Update 1-14-2009
With all the recent interest in my turbo conversion I thought I'd do a more detailed write up for those interested in doing this job for themselves.  We'll start with my personal favorite the 1978 Volvo 242.  This car came naturally aspirated with a B21 engine and BW55 3 speed automatic transmission.  Approx 104 BHP stock.  Not exactly overwhelming in the power department.

A turbo conversion on this model of car is relatively easy.  I say that because so many of the parts simply bolt on from similar cars in the vehicle line.  First let's identify the parts you would need to do this job.

• Exhaust manifold - Use the stock turbo exhaust manifold from any of the 240/740/940 turbo models.  Post 1990 is preferred
• Turbo - Stock turbos that will bolt up will be either the Garrett or the Mitsubishi
• Downpipe - 240 is desireable but a 740 DP will fit as well
• Intercooler - Be sure to get the brackets as well, intercoolers from either the 240 or 740 are preferred
• Piping - You can use the factory piping but for some models (like mine with K-jet fuel system) you will have to get a little creative
• Oil feed and drain - The feed and return lines may need to be custom depending on your year and model, we'll touch on that next
• Water lines - Stock water lines work fine, although for low boost applications you might not even use them
• Distributor - only necessary for engines using a block mounted distributor not a head mounted unit.

A turbo needs oil for both cooling and lubrication.  On early model cars like mine I simply T'd into the oil pressure switch fitting and had a custom line made at a local hydraulic supply shop to feed the turbo oil. Some folks have removed the square oil galley plug from under the water pump to feed oil to the turbo but I prefer the more straight forward method.  As for the oil drain, later model engines actually have an undrilled boss for the turbo drain line, so you can simpy step drill it and use the factory turbo drain tube.  My earlier model engine does not have this boss so most guys typically weld a drain bung onto the side of the oil pan.  I really didn't want to pull the oil pan so instead I drilled and tapped a hole in the lower part of the block and threaded in a fitting, see pic below.

I don't necessarily recommend drilling a hole in the block, but since my goal is to find the limit of boost the non turbo engine will take, I wasn't too concerned.  Next I needed a drain flange for the turbo itself. I had to make my own flange instead of using a factory drain tube because the turbo that I selected was a 16T turbo from a later model S70.   Since the mounting flanges and compressor outlet are oreinted differently in the 16T I had to clock the turbo and that put the wastegate actuator in the way for a standard drain tube.  Had I used a factory Mitsubishi or Garrett turbo I could have used a stock drain tube and wouldn't have had to clock the turbo at all, but you know me; gotta be different.  I went over to a local speed shop that I frequent to get a blank flange and outlet tube, one Tig welder and 10 minutes later and I had my drain flange.  

 

 

The original PCV system had to be changed so I used a flame trap holder from a 740 and installed it on the cam cover outlet and then ran that to the fresh air inlet to the turbo.  The purpose of a PCV system (AKA flame trap) is to burn combustions gasses that pass the rings and end up in the crankcase.  After some further run time I found that a catch can was necessary so I ran the outlet from the flame trap to the inlet on the catch can and the outlet of the catch can down to the air inlet nipple pre turbo (no pics of that yet).

 

 

Since the factory tachometer was inoperative and I couldn't source a replacement, I installed my boost gauge in its place, ran my vacuum line and connected it to the dimmer rheostat.

 

 

Here is a shot of the intercooler outlet tubing where it heads into the fuel distributor of the K-jet system.

 

 

 

The K jet system from a non turbo engine operates via a needle valve that is connected to a 'flap' (#2 in the pic below) that the air passes by.  The more the throttle is opened, the more air passes by, and the higher the flap lifts the needle allowing more fuel to flow.  The problem is, when under even just a few pounds of boost, the flap is already at its maximum travel an no more fuel can flow.  Another aspect of turbo charging is to understand that when the intake manifold is under pressure, that same pressure filling the cylinders is also pushing back on the fuel that is trying to exit the injectors, effectively this lowers your fuel pressure when in boost.  So to combat this, I removed the pressure regulator from the fuel distributor and added .080 inch of shims to it to raise the fuel pressure 16 lbs.  Bear in mind you'll have to lean out the idle mixture via the factory K-jet mixture adjustment or the car will start poorly when warm as the fuel mixture will be too rich from the added pressure.

 

 

In the pic below you can see an adjustable boost switch, this switch does two things.  At 3 psi of boost it turns on the cold start valve to spray more fuel in the intake.  It also grounds the wire on the frequency valve and causes the fuel pressure to rise, resulting in a richer mixture.   Not a perfect setup but certainly effective.

 

 

With fuel somewhat under control it's time for timing!  The factory non turbo distributor allows for advanced ignition timing when the engine is in vacuum and retards the timing as the throttle increase and the vacuum decreases.  However, when the engine is in boost, the distributor is not able to retard the timing further to help reduce the risk of detonation.  So a turbo distributor is necessary to keep timing in check if you plan on running more than 3-5 psi of boost.

 

 

Here is a wide shot on the intercooler (from an S60) and air filter location.

 

 

 

Given the boost charecteristics of the 16T I ended up swapping to a 13G from a 2002 XC70.  This turbo is really more suited to the way I want the car to run and the boost comes in so early its a bit suprising.  The 13G, 14G, 15G, 16T, 18T, 19T are nearly identical on the outside so swapping back and forth is easy as the mounting points and oil/water lines are all identical.  There are some variations in the downpipe connections to be aware of so be sure to get one that is compatible with your downpipe flange.

 

 

Using the formula below we can determine how well suited our turbocharger is based on our Horsepower goals.  My 1978 242 non turbo came stock with 104 bhp, I figure it has pretty close to 100 bhp now and I'd like to double it before I blow the motor up.  So here is a simple calculation to get us in the ballpark.  Bear in mind this formula does not account for things like environmental variables or intercooler effeciency, its a quick tool I use to ballpark a turbo and see how well suited it is.

 

 

 

Now with a pressure ratio of 2.2 (16 psi) and an aiflow of 20 lbs/hr we can plot the max HP point on the compressor map below.  Note* in the map below the airflow is in cubic meters per second and I have converted to lbs/hr.  As you can see we are in the 77% effeciency zone right at the peak.  So that tells us this turbo well suited for our goal. 

 

 

 Looking at the 16T compressor map below we can see that this turbo would be too large for our application, or rather the engine would be too small.  This explians the undesirable boost charecteristics I experienced and is namely due to flow rate.

 

 My first dyno run stock resulted in 87 whp (that's horsepower at the wheels), after the turbo conversion and 10 psi of boost I ran 163 whp.  So basically a net gain of 76 hp.  This means approx 180 bhp (horsepower at the engine, before drive train loss).  I'm pretty close to my goal but I think I've a little bit further to go.  So in an effort to reach 200 bhp, the next step is to convert to electronic fuel injection using the B230FT intake manifold and a standalone engine management.  I could do an LH conversion and either chip it or piggy back it but since I've already done that I think it's time for something new!!!

UPDATE:
It's been about 4 months since the last update and in that time I have changed out the K-jetronic fuel injection for a psuedo stand alone engine management system created from a SMT6 piggy back ECU, Unichip injector driver and 2 bar map sensor.  To accomplish this I had to replace the intake manifold and mechanical K-jet injectors with a manifold and electronic fuel injectors from a LH-jetronic system. 

Here's the new intake manifold, fuel injectors and fuel rail.

The SMT6 is normally intended to modify the signals into and out of the factory computer and provide a way to manipulate the ECU to adjust fuel and timing based on your inputs.  The SMT6 has a further provision to control an additional single fuel injector (common when adding a turbo to a normally non-turbocharged car) for supplemental fuel flow.  For my setup I used the SMT6's supplemental fuel injector map to drive the Unichip injector driver and control my bank of four fuel injectors.

The SMT6 requires the following inputs to function:
12V Key on power, ground
Rpm (from distributor)
Engine coolant temp (from block mounted sensor used from orginal K-jet system)
Load sensor (In my case a 2 bar map sensor)
Oxygen sensor

With the above sensor inputs an injection map can be made to provide the correct fuel at a given RPM/load value.  This is essentially the stand alone.  It is very rudimentary and does not provide all the functions of a conventional stand alone engine management system but it does do the job and with proper tuning works pretty dang well!

 

Here's a pic of the tuning screen used with the SMT6:

Given the limitations of the SMT6 'stand alone' I knew it would only be good for providing a system that would allow me to tune to get the appropriate amount of fuel with the boost level I'm running for the purpose of determining how much power my turbo converted B21 engine could handle before catastrophic failure. 

Knowing that the B21+T was going to need to be replaced at some point I decided I wanted to aquire a complete B230 engine/trans and factory fuel/ignition system to replace my current setup.  This gives me a larger engine and better trans than the three speed automatic I am currently running.  So after some searching on Craigslist I was able to locate the following car.  1986 Volvo 760 Turbo automatic (185K miles) and negotiated the price down to $400.

As you can see the car hadn't moved in quite a while as the google street view map showed the car in the same position when I showed up to purchase it (hadn't moved in over a year)!  With a fresh battery and some coaxing the engine fired right up and I set off to drive it home.  Initially the trans wouldn't shift out of first gear and I thought I might have to get a new transmission but after a quick pit stop at the gas station for some fresh fuel I found the kickdown cable had stuck in its sheath and was preventing it from shifting.  A bit of wiggling and some WD40 loosened it right up and the trans worked great.  Drove it the rest of the way home no problem.  Into the garage and time to pull the engine, transmission, wiring harness and fuel/ignition computers.

 

 

 

 

While the new B230FT engine is being built I decided to keep working on the B21+T setup in the car now.  Starting with pulling out the SMT6 engine management in stand alone form and converting to LH2.2 .  First I had to modify the LH2.2 wiring harness to integrate with the 1978 242 body harness. At the same time I decided to remove the EZK ignition module and simply use the SMT6 in piggy back form to condition the analog signal from the stock distributor into a square wave which is fed to the ignitor module and provides the control to the ignition coil.  This does take away the internal 'map' in the EZK module and the detonation retard from knock sensor input but my previous experience proved this system is weak at best and far too slow for my needs. So my timing will be ultimately controlled by the SMT6.  However, the factory vacuum/boost advance and retard actuator will still be resident so I'll only need to tweak timing rather than create a complete timing map. The EZK module originally controlled the ignition coil via the ignitor module and was fed in a square wave signal from the head mounted distributor which utilized a hall effect sensor.  This system is also known for somewhat common hall effect sensor failure so it was another reason to delete it from the final design.  Additionally the EZK signaled the LH computer as to when to fire the injectors, with the EZK gone I need a 'timing' signal to tell the LH when the engine is turning and at what speed.  Again, the SMT6 ignition output will feed into pin 1 on the LH ECU and provide this timing signal.

The LH2.2 injection system from the 760 uses a resistor pack to compensate for the low impedence injectors used in that model.  I have since removed the resistor pack and instead used injectors from an 850 which are high impedence so I can flow a greater volume of fuel.  This is not a requirement but does allow me to pick from a much wider range of fuel injectors to help dial in the fuel needs of my specific setup.

 

Pulling off the intake manifold and running the wiring harness for the LH2.2 injection. 

 

Here's the engine bay with the new LH2.2 harness and intake. Notice the alternator and PS pump have been repositioned using the brackets from the 740 model.

 

 

Update on the engine build:
After the 2.3L turbo engine from the 760 was disassembled I found far too much wear in the cylinder walls to simply 'freshen' the engine with new rings and bearings so machine work will be needed for sure.  My concern is the rather large ridge on the top of the cylinder wall that may be too great to machine out and still use standard oversized pistons. So the hunt for another block is on.  On the plus side, the cylinder head is in excellent condition including the valves, seats, and guides so a simple cleaning and replacement of seals/gaskets with a bit of port matching and we're in business.  

Here's the cylinder head going back together with newly ground valves, stem seals, and higher flowing turbo camshaft. 

 

The camshaft should make a noteable improvement in the midrange as the original camshaft on the B21 engine (non turbo) is not well suited for boost.
 

The new cylinder head is assembled and on the engine! 

 

Success!  I'm now running with 15psi of boost and approx 205bhp which is plenty quick for a car of this size! Air fuel ratio is a bit rich under boost (~11.4 : 1) but I want to be a little conservative to start out and we'll fine tune after a few more miles to season the headgasket.  So far I've driven the car about 100 miles and the power is quite considerable given the weight and handling of the car.  Traction is starting to become an issue even with a locked up differential and new tires.

 

UPDATE: 2-2-2009
Catastrophic headgasket failure!  After about 150 of driving I have breached the head gasket fire ring and blow the gasket.  The failure was due to some heavy detonation that occured just after a corner as I applied the throttle.  After further inspection I found that the small rubber tube that connects the fuel pre-pump to the sender assembly in the tank has split in half and starved the fuel pump for gas on hard cornerning when the tank was less than 1/4 full.  So hard lesson to learn, but at least an easy fix. 

On the down side, the combustion pressure that leaked into the cooling system from the blown head gasket allowed a pressure increase that was just enough to cause the heater core to start leaking.  I suppose this isn't much of a suprise given the age of the car but as any 240 owner knows, heater core replacement is about the worst job there is on this car.  More pics to come.

 

Here's where the headgasket failed and leaked combustion pressure into the cooling system.

 

Here's the corresponding witness mark on the cylinder head. 
 

 

UPDATE: 2-12-2009
The cylinder head is back on and the engine is re-assembled, the plan is to replace the heatercore this weekend, so in the mean time have a few days to play.

 

With all the work on the engine complete for the moment I wanted to finalize my AFR gauge mounting as well as test out a new boost gauge I had from a new supplier.  Since I had changed out my instrument cluster with one that had a working tachometer I needed a new mounting spot for my boost gauge anyway.  Here's a shot of the prototype gauge holder. This holder is made from 2" ABS plastic pipe, to cap the ends of the pipe I used a 2" hole saw and cut out some round blanks then used ABS cement to adhere them together.  The pipes are riveted to the upper column cover, then epoxied in place to provide additional support and allow for shaping the transition.  I drilled one hole in the bottom of each gauge cup to allow the wires to pass down through the steering column unseen.

Here you can see the ABS pipes joined to the upper steering column cover. The epoxy has set and it's time to sand and finish.
 

 

Here's the shot in the car. The gauges intrude into the cluster a bit but not enough to be of any issue. 

 

Having done my fair share of heater core replacement in the 240 series I opted to 'cheat' this time as I wasn't looking forward to investing 6-8 hours to do it properly.  To cheat this repair you effective cut an access hole in the heater box to allow the old core to 'slide out' and the new core to slide back in.  This method proved to be the way to go as the complete job was done in less than 90 minutes.  After cutting the access panel you simply adhere it back in place with some silicone or similar sealer.  Let it set for approx 10 minutes and then re-assemble.  Here's a shot of the under dash and heater core box with the access panel cut out.  Note how many pine needles, etc.. are in front of the core and keep in mind this car is garaged every night!

 

 

 

 

 

 

 

 

 

Some random shots over the last year

 

French toast sticks at Suby fest.

 

Me and Sean L. making fender flare molds from body filler for the XC70 Sema project.

 

Driving blind into the paint booth.

 

My interview on Fuel TV.

 

Making Gull wing doors for the C30 Sema project.