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 FAQ: B6T Swap Info 
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Location: Saskatoon, SK, Canada
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Post FAQ: B6T Swap Info
The B6T is found in only limited quantities around the globe. You need to source one from one of the following cars: '88-89 Mazda 323 GT/GTX (NA, Euro and Jspce) or '90-94 Mercury Capri XR2 (US and someother countries, not Canada). You do have the option of turbocharging the B6ZE found in the '90-93 M1 Miata or '93-96 MX-3 RS as they are basically the same motor with some minute differences. The increased CR among the newer motors is still very low and very effective with boost.
The B6T has been availabe since 1986 and you may end up with one of those motors, not to worry though as not much has changed. The turbo that is available differs with each country. Mine has the VJ13, others are equipped with the VJ6, VJ9 or more commonly the VJ14.

Some good sources for info on the B6T and performance modifications:
Larsen Motorsports

Road Race Engineering

GTX buildup

Jackson Autosport

323GTX Egroup

For those who do not know the fundamentals of a turbocharging, please read "Maximum Boost" by Corky Bell. Please read this and have a full understanding of how things work before asking any questions...saves time.

For SOHC to B6T (taken from MX-3RSR Page)

Mandatory Parts
-B6T motor
-'87-'88 RX-7 non-turbo MAF
-Boost Gauge
-Air/Fuel Gauge
-Hood Scoop

Optional Parts
-Boost Controller
-Larger Exhaust
-Larger Fuel Pump
-Piggy Back Fuel Computer
-Rising Rate Fuel Pressure Regulator
-Blow Off Valve
-Protege LX ECU
-Stiffer Motor Mounts
-Protege LX Tranny and Axles
-Upgraded Ignition

I am in no way a mechanic and before this swap had never attempted anything remotely as challenging. Do not attempt to do this if you need your car next week, and don't attempt this if you don't have a decent set of tools. Therefore, you have been warned and I will not be held liable for your screw ups. I highly recommend purchasing a shop manual, you can find an online version of the MX-3 Shop Manual on MX-3.COM. This will become your bible, Liquid Wrench will be your savior. The swap that I will be discussing is for the 1.6L SOHC B6e sold in '92-'93 MX-3 RS models. If you are planning swapping out your 1.6L DOHC B6ZE, the procedures are much the same.

Before you start, make sure you have everything that you will need. Make sure you tools include a torque wrench. Buy at the very least one can of Liquid Wrench. You will need everything that is associated with doing a complete maintenance overhaul on your motor. Once you have everything, it is time to begin.

You need to remove the hood from your MX-3, put it somewhere safe and out of the way. Put the car up on jack stands, depressurize the fuel system, and drain all the fluids. For step by step procedures on removing the engine, refer to the shop manual that you should have bought when you went out to get your supplies. Once the motor is out, seperate the tranny from motor. You need to remove the clutch and flywheel from your old motor. If you really want to make you life much easier, swap over all the sensors from your B6e motor to the B6T.

Now that you have the sensors swapped over it is time to move on to the driveline. If you have the money to buy a new clutch you can, it will save you some time later on. In my research, the only clutch that I have found capable of the requirements of the B6T is one that is made by ACT. The part is #Z33-XT00, it uses a street disc and the extreme pressure plate. It will be the most streetable. I have been using my stock clutch since I completed the swap 4 months ago, just recently has it started to slip. You will need to get your flywheel resurfaced, might as well shave a few pounds off of it while you are at it. The stock F25M-R tranny is quite capable of handling the power that you will be putting to the ground. If you want some added insurance, go and get a tranny from the Protege LX. Once you have the clutch and flywheel on, it is time to bolt everything back together. Make sure that you are using the starter from the MX-3.

Take a look at the differential, notice that on the motor side there is a flange that sticks out. This flange would have been used to bolt the old motor to the tranny. You will need to grind it off in order to allow the axle to fully engage in the tranny. Trust me, it would be much easier to do it now, then once the motor is all bolted in. An angle grinder works fine, just make sure you plug up the hole and be carefull around the tranny seal.

Before you get ready to drop the B6T in, you need to swap the engine mounts between the two motors. The left motor mount on the B6T is a pain in the a-- to remove, much easier when the motor is out. Trust me, I know. Now you can start lowering the motor in. This is best done with an extra set of hands. Be careful around all the hoses, watch out for the radiator too. Once you get past the frame rails, you're home free. Bolt the motor in and start connecting things back up. You are going to notice that the intake manifold is missing a connection, that is because it is still on the MX-3's manifold. Take it off and find a place on the firewall for it.

You will find that some of the connections on the wiring harness aren't quite long enough, lengthen them to the desired length. You will be using the distributor from your MX-3, this means you can get rid of the archaic, yet effective vaccum advance unit. Before you can actually start your motor, you have to do something with that intercooler.

I was running low on funds and had the opportunity to get and intercooler from a GTX for nothing, you can go with anything that you feel will meet your requirements. I used 2.25" mandrel exhaust piping that I bought online from Summit. I removed the front bumper cover, allowing me access to the sheet metal that seals off the fenders. Using some tin-snips, I cut large holes to allow the pipes to pass through. Depending on how you want to run your pipes, this isn't necessary. This way the pipes are up and out of the way from being damaged. Using a chop saw and an electric welder, I fashioned by pipes. It took a few tries to get things the way that I wanted. I eventually redid the pipes, mostly because of sealing issues. I recommend using Liquid Steel to smooth over the welding beads, make sure you push it in all the little cracks. Use some fine sand paper to smooth out the excess Liquid Steel. I used a wire brush attachment in the drill to roughen up the surface of the pipes before painting with a rust primer. You will need to purchase some silicone or rubber hose to make some of the connections. I bought mine from Road-Race Engineering. You will need to use an exhaust reducer where the intercooler pipes connect to the turbo and the pipe running over the valve cover. These are available at any automotive store.

Now that you have everything wired up, including your boost and A/F gauges, it is time to start refilling all the fluids. Since you don't have the motor running yet, make sure to check for airlocks in the coolant system later. Now it is time for the moment you've been waiting for, turn it over. Listen carefully to the motor. IF it doesn't want to start, it's because the timing is off. When facing the distributor, rotate it to the right, starting with a few degrees. Try starting again, repeat this until it starts. There is a mark on the disty housing that needs to match up to the mark on the brace holding the disty in. Not the best technique but since the distributor doesn't bolt up like the old one, you don't have too many options. Once you have it running, give yourself a pat on the back. You just did what took me almost 6 months in less than 2 weeks. I hope!

You aren't done yet, remember that hood? If you haven't already, either drive or tow the car to a muffler shop and get them to hook up the exhaust so the downpipe isn't firing into the firewall. You will need to get your hood to a bodyshop in order to get them to mount your scoop. There really isn't any way around the scoop issue. The scoop needs to be mounted fairly close to the windshield squirters to allow for clearance. This is also the time to get the hood pins mounted. Fortunately or unfortunately, depending on how you look at it, if you want to mount the intercooler up front the hood latch has to go.

Make sure your TPS is set correctly and all the fluids are in check. Now go and enjoy the boost!

DOHC to B6T Swap:

For the DOHC to B6T swap, the procedures are very similar. I do know that the Protégé LX ecu will not work as it is not OBDII. I believe the distributor still needs to be used from your DOHC. There has been talks that the front tranny/motor mount that bolts to the cross member needs to be drilled as it interferes with the oil return line for the turbo. Since you have the DOHC to begin with, you now have a few extra options that the SOHC owners do not. If you have the cash, and since the motors will be out anyways, pick up a head gasket kit. Swap the head from the MX-3 B6ZE to the B6T block, this allows the use of the side entry MX-3 intake manifold, negating the need to do any work to the hood (other than the hood pins for the intercooler).

Bolt on Turbo kit:

This mainly applies to those with the DOHC to begin with or those with the B6T who happen upon an unfortunate event leading to the destruction of their motor. It is possible to piece together a very good “bolt-on” turbo kit. You will need to decide what goals you have in mind as I do recommend going this route only once if you can help it. Decide on the turbo, there are many good turbos that have great characteristics for this motor. For the ultimate in drivability and performance, nothing beats a good T28. Flyin’ Miata specs their kits with the T28 and are able to produce 220-240rwhp reliably at 12psi. For those needing the extra power, Mitsubishi Heavy Industry’s 16G and Big 16G are very capable of 300-400hp ranges, as is a well spec’d T3/T04E….the choice is yours. Larsen Motorsports has a beautiful equal length manifold that they can mount type of flange you desire on to, this should be your manifold of choice. It is possible to use the manifold off of a 323GT/GTX if you wish and are on a budget. Intercooler piping is basically the same as with the B6T swap. You will need to source an intercooler, for low cost, look to the Starion or NPR versions. Fuel enrichment will also be needed, FC3S fuel pumps work well and are nearly a direct fit. Injectors from the ’88-91 FC3S Turbo (550cc) or ’88-91 FC3S NA (450cc) will work with your stock ecu as they are high impedance.

For more details on the procedures surrounding the “homemade bolt on kit”, check out Flyin' Miata.

I think that is all the info I can offer on this subject at this time… hope you find it useful.

Chris Malden
B6T Swap Info |IHI Turbo Sources

September 18 2002, 3:33 AM
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