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Debate: mpfi vs carbi in ej'ed older vehicles


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13 replies to this topic

#1 Yo'J

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Posted 10 April 2008 - 06:07 PM

So I'm wondering what the points to ponder are in the "New" version of the "ej it" statements are gonna be. If you can ej it now with the carb, what are the benefits and the downfalls going to be. Obviously time of installation are a considerable benefit. What about engine maintenance, durability of a durable engine, and mileage? Scott, here is to you!:drunk: :clap:

#2 beataru

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Posted 13 April 2008 - 10:57 PM

If you use an ej intake manifold with a carb the fuel is going to pool up because it was not designed to be a wet manifold.

now if that matters to you then its bad, it will work but, I wouldnt do it.

#3 GeneralDisorder

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Posted 13 April 2008 - 11:26 PM

If it's done right, either one will *work*.

MPFI is superior. Driveability, economy, off-angle running, maintenance, reliability, self-diagnostics, ect.

That's why everyone dumped carbs at the end of the 80's. Once you take a carb to the level's neccesary to compete with even throttle body injection it's far too complex and fragile to be of any use. It just makes more sense to tell the fuel what you want it to do rather than trying to trick the engine vacuum into doing it for you.

GD

#4 bratsrus1

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Posted 14 April 2008 - 09:30 AM

Hi This is Jerry, i have a EJ2.2 impreza engine that i have a 4 barrel carb on it. The engine has no lag nor dose the gas pool up in the manifold. Want to see it well then come to the show WCSS10 it will be there. I have the engine on a test stand now and when i open up the gas that engine will pick up one side the stand it's going into my hatchbrat in about 3 weeks. :clap: come to the show and see it. Thanks Jerry

#5 Loyale 2.7 Turbo

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Posted 21 April 2008 - 02:26 AM

... ...i have a EJ2.2 impreza engine that i have a 4 barrel carb on it. ...


Do you have Pics of That? ... Could you Post `em? :confused:

#6 Reveeen

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Posted 21 April 2008 - 04:38 AM

Let me throw a wrench into the works.............

I'm assuming you are throwing an EJ engine into a car with existing SPFI. Why not try to get the SPFI working on the EJ engine? (it should work with some fooling about)


That's why everyone dumped carbs at the end of the 80's.

Silly me. I *thought* they dumped carbs because:
1) Emissions warranty (they had to make vehicles that would pass emissions for 5 years).
2) They could not maintain a pool of trained monkeys (mechanics) that could fix carbs.
3) They decided they could sell FI as a selling point boosting the overall price.

There must be some reason the airplane guys use carbs?

#7 zukiru

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Posted 21 April 2008 - 10:40 AM

Let me throw a wrench into the works.............

I'm assuming you are throwing an EJ engine into a car with existing SPFI. Why not try to get the SPFI working on the EJ engine? (it should work with some fooling about)


That's why everyone dumped carbs at the end of the 80's.

Silly me. I *thought* they dumped carbs because:
1) Emissions warranty (they had to make vehicles that would pass emissions for 5 years).
2) They could not maintain a pool of trained monkeys (mechanics) that could fix carbs.
3) They decided they could sell FI as a selling point boosting the overall price.

There must be some reason the airplane guys use carbs?




I like this idea of running an EJ on the existing fuel setup...

#8 Gloyale

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Posted 21 April 2008 - 11:44 AM

I like this idea of running an EJ on the existing fuel setup...


The EA82 SPFI system does not run at high enough fuel pressure to satisfy the EJ injectors. You'd have to upgrade to the MPFI pump.

#9 s'ko

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Posted 21 April 2008 - 04:00 PM

Let me throw a wrench into the works.............

I'm assuming you are throwing an EJ engine into a car with existing SPFI. Why not try to get the SPFI working on the EJ engine? (it should work with some fooling about)



yeah. you could do that. If you had an SPFI, You would need to put a disty on the back of the pass side head, then use a coil to get power to the plugs, You will need the SPFI MAF sensor. Then you would have to figure out a way to get the SPFI throttle body to connect to the EJ intake manifold. Then it's just a matter of the EA computer being able to take in all of the readings from the various sensors on the EJ motor.

You can do it for laughs and giggles, but if you are really that set on diving into all of the wiring work, why not just trim your EJ harness and call it done?

BW

#10 zukiru

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Posted 22 April 2008 - 12:08 AM

I need help with that part, lol

if you can help me figure what to trim
I'd like to do an EJ swap ,,, but I am going to be so lost......
mechanical I handle

#11 Numbchux

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Posted 22 April 2008 - 12:34 AM

The EA82 SPFI system does not run at high enough fuel pressure to satisfy the EJ injectors. You'd have to upgrade to the MPFI pump.


nope. SPFI and MPFI pumps are the same. it's the carbed EA82 ones that don't put out enough pressure.

which wasn't the point being made, he was talking about using the EA82 SPFI system to control the EJ22.

#12 Gloyale

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Posted 22 April 2008 - 11:18 AM

nope. SPFI and MPFI pumps are the same. it's the carbed EA82 ones that don't put out enough pressure.


No they aren't

Posted Image

#13 Numbchux

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Posted 22 April 2008 - 01:29 PM

No they aren't


huh, never seen that page.....never looked.

So I just looked at the same page in the '92 legacy FSM. the EJ22e pump puts out 36.3psi and 80l/h, and the EJ22t gets 43.4 at 150l/hr.

so yea, SPFI pump is plenty pressure for either. but might not be enough volume for the turbo (although I know a guy who's running a mildly modded tleg on an N/A pump). In fact, I wonder if the MPFI pump is substantially too much, pushing 60+ psi might be hard on the pressure regulator.

#14 Gloyale

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Posted 22 April 2008 - 01:58 PM

huh, never seen that page.....never looked.

So I just looked at the same page in the '92 legacy FSM. the EJ22e pump puts out 36.3psi and 80l/h, and the EJ22t gets 43.4 at 150l/hr.

so yea, SPFI pump is plenty pressure for either. but might not be enough volume for the turbo (although I know a guy who's running a mildly modded tleg on an N/A pump). In fact, I wonder if the MPFI pump is substantially too much, pushing 60+ psi might be hard on the pressure regulator.



I see. Well, I will believe you that it works. I knew the pumps were different but admit I was just repeating something read here with regards to the EJ.

At any rate, you're right that wouldn't apply to using the whole SPFI on the EJ motor.

Some EJs came with SPFI in other regions. But probably not the same sytem as the EA SPFI.

Aside from fitting the Throttle body and mounting the injector, I guess you'd have to generate a CAS signal for the ECU. I wonder if there are any bolt in CAS style distys. Possibly later Escorts?




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