Update 10-8-2008

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.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 1991 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.  Now onto the 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 850.   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 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, another reason I choose the TD04 lineup of turbos.

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 or 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. 

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!

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.

Up next:
Rebuild the engine with 13mm connecting rods and forged pistons from RSI!

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.