As above, I have 6 degree cut back blades on my T34 , for what reason are they cut back as different people have given me different explanations.

Who is telling the truth and who is talking bollocks?

Please explain it to me

Many thanks

 

well i'll talk some bollocks then...

lol think it is along the same lines as adding a larger exhaust housing - i.e. lets more exhaust gas out of the engine. by reducing the width of the blades.

cutting them back means youll effectively lose efficiency of the turbine i.e. more lag but gain more flow and therefore top end power.

thats how i've taken it

 

....which also prevents overspeeding of the turbo (where the turbo is then operating outside it's optimum efficiency) - you won't lose the efficiency of the turbo as such, if the turbo (and any cut back) is spec'd correctly for the application. I think Matt was also correct in saying it reduces back pressure (which would increase if the housing was 'too small' - the cut back is correcting this to a degree)

 

So is there any point goin cut back on a T34 .63 housing STG III ECOs?

As obviously pretty laggy as it is....??

 

i feel sure mine has the cut back wheel to reduce its temperature (by reducing the back pressure).

i demanded a low lag engine so it meant small exhaust housing which with big boost means big temps lol it has a marham shaft also but that dont stop the exhaust wheel turning into a molten toffee apple lol

 

I'd say no Damo (but I ain't a tuna ), unless you were moving up a stage to nearer 380+ and you're trying to squeeze a bit more out of a T34. But of course there's more turbo options around for that spec' thesedays too......

Matt, as said above I do think you're right (I actually think we are both right and for the same reasons, but stand to be corrected if wrong)

 

cool - I was right in my other thread

 

i still remember a certain tuner telling me that they were cut back to stop them hitting the compressor housing!

 

It's true isn't it? That's what the banana told me

 

classic


who eats banana's ? ???

 

pmsl I remeber the thread now

 

I've had it confirmed by a fella that builds turbos and cut back blades is a thing that is only really required for race/rally cars where the Turbo is constantly spinning and reaching extremely high temps......

On a road car it makes no real difference....

 

they go round and round

 

@ Gus

 

Bollocks, it makes the SAME difference on a road car as it does a race/rally car - as in it does what it is designed to (reducing back pressure, increasing flow, lowering temps etc), but at the expense of an increase in lag .

 

Does the 'etc.' include slowing the turbo down (hence the extra lag) ??

 

Seconded

 

Thanks guys for the explanation, I now understand what the cut back blades do.

On my rs turbo I now have a T34 with maram shaft , 6 degre cut back blades ,360 degree thrust bearing and I kept the .63 exhaust housing from the cossie it was intended for.

The turbo now kicks in at nearly 4000rpm which suits me fine due to having a 1.9 lump. This also seems to have eliminated the unnecessary wheel spin that I used to get with the T3 that I had on there.

Although it has not been remapped it feels a hell of alot stronger through the revs and hardly laggy at all.

I can't wait till it the engine gets a few goodies such as forged pistons, steel rods, P8 ecu, greys and a remap. This will all be happening over the winter months

 

Mike
what you recon ?? my t34 with .63 has cut back blades and 360 degree bearing and it's along time since my car has hit 28 psi the most it has seen is 27.2 psi and that is peak ..... i know when the engine was dynoed it use to peak to 32 psi then back off to 25psi after 6.700 rpm

the engine doesn't smoke or nothing i know the turbo is fine , so do you recon i should get Ahmed to check it over ???

marco

 

Clif - mines the same - though still spins the wheels but the power comes in much smoother so you actually go forward rather than stay still with the wheels spinning LOL