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Discussion Starter · #1 ·
Hey
Got afew questions...
My friend owns a R34 GT-T and it had done just over 100k miles and the turbo blew, so we have had the turbo rebuilt by a very nice man at Conceptua Tuning, using a Garrett T34 middle section and the ends of the standard turbo machined to take it (sorry I havnt got a massive knowledge of turbos)

Now the thing is, its producing quite alot more boost than before and we're worried that it may now be producing too much for the rest of the system to cope with?

What can we do to cure this.. I seen you can get boost controllers.. which one is any good?

Other than the turbo it has a smooth downpipe and aftermarket exhaust system and airfilter and was producing around 300BHP

Cheers
Ben
 

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what is the actuator set to? you cant reduce boost any lower than actuator pressure
 

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Can someone please explain why you carnt reduce boost lower than actuator pressure.

If the boost pressure is bled off before the actuator with say a boost controller is that not lowering the actuator pressure????

Best boost controller on the market imo the apexi AVCR.

Best for money the GIZMO.
 

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Discussion Starter · #5 ·
thanks for the reply
I had looked at the Gizmo one... about £200?

whats involved in fitting one? and do we need it?

Ben
 

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If the actuator opens at say .5 bar that is the minimum boost pressure you can run.
A boost controller bleeds off pressure going to the actuator so it sees less pressure and stays closed.
If you bled off .1 bar, the actuator would only see .4 bar. even though the boost pressure was .5 bar. when the boost reached .6 bar the actuator would see .5 bar and the wastegate would start to open. therefore you would have a boost increase of .1 bar. Because of how they work a boost controller can only increase boost.
You could not open the wastegate at less than .5 because that is the minimum pressure reqired to override the wastegate actuator spring.
Unless you fit a softer spring or the wastegate actuator is adjustable.
jono.
 

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Discussion Starter · #7 ·
Brilliant...
Thanks for that reply, it makes abit more sense now!

So I need to get an adjustable wastegate to reduce the boost slightly, where could I get one of these?

Ben
 

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So you can reduce the boost lower but by controlling boost by when the actuator opens Either by a softer spring or adjustable actuator.

So I cant set my avcr to say .3 Bar as it would still boost to .5 as that is actuator pressure???
 

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Yes, you can only go higher than actuator pressure by using a boost controller. If your actuator is set to let´s say 1bar (factory setting on most HKS turbos) you can not go to something like 0.8bar using your boost controller. It doesn´t work. You can set it higher though, say 1.2bar.
 

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Brilliant...
Thanks for that reply, it makes abit more sense now!

So I need to get an adjustable wastegate to reduce the boost slightly, where could I get one of these?

Ben
I think conceptua sell them.
Best bet would be give em a call
jono.
 

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So hows the 2 stage stock set up work then???? What happens when you remove the 2nd stage (not the negative mod) dose it not boost to just .3 bar carnt remember what it actually is or what ever stock 1st stage boost is.

just trying to understand this
 

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Two stage boost from stock works by using the stock solenoid valve uping the boost over actuator pressure. From actuator you will run aprox 0.45-0.5bar (stage 1) and stage 2 will be around the 0.7 mark.
 

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On my GTT I was running 0.43bar on actuator/wastegate pressure. With the factory two stage boost activated I was running 0.65bar on second stage. That´s all I can say.
 

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Im not trying to catch anyone out im just trying to make sence of it

As on my 33, stock second stage boost was .5bar shown on a rr result

Also i carnt understand how you can get on average a increase of 50bhp MORE from just increaseing the boost by 0.1bar (not to splitting ends with other mods) it makes more sence if you increase it by almost half a bar!!!!

Maybe my math is wrong i dunno but it adds up with the two rr read out i have at least
 

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well .1 bar could b a couple of psi & also a bigger turbo requires less boost to make the same power if not more

you say running a lot more boost what was it running & what is it running now , this would of been benificial to no at the start of the thread
 

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You need to think more in terms of actual air flow, rather than by boost pressure.

A larger turbo with bigger 'blades' will flow a lot more air at the same boost pressure than a smaller one. Think of a sailing boat with sails. Larger sails catch more air even though the wind speed is the same...
 

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Thats cool thank you

but I'm talking stock turbo and upping the boost.

Or were you explain the original question

Ps sorry I've kinda high jacked this thread
 
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