The Yellow Lunchbox

[joorsh]

The 13 PSI that I run is only for the first 1500 RPM or so (to get the torque up) - it drops back to 11PSI quite quickly. Sustained high boost + high RPM is what makes these things crap out (well, aside from the usual culprits like oil starvation, foreign body colision, age, etc).

It's because of the way the turbine shaft is friction-fused to the ceramic exhaust wheel when they are made in the factory. They spin the shaft at INSANE speeds, and then press it into the centre of the ceramic exhaust wheel. The material then superheats and fuses together. You can actually load them up to 16+ PSI, but if you hold it there that's when they start to heat up, the friction-welds melt, and the exhaust wheel takes off down your dump pipe. You can run quite high boost through them and not shorten their life at all if you're smart about how you do it. As soon as you start towing heavy loads uphill, running it at the track or doing back-to-back drags runs, you'll heat them up and it'll come apart. It's quite interesting when they detach actually, because at high RPM and heat-load the welds will liquify, but it will still keep spinning and running happily. It's when you back off the throttle, and then load it up again (like during a gear change) that they shear off - I think because of the change in momentum experienced by the exhaust wheel.

[wolverine]

I found the snorkel to be a restriction ages ago. The airbox on a GTR shouldn't be compared to one on a GTS-t or Stagea, which is where a lot of that information comes from.

I would also suggest that the turbine will shit itself in its own good time regardless of whether you are running 10psi or 12psi or 14psi. I am not arguing the science behind what makes them fail but history has shown that some fail with little or no provocation and some are flogged repeatedly and won't die. Regardless, on an RB25 there is little risk of engine damage (unlike a 26) so drive it till it fails.

[joorsh]

Yeah that's true enough! Plastic compressor + ceramic exhaust isn't exactly the perfect recipe for longevity eh?

So re: the snorkel, is that where most of the power loss comes from? Many gains to be had changing out the airbox as well?

[wolverine]

With a decent filter and stock turbo it shouldn't be much of a restriction but you could have given it a single dyno pull without the filter element in to check.

I use a boxed pod but that was more for simplicity in making some other bits fit in. How much of a gain there is to be had (or not) I haven't measured.

[DaveB]

Awesome stuff guys. LOL @ the first post - 26kg of aftermarket extras!

I'm planning to fit one of the JustJap stealth black intercoolers soon; I have a couple of questions I'd love if you could answer:

1. where can I get a kit for $400 (on their website they're $499) ?

2. do you need to reuse any of the intercooler piping from BELOW the chassis (eg. on the SMIC unit itself) as I think the bracket which bolts the stock pipes to the body, where it goes through the bottom of the engine bay, is attached to the original SMIC unit itself?

cheers!

DaveB

[joorsh]

Hi Dave, see if i can get them all answered for you.

1. I got my kit second hand (but hadn't been used). You can often pick them up cheaper on ebay if you don't mind waiting for one to come up.

2. I re-used all of the standard hoses except one - pictured here bottom right:

Everything else got re-used. One of the standard intercooler hoses has a bracket attached to the hose and bolts to the body - this is the hose I didn't re-use.

Hope this helps mate!

[joorsh]

I hacked up an old R33 airbox this afternoon.

Not sure if it'll make any difference, but at least it kept me out of trouble for an hour or so.

I left a bit of the snorkel tab there because that part is closest to the exhaust manifold & turbo. I know it's not much of a heat shield, but meh. At the end I gave it a once-over with some leftover matt black to hide all my dodgy cuts & scratches. It ain't pretty, but hopefully the dyno will tell me I haven't completely wasted my time.

Edited December 13, 2012 by joorsh

[DaveB]

Hi Dave, see if i can get them all answered for you.

1. I got my kit second hand (but hadn't been used). You can often pick them up cheaper on ebay if you don't mind waiting for one to come up.

2. I re-used all of the standard hoses except one - pictured here bottom right:

Everything else got re-used. One of the standard intercooler hoses has a bracket attached to the hose and bolts to the body - this is the hose I didn't re-use.

Hope this helps mate!

Cheers Joorsh! From memory that pipe is the only one which fits under the body... and of course eBay I will check... thanks