SHOC to DOHC head swap

[dmc41gpros]

is it possible to swap the heads on a 1993 protege lx it has a 1.8 l SOHC but i want to swap to the DOHC head is this possible at all and what is in volved in doing this

[Kelly]

never heard of a mini me mazda. i havent ever seen anything here saying yes but other than that i have no idea.

[Tweeaks]

Yes you can do it, you'll need:

DOHC Head, Intake Manifold, Exhaust Mani, ECU, VAF (it's not necessary, but I was told that they both (SOHC & DOHC VAF's) send different signals to the ECU, and any gaskets that'll need to be replaced. I think that's it, oh wait, you'll also need the DOHC Pistons (Again not NEEDED, but you'll have a lower compression Ratio something like 8.5:1 I believe I might be wrong on that number. And the SOHC Rods are crap also....DOHC's are way stronger..The DOHC Tranny is also alot stronger and has a closer gear ratio than the SOHC Tranny...

In the end It'll be way cheaper to:
A: Sell your car and get a GT (I assume you're in Canada because your LX has a SOHC in the states the LX's come w/ the DOHC) or
B: Buy a DOHC engine and swap it into your car....of course w/ the DOHC ECU and wiring harness (although you can use the SOHC harness, but my SOHC & DOHC harness had different connectors so I just swapped the whole harness, it isn't that hard and only takes about 30 mins tops)

[Kelly]

huh whudda thunk

[Speed Protege]

Learn something new every day.

[dmc41gpros]

well i live in jeffersonville indiana i just bought this car from dodgersmith the trannie is being replaced as we speak it was blown to peices on the in side the cluth was laying on the bottom of the tranny does the DOHC tranny bolt right in or does it need moded any i want to do the bp18t swap but i dont have that much money thank for letting me know about this swap

[bruce95fmla]

go to the junkyard and get a nice BP for like 300 and then just swap that in..

You can change trannies if you opt to or just use your current goods.

[FineWine]

You can change trannies if you opt to or just use your current goods.

If you have the money CHANGE THE TRANNY AT THE SAME TIME! I cannot stress the importance of this. You'll regret not doing it later if you decide to go turbo, or if you break your tranny from future mods. Transmission work is a PAIN.

[Tweeaks]

The trannys are a straight swap, but you do need the DOHC axles, and the DOHC flywheel/clutch (not necessary if you use your SOHC clutch/flywheel, but you can't interchange the clutch/flywheel between the two you have to either use DOHC or SOHC stuff...

Yeah it is better to swap bothe the motor and tranny at the same time as it is less work, but if you don't dog your car too much then you will be fine, well some SOHC trannies have given out on the SOHC motors w/o mods so...I guess it's your desicion. I have been running my DOHC motor w/ the SOHC tranny for about 2-3 months with no probles, and I run my car pretty hard...

I am trying to go ahead and get the DOHC tranny though, that way I can at least use my SOHC as a spare if that one goes.

[FineWine]

The tranny can hold up against the DOHC if you do not pull your car hard, yes...but if you're doing the swap and plan on making a decent amount of mods later...and especially if you're gonna turbo, you better go ahead and do the tranny swap. It's not a requirement for DOHC swap, but it's a MAJOR time saver down the road.

[darkangel]

so are BP's plentiful, well since the egt's had them as well. and did someone say about $300 for one? i could by one if that's a going rate for one. how's about the DOHC trans?

[dmc41gpros]

alright i am going to call around later and see if any one has the DOHC engine and trans thanks to all of you

[Tweeaks]

Oh I didn't know that it also required different engine mounts....

Yeah the BP's came in the GT & LX proteges, KIA Sephia (not sure on the trim model), Escort GT, Tracer (LTS I think), I think that's about it, so yeah it shouldn't be too hard to find one, I got mine for free from a friend that bought a LX as a parts car that was rolled, they got it really cheap and all they needed was the auto tranny out of it. So I drove about 2 hours and picked it up..

Its funny because this same guy is running 7 PSI on his Civic and has blown the motor a couple of times, and all this time he had a Much Much more powerful motor sitting off in his junk pile...

[TheLastMarauder]

I heard once that the Kia Sephia BP is weaker internally. Any truth to that?

[Protoss]

this has been covered many times, but something new comes out each time so no harm there.

3 quick things.
when doing a proper dohc conversion, you will need to swap out everything. including pistions. so just buy a preassebled one and do an engine swap instead of a conversion

State you intention with the engine. it makes giving advice much easier. do you have to budget or means to need a turbo engine? do you race or is it a daily driver

and finally. welcome to the club