Boost readings, maximums, and where from?

[SimonMitch]

Hope someone can help me, I've been modding a s12 for drifting, I've followed all the cheap stuff in the mod box, cut and welded rear springs, cut front springs, welded diff, mbc valve, saab intercooler, fatter exhaust, 2.5inch no centre box, but now I have fitted everything, I read that the stock turbo shouldn't be set above 12psi, I have 2 readings, one directly on the turbo outlet thats feeding the actuator via the mbc valve and one at the intake, I have a nice constant 10 psi on boost at the outlet of the turbo (foot planted, revs near the red line) that does a little 2 psi twitch when I drop off the gas and the stand ard guage goes maxed out once I get near 8 or 9 psi on the new guage. These readings are pretty consistant through the gears, although I did read somewhere that it varies through the gears (couldn't work out why this might be?).

Anyway are these readings about right or can I get away with tweeking it up a bit more without it blowing up?
Many thanks in advance

Cheers
Si

[PukkaSilvia]

Max boost can only really be judged at full throttle .

Put it in 3rd or 4th and from 30mph just full throttle it to 5k. You will then find out what peak is.

Connect the boost guage to a vaccuum on the inlet manifold area. T off the fuel pressure reg feed Or there is a spare blanked off feed on the bulkhead just above the brake and clutch master cylinder,

There are not any benefits from going above 12psi on the standard turbo. It will just kill it for the sake of about 8hp when turbo cold

Get some proper springs made up. Chopped ones are horrid

[SimonMitch]

Cool, thank you for the answer, I'll have a look at the other pick-up. All the figures are on full throttle then letting off. So its 12PSI on the actual plenum? I read somewhere on here that there is a pressure drop between turbo and plenum? If I'm setting for peak 12PSI at plenum, I'll be seeing 14PSI or something at the turbo outlet? Is this right?

I'd have brought nice springs but everyone I asked said they needed patterns/specs, I contacted some of the companies listed on here and none were any help. All the off the shelf ones were £150 plus so we were nice and rough arse with them!! Its much better than stock, honest!! Especially now we replaced the totally knackered front wheel bearings and the rear crossmember bushes. I think I'll be doing the rest of the bushes when we have money and time.