Has anyone turbocharged a B20E and what turbocharger did you use? What were biggest problems besides cost?

Biggest problem is the compression of the "E" and the fact that the head isn't a cross flow. You have to be careful where you stick the turbo. I"ve always wondered if you couldn't just fab up a short manifold off the bottom of the dual down exhaust and run a smaller turbocharger from that low position. You also have to (well, should anyway) fuel inject rather than carb a project like this. Sure lots of people have figured out how to get things working with carbs (SU's are poplar), but why? It's rather a lot of work…now if you stand a B21/B23 up you have some of the problems solved right away.

I have, somewhere in a box, a draw-through turbo manifold for a B20 with some turbo and maybe even a carb.

As Craig says, your biggest issue will be the c/r of the B20E. It's already prone to detonation. Adding a turbo without dumping a pile more fuel and messing with timing curves will be nothing but problems. It's not what I'd call a plug and play deal...

I have my turbo diesel which is also not cross-flow and set-up is quite neat and compact. I would base mine on that system. Pylon, how much for turbo manifold? If you sent a pic I could see if it could be adapted to work with a B20E head with built in injectors so don't need draw through. Might have to go to CanTire and buy exhaust bends etc to make own exhaust manifold and then pipe turbo to adapted intake if it can be adapted. A friend down here has an FI head for B20 and I found a site that makes decompression pistons for compressing a B20. The timing would have to be guessed at then modified to get best results. I've been trying to find out name of fella with the turboB20 142 on youtube to find out how he did it. I still think it would be neat to open the hood and still be the old OHV engine under there. I would put turbo low tho not thru hood like his is.

Keith, once you've gone and done what you're talking about doing, you may as well buy a good condition B230FT (or really just about any red block OHC engine) and just stand it up. You get a better head, cross flow, 200 hp on stock parts with do drama, cast iron exhaust manifolds (gain, no drama) and with stock computers or on mega-squirt you're sitting pretty. I'm just throwing this out there to give you some ideas. The engines are the same physical size, so it all fits.

Putting the B230FT + EFI into my 242 ranks right up there with the best things I've ever done to a car.

Both ways are outside of most guys' comfort zone, really: there really isn't a bolt-in kit or a set formula to go either way. With the B20 you've got to build the motor and engineer a carbureted turbo system (don't even try to deal with a draw-through), and with a B230 you've got a ton of fabrication work. I think most people would find the B20 route easier but certainly costlier at first - once you factor in all the conversion pieces and sweat equity, I think you'd find it a wash.

I think the simplest way to do it is to use a B20 with the lowest factory compression ratio (which is 8.5:1 I believe?) and blow through a pair of carbs or a Weber downdraft kit (I have one of these to sell, by the way). Use the stock exhaust manifold and build a downpipe that mounts a turbo down low and back, about where the oil filter used to be, like Craig said earlier. Relocate the oil filter and feed the turbo off that. Blow the turbo up into a box that houses the carbs, tap into the box for boost-referenced fuel pressure regulation, get rid of the mechanical pump and install a cheapo electronic pump capable of 15 psi, and enrich and cool the system with water-meth injection if needed. If you need to rebuild a motor anyway start with a ’75 B20F and pray it’ll take a 92mm bore, install B21FT pistons and deck the block for tight squish. You should still end up with between 8.0 and 8.5:1 compression ratio but more displacement and knock resistance, and tougher pistons. It’s not going to be the most efficient or powerful system around, but it’ll work and won’t break the bank. The caveat being the available room for the turbo in your chosen engine compartment – in a 122 this is probably not an issue, not sure about a 544.

I’m guessing that installing any OHC motor into an early car requires a custom intake manifold or a B21A manifold. The EFI manifold puts the throttle body right into the inner fender / steering shaft, and the K-jet manifold’s plenum probably interferes with brakes. Either way you’ll have to convert the car to cable throttle control. There’s also mixing and matching accessory drives from 240 parts, the reduced clearance at the radiator necessitating an electric pusher fan, installing a B20 pan & pump, and the adaptation of a M41 behind an OHC motor which is particularly unique and challenging. Getting an M46 or T5 into a 544 is going to need a new transmission tunnel and the M46 isn’t meant to lay over at that angle anyway (not to mention the shifter will be hung at a goofy angle), while the T5 requires about $1000 in parts to get working (adapter kit, clutch, driveshaft, speedo cable). EFI requires high pressure fuel and a new return line, and doing the high pressure fuel properly means an in-tank pump or other fanciness in the fuel system, as most fuel pumps need positive head pressure. After all that, I’m still not sure that the OE turbo location will work with the front suspension. Quite a bit of this has probably been worked out by Tbrickers or insane Swedish people, but as always the result will only be as good as the effort put into the execution.

Dear god, I'm retarded sometimes. The M41 bellhousing bolts to an OHC motor, so this is probably the simplest part of the conversion. Duh! M41 behind a SLANTY OHC motor is the tricky bit.

I would really like to stick with the old OHV B20E engine but like I said all the parts would probably have to be manufactured because of non-cross flow head but I think would be easier than modifying the steering side of the engine compartment to make OHC engine work. I remember back in the 70's that you could actually get an adapter to use the original tranny hooked up to a small block V8 and saw a few in Edmonton running at the drags and seemed to hold together quite well (tranny and rear end). So I figure if I don't over do it the stock driveline should handle the boost. Would be a real retro-modern conversion.

Or you could just buy what I have...unless you want to do all that fabrication...