Turbo off R34

[Doctor]

Does any one know the max boost for these turbos. I have one on my RB20 and I've heard the exhaust wheel can fall off at 12psi.

Anyone confirm this.

Regards,

Doc

[XrSiSt]

I think it was from one of the HPI magazines that said that and

it's in one of the videos.. They said it broke at 12psi...

[Doctor]

Yeah I read that issue too. Anyone else heard/experienced anything apart from the HPI incident.

doc

[Cubes]

A few things to remember..

1. Was that 12psi where the r34 turbo broke running a std. Intercooler?

As it is not recommended to go over 12psi on a RB20DET with a std intercooler and the std turbo.

At the plenium it may say 12psi but at the turbo it will probably say some thing like 14-15psi.

In one case it was recorded up to an 8psi pressure drop on a R33 with a std intercooler.

2. That 12psi was on a RB25DET so that would be roughly the same as say 14psi on a RB20DET.

RB25DET's use more air than RB20DET's

Hence the turbo has to spin faster to hold the same PSI on the rb25det compared to that same turbo being on a RB20DET.

Its a pitty that they havn't brought out Electorically assisted turbo's yet..

Until then we wont know what RPM they are opperating at...

[Doctor]

Joel, isnt psi psi regardless off whats its on?

I'm only running 8psi with the occasional 10psi at the mo until I get my intercooler fitted.

Doc

[Cubes]

No not at all...

Ermm how do I explain it..

A bigger turbo on a smaller motor is not going to have to spin as fast to provide the same PSI & Volume of air as it does on a larger motor.

It is the RPM speed which kills the turbo's Not the PSI.

You could slap the RB20DET Turbo on a 8Ltr Dodge motor and you will find that it probably will make say 2 psi when the turbo blows.

Due to the pure size of the motor and the amount of air it consumes.

A vg30DET Ceramic BB turbo 'APPARENTLY' can run safetly up to around 16-17psi (ON a RB20DET).

It doesn't have to spin as fast to provide the same volume of air.

Hope that made sense. :confused:

On that note should we then be able to run say more PSI in the mid to provide the same amount of air as say 14psi at 7000rpm without blowing the turbo. i.e less rev's = less air is consumed = turbo doesn't spin as quick to make the same PSI??

--- hrmm... now i'm confusing my self...

[Cubes]

Just to throw a spanner in the works.

I could be wrong.. But it gives you somthing to think about.

[Doctor]

now you've gone and confused me. Ive always thought regardless of the engine 8psi is 8psi as psi is a fixed measuring unit. The only thing that is variable is the volume of air.

If you get what I mean.

Doc

[2rismo]

Hi all. I'm new to the group and very soon to be the proud owner of a Black R33. Anyway, back OT...

I always thought that the reason for not increasing the boost past a certain limit (say 10psi) was because of the way the compressor wheel is bonded to the shaft.

i.e. when it spins faster to produce more boost pressure, the turbo gets hotter and less efficient and can become un-bonded from the shaft in less than extreme cases. Very bad and potentially expensive.

Most aftermarket turbos solve this and in a perfect world, everyone would be able to afford T88-34D titaniums.

Cheers.

P.S. thanks for the help from people in the channel/club for their sensible advice in the purchase of my new toy.

[Cubes]

Maybe I did answer the Q a little wrong.

8PSI is 8PSI on every motor and every turbo but it is the RPM speed that you have to worry about to make that 8psi.

For example say a turbo blows at 200,000rpm (no idea).

As a guide we all know that on a RB20DET 14psi or over is where the turbo is going to hit that RPM blow up point.

Ok so say we slap a VG30DET Turbo on a RB20DET it isn't going to have to spin as fast as the Std RB20DET turbo to provide the same volume of air hence power.

?!?!?!??! Look it to it ..

Basically I am going off what TIM @ RPM Told me.

[whatsisname]

Joel,

The HPI R34 spat the exhaust wheel on 12psi ( boost indicated & controlled via AVC-R) It had a Apexi FMIC fitted & was making ~207rwkw @ that stage.

The failure occured after 5 laps of Wakefield Park race track, i.e it was being spooled up hard on & off the throttle! Seeing as how the RB25DET NEO runs a nylon comp wheel it's easy to see how it can overspeed very quickly!

[Cubes]

Wow 207rwkw on 12psi.

Either those NEO motors really do make a difference or the turbo is slightly bigger.

I'm sure my turbo would also spit its exhaust wheel after 5 laps as well.

For every day driving how often really are you driving it as hard as what you would on the track..

me = never.

[whatsisname]

The Apexi parts I listed above weren't the only parts the HPI R34 had fitted to make ~207rwkw (think it was 207?) It also had a Power FC, Apexi pod intake & full Apexi exhaust. They went on to rebuild & high flow the stock turbo & it made 225rwkw (not sure how much boost?).

[R31Nismoid]

Hey,

I'm new here... but i've been around the r31 skyline club...

Anyway... you can't run anymore than about 12psi through the turbo's due to the fact that they have a ceramic tubine wheel that shatters at around 12psi or more and fly off and will end up out somewhere behing your car.

you can pretty much safely run 10 psi with out a hassle at all.

The intercooler doesn't have much of an affect on stopping it. So in short, if you push it past 10psi, then the life of your turbo will be in danger... but that's ok, cause when it breaks.. you go buy a new BIGGER one

ash

[Cubes]

I'll say it again.

What blows a turbo is overspeeding.

Not PSI.

A Turbo from a motor that blows at 12psi will still make 12psi on a smaller motor but it won't flow as much air hence it doesn't spin as fast hence not as close to overspeeding.

Slap that same turbo on a 500cc motor run 20psi all day every day

SO... You can run it at a higher PSI, well on a smaller motor at least.

I guess there would be some equation to work out air flow vs rotational speed and breaking speed (overspeeding)

I've been running my RB20DET BB Ceramic turbo at 1bar now for around hrmm 2-3 months, 1 1/2 of those months was with the std IC.

Depends on how you drive and if you are always pushing it really hard on full boost.

Iv'e been told that my turbo wouldn't last past 14psi but so far it has.. and I wont get to find out if It blows as in the next couple of weeks i'm going to slap on a GT2530 terbs

[Clint32]

sometime you get lucky I suppose, my stock turbo at 15psi for about 12 months with some very hard driving at 4-6000rpm consistently with no probs, yet.

[TTT]

Joel.. I get what you mean..

I think that it's hard to explain in just words..

you have to remember something guys..

when you talk about 12 psi or 8 psi, you are talking about the amount of air pressure that is in your manifold..

The boost pressure that your boost guage shows is the amount of pressure (PSI) in your manifold.. not in your turbo.

see if I can make this a little easier (or completely confuse everyone and my self)

air gets sucked through the air filter.

Spins through the turbo and gets compressed.

this how air flows through the intercooler where it is slowed down a little as it is cooled.

it then heads up to the throttle body, where it enters the manifold and gets mixted with fuel and burnt, goes through your exhaust manifold, through the back end of the turbo and out your exhaust.

Agreed?

now, with our skylines (as an example, R32 GTST RB20DET with 10 psi boost.. it will make it a little simpler), the computer is set to open the wastegate when it sees 10 psi in the manifold.

The standard turbo on the RB20DET has to spin at (example) 150,000 rpm. this is the speed at which the shaft is spun.

When 10psi is reached the computer makes the wastegate open to make sure that it doesn't allow any more pressure to build up.

Now. you have heard about AR sizing and so on.. I don't really know which one means what and so on but basically if you have a larger AR, then it is going to flow more air in.

Lets say the standard turbo AR is .46 (what ever it is measured in.. mm??)

this turbo has to spin the shaft at 150,000rpm to produce 10 psi of air in the manifold.

The standard intercooler is a little restrictive so there is probably about 12 or 14psi of pressure just before the entry of the intercooler.

a better intercooler could show that at 150,000rpm by the turbo could produce 12 psi at the manifold because the intercooler is not as restrcitive.

back to the turbo..

If we stick on a different turbo (lets say the slightly larger turbo from the VG30DET), this turbo will have a larger AR (eg .52). this means that to produce 10 psi at the manifold, the shaft does not have to be spun as hard and could maybe produce the same psi at only 120,000rpm. this is because it is larger, has larger opening and larger turbine blades to flow more air in and out.

so if both the stock turbo and the turbo from the VG30DET were to have a SHAFT speed of 150,000rpm on the same engine, the standard would produce 10spi at the manifold and the other would produce maybe 13psi.

NOTE::: the figures I have used here are only examples..

I just used any old number that came to my head to get my point across.

main points..

psi is measured at the manifold.

a larger turbo can produce that same psi while working less due to it's ability to flow more air.

Well it makes sense to me so I hope it does to you guys too.

Giddyup...!!

[Cubes]

Agreed GTST..

PSI is the amount of pressure the flow and volume of air is causing on a particular motor because the volume of air is greater than what is able to fit in to the cyclinders with that specific turbo/motor configuration.

Thats another way of saying you can wind the boost up on a turbo that blows at say 12psi on a larger motor when on a smaller motor.

---

A Larger turbo will have a better effiency therefor the air will be cooler hence more dense that is why a larger turbo will pump the same amount of air through in weight but the actual restriction will be less due to the air using less space. ?!?!?! Sound right?

hrmm..

When that turbo blew at 12psi it could have been lots of things that caused it to blow..

i.e spark plug needed to be a cooler plug due to the constant thrashing that caused a little bit of the spark plug to break off and smash the ceramic exhaust wheel?!?!

I've heard of that happening before I think it was on the SDU Forums.

Ceramic Turbo's are a bit of a Lucky Dip Prize I Think...