Saabscene Saab Forum - Saab Technical Information Resource banner
1 - 6 of 6 Posts

·
Registered
Joined
·
277 Posts
Discussion Starter · #1 ·
Hi. I've done a few runs with my non-misfiring 9k CD (converted to manual)... I get about 13 psi at 3k rpm to 4k rpm, but when I go higher than that, it drops down to between 9 and 6 pounds. Is this normal? Anything I can do to help it keep the boost up through higher rpms? I've installed a MBC (Dawes Device), lightened the flywheel, disabled balance shafts, and K&N filter.

Edit: Little vague on the model.... 1991 Saab 9000 CD Turbo
 

·
Registered
Joined
·
1,086 Posts
I have had a similar problem when I had a MBC on my 9-3. It probably has something to do with where you tap the mbc in for pressure. It is probably easy to get it to boost higher by cranking up the mbc, but then you'd have to deal with the massive boost at lower rpms. Some people have tapped into the intake manifold for more consistent pressure through the mbc but this leads to big boost spikes as the boost to actuate the wastegate will take much longer to get there trough the long hoses.

This whole reason is why I chose a ECU upgrade as it offers the higher torque and hp that some mbc setups cannot acheive. My mbc was great for spool-up times and mid-range torque but suffered the same as your 9k on the top-end.
 

·
Registered
Joined
·
277 Posts
Discussion Starter · #3 ·
Interesting. I would much rather have gone with an upgraded chip but it's a little expensive. I'd even rather use my stock APC, but I belive the chips they put in the automatics in 91 have the boost cut back. I found a trick with the automatic shifter wires that make the ECU think it's a manual, I'll have to try it and see if the APC system is also tricked. I hadn't thought of different places to tap the MBC. I think the tube going from intercooler to throttle body would be a good median. Not to mention it has a VERY convenient nub that went to the automatic trans for whatever reason it needed. It looks like the perfect place to tap. I'll give the intake manifold a try as well. Thanks for the advice.
 

·
Registered
Joined
·
281 Posts
There's been lots of talk of a fuse trick also for the automatic. Is this the one your talking about. Something to do with removing one of the fuses at startup.
 

·
Registered
Joined
·
2,277 Posts
Tried this trick on a mates 2.3FPT last week, it seemed to give around an extra 10bhp at the wheels and cut the 50-70 time by half a second. Not too bad for just pulling a fuse!

Nick.
 

·
Registered
Joined
·
277 Posts
Discussion Starter · #6 ·
What fuse are you all talking about? I shorted the top 2 plugs on the actual connectors leading to the automatic shifter (or bottom 2 I can't remember ) And my automatic shift light on the trip computer showed no gear. I had to do this to get the car to idle correctly. For whatever reason the IAC was overcomphensating when it came to idle. When it was in this "manual mode" it idled perfectly.
 
1 - 6 of 6 Posts
Top