bellmouth dumps are all gasket matched. My top end definitely could use some tuning. I was surprised how little the flappers move when testing them. Like 25 degrees at 20 psi

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

    • PranK
      Chris' Toyota Mark ii JZX110

      By PranK · Posted

      This looks great! Awesome to have the 5 speed with an LSD in this. The Recaro's look like SR2's or SR3's. It's a shame they've been retrimmed as they would have looked sweet in their original colours. I think I'd want my agent to be a little more up front and informative too. I've never imported but I reckon it would make me a little nervous, so the more info the better.
    • soviet_merlin
      Duncan's V37.......race car?

      By soviet_merlin · Posted

      Thanks for doing that Duncan! Makes you a good person in my books. We don't get kangaroos or wombats here. But we have bats and it's similar. AFAIK it's often the mums with a baby attached that get hit because they drop lower when starting from a tree. If you hit an animal, check on it. https://www.ifaw.org/au/resources/wildlife-rescue-app An app to get the closest wildlife rescue contact.
    • Murray_Calavera
      Jacks that fit under GTR lips that can reach the subframe?

      By Murray_Calavera · Posted

      My dream is also to have a proper hoist, but I don't think it will ever happen. My quickjack is probably as close as I'll ever get, it really is very good though. 
    • Duncan
      Duncan's V37.......race car?

      By Duncan · Posted

      Yeah we keep on in the dailies, it is pretty poor how many animals get hit and the driver leaves without checking....have saved a couple of little ones over the years. Bit of a gruesome job though, pouches generally need to be cut open because they are so tight and often the joey doesn't realise mum is gone so they are still locked onto the teat. I checked the modules in front of the DS wheel where an oil cooler should go.... There is the radar unit - that can go for race use) One of the 2 HX water pumps, the silver cylinder. That needs to be kept but might be able to be relocated But the bad news, the big computer mounted vertically in front of the wheel (blocking any potential air exit) is the electric steering computer. That is required until/unless i do a hydraulic steering conversion, and in CAD based modern car design it is not like I can just pop a big unit like that somewhere else (plus the loom would be too short anywhere else too). So, the passenger side is OK to clear out (just use a smaller washer reservoir, potentially elsewhere), but the DS no beuno
    • Duncan
      Chris' Toyota Mark ii JZX110

      By Duncan · Posted

      Well, all the best with the new camry It was interesting to hear about the UK process, it is generally a lot more streamlined here with a shipping agent looking after all the import side (noting the exact final price can still be a surprise.....) and I've used a few different brokers on the japan (or US) side, and never had any trouble with any of them....luck of the draw I guess. You mentioned you didn't get the auction sheet (understandable since you bought it from a dealer, not auction), but I always try and get hold of that because they are pretty thorough. I've imported 2x R grade vehicles over the years and both were fine, repairs in Japan are pretty thorough compared to here in Oz.
×
×
  • Create New...