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Turbo Question

RB SANDY

By RB SANDY,
in Engines & Forced Induction

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discopotato03 Grand Master

discopotato03

Posted
Posted

I reckon that turbo can support a lot more airflow (power potential) than an RB25 could reliably withstand so a bit pointless unless you beefed up the internals . To get the boost threshold down to an acceptable point for a road car would mean using a small AR ratio exhaust housing so the 750 odd Hp compressor is wasted .

As Chris said you don't hear of these things surging , guesstimate only but HKS may have done the cover like that knowing that heroes like to put big turbos on small engines with small AR exhaust housings . By small I mean under 2L 4's .

Not sure what you mean by "efficient boost" . Airflow makes for power and pressure just moves it along . I have been told that these wheels make their greatest efficiency at surprisingly low pressure and flow rate but the "islands" are very long meaning that they work over a wide range of flow and pressure ratio . Its a pity Garrett dont make a 76mm version of this wheel because it would be a good thing with a GT35 turbine .

Cheers .

Slide Grand Master

Slide

Posted
Posted
the holes on the comp cover are a workaround for compressor surging

it allows air to enter onto the compressor wheel on the outer edge to balance out the some of intake sucking, which is commonly associated with surging. think of it as an anti surging device.

the bulk of the air enters the snout, thanks to the vacuum effect of the compressor wheel sucking in air, but a very small amount enters through the holes also to side step around surge

:)

The ported holes are there to assist in reducing compressor surge so that the air enters the compressor housing around the compressor not through it.

They are also meant to help stabilise the shaft when at high shaft speeds to help reduce turbulance which creates vibrations.

They are there to help at a very high level of boost and if boost preasure is run outside the capacity of the compressor wheel creating surge then the vacuum effectivly bypasses the air through the comp ports and past the compressor wheel.

blitzxtr Community Regular

blitzxtr

Posted
Posted
Also will this turbo go good on a rb25det or will there be a bit of lag, also what will

be the max efficient boost.

Depending on the size of the rear exhaust housing I have a t04z with a.81 housing and Ill be running 2bar of boost through my RB25 hopefully It will be at full boost by 4 .5 to 5000 rpm

R31Nismoid Grand Master

R31Nismoid

Posted
Posted

I'm skeptical will see 2bar @ 4500rpm with a t04z... you'd need some very well matched cams and some agressive tuning to do so.

Probably closer to the 5k mark as you say.

I saw 24psi around 4200-4400rpm depending on gear/load with a GT30/.82.

However but that wasnt street fuel so it had some super angry timing numbers screwed into it... cause we could :dry:

Definately post results when your done though dude.

It'll be interesting to see vs what i had with the GT30 :D

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