BPT swap into DOHC write-up

[OsoSlo z28]

BPT swap into a DOHC MX-3<P>Items Needed:<BR>BPT motor<BR>upgraded clutch(ACT)<BR>intercooler<BR>bov<BR>misc. hoses(master cylinder, waste-gate, bov)<P>90-94 Mazda Protege LX(DOHC) items needed:<BR>transmission<BR>transmission mounts and brackets<BR>flywheel<BR>drive-shafts<BR>jack-shaft<BR>pilot bearing<BR>throw-out bearing<P>Suggested Items:<BR>new belts(timing, alternator, power-steering-a/c)<BR>new spark plugs and wires<BR>fuel filter<BR>oil filter<BR>new motor mounts<BR>reprogrammed ecu<BR>upgraded fuel pump<BR>boost gauge<BR>a/f gauge<BR>egt gauge<P>Preparation:<BR>you want to start by putting the car up on jack-stands. disconnect/remove all of the intake piping. remove the battery. drain all the fluids(motor oil, tranny oil, anti-freeze). disconnect all the hoses/pipes (radiator inlet/outlet, heater hoses going into the firewall, a/c lines, power-steering lines, slave cylinder line, fuel lines)<P>once all that is done, you can start disconnecting electrical connections. it's best to leave the fuel injector harness on until later. un-bolt the brace on the back of the motor to allow access to the starter. <BR>disconnect it and pull it out. <P>take your wheels off and remove the hub bolt. take your brake pads out and un-bolt your caliper. don't disconnect the brake line, just hang the caliper up on a coil of <BR>your spring with a rope or coat hanger. un-bolt the spindle. there are three bolts; two on the back and one underneath on the ball joint. do this on both sides. the easiest way to get the passenger side drive-shaft out is to un-bolt the jack-shaft bracket on the back of the motor and pull out the whole assembly. then take out the driver side drive-shaft. get under the car and loosen the two transmission mount(front and back mounts) bolts coming through the bottom brace. there are two bolts for each mount. while you're down there, undo the shifter <BR>linkage and the stabilizer bar, as well as the down pipe off the exhaust manifold. then loosen the two side mounts. get an engine hoist and secure the motor. once the motor is supported, you can remove the motor mounts. if you don't take the front mount all the way off, you might have some clearance issues when it comes time to pull the motor out. if you have someone that can hold the hood up, taking it off is not needed. once you have the motor/tranny out you can replace the belts, gaskets, oil filter, and the fuel filter(on firewall).<P>replace the pilot bearing and throw-out bearing in your tranny/flywheel. mount your clutch(make sure you have an alignment tool) and tighten down your pressure plate. bolt the tranny up to the motor. <P>put the motor in the same way you took it out. once you have all the mounts bolted down you can get rid of the engine hoist. now it's time to put things back. if you haven't already, put the starter back in and bolt it up. reconnect all the hoses and lines. the master cylinder port is on the other side of the intake manifold so you need a longer hose to route it. one of the heater hoses will need to be re-routed to the back of the motor because the bpt has an oil cooler on it. some electrical connections on the bpt won't be used. there's one on the back of the motor and one on the side. reconnect all the connections you can. the water temp sensor needs to be replaced with the mx-3 one(it screws out). you'll need to use the mx-3 tps and distributor. the idle control valve has to have the bpt plug so you'll have to cut off the mx-3 one and splice on the bpt one. this should have covered most of the electrical part. remove the injector harness from the bpt. get the mx-3 harness and put it on the bpt. there are two valves connected to the mx-3 fuel pressure regulator. those are the prc and prc #2. take those off with the harness if you can. the bpt has one of those valves on the distributor side of the valve cover. you can take that off. route the vac lines to the other side by the fuel pressure regulator. you should have all the vac line you need between the bpt and the mx-3. splice the two valves vac lines that go to the fuel pressure regulator together so they only have one line because the bpt fuel pressure reg only has one vac port. this should leave you with two extra harness clips. one in the injector harness for the egr and the other by the throttle body for the vics.<P>now bolt the jack-shaft to the back of the motor. put in your drive-shafts. mount your spindles, calipers, and brake pads. put your hub bolt back on. put your wheels back on. <P>fill the car up with fluids(anti-freeze/water, power-steering fluid, brake/clutch fluid, motor and tranny oil)<P>what you do about the i/c piping and exhaust is up to you. i removed my cat and ran a straight pipe.<P>Issues:<BR>you may need a different speedo gear. the mx-3 gear is electronicly driven and the pro lx is cable. the mx-3 gear is too long to work with the pro tranny. you can get a gear from a mx-6 from 93+. just compare to make sure it will work.<P>if you take out your a/c, you can get a power-steering belt for the non-a/c protege.<P>the rear tranny mount bolt interferes with the shifter linkage. i had to cut the excess bolt after the nut to get it to fit. if you do this, i suggest doing it while the motor is out of the car.<P>the idle control hose and the waste-gate hose need to be fitted to the intake pipe. the bov line can connect to the back of the intake manifold.<P>if i have forgotten anything or you have any questions...let me know.<p>[ April 30, 2002: Message edited by: cre8v mx3 ]

[justin h]

THANKS!<P>Also, was the TPS thing the only difference btwn the SOHC & DOHC or does that only have to do with the wiring for the engine mgmt.?

[OsoSlo z28]

i'm unsure of the electrical differences between the SOHC and the DOHC.

[natural born honda killer]

well i beleive from what derrick said was tat the biggest difference was that some came with a 3 wire tps plug and others came with a four wire. the 4 wire makes it a lot easier cause it basically matched up with the 4 wire of the bpt. so i would think that the 3 wire is the sohc and the 4 wire is the dohc. not sure but i beleive thats what it is. i do know that the 4 wire plug is a lot easier to do the swap but since i didnt have the 3 wire i have no idea what is involved but i do know that derrick said it makes it a lot more difficult. but just call derrick at corksport and see what he says.<P><BR>oh yeah ashley great write up. it should go well with the prices i listed. so know just about everything has been answered on how to do the bpt swap for the dohc at least. so the sohc swap is the only thing left to find out.

[Marlon]

cre8v mx3 and natural born honda killer <BR>what kind of boost r u running now?<P>what r the major differences from the dohc and sohc install just the tps?

[OsoSlo z28]

currently i'm running stock boost which is around 8-9psi.

[jaydog5678]

Will the power steering pump and AC pump from the 1.6 dohc work with the BPT? The 1.6 alternator works? Also, what fuel pump are you using?

[OsoSlo z28]

you should have the bpt p/s, a/c, and alt. if not, the b6's will work. as far as the alt. if you didn't get one with the motor, you'll have to get an alt pulley from a protege. the bpt/pro alt uses a v-belt unlike the mx-3. but everything bolts up in place of the other so fitment isn't an issue. i lucked out i guess because i had all of these items on the motor i got.<P>how's the motor work coming along?

[jaydog5678]

It's going really slow right now. The machinist has'nt even touched my block and it's been with him for 2 months. At the rate he's going, I may take it somewhere else and get my money back. I called JE and the piston's should not take, but 5-7 days to get, unless he just never ordered them. It's really pissing me off. <P> Again, what fuel pump are you using? Thanks man.

[OsoSlo z28]

right now i'm using the stock pump because i'm running stock boost. but since i upgraded my exhaust to 2.5 w/o cat..i might experience boost creep. if so, and i start to lean out, i'm going to put in a 3rd gen rx-7 pump. or i might switch to a 2nd gen. i believe that they have similar specs, but the 2nd gen is a direct swap and the 3rd gen needs a custom bracket.

[neverenuff]

Hey people aight well I have a 92 aoutmatic trans sohc motor, will all this info aply to me also? I know my speedo is cable not electronic . If anyone can help me I need all the info I can get on this matter. I know I want to do a bpt swap and I know it can be done just don't know what I need. If anybody has swaped a sohc for a bpt please tell me all that is involved and what I need down to the last screw if possible.any info I can obtain would be great. Tanks people<p>[ May 14, 2002: Message edited by: NEVER ENUFF CUSTOMS ]

[OsoSlo z28]

your best bet for the sohc motor swap is to call derrick at corksport. i believe they've done one. the only prob i think is with your tps. other than that, it's a pretty simple install. good luck and post any info you find.