Bob Rawle

Alan, yes soemthing like that, if blade temper was not what it should be maybe that could be the cause, another theory.

bob

Jack0

Hi Bob,
so are you suggesting IYHO, that it is possible that over shimming a RED spring in a Forge Recirc, could potentially result in Comp blade failures???

Wow, I never thought that VF's were that toffee like...!

p.s I am dynoing the 5 on Friday!
Jacko.

EMS

Jacko,

I should realy be carefull with stronger springs in the DV when using a VF turbo! I have the same experience as Bob, with snapping blades because of pressure peaks at part throttle. The compressor wheels of the VF turbo´s are not very strong. (to say the least!) However the Mitsubishi turbo´s are almost unbrakable.

Mark.

Bob Rawle

A red spring is only about 7 psi and in reality doesn't even hold that but if you use anything that much stronger then VF wheels become fragile. A strong spring on an uprated engine provides for benefit especially on gear shift but you do have to set them up carefully to suit. My Sti5 bov is set to hold 1.3 bar b4 opening but I do have a Garrett hybrid, the Mitsu turbo's also have strong wheels.

bob

JamesS

muuummmm...

Is the BoV diaphram not connected to the manifold?

Therefore if you are running 1.5bar say, you will have 1.5bar on the back of the BoV holding it shut?

Surely the spring is only there to stop the BoV opening as boost rises and you have a slight variation between I/C side of BoV and manifold side, in-addition to influencing how much/fast the BoV opens on a throttle lift???

AlanG

If you have full throttle open, then yes both sides will see the same pressure and hence the dump valve will be shut, but on part throttle you can have low pressure (boost) in the inlet manifold but high pressure in the intake to manifold before throttle butterfly, so dump valve will open due to differential pressure.

Alan

JamesS

.....but if you are making any positive boost the pressure will be roughly equal before and after the throttle plate (bar loses through the throttle body which will be small)?

Bob Rawle

Not true, at 0.5 bar in the manifold my STi5 makes an easy 1.6 bar in the intercooler if I let the revs build. Use about 25% throttle maximum to hold that. As Alan said you only get equal pressure on wot.

bob

Jack0

JamesS, hi matey, but I still disagree with you on this one as do others...

Mr Rawle, so for my setup, I should be using RED spring only???? or ditch altogether and go for a 9?

Jacko.

tweenierob

Post to fix error....

May as well add something useful...

Andy F, would i be right in saying that your engine is running with Lateral Performance supplied Pistons

Rob

Andy.F

Exducer tangential velocity Easier than saying 'tip speed'

Adam - What


Nom - Not quite ! The speed of sound increases with temperature - example at 20 degC it is 343m/s and at 100 degC it is 392m/s Thats a 14% increase.

Bob I'm not sure how Alans DV is routed, it's a possibility though.
We'll soon see if it destroys his new TD05/06-20G

Surge could bend the blades backwards, as high pressure air blasts in a series of pulses backwards through the compressor although I am reliably informed that the 141 does not surge.


Andy


[Edited by Andy.F - 9/11/2003 11:10:43 PM]