No Idea What To Do Now

[Sammy34]

2 months ago I decided it was time to upgrade my turbo and supporting mods. My car had been suffering from compressor surge. So I decided upon a hypergear hiflow turbo, 550 siemens injectors and z32 AFM. The install was done on the car but during the first lot of dyno time the car had serious issues with compressor surge/bad batch of fuel and bad dyno conditions. And further down the track we solved a few boost leak issues the car was having.

Since then every part of the car has been gone over witha fine tooth comb by my mechanic. Everything has been checked up until pulling apart the engine and checking internals. My mechanic has and tuner has spent hours off the clock trying to tune the car to the best of there abilities. They have informed me that the turbo is jsut not suited to the engine. The turbo to my knowledge now is the hypergear g2 profile.

All in all im extremely frustrated with the outcome as anyone else would be. After running some engine cleaner through the engine it managed to get 207rwkws and 1200lb of torque, the turbo wanted to spool more and more but the compressor surge was killing the top end power (please see dyno graphs posted bellow). Anything over 13 degress of timing and car would ping its head off.

Please help me here, Im basically to the point where im going to get rid of the car. I want to upgrade the turbo and try to pursue over 300rwkws but I dont think I can stand driving around the car as it is atm.

Edited June 12, 2009 by Sammy34

[blind_elk]

What ECU are you running?

Something I discovered when trying to tune mine - you can't always cure pinking with timing, but you can by fuelling.

[Sammy34]

What ECU are you running?

Something I discovered when trying to tune mine - you can't always cure pinking with timing, but you can by fuelling.

Nistune mate.

[hypergear]

I really can't work out what is wrong with it. I really don't believe this is the turbo causing that issue. Every one's getting around 230rwkws in that profile with it with a totally different looking power curve. Maybe your Auto Trans slipped or stuck in gear? Compare with a normal RB25det manual result:

We only made the turbo, and like I said I'm happy to check it for you. But we won't be able to do much else. PM Status Tunning, show him your result and see what he think

[wolverine]

sammy

what BOV are you running? intake pipework mods?

has the tuner tried shifting the VCT around? (most notably downwards)

long shot but could the timing belt out a tooth?

i have been down a similar path with neo RB25DET and a whole bundle of little things conspired.

[paulr33]

please check your method of boost control

please check boost pressure in at least two spots past the compressor outlet

compressor surge, if that is what you are seeing, occurs when the pressure past the compressor outlet (or wheel) exceeds

what the compressor (and its map) can actually supply. that is, if the compressor and its wheel design and its best effiency dictate

that at most it can supply around 15psi of compression (lets say) but on your car (lets say) its spiking and running well past 20psi

the end result is the pressure past the compressor exceeds what it can supply, so the compressor wheel surges

this is usually referenced as compressor surge, where boost exceeds far beyond what the turbocharger can actually supply

the common causes of this

- poor turbocharger setup

- mismatched turbocharger components

- mangled hiflow spec turbochargers

- poor / mangled boost control

- mangled bov setup can cause it

check the common basics, check pressure everywhere when it surges

check your cooler piping and other simple stuff

and lastly if all else fails get the turbocharger checked

also double check it is actually compressor surge

why do you think its compressor surge? just because something goes wrong when its on boost?

you mentioned you had compressor surge before you changed the turbo?

was the same thing (what you call compressor surge) occuring on the stock turbo?

its unlikely and almost unheard of see compressor surge on the stock turbo as its balanced, setup correctly and wont surge within reasonable means

[SS8_Gohan]

damn, still having problems mate

i've got the G3 (OP6 rear housing) hypergear and with stock airbox, still getting 255rwkw, if you've got a pod add maybe 7-10rwkw more. Is you car auto?

My car with the G2 only made around 220rwkw (see the difference between the graph above, that car had a pod but same turbo). If you have an auto, i'm not sure what you would expect from a G2?

i don't really know much... but have you dropped the exhaust and done a run?

[hypergear]

Look at this power curve. Even with the smallest prototype that we built for SS_Gohan (Its not a G2, Its a one off custom turbo):

Compare both stock power run and "one off" curve to dyno sheet on the topic.

What are all this "lumps" in Sammy's power curve. and power just dies off to before the car started to run in a sudden. It looked like the car turned off.

Also to actual compressor surge on a 71mm Comp wheel, Thats not possible using a 65mm turbine.

Edited June 12, 2009 by hypergear

[mad082]

it certainly has potential as it is making the power nice and low, it is just falling over up top. if it's pinging at anything over 13 degrees then there could be a few issues causing that. now people will probably post up ruling out most of this stuff, but i am just going through the "this is going to sound stupid but...." list of ideas

first of all, could be a fuel issue. while the afr's overall may be ok, 1 cylinder may be serverely lean, possibly caused by a dirty/blocked injector.

secondly, what plugs are you running? they may be too hot of a heat range.

thirdly, it couldn't possibly be that the engine is a NA that has been swapped in at some point? that would explain the pinging at low timing. maybe get a compression test done.

also the dyno graphs don't really appear to show any compressor surge as the boost reading seems pretty stable. maybe it is just your gauge that is a bit dodgy.

[Strik3r]

I'd be looking for:

- boost leaks

- exhaust restriction (either in the exhaust itself or the manifold)

- intake restriction (check pressure before and after intercooler)

if you check those 3 and they are all fine, check for:

- boost leaks again.

Think about what happens when you have a boost leak. Your turbo starts to spool up and makes some boost, the leak gets worse and air starts escaping. Boost level starts to drop off, your boost controller tries to compensate by keeping the wastegate shut and spinning the turbo faster and faster, but all the extra air is just escaping out the leak, MEANWHILE your turbo is working so hard its actually heating up the air, causing high intake temps and your engine to ping with any timing.

Kinda fits the symptoms doesn't it? It could also be an exhaust restriction although that doesnt really explain the issue with the timing but backpressure can do funny things.

I'm no expert by any stretch of the imagination, but i'd be examining every inch of piping between your turbo and your plennum.

[Sammy34]

Hi Guys thnx for all the help. So far the car has been hooked up to a smoke machine, to check for boost leaks, we found one minor leak that was on the plumb back pipe and was resolved, was jsut one of the shitty stocko nissan hose clamps. I have upgraded my BOV to a turbosmart plumb back. All intercooler piping was checked for blockages, although Iam still running the standed pipeing from the turbo to the intercooler, then aftermarket from the throttlebody to the cooler.

Injector blockages... possible although the injectors were only just put in when the turbo was. Not sure if theres anyhting that could have fowled them up that quick, did run a bad batch of fuel at one stage but that was all sorted. (Dont fill up at caltex) lol.

Plugs are splitefires.

Im assuming what img etting is compresor surge, this si a video of exactly the sound my car is producing when I say (it starts surging)

[hypergear]

This is defiantly compressor side surge. Turbo's sucking air in and splitting air out on the same time. This is some thing I've never seen before. Its not doing it because its spinning too quick. Its doing it because air goes to a dead end and bounce back. If your stock turbo was doing the similar sort of thing probably need to check blockage or inlet cam angle as in timing belt skipped a tooth or incorrectly installed.

[Sammy34]

This is defiantly compressor side surge. Turbo's sucking air in and splitting air out on the same time. This is some thing I've never seen before. Its not doing it because its spinning too quick. Its doing it because air goes to a dead end and bounce back. Was your stock turbo like this as well?

yeh stock turbo began to do this but not as severally obviously. Its strange, as the car will not surge if I boot it from a stand still, it will just performe beautifull, but hold it in 4th or boot it on a highway and it surges.

[666DAN]

Sam, I think our cars were made on the same day buy the same tool at Nissan, whatever he did it was very subtle and has me at a loss as well....I should be making a fair whack more and can't get through the strange 'ceiling'

That chart was a different turbo to what I've got now, but the new turbo still has the same boost drop-off but makes a bit more power. Over the past two years I've tried and changed so many components it's not funny, ruled everything out except it being a 2L and not a 2.5 block (which would explain a lot)

Everything anyone has listed here has been checked in my car, the whole system is leak free, dropping the exhaust before the cat did nothing, changing timing with cam gears to massive extremes did bugger all. I don't get the same surge noise, my one is more like someone sticking their fist in the exhaust the second I get ~4000rpm

The funny thing is I can let the car free-boost and still get that sort of boost response, trade it in and get an Evo, don't turn into a bitter old R34 owner

[SLAPS]

Has the car been hit with a timing light on a power run to ensure the cas is playing nicely? Or at least swapped out the cas?

[666DAN]

Has the car been hit with a timing light on a power run to ensure the cas is playing nicely? Or at least swapped out the cas?

My ones has, and I'd assume they checked that with Sammys sar as well as they'd have live feed of the timing advance directly from the CAS with that software.

[Sammy34]

yeh the CAS was checked. Was the first thing I got them to do when the car got on the dyno the second time around. As I said, EVERYTHING has been checked on the car apart from pulling apart the engine, as for tuning im not an expert but I trust the bloke that tunes my car and hes an excellent tuner, has tuned many QLD skylines on this website. This whole thing sort of has everyone stumped. I think you mite be onto something with the head dan. Would explain alot, when my car was first tuned for the Nistune on the stock turbo it seemed to be a bit low on power for the modifications the car had, I believe the car made 178 ish rwkws. With all supporting mods bar injectors, airflow meter etc.

[666DAN]

yeh the CAS was checked. Was the first thing I got them to do when the car got on the dyno the second time around. As I said, EVERYTHING has been checked on the car apart from pulling apart the engine, as for tuning im not an expert but I trust the bloke that tunes my car and hes an excellent tuner, has tuned many QLD skylines on this website. This whole thing sort of has everyone stumped. I think you mite be onto something with the head dan. Would explain alot, when my car was first tuned for the Nistune on the stock turbo it seemed to be a bit low on power for the modifications the car had, I believe the car made 178 ish rwkws. With all supporting mods bar injectors, airflow meter etc.

Yeah exactly the same, my car was always down on power compared to another R34 with identical mods. The first time I ever thought something was up was when we both got our CES exhausts fitted at the same time. My car felt mostly the same, his went a lot quicker.

I'd love to have the time to rip the head off and have a look at the cams and everything in there to compare and see if anything isn't right

[Sammy34]

Yeah exactly the same, my car was always down on power compared to another R34 with identical mods. The first time I ever thought something was up was when we both got our CES exhausts fitted at the same time. My car felt mostly the same, his went a lot quicker.

I'd love to have the time to rip the head off and have a look at the cams and everything in there to compare and see if anything isn't right

If I win the lotto tonight i will give you my car to pull apart lolz.