For the last 20 years I’ve wanted to do a turbo 2 engine swap into a 1st gen RX7 but never had the time, money or facilities available but given that my current 12a engine is now coming to the point where it needs a rebuild I’ve decided to go for it and drop a series 5 turbo 2 13b engine into this car in an effort to improve the grin factor by upping the power a fair bit.
My plan is to prepare everything as much as possible on the bench before doing the actual conversion on the car in an effort to minimise my downtime..... I don’t want the car stuck immobile in my garage for months or years on end and want to keep it on the road until I have everything ready as much as possible to do the swap.
The first thing I needed to do was to send the smoking and worn out Garrett AI Research turbo from my Elford turbo off for repair to enable me to keep using the car while I prep the 13bt engine etc.
At the moment, my car is using a turbo borrowed off Keith but that going to be returned to him after the RetroRides gathering so my sick turbo has now gone to
http://www.turborebuild.co.uk/ for a rebuild.... it should be back next week.
The first thing I needed for a 13BT engine swap is, well, a 13BT engine really so with that in mind I bought this.... a 1990 series 5 turbo 2 cabriolet parts car...
The seller told me that he had got the engine rebuilt 3000 miles previously as well as adding plenty more new parts... I didn’t have any paperwork for an engine rebuild but all the other new parts were there so things looked hopeful.
My first task was to get the car started to make sure it ran. This was complicated by the fact that it was fitted with a professionally installed alarm/immobiliser but the remote fob was knackered. Every time I connected the battery it armed itself and then activated once I touched anything on the car. The only option was to find and remove the security but as I'm wasn’t at all familiar with FC's and the last thing I wanted to do was cut a crucial wire to the ECU or something, I had to tread very carefully.
Following the wires, I ended up removing the glovebox and found the module. All the wiring had been wrapped in black tape to disguise it as a factory loom and lots of this had to be cut off and peeled away. Eventually I also found 2 relays also wrapped in tape that had broken into the ignition and fuel pump circuits respectively. Crimped these wires together off each relay and hoped that would disable the immobiliser circuit.
I also took out the door pin switches and the siren and hoped that would take care of the alarm.
Next up, I drained the stale fuel out of the tank, put some fresh unleaded in it then dropped the leading plugs out and squirted a touch of engine oil into each chamber with a syringe.
The moment of truth then arrived and it fired up fine and sounds awesome in my garage..... this video doesn't really capture how good it sounds....
Next job was to slowly disconnect the loom until I end up with only the bits I needed and then strip the car and pull the engine and the gearbox together so I invested in this...
Which pulled the lump out just fine...
The big empty engine bay it came out of...
These old cabriolets rust like mad......... I suppose not having a proper roof doesn't help
I pulled the seat belt mounting point out with my bare hands...
I stripped the rest of the shell, dropped the suspension off it and weighed it in...
I was then left with a pile of parts which I ebayed....... I might use these wheels one day if I ever get around to doing a FC subframe swap with the front suspension off this car... I quite like them...
But the main thing was that I was left with this...
This engine looked huge and as if it would never fit into the Fb’s engine bay but underneath the turbo, heat shields, power steering pump, air con compressor etc is an engine hardly any different in size to the 12a so I set to work stripping off the ancillaries...
First to go was the fan...
Then the a/c compressor, oil cooler and the power steering pump...
Then the turbo heat shields, downpipe and oxygen sensor...
And finally the turbo itself...
Next jobs are to strip all the emission control stuff off the engine, swap the front cover for a 12a item and swap the sump for one off a GSL-SE so plenty to be getting on with.
My plan is to use the series 5 transmission and clutch so the gearbox will need modifying to bring the gear lever up in the right place inside the car. This will also mean I will need a custom propshaft making up which uses the S5 front yoke and the FB rear flange. As I'm stripping all the emission stuff off the engine I will be able to lose the factory ECU and the electric OMP...
These OMP's are a bit of a pain in the ass if sticking with the factory ECU when doing an engine swap into a FB. In order to get the engine to use the stock engine mounts in a FB, the front cover need to be swapped and the S5 OMP doesn't then fit but it's not possible to just remove it and fit a 12a mechanical OMP as the ECU will detect that the S5 OMP is missing and will put the engine into limp mode.
This is another reason to lose the factory ECU which is what I'm going to do. I'm going to build a Megasquirt standalone engine management system which will give more flexibility and tune-ability
The build will be a big learning curve hence my plan to continue to run my Elford setup and whilst I build this 13BT conversion on the bench as much as possible.
........... gotta love German quality control! 
That's why VAG and BMW set the standard for build quality!
