M35 Boost Level

[zei20l]

my car is apparently stock. after going in your car i can sorta hear your turbo boosting, in my car, its loud as hell! its possible mine is already different. maybe failing in japan

but yes, im happy to chuck the boost gauge on my car for a looksee, i actually wouldnt mind chucking it on the dyno - when the cash allows.

[andy65b]

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.

Oooohhhhhh

Forgot about that coming up. I might have to see if I can make that as it will be interesting to see the effect of the new exhaust.

Only drama is I haven't done a oil change for about 5000km. It is due soon. and no time this week to do it.

[zei20l]

hahahah mine hasnt been done in 10+

i should do one too very soon!

[andy65b]

my car is apparently stock. after going in your car i can sorta hear your turbo boosting, in my car, its loud as hell! its possible mine is already different. maybe failing in japan

but yes, im happy to chuck the boost gauge on my car for a looksee, i actually wouldnt mind chucking it on the dyno - when the cash allows.

I would offer to let you try mine on you car but at 2 hours to fit it, It is not coming off in a hurry.

[zei20l]

nah dont worry, when funds allow ill be buying an EBC. i just bought the rear half of a JDM cat-back exhaust tonight

[mxfly]

Would be really good if have a few Stags up on the same dyno on the same day. That's the best basis for comparison.

[Jetwreck]

my car is apparently stock. after going in your car i can sorta hear your turbo boosting, in my car, its loud as hell! its possible mine is already different. maybe failing in japan

but yes, im happy to chuck the boost gauge on my car for a looksee, i actually wouldnt mind chucking it on the dyno - when the cash allows.

I have a spare gauge at home if you want to check it out.....its also for sale at a very cheap price if you want it.

[andy65b]

nah dont worry, when funds allow ill be buying an EBC. i just bought the rear half of a JDM cat-back exhaust tonight

Ok, spill the beans..... what model?

[iamhe77]

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.

Actually, 1bar is 14.5psi which is around what you were getting yes?

Also, it would make sense as you said that Jet's gauge was reading 1-2psi high which would take it to around the 14psi mark.

Can't imagine that Nissan would put an inaccurate boost gauge in a car as standard.

Local or JDM exhaust?

my car is apparently stock. after going in your car i can sorta hear your turbo boosting, in my car, its loud as hell! its possible mine is already different. maybe failing in japan

but yes, im happy to chuck the boost gauge on my car for a looksee, i actually wouldnt mind chucking it on the dyno - when the cash allows.

My OE turbo with original exhaust was loud as hell as well (from the first day).

Sounded like a Jet taking off and turned heads quite a often.

nah dont worry, when funds allow ill be buying an EBC. i just bought the rear half of a JDM cat-back exhaust tonight

Which?

I saw that there was a Legalis going on IM for a pretty good price (there was also the Freeway/Dolphin cat-back with the de-cat front pipe available).

I have a spare gauge at home if you want to check it out.....its also for sale at a very cheap price if you want it.

LOL..... If

[andy65b]

Actually, 1bar is 14.5psi which is around what you were getting yes?

Also, it would make sense as you said that Jet's gauge was reading 1-2psi high which would take it to around the 14psi mark.

Can't imagine that Nissan would put an inaccurate boost gauge in a car as standard.

You keep telling us that the gauge does not work! LOL That makes a pretty crap gauge to me.

Local or JDM exhaust?

Local. Same guy that did Jetwrecks but aiming for a little quieter.

[iamhe77]

You keep telling us that the gauge does not work! LOL That makes a pretty crap gauge to me.

lol. Yeah it did stop working. Then out of the blue it started again... but then stopped.

Oh well, easy come easy go.

Never said anything regarding the build, just saying that I couldn't imagine Nissan putting in a gauge that read incorrectly, even if it only worked for 100,000kms.

[zei20l]

the exhaust is whats left of houdinis exhaust that he has removed. ill get the rest made up locally to the cat. and do the rest when i get the cash!

i cant remember the brand. but its what i was looking for!

might do one on the fiat too if the mrs lets me

[Houdini]

the exhaust is whats left of houdinis exhaust that he has removed. ill get the rest made up locally to the cat. and do the rest when i get the cash!

i cant remember the brand. but its what i was looking for!

might do one on the fiat too if the mrs lets me

Apexi N1.

I'd love to go to a dyno day. It's a mystery to me what my car makes at the wheels or otherwise. Far as I know it's got an Apexi air pod and a fairly loud blow off valve matched to my exhaust which has the large front cat and a tiny middle cat and then the free flowing twin pipes. No resonators or anything.

I have no idea if it's got any other mods but I have to say it goes like S*#t off achrome shovel and if it's 206kw's then look out when I start to up the ante because it's going to scare the crap out of me!

I'll have to get someone else to watch the gauge while I'm driving to see what boost it shows because I haven't been game to look down while flooring it .

[zei20l]

duh! of course N1! i friggen identified it hahaha

hahah take your wife for a ride and ask her to look at the gauges while you hammer it

[pixel8r]

You keep telling us that the gauge does not work! LOL That makes a pretty crap gauge to me.

My factory guage also stops working - but its intermittent. As far as I know it may not be the guage thats faulty. When we say its faulty we dont mean that it gives a slightly faulty reading. Its either working or it isn't (ie. it just sits on full negative boost - when it sits on anything else, including zero - then it is definitely working). So yes you can trust the factory guage - mine is exactly the same - reads 0.8 bar.

Also, to touch on what was discussed earlier - I believe the 14psi limit was "discovered" on the rb's so not sure if the same applies to the vq25det. The limit isn't actually the pressure, its the heat. The ceramic can only take a certain amount of heat. Not sure if pressure relates exactly to heat or whether other factors would be involved as well? ie. on a different engine/configuration the same pressure may generate more heat or it may generate less??

Another thing is that when you're measuring boost on the dyno, where are you reading the boost pressure from? Are you measuring manifold pressure or turbo boost pressure? The RB's had a nipple on the side of the motor specifically for reading the boost level, but as far as I know the VQ doesn't have one. I believe the boost reading may be higher or lower depending on where you're reading it from. Or I could be talking utter crap... ??

However I think the boost level we're interested in is the same one that the factory guage is reporting - which is 11.6psi. Note that the boost sensor on the VQ25DET is located just before the throttle body - not sure if thats where the factory guage is reading it from though - I presume this sensor provides the boost level to the ecu primarily but maybe it is also connected to the boost guage in the cabin?

[andy65b]

With an aftermarket boost gauge you take the reading form a nipple on the side of the manifold. ie, after the throttle body.

[nickcorr]

With the talk about these ceramic exhaust wheels... It is not the itself wheel failing, they are usually fine..

What happens is that when they get get too hot from being over boosted beyond their design limits, the glue holding them onto the shaft fails, and so the wheel falls off, and end up in the cat... This may ping off bits of the turbine. Also the fitment of the plastic intake wheel as on the RB25DET, not sure what it is on the VQ25DET, is not on it's own a bad thing. The plastic wheel is light, and so is able to spin up faster than a metal one, therefore boosting more quickly than a steel wheel equiped turbo.

And if you want to see a ceramic turbo that really hates to be boosted above design specs, speak to the JZZ30 2.5TT Soarer guys, and they have two of them failing...

[zei20l]

the compressor wheel is most certainly metal on an M35 turbo. i have seen andys one to confirm.

i cant remember exactly, andy you can confirm this, but i think the turbine is bolted to the shaft, not glued, as is the compressor. but i dont have the auction pics on me to be sure.

[andy65b]

the compressor wheel is most certainly metal on an M35 turbo. i have seen andys one to confirm.

i cant remember exactly, andy you can confirm this, but i think the turbine is bolted to the shaft, not glued, as is the compressor. but i dont have the auction pics on me to be sure.

It is in the boot of the car and too cold and wet to get but from memory there is a bolt on either end of the shaft keeping the impella's in place.

[mxfly]

You can measure the boost anywhere from hotpipe to end tanks, to pipe going into the throttle body, they should be all the same. Even when using a Chinese made cooler, there's little pressure drop across the path.