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morghen · Joined: 21 Jan 2005 Posts: 9102 Location: Romania

I've just replaced the wastegate diaphragm, the old one had a hole that you could put your finger trough and the turbo was producing 1.5+ bar.

Last year i installed a 1.0 Bar spring and the boost climbed up from 0.6 to ~0.8 bar. Performance went up too...but i was expecting the 1 bar spring to produce 1 bar.

When i installed the new WG diaphragm i also installed a 0.75 inch or 20mm aluminium spacer in the wastegate to help the spring...thinking it will upp the boost to the much desired 1 bar.....well it didnt...actually it didnt doo anything...the gauge reads 0.8 bar maximum.

any ideeas why?
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morghen · Joined: 21 Jan 2005 Posts: 9102 Location: Romania

i'm thinking:

well since with a hole in the diaphragm it made 1.5+ bar boost...it does not smoke at all...eats no oil...has no play...the turbo must be just fine !

so...its the wastegate.

a possible fault would be the piston that actuates the valve to have some sort of damage...but i checked...it works nice and easy..no radial play...and no sign of gunk anywhere so the piston seals and works.

next ideea would be that the valve itself does not close but from what i've seen it does not look damaged or bended.
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morghen · Joined: 21 Jan 2005 Posts: 9102 Location: Romania

ok...the WG is in good condition and a very simple device...there is no sign of wear so mechanically its sound....i'm ready to admit that i've been ripped off and i've been sold a 0.8 bar spring instead of a 1 bar spring....i cant see any other solution to this...
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Rich H · Posted: Wed Mar 24, 2010 6:12 pm Post subject:

But the 20mm shim should have made a difference....

How about the dump valve - is it holding pressure?
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1994 Lotus Esprit S4 - Work in progress...
1980 Porsche 924 S2 DITC Turbo - Original spec
1978 Homo-Sapiens - Tired spec
1953 Landrover S1 - Pensioner Spec

morghen · Joined: 21 Jan 2005 Posts: 9102 Location: Romania

Rich H · Posted: Wed Mar 24, 2010 6:59 pm Post subject:

Fair enough! Sounds like a duff spring then. Was it new?
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1994 Lotus Esprit S4 - Work in progress...
1980 Porsche 924 S2 DITC Turbo - Original spec
1978 Homo-Sapiens - Tired spec
1953 Landrover S1 - Pensioner Spec

morghen · Joined: 21 Jan 2005 Posts: 9102 Location: Romania

no, i've got it off ebay...the guy said its the right thing...but i guess he didnt test it.

now....anybody in europe that can send me a tested and working 1.0 bar spring?
i would prefer to buy one...but if you have one and dont need if for the next month or so...i would be glad to pay for shipping just to test it and confirm that the spring i have now is an 0.7bar

or....if anybody needs a 0.7 bar spring and a 0.6 bar spring...i can trade.
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ideola · Joined: 01 Oct 2004 Posts: 15550 Location: Spring Lake MI

morghen, I don't understand why you're so intent on having a 1 bar spring. You have a boost controller, correct? And a dual port one at that. Why the need for a 1 bar spring???
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morghen · Joined: 21 Jan 2005 Posts: 9102 Location: Romania

Dutch924-racer · Joined: 23 Jul 2007 Posts: 1081 Location: The Netherlands

I have a 1 bar spring for sale, pm me if you are intrested.
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9xx · Joined: 18 Jun 2006 Posts: 627 Location: Jarvenpaa, Finland

Morghen and Dutch924-racer: did you buy your springs from Ebay? Seller was perhaps "rufyellowbird"?

I bought a spring that was claimed to be a 0.8 bar spring, however it is a 0.5 bar spring so I ended up downgrading my car into US spec. I have to change it again.

Be aware if buy spring from this seller because he obviously doesn't know what he is selling. I don't think he is trying to cheat though.
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Mikko

All gone: 931 '82 Alpine White, original option "220" G31 with LSD + 3 x 944

flosho · Posted: Thu Mar 25, 2010 2:12 am Post subject:

Manual. Boost. Controller.

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Rasta Monsta · Joined: 12 Jul 2006 Posts: 11733 Location: PacNW

I have a Weltmeister 1 BAR spring for sale.
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WeiBe (1987 924S 2.5t) - 931 S3

9xx · Joined: 18 Jun 2006 Posts: 627 Location: Jarvenpaa, Finland

ideola · Joined: 01 Oct 2004 Posts: 15550 Location: Spring Lake MI

I think that depends on the boost controller you are using. As a genearl rule, wastegates suffer creep, and I suspect a weaker spring would creep more when used with a MBC. However, the MBC morghen had should have offset that effect because it was designed specifically for a dual port wastegate, which our cars have, which routes part of the bled signal to the upper port to force the spring to stay closed and prevent creep. I've not experienced it myself, but from what I've read, this technique cause the boost to come on suddenly, and is more definitive than even a stronger spring, which will experience some creep by itself. I suspect in your case you had a basic MBC that was not acting on both ports...
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erstwhile owner of just about every 924 variant ever made