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Discussion Starter · #1 ·
I finally got my hands on a boost gauge and did some measuring. My base boost seems to be set at about 6psi, which according Bill J's table is correct.

I was also watching the boost during acceleration once the car is warmed up. The highest I ever see is 10 to 11psi, but that is only a momentary peak when you open the throttle quickly. It almost immediately falls back to about 8 psi. If you open the throttle gradually, boost doesn't go above about 8psi (i.e. you don't get the initial spike). This is even with your foot to the floor in fourth.

Occasionally the boost holds a bit higher, at maybe 9 or 10, but this seems rare.

This doesn't seem right to me.. What should peak boost be on this car?
 

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John, Saab does list the peak boost at .81 bar (~12 psi) and yours is close. But I would think that it would hold that pressure for a few hundred (maybe a thousand?) rpms. And to think that my dearly departed Aero used to peak at 24.5 psi from 3500-4500 rpm I would look over all the control hoses and maybe the BPV, checking for leaks.
 

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when i had my "holy" dump valve, it used to spike to 9 psi then sit at 7psi afterwards... i had a hole/split that was almost 1/2 way round the diaphram. got a used one from a 9-5 aero and the hooting on partial throttle stopped, aswell as a peak boost of 16psi (modded apc) that i can hold from 3000-6000 on a good day. check the DV.
 

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So what is the peak boost of an un modded aero? I was thinking of getting a boost gauge but wanted to get one that could fit full boost in but at the same time give me sufficient resolution to allow me to set the base boost with it.

Kev
 

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Discussion Starter · #5 ·
I am pretty certain it's not the dump-valve. I've got a Bailey double-piston atmospheric one... and it made no difference to the running of the car. Also, I am as certain as I can be that I have no leaks anywhere.

Can anyone tell me, incidentally, how to check the charcoal canister. Should the valve be closed if the car is not running?
 

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John, is the valve new? I fitted a secondhand Bailey recirculating valve and it started leaking after only a few months. Kevster, peak boost on the Aero varies by year. Up to '95 it was 0.98 bar. '96-on was allowed to peak briefly at 1.08 bar before falling back to 0.98. I assume we're talking about the manual version with the B234R engine.
 

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Hi Bill
I have a 1993 manual B234R aero. If 0.98 bar is my max' then I assume that a -0.5 to 1 bar guage should be the most informative..although 1.5bar may be worth while if I intend to go for a few mod's?
Kev
 

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On my unmodded 93 Aero I would see spike to 1.25 bar and running at 1.1bar.

With my Stg 3 I now see 1.4 and 1.45bart running and the overboost cutout is 1.5bar (and it feels hard!)

I used to have a 2bar (30psi guage in that car but have now changed it down to a 1.5bar one which is easier to read and just right for up to stg3.

Andrew
 

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Discussion Starter · #12 ·
Originally posted by BillJ:
[qb]John, is the valve new? I fitted a secondhand Bailey recirculating valve and it started leaking after only a few months. [/qb][/b]
Hmm that doesn't sound good. It's an ebay special. Looks new, but admittedly doesn't have any manufacturer's name stamped on it, although it appears identical to a bailey double-piston type.

As I say, I got the same with my previous standard Saab item, which I think was OK.
 
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