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I've just purchased a 1997 940. 2.3l turbo engine which has a m90 box with oil squirters and the boost cracked up to 12 psi. I'm looking to get it to run a safe 250bhp and I'm finding a lot of contradicting info online about what turbo,injectors and maf to upgrade too? Ive already got a bigger intercooler for it. Can anyone help me out as I'm a bit of a noob lol,cheers
you'll struggle to get to 250 bhp with the stock turbo of course.
There is a lot of contradicting info out there but that's because there's no one way to get to your power goals, although there is a general path that most people follow especially in the UK.
First of all, sort out all the vacuum hoses, seals, blah blah that will cause issues. Stage 0 basically. Then get a wideband.
A rough list of specs for 230 wheel horsepower from an old turbobricks thread (so around 260 ish at the flywheel):
TD0416T at 16psi, angled flange housing (so the least restrictive hotside you can get)
Plus porting of the manifold and outlet flange, wastegate etc just to make it flow as good as it can. It's still a pretty small turbo though.
3" exhaust from turbo back.
KL racing intercooler or DO88, anything that flows better than the stock one really. The stock one is kinda restrictive and also likes to blow apart the plastic end tanks at higher boost.
A/D/VX3 cams (depending on what's available)
~ 370cc injectors (blue or white from an 850 / early S70 T5 will do) and you'll need to make sure they're the right impedance. So will require a modification to the resistor pack if you get low impedance injectors.
Most people have had at least a basic port job on the manifolds and head, even if they don't go with bigger valves.
People seem to like messing about with 3 inch MAFs (and then shove it through a tiny TD04 or the cheapest eBay turbo they can find) but honestly they seem to present a lot of running issues... most people do it to allow them to fool the ECU and run bigger injectors on the stock fuel map, but the best course of action is to actually just get someone who knows what they're doing to do a proper tune for your setup and burn you a chip with proper scaling for the injectors you want to run.
Martin Smith is the go-to guy in the UK for these. I'd be inclined to get this done and just run the stock MAF for as long as you can to avoid the headaches it can cause. The stock MAF is unlikely to be the limiting factor even at 250 wheel hp.
The major limiting factors on these cars are the small turbos and restrictive exhaust housings, through restrictive exhausts. Then the cylinder head doesn't flow amazingly but the quick answer to that is more boost. THe stock injectors aren't as bad as everyone thinks either - I'm running about 15 psi on a 15G (small turbo still) and my AFRs are in the 10s above 4500 rpm even with a chip. It's a safe bet to chuck bigger ones in for headroom but you don't need to go overkill for 250 at the crank
Martin Smith as mentioned above is really the guy one these, these days. His build is seeing 460bhp at present on the rollers and has the scope for more yet, send him a pm about build and mapping, I'm sure he'll point in the right direction to easily achieve your goal.