Rb26 2860 -5's Compressor Surge

[Mark-32]

Just wondering if its a common issue when using the -5's on a 26 as I have never heard of it before?

When im in 4th or 5th gear coming onto boost the car sounds like a steam train and it is really bloody loud.

The car is only running one bov on the plenum side of the cooler, and someone told me that this may be the problem???

Its not a major issue but it hapens at about 100-120kph so when im on the highway its pretty constant and its doing it nearly all the time unless your on it.

Motor is a built 26 making just over 320rwkw, boost is at what the actuators are standard, and boost gauge says 0.9 bar

Any help is much appreciated.

[R31Nismoid]

If you have removed the factory BOV's then this is the most common cause.

They 'leak' at low throttle to alleviate this.

Also just to check, do you have 100% factory intake piping?

[Mark-32]

If you have removed the factory BOV's then this is the most common cause.

They 'leak' at low throttle to alleviate this.

Also just to check, do you have 100% factory intake piping?

Oh ok, I have removed the plum back setup and im using a greddy suction kit on the turbo side with the plum back holes blocked up so that may be the cause?

I have a hks bov that is mounted right after the intercooler down under the gaurd?

Do you know how I could stop this without using the stock plum back setup?

[R31Nismoid]

So by suction kit you mean just the POD's?

So still using factory rubber intake (to the turbo) piping?

I believe the comp surge can be tuned out to an extent in some cases - so it's going to be a tough call if your issue can be fixed or not.

I've never encountered such issues (nor any of the cars here in Vic)... reason being all of them run the Factory GTR BOV setup, and most are also running 100% Factory intake/piping setups as well which are all working together to stop this with -5's.

[Mark-32]

No i mean the whole 1300 dollar greddy pipe kit that goes to compressor in let and outlet. Then down into the gaurd on passenger side.

Do you think if i ran the plum back setup it would solve the problem?

[Dale FZ1]

If you've still got all the stock gear, spend an hour or two reinstalling it and let us know. Now I'm interested to find out.

[R31Nismoid]

No i mean the whole 1300 dollar greddy pipe kit that goes to compressor in let and outlet. Then down into the gaurd on passenger side.

Do you think if i ran the plum back setup it would solve the problem?

Ah rightyo - all hard pipes.

Going back to the stocker BOV setup might fix it... might not.

Some people have issues with stock BOVs + hard pipe kit, whilst others do not.

[GT-R32]

I don't have these issues with the HKS kit and stock BOVs, they make their typical somewhat annoying noise LOL.

[Mark-32]

When I first heard the noise when ithe car was on the dyno I thought someone was using a rattle gun near by. Didn't even think it was coming from the car as it was so loud and I had never heard anything like it before.

When doing the initial running in and tuning on the dyno we couldn't run any more boost than what the actuators would produce standard into the engine. The reason for this was because the single in tank 044 pump was only wired in via the body loom and was starting to struggle at big revs causing the car to run lean.

Once we hard wired the fuel pump to the battery it fixed this problem but it still needs 2 external 044's and a surge to be safe.

So do people think the compressor surge will get even worse once I wind the boost up? Or would it improve?

I dont fully understand how compressor surge works, but im under the impression the turbos dont have enough exhaust flow to produce positve boost pressure at the low revs?

If thats the case I would assume that once I run higher boost this problem will get worse as the turbos wont positive boost pressure until later in the rev range?

[GT-R32]

Rattle gun? Sounds like engine knock to me, not compressor surge. Particularly since you're talking about fuel.

Compressor surge is air going back through the compressor... Erm... As it surges on throttle shut off.

[Mark-32]

At the end off this vid you can hear the noise im talking about. Its not knock, I was just asking the question that if i wind the boost up will the surge get worse?

And here is a vid of its first proper run-in pull

[GT-R32]

Oh... WOT surge, not shut off surge. Depending on what's causing it, more boost will definitely make that worse. In fact, it'll probably just surge at the same point except possibly more. That's bloody weird you are getting it with -5s on a RB26. I've never heard of it (but I don't know much). It needs the engine to ingest more (revs come up), ie. the exhaust wheels to flow more, possibly actuator issues/wastegates to even the in/out of the system. Or, like you suggest, maybe the intake is restricting it somewhere throwing off the balance.

Can you describe at what RPM it comes on... I assume it happens reasonably early on then the engine 'catches up' and ingests the air which balances it?

[R31Nismoid]

^ RPM wise i'd say around 3000-3500rpm at a guess.

It's only surging in lower RPM as described. Adding boost wont affect it/make it worse.

I say this neccesarily because it's all in the "building" stage of boost, you are yet to reach your peak pressure and the surge is occuring WELL before.

It's not surging anywhere near peak boost (as advised) so this is a clear and reasonably common problem once BOVs/intake piping is altered.

[Mark-32]

^ RPM wise i'd say around 3000-3500rpm at a guess.

It's only surging in lower RPM as described. Adding boost wont affect it/make it worse.

I say this neccesarily because it's all in the "building" stage of boost, you are yet to reach your peak pressure and the surge is occuring WELL before.

It's not surging anywhere near peak boost (as advised) so this is a clear and reasonably common problem once BOVs/intake piping is altered.

Yeah thats right it happens at around 3 grand as its building boost then it sort of clears itself so to speak.

I guees i will just put up with it then, as i really cant be farked setting up the plumb back setup again because its so tight on the turbo side of the engine.

When just cruising on the highway its near impossible to stop the car doing it unless your sitting in a different part of the rev range, and that would have the car doing about 140-150kph.

Its mainly for the cops that I was keen to fix it, because all it would take would be for a cop car to roll past and hear it as its so loud and bingo your pulled over with the bonnet up.

Thanks for everyones help, i was just very interested to know what was causing this and if it could be rectified.

I also seems that though there is heaps of info in the forums here on the dash 5's on 26 engines, there didn't seem to be any info on comp surge. I would have thought that with the amount of people running these turbos that the problem would have been more common, and that there would have been more info.

[R31Nismoid]

Probablem is though mate it's actually hurting the cars performance.

If there was no surge going on boost would be raping up faster etc.

I'd be surprised if you didnt see evidence of this on the dyno curve (if the runs starts from 2000rpm say).

Most people are running stock BOVs and intake piping... hence they don't have the problem

[Mark-32]

Probablem is though mate it's actually hurting the cars performance.

If there was no surge going on boost would be raping up faster etc.

I'd be surprised if you didnt see evidence of this on the dyno curve (if the runs starts from 2000rpm say).

Most people are running stock BOVs and intake piping... hence they don't have the problem

Well heres the dyno run, not sure if it shows any evidence of the comp surge on the dyno curve as im not 100% sure whats what.

Im interested now to see what you think r31nismoid.

[R31Nismoid]

Well if the scaling was better you'd be able to see much better - but from the lower end you can see the comp surge hurting around 72km/h on the graph where its rising and then stops for a bit.

Mine looked exactly they same when i had my 600hp GT30 comp surging around the 2000-2300rpm mark... Graph started to come up, then backed off, then kept going again.

If both axis was scaled better it would be far more obvious (along with a boost plot, nice heavy ramp rate etc). I'm a bit surprised JPC left it like that to be honest.

[R31Nismoid]

Honestly to me - it would be a problem worth fixing, especially considering how easy it is to fix

How much boost was running?

Is the motor built?

[WHITER33GTS-T]

My RB25 did exactly this same thing when it had the twin turbo setup. It was due to the turbos forcing more air than the engine could take at low rpm so the air choofed back thru the filters. At top end this problem was gone and made good power. (399rwkw @ 17psi)

I changed from the twins to a T51r and the problem was gone. I was told it will damage the turbos as the exhaust wheel turning one way and the extra air trying to turn inlet wheel the opposite....

[Mark-32]

Honestly to me - it would be a problem worth fixing, especially considering how easy it is to fix

How much boost was running?

Is the motor built?

Its only running 0.9 bar which is was the actuators are standard.

Its been built to run some decent boost though the main specs of the engine are

TOMEI 260 Deg Cams

Greddy Adj Cam Gears (set on zero)

Nitto I beam Rods

JE/Nitto 20th piston kit

Nitto oil pump

nitto crank collar

acl main conrod bearings

ARP head stud kit

ARP Main studs

Gates timing belt

Nitto Drag 1.2 head gasket

Greddy Oil Cooler

10L RWD Sump

vi-pec

bla bla bla