Platform: 1989 Mazda Rx7 GTU (manual)

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Project Goal:

My goal was to do a mostly stock swap. Few things I was aiming for were:

• Boost more then stock but without having to turn to a stand-alone or piggy-back system.
• I aimed for a 'peak' boost of 10psi or less.
• I wanted to use my current 2.5" diameter exhaust (Apex'i N1 muffler, 2.5" hi-flow racing cat, straight as possible 2.5" piping).
• I wanted to have an aftermarket blow off valve just for the noise.
• I wanted to have an LSD!

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Optional Upgrades (before deciding to go from naturally aspirated to turbo):

• Upgrade the brake rotors and brake pads (my case: slotted, vented, drilled Brembo rotors front and back with Hawk brake pads)
• Replace your rear calipers with the turbo caliper in order to accommodate vented disk breaks
• Upgrade your rims and tires (example: 17x8" rims with 225/45/17 front, and 17x9" rims with 255/45/17 in the back)
• Upgrade the suspension (my case: Tein Flex Damper Coilovers)
• Upgrade the fuel pump; since you will at least need to replace your NA pump with the turbo one (my case: Walbro 255)
• Install a boost gauge (my case: I got an Autometer boost gauge and a narrow band A/F gauge)
  

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Buying Parts Before Buying The Engine:

• Required:
  • Turbo Fuel Pump (unless you have already upgraded it before like myself)
  • One or two sets of new spark plugs (my case: two sets of NGKs from the dealer)
  • Engine oil (my case: 20W 50 Royal Purple and 10W 30 Penzoil for extra oil changes after swap)
  • Radiator fluid
  • Break fluid (for clutch)
  • Turbo down pipe and gasket unless a stock one comes with your engine (my case: Racing Beat 2.5" DP with gasket, and two more regular exhaust gaskets)
  • Turbo LSD (my case: used S5 Tii LSD - viscous)
  • Turbo axles
  • Turbo drive shaft (my case: new Mazdatrix drive shaft with replaceable U-joints)
  • Turbo throttle cable (much longer then NA one)
  • N370 pressure sensor (might come with turbo engine)
  • N374 ECU (was bad, later explained) or N370 ECU (was good)
  • New oxygen sensor (a very good idea)
  • S5 air fuel meter (my case: Cosmo RE AFM which is the same as S5 Tii AFM)
  • 89-91 Fuel Cut Defender [FCD] (Required IF you use a bigger diameter exhaust then stock to avoid fuel cut to the rear rotor over 8.7psi!!!)
  • New intake piping [3" recommended] (my case: 3" piping with filter, HKS look-a-like from EBay)
  • New oil filter(x3, depending on how many oil changes you would like to do soon after the swap)
  • Turbo clutch slave cylinder came with the engine (UNLESS: your turbo transmission already comes with it!)

• Optional:
  • Engine and transmission mounts (my case: Mazdatrix competition mounts)
  • New thermostat
  • Aftermarket blow off valve (my case: 86-91 HKS S.S.Q.V. kit)
  • Top intake manifold gasket(you might still be able to use your old one, but you WILL have to removed the TIM in order to do this swap)
  • New fuel filter
  • New clutch & pressure plate with pilot bearing, throw-out bearing (you might be lucky enough that the clutch which comes with your engine is in good shape: my case; stage 2 clutch with pressure plate)
  • New drive belts
  • Other small stuff (like exhaust heat wrap, etc)

WARNING:

Most JDM engine do NOT come with the stock ACV valve, or blow off valve, and having to buy some sort of blow off valve might become a necessity. Also, high chance of N374 ECU might be damaged in shipping from Japan!

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Buying The Engine: (My experience)

I bought my first engine from EBay: complete engine block with ECU (after receiving it and removing the spark plugs and exhaust manifold, we realized that the engine was full of coolant(moisture, orange color, rust), and EVERYTHING inside was rusted including rotors and combustion chambers). Basically, this engine was useless so I returned it and go my money back!

I bought my second engine from: www.tigerjapanese.com (they said they actually look at the engine before they ship it to you). This engine did not come with the ECU, AFM, or stock blow off valve, so I bought those separately. This engine was luckily in good condition and I was ready for engine preparation before the swap itself!

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Turbo Engine Preparation:

1. Check the original spark plugs (no orange coloring on the tips and no moisture on them is usually a good sign)
2. Take the exhaust manifold off and look inside the chambers (look for similar signs that you did at the spark plugs)
3. Check if the turbo spins smoothly, and make sure the fins are not damaged
4. Flood the engine with ATF, let it sit for about a day, then slowly start turning the engine(fan of course has to be removed)
5. After the engine turns smoothly, check to see if there are 6 out of 6 good/strong puffs coming out of the exhaust ports for each of the 6 rotor faces (IF not all 6 puffs are strong or evident, there is a chance your side seals might be stuck from carbon build-up, in which case, use more ATF to further soak those particular seals in it, or even use Marvel Mystery Oil instead of ATF)
6. Remove the A/C and Power Steering (IF you do not want to have it in your car)
7. Take the inter cooler and top intake manifold off
8. Remove the harness by numbering each sensor with plug by the same number (example: number the plug on the turbo harness for the front primary injector #7, and also number the front primary injector on the turbo engine... #7)
9. Clean the whole engine
10. Put the exhaust manifold and turbo back on the engine
11. Check all the lines to make sure there are no cracks and make sure the engine has everything on it that you have planed to from the beginning
12. Replace the engine and transmission mounts. (IF you decided to upgrade them)
13. You don't have to, BUT you could also remove the oil pan and make sure you get out most of the ATF and other crap, then replace the oil pan gasket, and put the oil pan back on the engine
14. Put the down pipe back on the turbo (IF you have decided to upgrade it or you have already taken it off the turbo housing)
15. Remove the shifter from transmission and wait to put it back in from inside the car; after the turbo engine and transmission are already in the car
16. Put new oil filter and new spark plugs on the turbo engine
17. Replace all drive belts if you decided you wanted to

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The Swap Process:

1. Bring your car in!
2. Take the hood off
3. Remove battery
4. Remove the fan shroud, fan, radiator, NA drive shaft, NA differential, NA axles
5. Replace ECU located under passenger seat with the turbo one (N374 or N370)
6. Replace N350 sensor with N370 pressure sensor (along plug in FCD if you decided that your car will need one)
7. Unplug break booster line, oil lines, fuel lines, coolant lines, A/C lines, Power Steering lines, etc.
8. Remove the top manifolds of the NA engine still inside the car

1. Unplug the NA harness from its sensors on the engine (including the transmission plugs). Make sure that the numbers on the turbo engine matches the numbers on your NA harness (example: mark the plug on the NA harness that went to the front primary injector on the NA engine #7, so when you plug the NA harness to the turbo engine, it's only a matter of matching #7 plug with #7 sensor)

The TWO exceptions are:

Take NA Engine With Transmission Out Of The Car!!!

1. Replace the fuel filter with a new one if you decided to
2. Replace your fuel pump if you have not done so prior to the swap
3. Replace throttle cable
4. Install boost gauge and other gauges you wish as well

Pop Turbo Engine With Transmission In The Car!!!

• Start plugging in the N/A wiring harness on the turbo engine and transmission. Everything should go right in; there will be few plugs that will not have anything to connect with if you don't have certain options on your car, and also remember that the JDM engine does not have the AWS system.
• For the 5th gear/reverse switch you only need to hook up the reverse lights, because the JDM transmission does not have a 4pin connection, only 2 pin since they do not use the 5th gear switch!
• Make sure you have the injectors the right way and the right angle and don't crush one of the primaries by accident when putting the TIM back on
• Replace the top manifold gasket if you wish, then put the TIM back on, then the inter cooler
• Connect all the wires to the transmission and starter
• Put radiator back in
• Your intake piping with air filter and AFM connected
• The two hoses coming from the turbo duty solenoid and oil cap breather can get plugged back into the intake system before the turbo but after the AFM
• Install the blow off valve or stock ACV
• Install new O2 sensor
• Plug in the fuel lines,oil lines, coolant lines, vacuum lines, b.o.v. lines, boost gauge lines, break booster line, and if you have power steering and a/c, then those too!
• THE LINES FOR THE FUEL GO BACKWARDS (JDM engine)

• Fan shroud back on, then fan
• Put LSD and axles, then put turbo drive shaft back in
• Finish your exhaust from the down pipe down
• Put shifter inside car
• Put new oil in, clutch fluid, coolant, trans oil, LSD oil, etc
• Put radiator back in, fan shroud, and fan
• Reinstall the battery
• Put the hood back on (or you could leave the hood off until you know for sure your car will start and run)

WARNING:

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Getting the car started:

It might take many minutes to get the car to start, and in my case it
took over 10min. I recommend many breaks in-between to not burn the starter or drain the battery.


My Experience:


When my finally start… besides the ton of smoke that was expected... it didn't sound right even though you could rev it fine and did idle good. I took it for a slow test drive, and it felt like it had NO power. I went back and did an immediate oil change to make sure no ATF or other crap is still in the engine. (FYI: We originally started the car on the old spark plugs which we have cleaned). After the first oil change and new plugs, we decided to call it a night at 4am and figure things out in the morning. Next day after driving the car a little more, we looked the the new plugs and realized that the rear plugs were still brand new; coming to the conclusion that the rear rotor was not combusting due to lack or fuel! The next day we put on the N351 ECU and the car drove perfectly (with a slightly high idle)… and that's how we knew the N374 ECU was bad, which seems like a very common problem when doing this kind of swap. [For the rear rotor not combusting: we did additional test like injector resistance check, pulsation, and spark and coils were tested as well.]

I drove the car for about a week on the N351 ECU, without being hard on it (clutch had a 750mile break in period, and your supposed to be nice on engines that haven't run in God knows how long). I got a used N370 ECU and put it in, then the car ran even smother, and eventually I got another JDM air pump and my alternator belts stopped snapping. I have 9.5psi peak boost with ~7psi @ red line. I did two more oil changes and a final one after I put on 800 miles since the swap, where I changed to 20W-50 Royal Purple, and new NGK spark plugs (and of course new oil filter from the dealer).

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Overview:

I would like to THANK everyone at www.rx7club.com who has helped me with my questions, and made this swap possible and a success. (For further questions, my screename on rx7club.com is 2RotorSpeed)

Here are also some links that I used from rx7club.com that has helped me a lot in doing this swap (and also having the Rx7 Hanes manual doesn't hurt either!!!):



[»http://www.rx7club.com/archive/index.php/t-26647.html»]
[»http://www.rx7club.com/showthread.php?t=552709»]
[»http://www.rx7club.com/showthread.php?t=563202»]
[»http://www.rx7club.com/forum/showthread.php?t=530860»]
[»http://www.rx7club.com/showthread.php?p=6277949#post6277949»]

See Also...

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• [FC Modification Manual]
• [FC Community Service Manual]