How Much Boost Is Too Much [Archive] - SaabCentral Forums

: How Much Boost Is Too Much

20th May 2002, 09:04 AM
How much boost can I safely run on my 1991 T16S if I disable the fuel cut switch and sort out a RRFPR/LH Chip for it. I want to run something in the reason of 1.5bar, with a bit of APC tweeking and a trent actuator.


20th May 2002, 10:54 AM
You will be able to peak at that level but knock detect/APC will still cut it back to say 1.2 bar.


20th May 2002, 01:53 PM
Thats fine, at the moment it peaks at 1.1 and drops back to 0.8 bar. What will I have to uprate? Will the stock headgasket be okay? Would some SPG9 fuel injectors be a good bet along with a RRFPR/Chip?

Thanks in advance

Johann F
21st May 2002, 01:13 PM
Just do the RRFPR and tune it to suit -the Lucas FI with stock injectors is not going to limit your power - it's a combustion temp thing!
The rest of the stock items should hold out with this power - except the gearbox but thats an unknown quantity - depends on it's previous life. What I would do is to change the gearbox oil - there is no drain interval and it' s probably well past it's best.You will have to remove the rear diff cover to do this. Also make sure you change the engine oil at least every 3k miles with a good fully synthetic such as Mobil1. Make sure you have newish ignition components as a misfire will be easier to induce at higher boost - NGK BCP 7EV plugs are essential! Also make sure you are going to be able to stop as well! - good pads and disks and also concider new shocks if they are much over 60k miles old .The best advice I can give for prolonging the life of the box is; do not hammer it in 1st and 2nd (Alan will probably agree with this) this means tearing away from the lights is best avoided. Only apply full power with the engine fully warm, avoid boost rising sharply then dropping back very quickly in a surging manner - reduce the P setting a bit at a time until it becomes a controled boost gain -you will actuly go faster as the boost is not being cut back so sharply.

21st May 2002, 01:36 PM
Thanks for all the advice. One of my freinds can sort me out with 320mm discs with 4 pots on the front and 300mm discs on the back so I'll let him get on with that. Will change gearbox oil. One thing, my car dosn't have a gearbox dipstick, is this normal, theres no tube just a bolt in the gearbox where the dipstick should be.


21st May 2002, 05:19 PM
Just remember, boost is addictive and after a while what seemed like a major hit just becomes the norm and you will start to experiment just to see what a little more feels like.

BTW to fit 320mm disks I would have thought that you would need 17" rims to fit them under.

Johann F
21st May 2002, 06:17 PM
Yes - check those disk sizes against your wheels.The bolt you see on the gearbox has a dipstick built into it .I've never been able to figure out why Saab thought you could run a lot of power through a gearbox ,generating a lot of heat in the prcocess, and not get any deterioration in the oil - when I drained mine ( after 125k miles and a FSH which does not include a change of oil) it was dense black and piss thin!