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Miker · Joined: 25 Jan 2005 Posts: 47 Location: Cali

what can I do, I have read in the past a 930 spring. But have not been able to find one. Is this right, what benefits, what years? Thanks

Paul · Posted: Wed Jun 29, 2005 6:18 am Post subject:

Andial sells them, but they are 1 bar springs. 1 bar can damage your motor if it causes denotation.
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Owned and repaired 924s since 1977
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Miker · Joined: 25 Jan 2005 Posts: 47 Location: Cali

ok, so your saying that use at own risk!! why would thesring cause detonation?
Mike

Smoothie · Posted: Wed Jun 29, 2005 9:38 am Post subject:

The original equipment spring in a US 931 allows approx. 0.43-0.47 bar of boost pressure and for Europe it's 0.62-0.73 bar. A 1 bar spring more than doubles the boost pressure for a US car. Raised boost = increased compression and the likelihood of having detonation occur increases as compression goes up. Those that use 1 bar springs generally incorporate other mods to keep detonation under control such as - an intercooler, water injection, fuel enrichment, timing controls, or as numbbers does with his boost dialed up to something like 17psi - he drives a mile higher than the rest of us.
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"..it's made in Germany. You know the Germans always make good stuff."

'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox

Miker · Joined: 25 Jan 2005 Posts: 47 Location: Cali

I have completed the wastegate spring 1.05bar and the new boot from andial cost me about 130 or so i think. Hope its good!!!! The size diffrence of the two springs is just amazing!!! Thanks guys Mike
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1980 924 Turbo (in pieces right now, but getting there) almost there
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2000 Getta VR6

-nick · Joined: 16 Nov 2002 Posts: 2699 Location: Cambridge, MA

I've been chatting offline with Wayne at "The Power Group" (who is a goldmine of 931 performance info). He has found that at 1bar fueling becomes a problem (I'm guessing it can go lean) which makes short work of headgaskets. He also alludes to the timing not being quite optimal at such pressures.

Just a note of caution.

nick

WEASEL149 · Joined: 19 Aug 2005 Posts: 595 Location: UK, Sheffield

John H has run 1bar+ in his GT replica for some time without mishap.
I think he also uses standard head bolts instead of aftermarket fasteners.

I think if you're going to run 1bar all the time you need to make a few changes IMO, and also check a few things.

If your car is a series 1 with the lower compression it's obviously going to be easier to run more boost, before the onset of pinking/detonation.

First of all I would recommend fitting an intercooler - more boost means more heat. Fitting a 951 intercooler to my car made a huge difference to intake temps.

After this, the increase in boost and the denser charge will put more stress on the cooling system. Either fit a more efficient/larger capacity aluminium rad or a copper one. You can also rig the fan to come on earlier.
John H also has an extra oil cooler plumbed in. Basically it's a matter of keeping oil and water temps down, making the headgaskets' life easier.

Lastly, check the ignition timing and make sure it isn't too advanced. Also it doesn't hurt to run checks on the fuel system to make sure it's 100% remembering to run the car a little on the rich side.

Remember to run decent fuel (higher octane) and/or some type of water injection.
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1979 UK 932

WEASEL149 · Joined: 19 Aug 2005 Posts: 595 Location: UK, Sheffield

When I increased my boost from 0.73 to 1.0bar the difference in performance was quite large. I imagine anyone moving from 0.47 to 1.0bar is going to have a big grin on their face!
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1979 UK 932

numbbers · Posted: Wed Sep 28, 2005 10:58 am Post subject:

Yep, I run 17 PSI (one bar is about 14.5 psi). You will definitely notice the difference.
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1980 924 Turbo

Archie9xx · Joined: 06 Feb 2005 Posts: 78 Location: Finland

Wouldn't it be smarter to install boost controller instead of just swapping the wastegate spring? With that you can adjust the boost level quite safely and continuously to the exact level you want. Also 931's wastegate is bleeder type, so it lets exhaust gas pressure to escape little before the wastegate reaches it's opening level. With boost controller the gate stays closed until the pressure reaches the level you chose - the increase in mid-range torque is noticeable.

http://www.turbosmart.com.au/
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john h · Posted: Mon Dec 19, 2005 7:12 am Post subject:

Archie9XX

is correct - when I upgraded my boost many years ago (1987) The turbo guru in NZ at the time recommended against a 1 bar spring, for the reason that even though in his opinion 96 octane would be ok most of the time when, if I decided to drive the car hard for a period of time (but not on the track) detonation could occur and an adjustable unit would be better..
Makes it much easier to adjust and makes the car more flexible - occassinally I've brought gas from a station that has crap gas - water and such in it and it really useful to be able to quickly turn the boost down till I eitehr drain the tank or the stuff gets out of the system.
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