Anyone Had Roblems With Compressor Reversion

[lolorodeo]

Howdy guys,

I had my car on the dyno yesterday and afterwards my tuner said that there was aproblem with reversion in the inlet and that he reccomended i ditch the shitty emanage unltimate i have(which i was going to do anyhow) and just put a d-jetro in. Now my car is a 33 gtr v-spec with garret gt2860r-7's, 12psi, cat back and thats about it. I thought reversion was a problem reserved or big turboed cars so has anyone else had this problem on their gtr? It seems strange to me that everyone else runs regular power fc's with seemingly no problems and yet my tuner thinks i need a djetro.

Thanks guys,

Kagan

[R31Nismoid]

Well considering everyone runs a l-jetro PFC (AFM), and no-one has issues with small turbos...

That clearly tells you that whoever is tuning your car, simply put, is a muppet.

You should not be having any issues with reversion at all.

Do you have a aftermarket hard intake piping kit?

Aftermarket BOV's?

If you answered no to the above two questions, then you shouldn't be having any problems at all.

[Bakes]

Yep, get a better tune

[paulr33]

it's not the tune, check your intake piping as r31nismoid said

if youve replaced the stock instake piping (the accordian style crap) then you get reversion across the AFM wire

the makes the car run like ass

the fix is to either refit the accordian style pipework (the bends break up the airflow) so that it doesnt cause reversion

if you are stuck with what you have or want to keep the same pipework etc then place a large bend it, or the biggest bend you can fit. the bend will break up the airflow enough to avoid the reversion

[lolorodeo]

All the stock piping is in place, stock bov, stock cooler....its just the turbos and pods. The tuner is one of the best in WA so i was kinda suprised when they said that it was a problem. Hmm maybe ill look into it a bit more.

[paulr33]

also describe what you call reversion

do you mean you can hear the vl turbo tututututut when its ramping on boost?

do you mean you can hear the compressor shuffle when its ramping on boost?

do you mean you can see the AFM signal go wonky during boost build?

describe as best you can, we may think it's something else vs what you think

[lolorodeo]

Unfortunately im running with what the tuner told me as i havent heard it myself and the boost gauge is rock solid whilst shes boosting. Basically i hadnt noticed it but the tuner said it was an issue. He said that due to the uneven pulsing of the banks feeding each turbo, the manual boost control and the size of the turbos that it was an issue and he was reccomending a djetro. I asked why then does everyone run similar size turbos on a regular power fc and he said that it was common and they were just ignoring the problem. He wasnt talking about compressor surge though if you think thats what im confusing it with.

Hmm well im thoroughly confused as to where to turn next as i cant verify the reversion but the tuner is one of the top gtr specialists in perth so im inclined to take his word for it.

[lolorodeo]

Im tempted to just get the djetro anyhow as i was going to put a power fc and z32 afms in anyhow and id think the cost would be pretty close anyhow.

[Tangles]

most likely on about AFM's

and reversion across the wires. the cheap fix is to clamp the signal.

the expensive fix is to go d-jetro

[R31Nismoid]

Unfortunately im running with what the tuner told me as i havent heard it myself and the boost gauge is rock solid whilst shes boosting. Basically i hadnt noticed it but the tuner said it was an issue. He said that due to the uneven pulsing of the banks feeding each turbo, the manual boost control and the size of the turbos that it was an issue and he was reccomending a djetro. I asked why then does everyone run similar size turbos on a regular power fc and he said that it was common and they were just ignoring the problem. He wasnt talking about compressor surge though if you think thats what im confusing it with.

Hmm well im thoroughly confused as to where to turn next as i cant verify the reversion but the tuner is one of the top gtr specialists in perth so im inclined to take his word for it.

The turbo's you have are barely bigger than factory.

So size of the turbos unfortunately is irrelevant as not one person i know of with -7s or -9s (myself included), has any issue what so ever.

It's not about ignoring the problem, it's more that there simply is not one.

I'm 99% confident i know who you are talking about as djetro is the answer to everything apparently, not the first time someone has posted up saying what you are.

You could take it elsewhere for another opinion, which is what i would do if it were me.

[paulr33]

agree with r31nismoid, perhaps there is some information missing?

HKS made a split manifold that had join / balancer pipes - is that needed maybe?

please read up on the djetro kit and understand everything before install

the djetro kit is going to be sub $1300

[paulr33]

Nissan - Skyline - BNR32/33 89/8 - 98/12 - D-Jetro

D - Jetro Harness X 1 GT-R

D-Jetro PFC Nipple X 2

D - Jetero Map Sensor X 2

$1398 delivered from nengun, but you can sell your old PFC and AFM's etc

but if you can keep your current setup, sell old AFM's etc, changeover shouldnt be that bad

[STATUS]

is it reverasion causing bad idle or is it shuffle whilst driving? Ive heard some cars get a bit of shuffle going up a slight incline at low throttle.

[lolorodeo]

Ok so i finally got hold of the written report and had a squiz at it. The tuner wrote that due to the larger turbos fitted there was an inevitable problem with shuffling from the turbos AKA compressor surge and therefore they reccomended the fitment of a djetro. Now i remember asking him "isnt compressor surge caused by the bov not functioning or something similar" and thats when he explained about the uneven pulsing of the cylinders and what not.

So does anyone want to try explain what they intepret from that? The cars running fine so im not that worried, im just decding where to take my ecu selection from here.

Thanks guys.

[paulr33]

going to djetro doesn't fix the shuffle, all it does is let the ECU run off map sensors instead of airflow meters

the turbochargers will still shuffle after you install the djetro kit

if you want to prove it and verify without actually buying anything

go and unplug all your AFM pipework etc and just leave the AFM's open mounted

or even try taking them off completely - depending on how you plan to setup your intake once you install the djetro kit

djetro is simply a workaround on the shuffle problem. but not a correct fix

[lolorodeo]

So can someone give me the quick rundown on shuffle?Is it bad or just something that happens? How is it resolved?

[im late]

Problem is this. Would your tuner be using the correct industry standard description of the problem?

There are a few descriptions (turbo shuffle, compression surge, reversion). They all title different issues but the true meaning of each is lost with the endless mechanics out there that describe issues differently.

As what has been said above, the -7's that you have are almost the same size as stock. They would unlikely cause the above mentioned problems.

-5's, GT-RS, HKS 2530's are turbos that are known to cause COMPRESSION SURGE

This, untreated for a long time is not good at all.

Sometimes you wont even hear the problem if you have an airbox and stock piping.

I heard the problem becasue I had a hard pit kit and pod filters.

I have learnt my lesson.................................

Edited February 1, 2010 by im late

[lolorodeo]

Care to elaborate?

[R31Nismoid]

Sometimes you wont even hear the problem if you have an airbox and stock piping.

I heard the problem becasue I had a hard pit kit and pod filters.

I have learnt my lesson.................................

You mean most of the time with the factory piping you will not have the issue.

Hearing it vs actually having it - are distinctly different in my opinion

It's well known that hard piping kits can cause the comp surge (using 2530's/garrett -5s) as the factory ribbed piping actually flexes a bit which can stop the problem from occuring at all.

There is lots to be said for some OEM stuff - and the intake piping is one of those such items.

And yes i understand factory piping doesnt look good etc, but it most certainly serves a clear purpose.

[im late]

Care to elaborate?

mmmmm elaorate...............

I would but it would point out my utter stupudity (see I'm not afraid to tell the world I f^$ked up)

Oh well I will then

Built motor, -5's, tuned by a mob which I thought new what they were doing, ingnored the compression surge (which the tuner pointed out as well), ignored the PFC flashing the exhaust light.....bang, crack on bore 5.

No I am NOT saying that compression surge was THE casue of the problem, but I am sure it did not help things overall.

Lets get back on topic now.