Jump to content
Ultimate Subaru Message Board

Carb->SPFI engine swap


Recommended Posts

In order to swap a complete SPFI engine into a car that currently has a carbureted engine in it, what else needs to be switched?

 

Stuff I can think of:

-ECU-where is it located?

-engine control wiring harness

-fuel pump and its wiring

-Y pipe w/oxygen sensor

There has to be more than this. Oh yeah, and if I go through with this, I'm gonna do T-belts, oil pump seals, maybe water pump, cam seals, crank seals, cam block seals, valve cover seals, oil pan seal, clean the lifters, and make everything nice 'n shiny.

Link to comment
Share on other sites

I want to keep the ENTIRE ENGINE as one piece during the swap. Engine, intake manifold, throttle body, sensors, etc. come out of one car and go into another. No removal of manifold or anything like that. I have to swap everything because the Japanese market engine that is in the car right now can't pass emissions.

Link to comment
Share on other sites

Yeah, fuel lines are a concern. I do have a complete parts car in addition to the car that the engine is coming out of, so I should be able to just take the lines off of there if mine doesn't have them.

 

If I can use my existing fuel lines, will they handle the pressure? There's a big difference between carb and spfi fuel pressure. I think carb cars run less than 5 psi, whereas the spfi cars run 53 psi.

Link to comment
Share on other sites

Snow,

sounds like you have a good handle on this, hope you give it 'ell

As for your fuel line question, we are only at about 35 psi **but you are correct the fuel lines should be changed from the pump to the injector atleat (note: somebody has mounted the SPFI pump inline under the hood and let the carb pump feed it (think it is Noah with his CIS conversion) The more effiecant SPFI will use less gas than the carb so fuel delivery volumes should not be an issue) The return line is a minmal pressure line so it should be fine.

** I say this because normal "fuel line" is rated to about 40 psi and costs pennies per foot.

fuel injection line rated for 100 psi is dollars per foot (at NAPA any how, just tried to buy some, put normal fuel line on my turbo wagon and it shows no signs of swelling or problems)

 

You did ask some questions

-ECU-where is it located?

-engine control wiring harness

-fuel pump and its wiring

-Y pipe w/oxygen sensor

The ECU is under the steering col.

The main harness goes in the driverside of the bulkhead.

Fuel pump - covered

Y pipe and 02 sensor. the 02 sensor is essential but a bung for it could be welded into your existing "Y" if ness.

 

Good luck, I have complemplated this swap (minus the lump) into one of my Brats

Link to comment
Share on other sites

I forgot some other stuff that I wanted to check on before doing this.

 

The spfi engine is coming out of a car with an automatic and going into one with a manual tranny, which raises two issues.

 

1. Do I just bolt on the flywheel and clutch assembly from the MT car, or does more have to be done?

 

2. Do I need to change the distributor? If so, will the one from the carbed motor work, or should I take the one off of my MT spfi parts car? Or can I just leave that one in there?I haven't checked to see if the spfi distys have any electronic gismos in them that the carb distys don't.

Link to comment
Share on other sites

Yes, you will need the flywheel and clutch set up

 

yes you will need the SPFI distributor

 

You will also need to tell the ECU that it is now a manual vs automatic tranny. This is done with a jumper on the pin in connector.

Since you have some time, my suggestion is to start shopping Ebay or where ever for a FSM (Factory Service Manual)

It will answer many questions that you may have concerning this endeavor.

Best of luck

Link to comment
Share on other sites

  • 3 months later...
You will also need to tell the ECU that it is now a manual vs automatic tranny. This is done with a jumper on the pin in connector.

 

Really? Is it different for a turbo car? When I did my auto to manual swap I didn't do anything like that. Could you elucidate further on thy why's of the matter and possible consequences of not doing it? I didn't see anything in my FSM that would lead me to believe this was an issue.

Link to comment
Share on other sites

dont forget to swap over the airbox

 

on the carb fuel system: replace the rear filter and pump with the spfi pump

 

Replace the filter under the hood with the canister fuel injection type filter..

the line from the filter will connect to the bottom nipple on the spfi throttle body. the return line will go to the top nipple on the throttle body.

 

the vent line from the top of the carb fuel filter will go to a vac steel line that sticks up at a 45 drg angle on the back of the manifold. this line goes to the charcoal canister ststem. leave the canister connected to the motor when you swap

 

my 2 cants...

 

trashwagon5 has the canister fuel filter under the hood, but with a carb

Link to comment
Share on other sites

Please sign in to comment

You will be able to leave a comment after signing in



Sign In Now
 Share

×
×
  • Create New...