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Is Is Compressor Surge?

iplen

By iplen,
in Engines & Forced Induction

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t_revz Grand Master

t_revz

Posted
Posted

This basically happens when the engines displacement is too small for the turbo application. What you need to do is think of it a little like this. An rb26 with twin turbos is essentially like having x2 1300cc displacement engines with single turbos on each (which in most cases is too large for the displacement. As you can imagine as you increase the turbo size (say gtrs's, -10's or even -5's) your tubro shuffle, compressor surge or axi-symmetrical compressor stall (what ever the hell you want to call it) will get worse. Hence why almost all gtr's fitted with gtr's or -10's will shuffle at some point in the rev range. Get an sr20 slap on one of the said turbo's to it and you wont see that type of shuffle (2000cc displacement engine running a turbo more efficient for its displacement).

Now on how to try cure it. You can increase tge turbine housing to try slow the compressor down, (or use smaller turbos), but here you will run into another dilema, LAG. You can increase the engine displacement (why you generally wont here shuffle on a rb30/26 engine with -10's etcetc). You can try have your tuner tune it out, baffled turbo pipes etcetc. But the most effective way ive found is to use a 3 dimensional boostcontroller. Its basically an electronic controlled solenoid (by the ECM) with an rpm input ( which alters the duty cycle of the boost control valve as the RPM changes), and a throttle position sensor input (tells the turbo how much power the drive is demanding and essentially tells the turbo how much air the engine is capable of swallowing to avoid such a surge). 9 times out of 10 this will work.

p.s ( i love brackets)

just finished re-reading HPI 126. was like de-ja vu reading this 20 mins later on. even same examples... except for the brackets

J - Rad Veteran

J - Rad

Posted
Posted

just finished re-reading HPI 126. was like de-ja vu reading this 20 mins later on. even same examples... except for the brackets

Thought the same thing. Maybe Martin Donnon has a second account hes using on here?

Rolls Grand Master

Rolls

Posted
Posted (edited)

can u put more preload or tighten the bovs?

i think the bov's are opening on light throttle load - dont know why tho

The bov opening on low throttle (the stock ones do) will actually fix mild compressor surge.

Is now all but gone, Ignition timing appears to have shifter (car was feeling really slow) anything upto 15degrees retarded (yes really) barely does it now

Running too much retard will cause the turbos too boost much earlier and also cause it.

Edited by Rolls
  • 1 month later...
iplen Mentor

iplen

Posted
  • Author
Posted

Time resurrect this.... because it is BACK!!!! Timing is now spot on 15deg, the turbo shuffle went, and with no changes made it has started to get turbo shuffle again.... But now.. It also has a couple of flat spots, and after a while of normal driving will really need a couple of decent runs to clear it out and get it going properly, it is not that long since I ran injector cleaner through it (not because it was playing up, just figured it could be worthwhile) but was still before it was running perfectly that the injector cleaner was in it. So all that has happened since it was running perfectly is that it has been driven to and from work, it has had a couple of little blats here and there but the thing gets babied 98% of the time.

I have not ruled out the possibilty of a cam being a tooth out, but is this likely to cause the probs I am getting?

iplen Mentor

iplen

Posted
  • Author
Posted

Light throttle application, normally going uphill, the only way to stop it is to get off the throttle all together and start again, pretty much anytime you try to maintain a speed going uphill it does it. Has standard ECU, does not seem that accelerating will solve it

R31Nismoid Grand Master

R31Nismoid

Posted
Posted

I've had GT-SS's, I now have -5s - no comp surge at all using factory piping and BOV's.

I've even used the stock ECU with GT-SS's on 15psi and it was fine.

Sounds like you need to visit a dyno and see what is going on. Timing/AFR etc.

Also you kinda do need a tune dude with larger turbos...

Wheezy Mentor

Wheezy

Posted
Posted

Yeah, have the PFC and am working to get approval for the tune... Just seems funny it went away for 2-3 months...

Weather is starting to change now that we are in a new season, probably effecting the way the turbo is making positive pressure. Air density, temp, precipitation changing etc will all have an effect...

Nee-san Grand Master

Nee-san

Posted
Posted (edited)

I get the feeling people are crawling up hills using 1.68% throttle especially at higher speed.

Throttle body not open ?

That's ok here is a nice big high speed high load condition for you Mr Rb26.

WEEEEEEEEEEEEEEEEEEEEEEEEE.

WOO WOOOOOOOOOOO

"Come on Thomas, you have to help Percy up the hill" Said the Fat Controller.

Edited by Nee-san

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