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What turbo is this?

Bazooka

By Bazooka,
in Engines & Forced Induction

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Bazooka Rookie

Bazooka

Posted
Posted

Sorry for sounding stupid but I know very little about turbo sizing and what all the numbers mean.

I have in my possession a turbo that I was told is from an RB25 but noone knows for sure.

There is very little on it to say what it is so I hope someone on here can help me to decipher it.

The compressor housing has 45V2 on it and nothing else apart from "nissan".

The exhaust housing has 21U and 928A on it.

There are no AR numbers or anything.

Does this mean anything to anyone?

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MattSR Community Regular

MattSR

Posted
Posted

Boost pressure has nothing to do with it - it's all about shaft speed.

If you increase the VE of the engine (ie a set of cams, or new inlet manifold, or exhaust system) you will find that the turbo will now fail at, say, 11 or 12 psi, as higher engine VE = more compressure RPM for the same boost.

:O

Cheers,

Matt

Sciby Experienced

Sciby

Posted
Posted

Well, technically boost pressure *does* have something to do with it, because on the stock turbo, at a given psi, you'd know that the shaft is spinning at X rpm... so we know that at around 13-14psi, the shaft on a stock r33 turbo would be doing the magic 'breakpoint' of X rpm, and would break itself into teeny bits and pieces.

I'm not following your example... feel free to enlighten me on what 'VE' is... but anyway... I disagree with it. :O

When the shaft is doing X rpm, it will fall apart, and you can use the fact that the *stock* impeller, will be pushing X PSI at that point. Even if it was spinning up faster or slower, that won't effect the shaft speed at which it'll break. Changing your cams or a manifold or exhaust system won't change the fact that the turbo will break at roughly X rpm, and thusly, will break when the stock impeller is generating 14+psi. Those mods won't change the spool profile of the stock turbo.

Edit: I've actually walked away and thought of something. I apologise, you're dead right: with a bigger intake manifold, tehre's more space for the turbo to fill up, therefore the turbo will be at Breakpoint rpm, but not reached the magic 14psi. Therefore, it will break at a lower psi. However, if the intake/manifold is stock, and the exhaust is changed, or the cams have changed, it won't break at an earlier psi, it'll just reach that psi faster.

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