Tech, Repairs, Upgrades > Engine & Drivetrain Swaps

BP Swap

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Rocketman:
The 1.8L Mazda DOHC known as the "BP" engine is becoming a more common swap into the Capri. There are JDM versions with a turbo, known as the BPT & BPD. They come from a second gen 323 (BG chassis) GTX & GTR, respectively. The BPD has the highest power output, around 210hp. IIRC the BPT puts down 180hp.

The nonturbo BP was available here in the states in the Ford Escort GT, some Mercury Tracers, Mazda Proteges and some Kia's in FWD format. Certain year Miata's also came with a BP but they're RWD, necessitating location of all the FWD accessories. The "best" option is the Mazda Protege BP closely followed by the Escort GT, they are the closest match to our cars.

Physically, the BP is about an inch longer than the stock 1.6L engine. This creates clearance issues. Also for this reason, the manifolds do not interchange. You will need a complete BP with manifolds.

Off the top of my head, here are the physical modifications needed to fit an Protege/EGT BP into a Capri XR2 (will go over NA further down)
-Clearance the passenger framerail. This can be done by cutting/welding or creative use of a hammer. You will need an additional 1/2 to 3/4" around the engine & alternator pulley.
-Passenger engine mount will need work. You will need to swap the B6T engine bracket onto the BP & cut the timing cover backing plate to go around it. The B6T unit *may* work. The mount will be further over, slot the 3x holes on the mount itself and slot the bolt holes in the bracket on the vehicle to move it further toward the fender.
-The fuel lines on the BP are a different location. Use correct high-pressure fuel injection hose to route new ones. The Protege uses barb style fuel rail (like stock) the Escort uses quick-disconnects. If you end up with an Escort engine, try to source a Protege fuel rail.
-The throttlebody & intake tract will be re-located. You will have to come up with a whole new intake piping system. This will depend on turbo/na applications & is up to you. Note that the BP throttle will be very close to the brake master cylinder, using a silicone coupler/bend here with a tight radius can help with clearance.
-The exhaust downpipe will be in a different location. Plan on fabricating a new downpipe for both NA & turbo BP swaps
-If mated to an XR2 transmission, the oil pan will not bolt up in all places. Just bolt together what does line up - the other bolts are not critical.
-The XR2 intermediate shaft will no longer line up with bolt bosses on the block. By welding on an extension to the bracket & re-drilling it can be made to fit. You can also source a newer Kia axle which deletes the intermediate shaft but may have unknown effects on torque steer.
-The throttle cable does not fit the BP throttle as-is. The throttle cam can be modified to accommodate it but there may be better solutions - maybe swapping a stock cam gear onto it?

I believe that's it for the physical work, there may be small details I am looking over. It's been several years since I did the swap.

Electronics:
I do not have a writeup for electrical concerns with the BP. If you have a turbo BP, you can use XR2 electronics - ecu, harness, injectors, distributor, knockbox, etc. If you buy a JDM BP with harness, try using it. Use the stock start/charge harness, it is separate.
If you are swapping in a nonturbo BP, I would recommend using the BP harness, ecu & electronics. The BP harness and B6 harnesses have a bulkhead connector where they connect to the body harness - you will need to sort out a dozen or so wires here, it shouldn't be too difficult. Things like power, switched power, gauge signals and such travel through here. If you get to this point I will be happy to help sort it out.

Notes for N/A capris:
I have seen a BP swap on an automatic capri before. This seems viable, though I question the reliabilty of the transmission.
The nonturbo manuals capris have an F-Series transmission. The BP will indeed bolt to this, but you are at a disadvantage. The clutch and flywheel are smaller, and will definitely need an upgrade to hold the BP's power. Beating on it will more than likely result in a blown f-series transmission, they're just not build to hold that kind of power.
-The N/A manual capris could benefit from swapping the whole BP + protege/egt transmission. This is a whole new can of worms but a good option. You will need Capri XR2 axles (or the capri/kia combo mentioned above), and the engine mounts will need different modifications from those discussed above. The BP transmission is different - it tilts the engine forward several degrees. It is also hydraulic so the stock clutch master cylinder can be used.

Hope this helps, sorry it may not be super clear but there's a lot of possible BP engines into a lot of possible Capri options, lol. If you need clarification please ask!

Advancedynamix:
Been thinking about going BP in my XR2.  I have all the stuff necessary to BPT it, and I am pulling the b6t to reseal it and do a clutch anyway, so why not just bite the bullet and go big. Has anyone other than Matt (thank you for the write up Matt) done this swap?

Rocketman:
I've seen 5 or 6 other Capris with a BP swap.

There was a gent on the Yahoo! group who swapped one into his Automatic
There was someone in New jersey who had a BPT swap with a custom turbo setup, but wanted crazy money ($7K?) for it. Engine looked good but the rest of the car looked hacked. Not sure whatever happened to it, this was 4-6 years ago
Dean Fayzal from Australia has a two show cars, one a 100% chromed B6T, the other has a BPT. He's on here, but I don't see him much
There's another red capri in Australia with a BP and some absolutely massive crazy huge turbo bolted to it, if it spools at all I'd be surprised lol

That's what I can remember off the top of my head. there's probably more undocumented swaps out there

fchalvet:
I need help please!
I left my NA capri to someone who had done a BP swap.
But He didn't finish his job and I try to find a solution. It's even almost impossible to put the 1.6 back, as I have lost a lot of parts, fuse box, etc..

Right now I have the BP ECU and harness.
However I'm completly lost to connect the black connector from the Capri harness to the BP harness, on the passenger side.
Also I have the BP fuses box, and my other problem will be to connect the Capri harness on it, for the lights, etc
Hope someone can help me
Thanks

Rocketman:
I think you need to keep the Capri charging harness & fusebox.

The wiring on the big black connector is pretty straight forward, admittedly I have not done it myself though. You will need a diagram for the Capri connector, and one for the BP connector, the wires are mostly all the same just different location.

There is a BP swap wiring guide on the Yahoo! 323 GTX group. It's from the early 2000's, I don't know how accurate it is - but might be worth looking into

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