Mostly because you'd also have to change the entire wiring harness right to the ECU, bare minimum. Giant PITA in my book, but it's really up to you.

 

Plus the fuel tank and lines IIRC

 

Thanks for the information. What is the difference between the different engines? is it just the heads?

 

Your sig. says spi 2.0. Its the whole motor is different= a d-tech/mzr motor & spi. Thats why there are different engine sections in this forum= spi, zetec, d-tech. Like said above, you'd have to change out the pcm & wiring harness, & w/ a 23 you'd need to get the motor monts & don't forget to get the transaxle that goes w/ the 23 motor. Yeah, it can be done, if you have the time & all the parts. I'd add up all the parts & pieces that you'll need & then your time vs a 23 powered car to begin w/. Just to add the '05-'07 st's have a 23 & 4wdb's & a few other mods.

 

OK thanks. I did a bit of reading about having to do the switching of the ECU and the wiring harness. I saw the different threads about the different types of engines .. but I just didn't know what the difference between them are. I know what the difference is between a DOHC and SOHC but do not know the difference between a duratech, SVT, SPI. (Sorry... just new to the focus family of cars)

I guess with all things considered the easiest route would be just to replace the OEM engine with another OEM engine and not worry about performance.

I bought the car for 700 dollars. It would be kinda hard to find another one where the body and interior is in as a good shape as the one I bought. The one that I did buy is good except under the hood. Here is the link to some pictures that I took.

http://s828.photobucket.com/user/stevemcc0372/library/

 

I guess with all things considered the easiest route would be just to replace the OEM engine with another OEM engine and not worry about performance.

If you get another SPI, be sure the heads have been reworked to fix the dropped valve seat issue.

 

The different names are just names but completly different in every way.

Different compression, strokes, piston size... etc. the cams are all different the heads are all different IIRC the duratec has the intake on the front of the motor vs the zetec has them at the back.

the crank shaft is different requiring different flywheel and such.

The motor mount points are similar but mounting to those points are different. the ECU's are completely different.

they are different families.

they likely share as much in common with each other as a Ford 302 and a 350 Chevy

 

I would sell what you have and buy another Focus. 02's to 04's are selling for around $500 in the Toronto area. If this car is your daily driver buy the newest Focus you can afford or even better buy a Corolla or a Civic.

 

Thanks for all of the information guys. I think I will end up selling the car to battered womens shelter after I get everything all fixed on it since it is my second car. Just might get another car.