R33 Std Turbo And R34 Std Turbo Boost Query

[wallas]

Ive heard alot of different opinions here about the r34 rb25 turbos. Upon inspecting both ive found the r34 turbo to have a steel rear wheel amongst other minor things. Now im aware of r33 rb25 std turbos not agreeing with higher boost levels due to the rear wheel letting go being ceramic. What are your opinions with boost and an r34 rb25 std turbo remembering that it has a steel rear wheel. Let me know your thoughts..

Edited May 25, 2009 by wallas

[paulr33]

never heard or seen of a steel rear wheel on ER34 turbocharger

please double check and confirm

and even if it is steel rear wheel, the compressor will stilll run out of effiency and past its effiencny island

which in turn just dials heat into the intake charge, so steel or no steel, doesnt really help a lot, just means it wont fail from excessive shaft speed / heat

typically 12psi is the island / max spot of the compressor map - so any more, is more heat for little to no gain

[mad082]

i have to disagree with you about it not making power above 12psi. a mate of mine put his stock turbo'd 33 on the dyno and just started winding the boost up (aftermarket ecu obviously). started at 200kw at 13psi and the power kept rising until they stopped at 16psi whnere it was making 220kw. i also ran my stock turbo at 14/15psi for quite a while with no issues either, and it felt much more powerful than 11psi. i wound it back down one day and it felt much less powerful.... so i wound it back up.

as for the r34 turbo, they don't have steel wheels unless they have been highflowed. the series 1 r33 turbo has steel compressor wheels but they all have ceramic exhaust wheels. the r34 is a bigger turbo than the 33.

[R31Nismoid]

R33/R34 - basically idential in terms of thier limitations and so on.

R34 turbos are just newer, so will take 14psi 'longer', they will still fail and are still ceramic rear.

If yours has steel (test using a magnet) then its not a standard R34 item.

11-12psi is the limit, push it and it will die

[Pattygtst]

  mad082 said:

i have to disagree with you about it not making power above 12psi. a mate of mine put his stock turbo'd 33 on the dyno and just started winding the boost up (aftermarket ecu obviously). started at 200kw at 13psi and the power kept rising until they stopped at 16psi whnere it was making 220kw. i also ran my stock turbo at 14/15psi for quite a while with no issues either, and it felt much more powerful than 11psi. i wound it back down one day and it felt much less powerful.... so i wound it back up.

as for the r34 turbo, they don't have steel wheels unless they have been highflowed. the series 1 r33 turbo has steel compressor wheels but they all have ceramic exhaust wheels. the r34 is a bigger turbo than the 33.

When i had my stock turbo tuned with pfc there was no difference in power between 10 -13psi just an increase in low end power. So my experiences will disagree but every car is different i guess.

[mad082]

but that could also come down to the tune, and if it was done on different days, etc.

i have seen pfc tunes where they have put out less power than stock ecu's for the simple fact of the tune is dodgy. i compared a dyno sheet from my stock ecu with that of a with a pfc and his made a few kw more than my car throughout the rev range until about 5500rpm where his pretty much flattened out but mine kept going until it hit the speed limiter and so i ended up making about 20kw more.

[gotRICE?]

You also need to look at power/psi. So as mentioned.. efficiency.

Back to back dynos against a mates 33GTSt and mine, his made 5 morw rwkw with 5psi more boost. Exact same mods, bar his being Link tuned, and mine Stock ECU.

1kw per PSi doesnt feel like efficient power to me. Sounds like a whole lot of hot air

[mad082]

but that could be caused by other issues as well. crap tune, sad motor, etc. to compare different cars at different boosts is a bit pointless. but i know from seeing the evidence first hand on back to back dyno runs that there was a gain of 20kw by going from 12 to 16psi.

but then my car made 15kw more than 2 of my mates cars with the same mods, and another car with the same mods made pretty much the same power as me (was within 1kw)