M35 Boost Level

[Bis-e Bee]

Just to confirm the feedback above from pixel8r, this quote came from a rep at GCG Turbo's

"All of these units come with a ceramic turbine wheel, that has a boost limitation of 14psi. Once this boost level is exceeded, the risk of losing the ceramic turbine wheel greatly increases."

This we suspect may be the reason that Jetwreck's turbo kicked the bucket, his was exceeding the 14psi mark and eventually the ceramic turbine broke.

So you may wish to have yours checked out before you run the risk of losing the turbo, the cars are very difficult to drive without a working turbo (especially all the way back to Sydney from Philip Island lol).

[zei20l]

why is 14psi the magic number? is seems that 14psi is the magic number on all ceramic turbos. when i get an EBC ill check my own boost levels. or when i finally install the emanage and i can map it across the rev range

and the car looks great!! i had the option of buying a white aero RS when i got mine. went with the RX tho

[Bis-e Bee]

why is 14psi the magic number? is seems that 14psi is the magic number on all ceramic turbos. when i get an EBC ill check my own boost levels. or when i finally install the emanage and i can map it across the rev range

and the car looks great!! i had the option of buying a white aero RS when i got mine. went with the RX tho

"Because the pressure in the atmosphere is no more than 1 atm (approximately 14.7 psi), there ultimately will be a limit to the pressure difference across the intake valves and thus the amount of airflow entering the combustion chamber."

From wikipedia, maybe it has something to do with that.

[zei20l]

im talking about the turbo mate

as in, why is 14psi the limit? if the turbo is on a different engine (for example) its not working as hard, yet apparently the limit is still 14psi........... i dont get it. i rekon there is a LOT of guesswork with that number.

[Bis-e Bee]

im talking about the turbo mate

as in, why is 14psi the limit? if the turbo is on a different engine (for example) its not working as hard, yet apparently the limit is still 14psi........... i dont get it. i rekon there is a LOT of guesswork with that number.

I was talking about the turbo mate

Maybe the ceramic material cannot handle any more pressure than that, did you see what happened to jet's ceramic?

[scotty nm35]

Are you SURE?

My M35 RS4 is 100% stock, haven't touched the car mechanically except servicing and I changed the stereo. According to the factory guage its maxxing out at ~0.8bar which is under 12psi. That sounds more likely. I've never heard of any Nissan coming out of the factory with more than 12psi except for the new gtr. and even the aussie version of that runs 12psi.

You may have a modified exhaust/turbo or intake?? Maybe pressure is being leaked somewhere, causing the wastegate to stay closed longer?

It is a ceramic turbo - so it seems very unlikely Nissan would design the car running higher boost than the turbo can handle. And we all know that ~14psi is the physical limit of the ceramic turbo.

Thats the reason I fitted the boost guage, My stock guage has never worked and I needed to know what was going on. Isnt the stock one in KPA? or is yours BAR?

I have already replaced the thin rubber hose from the manifold to the left side (plastic box with wires) due to it being perished so there could be more. I cant see the wastegate from the top to check it, but it could be perished too.

The turbo is covered for 3 years under dealer warranty but I dont want the car off the road while its fixed.

[mxfly]

Are you SURE?

My M35 RS4 is 100% stock, haven't touched the car mechanically except servicing and I changed the stereo. According to the factory guage its maxxing out at ~0.8bar which is under 12psi. That sounds more likely. I've never heard of any Nissan coming out of the factory with more than 12psi except for the new gtr. and even the aussie version of that runs 12psi.

You may have a modified exhaust/turbo or intake?? Maybe pressure is being leaked somewhere, causing the wastegate to stay closed longer?

It is a ceramic turbo - so it seems very unlikely Nissan would design the car running higher boost than the turbo can handle. And we all know that ~14psi is the physical limit of the ceramic turbo.

My car was 100% stock when i dynoed the car last year. Now it has a high flow cat and aftermarket dump/front pipe.

But no shit, it hit 14psi (not 15) on the dyno.

[scotty nm35]

My guage could be out a bit? I cant see the turbo exploding at just 2 psi above standard anyway. Surely nissan have sourced better ex. wheels due to the common failures on the rb. If not, what boost will the highflow run at?

[zei20l]

I was talking about the turbo mate

Maybe the ceramic material cannot handle any more pressure than that, did you see what happened to jet's ceramic?

lol you quoted something from wikipedia about valves and intake manifold. its the exhaust wheel that comes off not the compressor. yes i know they are connected by a shaft

i didnt see pics of craigs turbo post failure, wish i did! haha

anyway, scotty is onto something, with the common failure of boosted RB turbos, they would 'probably' fix that problem knowing that people mod their cars. i think our turbos are more robust than people think. personally, i think most of the problems come from people in japan not performing regular services thus the oil loses its lubrication properties and the turbo fails. the engine is probably a little more leanient to bad oil, but turbos get hot and there isnt much room inside the oil channel so gunk can build up and create problems.

thats MY opinion anyway

[KiwiRS4T]

You better believe the limitations of the stock Turbo unless you're ready to upgrade. Apart from the cost of the new turbo there is a lot of labour involved in getting your turbos in and out. For those new to this make the GCG highflows replace all the ceramic/plastic bits with steel parts. Also check the scale on your boost guage - i don't know what is standard but some are measuring bar, some p.s.i., some hg some various metric measures.

[iamhe77]

Are you SURE?

My M35 RS4 is 100% stock, haven't touched the car mechanically except servicing and I changed the stereo. According to the factory guage its maxxing out at ~0.8bar which is under 12psi. That sounds more likely. I've never heard of any Nissan coming out of the factory with more than 12psi except for the new gtr. and even the aussie version of that runs 12psi.

It is a ceramic turbo - so it seems very unlikely Nissan would design the car running higher boost than the turbo can handle. And we all know that ~14psi is the physical limit of the ceramic turbo.

Yep, my RS was maxing out at 0.8bar (11.6psi) on the OE gauge (when it worked).

Even now with the exhaust and the high flow, I max out a touch over 1bar (~14.5psi) on the OE gauge (again, when it works).

From all indications it would seem that ARX's boost to ~15psi for some reason.

Maybe to get the extra weight moving?

[zei20l]

that would indicate they have different ECUs....... anyone with an ARX wanna remove their ecu and get the part number from it?

[iamhe77]

Also check the scale on your boost guage - i don't know what is standard but some are measuring bar, some p.s.i., some hg some various metric measures.

Standard RS boost gauge is in "x100kpa" and ranges from -1 to +1

(100kpa = 1 bar = 11.6psi)

[scotty nm35]

Yep, my RS was maxing out at 0.8bar (11.6psi) on the OE gauge (when it worked).

Even now with the exhaust and the high flow, I max out a touch over 1bar (~14.5psi) on the OE gauge (again, when it works).

From all indications it would seem that ARX's boost to ~15psi for some reason.

Maybe to get the extra weight moving?

My standard gauge is in kpa... not that it works.

The m35 must run a better ex. wheel as the 34's would be failing at that pressure, correct?

And 15psi seems to be standard across all model m35's then?

[iamhe77]

My standard gauge is in kpa... not that it works.

The m35 must run a better ex. wheel as the 34's would be failing at that pressure, correct?

And 15psi seems to be standard across all model m35's then?

Nope.

~15psi for AR-X

11.6psi for RS (and RX I presume)

[andy65b]

Nope.

~15psi for AR-X

11.6psi for RS (and RX I presume)

Hi Cam

I don't think that could be right. The power out put for all M35 fitted with the VQ25DET is 206kw and 406nm torque.

this suggests that the boost is identical for all our cars.

It would seem that the factory boost gauge is less than accurate as most of you report problems with them.

I think the factory boost level when stock is about 14psi. Jetwreck was say 15-16 with a modded exhaust and it is possible that his boost gauge may be showing one extra psi.

I will see if I can find anything in the car manual I have.

Cheers

Andy

[iamhe77]

Hi Cam

I don't think that could be right. The power out put for all M35 fitted with the VQ25DET is 206kw and 406nm torque.

this suggests that the boost is identical for all our cars.

It would seem that the factory boost gauge is less than accurate as most of you report problems with them.

I think the factory boost level when stock is about 14psi. Jetwreck was say 15-16 with a modded exhaust and it is possible that his boost gauge may be showing one extra psi.

I will see if I can find anything in the car manual I have.

Cheers

Andy

I know Andy. It doesn't makes sense.

I can tell you for sure, 100%, that stock 250t RS Fours push 0.8bar (11.6psi).

My boost gauge showed .8bar at 3200rpm. My mates blue M35 RS Four showed identical numbers and it seems that Scott's RS showed the same when his gauge worked.

Hence the reason why I was surprised when you guys were stating that your gauges were showing 14-15psi.

Don't forget that the M35 with he VQ25det was released while the "gentlemen's agreement" was still in place in Japan.

I mean R34 nur GTR's had a max power output of "206kw" as well. (put them on a dyno and they actually have about 10kw more at all four wheels!)

[mxfly]

I wouldnt mind having a drive of somone's RS/RX and see if I can feel a difference. Anyone can have a go of my car as well but it's now got a different front end so it's boosting a little more than stock.

[andy65b]

I know Andy. It doesn't makes sense.

I can tell you for sure, 100%, that stock 250t RS Fours push 0.8bar (11.6psi).

My boost gauge showed .8bar at 3200rpm. My mates blue M35 RS Four showed identical numbers and it seems that Scott's RS showed the same when his gauge worked.

Hence the reason why I was surprised when you guys were stating that your gauges were showing 14-15psi.

Don't forget that the M35 with he VQ25det was released while the "gentlemen's agreement" was still in place in Japan.

I mean R34 nur GTR's had a max power output of "206kw" as well. (put them on a dyno and they actually have about 10kw more at all four wheels!)

The only answer is to stick it on a dyno and see what you get.

I recon the boost gauge that the RS has is maybe not that accuarte. As you said, it only goes to 1 bar (11.6psi) and this is too low to show the level we are seeing from all the ARX.

I'll have to talk Iain into putting one on his car to see what his car gets. His car is still stock so it will be a good test.

I will be interested to see what my car pulls after the new exhaust goes on this week.

[mxfly]

There's a dyno day next weekend at Auto Tech and i'm going to put my car up to see if it's boosting over 14 psi with the new front pipes.