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Okay, so now we're getting somewhere.
Your B21FT is a good strong motor. Depending on how many KMs it's got, it could have lots of life left in it. Athal and I both had B21FTs that plumb wore out, though, long before they stopped making power. It's a funny thing - we were both changing oil every 3-5 days because it was getting diluted with gasoline, blowby from worn out rings, but neither car burned a drop of oil.
The B21FT has the luxury of having really thick cylinder walls, tough pistons, and low compression. On the other hand, it's missing 200 ccs from the B23 and B230 turbo engines, and the lower compression hurts both fuel economy and throttle response. The low compression allows you to run MASSIVE boost safely, though!
I have personally installed Megasquirt and tuned up a B21FT in a rally car and was pretty happy with the results. It had a stock bottom end but I don't remember the cylinder head it had (not really that important), it had an IPD Turbo cam (same as an Enem V15 Turbo) and it had a 90+ exhaust manifold with a built TD05-15G turbo. The engine ran happily on 94 octane at 18-20 psi of boost and it was massively responsive. Being that it was in a rally car, it was built to be responsive, otherwise it would have had a larger turbo and would have made much more power. In my opinion, it SHOULD have had a larger turbo - the response wouldn't have been hurt much and it would have made a ton more power, and been more controllable in the gravel. Anyway, the power difference before and after the installation of Megasquirt (and a cheapo eBay intercooler) was night and day.
We'll ignore my engine for now and I would suggest you see how far you get with your own first. Get your T5 installed with a strong clutch, I've got a driveshaft for your car ($200, ready to go, from my V8/T5 244), and make sure your fuel pumps and ignition system are in good shape. Get a 3" downpipe and a minimum 2.5" exhaust with free flowing mufflers. Get a decent wideband O2 sensor system for tuning. Make some "detcans" (search Tbrix for these - very simple, some cheapo earmuffs, some surgical tubing, and a squashed piece of copper tube that gets bolted to the block. These allow you to listen for ping or knock, to hone your ignition tuning skills). Play with all this junk on your current engine, mess around with the boost and ignition, and get to know what feels good and what feels bad.
First modification after the exhaust system would be, for me, the Megasquirt. Any aftermarket EMS will be essential for 300+ hp on your engine. You will screw up your tuning several times learning how to tune and learning the sins. We can start another discussion when you like - maybe another thread. Anyway, don't be afraid of throwing your tunes out because you're going to be retuning just about from scratch every time you change anything, and if you're like me even when you DON'T change something. I promise you that you'll want to keep a laptop handy, just about 100% of the time, and you'll monkey with it constantly. There are several threads on Tbrix on what parts to buy, what version of Megasquirt to get, and how to do the install, so I won't go into it here. What I will point out are the differences in intake manifolds: The EFI intake manifolds are good and simple, but are a little restrictive at the power levels you're looking to reach. The B21F/B23E intake manifolds are much better, but do not have injector holes. You, however, have a K-jet head and the K-jet holes & EFI injectors/fuel rail can be made to work together. Your call.
An option you may investigate is to install LH 2.2 or LH 2.4 on your B21FT. This can and has been done to great success, and there has been a lot of success in tuning up the LH 2.4 to allow massive injectors and big boost, as well as raising the RPM limit to some degree. This is much less well documented and much more experimental than Megasquirt is, and the results may or may not be satisfactory. The advantage is that you'll be dealing with factory stuff, but the factory stuff uses hardware that's vastly inferior to the Megasquirt - much slower processor and with much less memory. You may find it to be less sensitive to atmospheric changes, being that it's MAF based and not Speed Density like Megasquirt, so the tune might be more stable but won't be as sharp as a well tuned SD system.
Once you've got your spark and fuel tuning chops, THEN I would say it's time to start thinking about the turbo and exhaust manifold. A good start would be a 90+ Volvo turbo exhaust manifold, AS LONG as you open it up to match the inlet of a Garrett turbo. Junkyard turbos are getting scarce in decent shape, and are even tougher to find in the larger sizes. You'll pay someone just about as much for one as you will a good rebuilt one from somewhere like Cherry Turbo or Alamo. Personally I wouldn't bother with either anymore - they're better than what you've got by a long shot, but not as good as you can get if you're willing to spend some money. Instead I'd look at spending the money on an RSI header and a proper, state-of-the-art turbo like a Garrett GT series. Talk to a turbo guy for this. I think the headers are north of $600 and the turbo will set you back double that, plus plumbing and a different downpipe, but you'll be happy you did. This will be complete overkill unless you start moving on the next few modifications quickly.
Another option for the turbo is the ubiquitous Holset HY35W or HE351W. These come on later Dodge Cummins diesels and are designed with a 5.9 litre inline 6 oil burner in mind. They can and do work on a Volvo 8v, but you're probably going to need an external wastegate so consider this in your costs and in your header selection.
Get a different intercooler, for sure. One with proper end tank design is the goal - those eBay ones aren't very good. Unless you're able to get one from an Isuzu NPR delivery truck, or secondarily one from a Nissan UD, you're going to be spending some money getting one built. Maybe RSI has developed one by now, I'm not sure. The Powerstroke fits... IF you cut your frame rails and disable your bumper shocks, AND go with a flathood and single round headlight conversion. Not my idea of a good idea, but it's been done very effectively. It is possible to shorten a Powerstoke intercooler but you'll be spending plenty of money on a not ideal solution. Look around at what the big boys on Tbrix are running, and ask some questions.
You can definitely do better with the cylinder head. The 530 from a B230 is a good choice as long as you're using the EFI intake manifold to match. This head is tougher than the one you've got, but doesn't flow as well as the 405 which doesn't REALLY fit your engine, even though lots of us have installed one. Get a good 3 angle valve grind and get the valves back cut. Some light porting in the exhaust bowls is helpful, but these heads don't flow very well without major work, and even then I'm not sure how well they can flow. As far as a camshaft? The T cam is just fine as long as you get the rest of the engine flowing. You can do better, obviously, but the B21FT and it's low compression ratio doesn't lend itself to radical cams. The IPD/Enem turbo cam is a good choice if you want to rev above 6000 RPM, or you can go even further if you're confident in your engine's health and your valve spring strength. There are many other choices, but I wouldn't worry too much about the camshaft if I were you.
There you go. Recipe for 300+ horsepower. Now go do it. It's not difficult, but what most people stumble on is scraping the cash together for the essentials. Getting your engine to 200 hp costs about 50 bucks. Getting it to a reliable and safe 300 hp costs considerably more, and it's helpful if you're handy with a TIG welder and can scratch together junkyard parts or are willing to experiment. Getting it to 400 costs more than 300, plus you're now breaking lots of other stuff like transmissions & clutches & rear ends, the bulletproofing of which costs more money.
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