1988 Mazda RX-7 Turbo II

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10/25/05
Initially, the TII needed a lot of work.  I fixed the coolant leak.  The lower radiator hose was not clamped down all the way, and was not in the best condition anyway, so I replaced it with a new one.  Every once in a while the coolant level buzzer/alarm would go off when driving, which is very annoying.  Congrats for Mazda for making the most annoying buzzer sound ever.  I cleaned the coolant level sensor and made sure there were no air pockets in the system, and it seems to have worked.  Next, I flushed the oil; two oil changes in the same week, using Castrol GTX 10W-30.  There also was an exhaust leak, making the cabin smell like exhaust if you had the windows rolled down.  I replaced some missing exhaust downpipe nuts, and the smell isnt as bad, but still stinks, I guess because the emissions are removed.  I also rerouted some vacuum lines that were not going anywhere.  The idle was too low; it would stall when coming to a stop especially when not warmed up.  I bumped it up to about 900 rpm.  The emissions removal got rid of some of the cold-start idle control, so I set the idle kind of high so it wont stall out so easily.  Some parts were swapped from the GXL too.  The seats, back hatch window, S5 Turbo rims, exterior trim, rear bumper, and some interior pieces.  Also painted the front bumper trim to match the car.  Also replaced the throttle cable, fuel filter, and changed the tranny and differential fluid with Redline 75W-90 and MT-90 gear oil.

                               

3/06
It broke down and left me stranded a mile from my house one night.  Left it there to fix it in the morning.  The next morning I found it broken into.  The geniuses broke the passenger side window and ripped out the stereo, leaving the $300 SAFC and the $100 turbo timer on the ground.  The problem ended up being a blown engine fuse, which was later found to be caused by loose/unshielded fuel pump wiring.  I dont plan on putting the SAFC or the turbo timer back in for fear of future thievery.  Turbo timers are practically useless for water cooled turbos anyway.  I plan on ordering the RTEK 2.0 ECU, which will control fuel mixture better than the SAFC.



4/06
Started installing a FMIC.  Bought an ebay intercooler, 9" by 20" core, bar and plate type.  Total costs:  IC, $190; Higgi'sTB adapter, $100; ebay 2.5" IC tubing kit, $120; various couplers and mounting pieces, $30; 2.5" BOV adapter, $45; total:  ~$500.  The Greddy "bolt-on" kit is almost $1000, so it definately was a better deal making a custom setup.  Also relocating the battery to one of the interior bins for room for IC piping.  I noticed a 1 psi drop in boost pressure, but i suppose it is expected due to all longer/bigger piping and bigger intercooler.  It does feel like its lost a little power, but that is because the stock turbo is a little undersized for this intercooler.

                       

5/06
I sent the ECU to pocketlogger for the RTEK 2.0 upgrade.  Got the ECU back a week later.  The 2.0 upgrade includes fuel and timing tunability, as well as sensor readouts and built-in 720cc injector presets.  Also ordered an AEM UEGO wideband oxygen sensor to tune with. I took it out and did a few test runs with the fuel map set for stock, logging the AFR with the rtek, and found out it was running in the mid 12's, which was a tad too lean for me.  I was aiming for low to mid 11's under boost to be safe.  As it turned out, I had to set the rtek for +15% correction to get the AFRs down in that range.  I have not messed with timing; I dont really know much about the timing effects.

7/06
Installed a cold air box for the intake.  The box was made from a sheet of aluminum which worked out really well.  It made a big difference on the AFM temp sensor (using RTEK readouts).  

                        

                       

6/07/08
I have not updated this in a while, but the car has had a lot of progress.  I upgraded the injectors to RC Engineering 750cc primaries and 1000cc secondaries.  The 750cc primaries are high impedence, so no in line resistors were needed.  The 1000cc secondaries are low impedence, so 6.2 ohm resistors were wired inline.  I also rerouted the intercooler piping to reduce bends; it is down to four major bends for minimal turbo lag.  I also finally sent the turbo to BNR Supercars for a Stage 3 overhaul.  This replaced the stock compressor side with a 60-1 compressor in a T04B housing.  The exhaust side is kept stock except for clipping the wheel for less backpressure and porting the wastegate to 35mm.  

                       

Since then i have had it to the dyno several times for tuning.  The 750cc/1000cc injector combo seems to small for the setup.  I was hitting 90% duty cycle at high 11's AFR.  Check out the dyno plots:

This was on the stock turbo at 9 psi; the boost dropped to 6 psi by redline:



This was just after installing the BNR Stage 3.  Boost held steady at 6 psi wastegate pressure to redline:



This was a few weeks later, after installing an electronic boost controller.  This run was at 12 psi, with very conservative timing.

As you can see, the AFRs were fairly lean.  I replaced the 1000cc injectors with RC 1600cc later on.  Shortly after the new turbo, the coolant seals started showing leakage.  It still starts and runs like normal, but you have to top off the coolant regularly.  A replacement S4 TII block was rebuilt by RX7world, with Rotary Aviation 2mm Super Seals and a mild streetport.  



I still have not installed it yet; i would like to get the tuning finished on the old engine.  I also ordered a full set of Tein flex coilovers; the handling was improved immensely.  It is very stiff, but if feels like a go cart in the turns.  

       

The old brake rotors were also upgraded to slotted type all around with new brake pads.  The first two pics are of the old rotors; take a look at the trenches dug into them.  A  previous owner forgot a washer on one of the caliper mounting bolts, and it was making contact with the rotor.

                       

Lastly, a few cosmetic items were installed:  used stock S5 TII sideskirts and an S5 TII replica lip from JKL Engineering.

               

The next things to do are install the new engine and send it off to a body shop for dent removal and paint.