Table of Contents
B2200 / B2000 Turbocharging
How to turbocharge a Mazda pickup; Turbocharging is one of those bugs that seems like all import and mazda drivers want to get. Fortunately the B2200 and B2000 have the option of using the turbo system off of an 88-91 MX6, 626, or Probe GT. Unfortunately only about 27% of the trucks out there are fuel injected which makes the modification very difficult to source parts for.
Now if you already have a fuel injected truck you pretty much have it made since you won't have to find a fuel injection system and convert it. All you will have to do mechanically is find the exhaust manifold, intercooler, and turbo.
The F2 engine seems to be pretty stout. The Allison Legacy Racing series runs the stock 8-valve F2 engine and many drivers in that series run their cars at 7,000 rpm through entire seasons or more without any bottom end problems (not that they're making more power at that rpm). Members on MX6.com have reported running over 200 hp on stock crank, rods and pistons and Solomiata used an F2 crank with cap girdle to make a 275 hp stroker motor red lining at over 7,000 rpm. Without using a girdle another way to strengthen the bottom end is to have a shop install studs for the main caps instead of using bolts. The studs will help keep the main caps more sturdy.
The turbocharged cars use the same rods as the B2200 but use 7.6 CR pistons instead of 8.6 : 1. The 8.6 compression ratio will probably require an intercooler to prevent detonation. Most B2200s we have heard of running with a turbo setup where running forged rods and pistons. We would highly recommend forged rods for anything above 150 hp. Forged pistons run about 100 deg F cooler at the top of the piston than cast which reduces the chances of detonation and also reduces stress on the top ringland and compression ring. Several people have used hypereutectic pistons, these have a high silicon content which makes them hard and resistant to expansion. These properties give them the advantage to be fit to tight tolerances and have little piston slap. Unfortunately silicon is basically glass, hypereutectic pistons are very rarely recommended because they are extremely brittle and cannot handle any large stress or detonation also when they let go the engine is typically done for by sending sharp hard shrapnel through the engine. They are NOT recommended for high heat, high compression, high rpm, or high performance applications. We have been told by a man that builds engines for NASCAR Bush teams that they are ok for stock applications for the few benefits mentioned above but are still not recommended.
When building a supercharged engine there are dozens of things that should be tweaked to not only ensure you get the most power out of the engine but also to make sure it will hold up. Of the things you will need to do is not have the engine bored more than it needs to be when doing a full build. Believe it or not even though an engine block is thought to be a large chunk of rigid steel they do flex. Boring the engine more than you have to can lead to many problems. Worst case is probably blowing a cylinder. This can happen with the continuous heat cycling of the engine and the stresses that boost will have on the cylinder walls. If the walls can't handle the stresses of your build they will start to flex and probably crack. If this flexing is bad enough it is possible that the cylinder walls will distort and allow blowby into the crankcase. Blowby is always bad and can be extremely hazardous on a boosted engine. When blowby happens raw fuel, carbon, and pressure escape past the rings and into the crankcase. The fuel thins the oil and the carbon is like putting sand in with it. When thin gritty oil hits the turbo bearings you can bet your butt you can expect it to grenade prematurely. Also the thickness of the cylinder walls is required to help absorb the sonic vibrations caused by combustion, if the walls are too thin cavitation in the cooling system can occur. This cavitation can cause overheating problems and erode the metal around the cylinder walls until they fail.
Cylinder Head Modifications
Turbocharging changes all the air flow dynamics of the head. Since we are forcing air flow through the intake port and the turbo obstructs normal flow through the exhaust scavenging now works a different way. Normally the way air flows is controlled by the valve sizes, lift , and overlap. The larger intake valve has more pressure behind it which helps insure intake air is pushed in. The exhaust valve is smaller to keep the pressure balance right. Since we are now forcing air into the intake at higher than atmospheric pressure we no longer have to worry about the exhaust side pressure overcoming the intake and causing reversion. Air is forced in one direction now so the overlap on the stock cam which is designed to take advantage of scavenging can now hurt the turbo and gas mileage instead of help it. A custom ground cam with a turbo profile should be put in, these cams have less overlap to help eliminate any loss of exhaust pressure or reversion, it will also reduce the amount of fuel that gets pushed straight through the intake and back out the exhaust which helps reduce the temp of the turbo and optimise fuel economy.
You should be able to increase the exhaust valve and port size slightly but they still need to remain close to stock to keep velocity high. Research should be done to select the right type of valve and seat, most places that sell performance valves have already designed valves for this application. One of the biggest differences we know is that turbo valves have a thicker valve margin to dissipate more heat, other differences may be angles on the head, different material hardness, special stem design, different alloys, etc… After that and some porting you should be able to get more performance out of the turbo. Even though opening up the exhaust will help the turbo it doesn't mean that you focus entirely on the exhaust and doesn't mean that the ports need to be dramatically larger. They still must remain proportionate for the application. This means that if you open up the exhaust you should probably work on the intake a bit, also it is still possible to overport the head even though the intake charge is being forced. The 8 valve head found on the pickup trucks have a very poor flow ratio on the exhaust side so we would focus most of your work there by installing 1mm oversized valves and doing some port work, intake ports we would blend then leave alone. We have not flow-bench tested the 12 valve head to know where to make the best port modifications.
You will also want to make preparations to the head to help keep it and the rest of the engine together. Of these one thing that will be critical is deburring the combustion chambers and just because the outside of the head isn't exposed to combustion doesn't mean that deburing the outside of the head won't help either. Cast aluminum doesn't exactly have the best of yield or tensile strengths and in any part if it breaks or cracks it will do it at the point with the highest stress. Burrs, casting flash, and sharp corners all increase and pinpoint stress in areas of the cylinder head. Also any performance aluminum part is going to have all the bolt holes helicoiled. Helicoils are much stronger than bolting straight into the aluminum, they are made of a hardened steel which holds up to the shearing of removing and reinstalling the bolts often. They also have better load distribution through the part because of more surface area to hold to since the original hole is drilled and tapped larger for the insert to thread into. These two main areas these should be used if not everywhere is where the cam caps thread into the head and for the exhaust manifold studs, also any aluminum part that will be frequently taken apart should be helicoiled.
For some quick notes some of the older fuel injected 626s and 323s have systems that can be used to convert the B2200 and B2000 to injection. Some of the forum members have used these manifolds on their conversions but these options have not been completely investigated yet. There is also a JDM Truck engine which uses the 12 valve head with a side-mount throttle body intake which makes a huge improvement. You can use the 12 valve head with an intake from one of the sports cars but will have to get rid of the distributor and do modifications to the upper intake manifold so it doesn't run into the firewall.
Almost all people who install a turbo on their F2 engine use the OEM exhaust manifold off of a 626, MX6, or Ford Probe GT. For those who are considering alternatives there are some other things to consider. There is a stage in engine combustion few hobbyists know about and that is blowdown. Blowdown happens right before the end of the power stroke and right before the beginning of the power stroke. Right before the piston has reached BDC of the power stroke the exhaust valve starts to open and at this time exhaust pressure is still fairly high. This high pressure then tries to rapidly escape (like firing a cannon) and creates an extremely high velocity burst of exhaust gas which does most of the work of spooling the turbo. For this reason the turbo must be as close to the exhaust ports as possible for the most power and efficiency out of your turbo setup. Having the turbo farther away allows these gasses to lose velocity and cool down which is energy lost, this is especially bad if a collector pipe is used in between the manifold and the turbo because the exhaust gasses will be dumped into a large area with a lot of volume. This is kind of like having a fast flowing river dump into a lake obviously the water in the lake.
Oil Return Line
Most people when doing a turbo install really worry about getting oil in, what size line to run, and if they should run an oil cooler many of these people overlook the fact that getting oil out of the turbo is just as important. Oil needs to drain out of the turbo as fast as it can for this reason the oil return line should larger than the oil supply line. Since the oil is gravity fed back to the crankcase the line must constantly move downward and not have any dips or traps that could cause oil to collect. Below is an illustration on the wrong and right way to run the oil return line.
On the left the oil return is below the oil level in the pan, this is the wrong way. If you run the line like this draining oil must overcome the pressure of the oil in the bottom of the pan. As the engine runs oil will start backing up to the point that it can't get out of the turbo housing, when this happens air in the drain area of the housing gets whipped into the pressurized oil with shaft speeds exceeding 100,000 rpms this could cause your turbo to go off literally like a frag grenade. The backed up return oil in the turbo housing also cannot recirculate to a cool area and the oil starts to coke or essentially bake to anything it touches, this can not only toast the turbo really quick but will also send chunks of carbon grit into the engine causing damage to the internals. All of these things can also be caused by excessive blowby past the piston rings or a faulty PCV system as either would caused increased pressure in the crankcase that the returning oil would have to overcome. For the reasons above the oil return should also never be ran to the valve cover this causes additional problems as well since the cylinder head is exposed to more heat than anything moving in the engine you don't need to complicate this by dumping 250 degree oil onto it.
Firing it up
Before firing the engine double check everything in the engine compartment. Double check timing marks, water and oil connections, make sure no tools are left on the engine, and double check your fluid levels. Do not attempt to fire the engine until you have primed it and verified oil flow from the turbo. Since the oil pump on the F2 and FE engines is driven directly off the crank we are going to use the starter to do this. Some oil in the pump may be needed to get it started, this can be done by removing the plug on the upper passenger side of the pump and pouring some oil in. Make sure the battery is fully charged and disconnect the primary on the ignition coil. At this time we want the smallest load possible on the parts so we are also going to remove the spark plugs. If the car is fuel injected remove the fuses to disable the fuel pump or fuel injectors. Once you are sure the engine won't fire crank it for about 10-15 seconds. You may want to remove the valve cover to check that oil is flowing there. Continue to crank in about 10-15 second bursts until there is oil by the cam and dripping out the return line of the turbo. Once you know it is dripping out the turbo crank it a little longer and make sure it has a steady stream coming out.
Sources and Credit
Mazdatrucking.com - Website is no longer up
Salvaged by @reyxil Thanks to BadAssRX7, RussD, SixSick6 and others for their input on the mazdatrucking forum