Anybody in Calgary have a header for a B21 kicking around they want to sell?
Also might be looking for a head.
It's for my 242GT

Also maybe in the market for a K cam. (or VX?)

I have a Stahl header, but it's not in very good shape and should probably just become garage art. Why do you want one? They don't give you a lot with the cam you're looking for.

I was thinking along the lines of 'every bit helps.'
Honestly, I'm not sure where to go next with the car, but I do want to make some more power out of it without getting into a significant build.

What cam do you have in the engine now?

I think we need some more details on the car. What sort of shape is the engine in? Have you had a leak down test? What are the compression numbers? Stage 0? Then I'd do a cam swap as Greg is pointing at...but honestly, naturally aspirated HP on the cheap is just not going to be very satisfying in my experience. Best case scenario would see you make 140 hp. So that 242 will still be lagging behind.

I haven't had a chance to look into the engine much, but expect it to be 100% stock. Original Canadian market 242GT.

I wasn't suggesting a cam swap at all...quite the opposite. A stock North American market 242 GT has a b21f in it which should have the B cam in it. In terms of Volvo cams, its a pretty good one....fairly similar to the A cam (which is usually seen as a reasonable upgrade), but it makes much better low-end torque to the K cam. Unless you alter the cam timing of the K cam you want, its a very peaky cam, particularly in in the b21, and for driving around town, you have to rev the snot out of it to make it do anything. Having run a K in a b21f for many years, I must say I had a good time with it, and at the top end it was a hoot, but the reality is the B is a better cam for street use. The VX you suggest isn't that different from the B to make a noticeable difference in power either.

As far as a header, running one with a stock engine won't make a noticeable difference in power either. The stock manifold flows well enough. A larger exhaust will give you few extra horses, but beyond that, I'd say just make sure your engine is in good tune, and leave the B cam in there. Sorry there isn't more I can suggest without opening the engine or adding a turbo.

Not much I can add to what Greg and Craig have already posted. The reality of the matter is the B21F is just not going to make much power no matter how much money you throw at it. I'm sure there is someone making 200 hp with one but it'll need to rev to the moon to do it and that's not terribly desirable in a street car. It evolved from a tractor engine. It's heavy, strong and durable.

The K cam was in the B23E and the extra displacement helped with the bottom end torque a bit. Not a good match for the B21 for a street car. It will, however, rev until you lose your nerve. If you've got a serious pain threshold, I've got an RSI NA cam here somewhere...

Depending on the year of 242 GT that you've got you'll have either 104 or 107 hp. The exhaust flows well enough to make well over that so it's not a huge restriction, the airbox moves more air than the engine can ingest so that's not the issue...the exhaust valve is a for sure restriction and the cam selections are somewhat limited.

As I see it, you're stuck where we all have been before...wanting the car to at least be peppy. I always think that for the time, when V8's were making just a little more power than this little 4 banger, it was pretty good. A lot of Volvo people think that the NA cars were just fine - and I'm not arguing against that, but they were not performance cars (even with the GT badge) and the market for performance NA Volvo stuff (and I'm going to stretch this just a little) is dominated by the older pushrod engines. We have cams, mods, valves and other goodies that are basically drop in and we can hit 160 HP on a pretty reasonable budget (not no budget, like $4 - 6K). That gets you a very nicely rebuilt engine with nice usable torque band and OK performance.

So where does that leave you? Well...there is hope. The B21F came with either 8.5 or 9.3 to 1 compression ratios. If the engine's in good shape (and they often have more miles on them than you'd like and the bores are pretty shiny etc...they don't run forever), then a stock rebuild ($1500) would get you in the game of what is called a "+T" which means you've added a turbo.

In stock trim (5-7 psi), that gets you 140 - 150 hp. You've got to handle the fuel and spark management somehow (stock NA K-Jet isn't going to cut it) - an EFI swap using MegaSquirt or LH 2.2 (Bosch Jetronic) will have you smiling and be a very nice wake up. This is stock stuff - stock turbo, stock manifold, stock drive train.

Let's call that the first stage of the fun. Some guys find it easier to just source a reasonable 700 series turbo car (literally free sometimes) and swap the engine over - this costs mostly time. Unobtanium parts include things like the fan shroud - get creative or find a 240 one. Maybe a set of rings and a bottle brush hone if you're sort of serious. We can help you with that swap as just about everyone commenting in this thread has done it (we don't have any BS guys on this forum). There are conversion wiring harnesses available for this swap - it's that common (Google Dave Barton wiring harness LH 2.2 - Greg's got the prototype in his car).

Next up would be to find a late 700 or 900 series car and go up to Jetronic 2.4 (called LH 2.4) - this is what I'm running. You do need to start to assemble things, but the process is relatively painless. So you'd need a wiring harness from a later 240 (I'll list contacts later) and a few other things. Many of these cars were automatics and that isn't the end of the world, but it's not as much fun...so you'll need a drilled flywheel to run 2.4 (60-2 pattern) - these can be sourced or just made (I've got a build thread - it's covered in there). You'll need the auxiliary shaft from an LH 2.4 240 (they were all NA) and the dizzy as the 9XX cars run a head mounted dizzy that won't fit in a 240 without surgery and have a wiring harness that is a nightmare to convert. LH 2.4 needs a signal to indicate if the car is rolling or not and it doesn't care much about what that signal might be so lots of solutions have been tried and most work. Then there is about 9 wires to connect and you're golden.

2.2 is considered the easier swap as it doesn't require the drilled flywheel and movement signal, the dizzy was in the same place on cars running 2.2 so you just need that and the ignition box as well as the ECU. Other nice things to include are a turbo manifold from a 1990 and up car (referred to as the 90+ manifold), a larger turbo from an 850T (more work to fit) and a bigger exhaust (2.5" is fine). My set up makes around 250 hp at the crank at 2 bar, starts when it's -30° C and gives me a solid 10 L / 100 km on the highway. This version costs money and is a project. Wiring harnesses are available from a guy called Philski o'flood on Turbobricks...he's got the ignition and ECU's normally as well.

You could also Megasquirt it if you don't want to go with stock fuel and spark management. Matt and Dale are among the first guys to have done this to these engines...so the knowledge lives here. It's been done a lot and the problems are sorted out - but you've got to like tuning and understand what everything is doing as you're at the base level of management. So if you want a black box, then LH swap it. If you want to play, then MS (or some other stand alone).

Band-aid ripped off. Sorry.

I'm not sure it's as bad as all that. The B21 has a few limiting factors, though:

9.3:1 compression ratio in the K-jet cars (8.5 in the carburated cars)
Smaller bore = ultimately limiting valve size and installing the "better" head isn't the right thing to do
Engine geometry - long piston, short rod, big bearings
Exhaust port - similar restriction on ALL Volvo OHC heads.
K-jet, K-jet, K-jet.

I haven't built a proper B21 so I can't give you the recipe or the projected results, but I know that Volvo has left a LOT on the table and that you'll be able to make reasonable power from it. It'll never make 200hp as it is still limited by several factors but depending on how far you want to take it, you can certainly see improvements.

None of it is as easy as getting a free-$500 740T and swapping the engine, though.

Turfing K-jet is probably the first, best idea. If you converted the engine to Megasquirt or even LH2.2, you'd gain power immediately and across the board. Rebuilding a 530 head with 46/38 valves, a mild port, and a nice 3 angle grind will also pay dividends across the board. Without bumping the compression ratio (properly) to something closer to 10.5 or 11:1, I wouldn't bother with a camshaft, and even then you're fighting an uphill battle because the mechanical losses inside the engine are so high. The B cam is pretty good but there are better ones, look for ones with more lift and similar duration, resist the temptation to go crazy with duration because that'll kill low RPM power and you'll have to spin it into the zone of diminishing returns.

As the other guys have said, the stock manifold flows really quite well and is robust. Make sure you don't have one of those crappy dual-wall aftermarket downpipes - they're very poorly made and restrict flow. A 2" exhaust with smooth bends and free-flowing mufflers will not be restrictive below 145 hp or so, but 2.25" will cause no issues and will give you the headroom for a 200hp turbo engine if you do end up going that way. Going bigger than that just makes noise on your car, but 2.5" would be good for a proper turbo (250 hp or so).

Add lightness. Ditch the big stereo, install a lightweight battery, keep the wheel and tire selection light, make sure your spare is one of the temporary ones... think along those lines. Lightweight oils and greases too. Keep it tuned, concentrate on handling and braking, learn how to drive it well, and don't pick fights you can't win.

Edit - one other suggestion I have is to consider a T5 transmission and adding a 0.8 5th gearset to it. 1-4 are stacked more closely in the T5 than in the M46, which means you'll make good use of 1st gear and won't have to span such a broad RPM range every time you shift. You can use a slightly peakier camshaft if you can keep the engine in a tighter RPM range, too. While you're doing the transmission, get a nice light steel flywheel and consider a limited slip differential. None of this will make any more power, but it'll get it all to the ground a lot easier.

TONS of great info here, this thread should be split and moved to Technical for future reference.