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Difference between 3.1 MPFI and 3.1 SFI and other questions.


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Posted

I have a 94 GP Coupe with the 3.1 SFI - the upper intake manifold looks like this:

 

http://images.cardomain.com/member_img_a/225000-225999/225068_11_full.jpg (not my pic)

 

2 Questions:

 

1. What is the difference between the 3.1 MPFI and the 3.1 SFI.

2. I have heard that my engine is actually a 3100 and not a 3.1. I read about this topic in a post just last week and didn't understand the jist of what was said, and was wondering which engine i have. I hope i don't sound stupid. I know the 3100 has better flowing heads and such. Please explain these questions for me.

-Thanks in advance.

Posted

Here we go.

1) your motor is the 3100

2) The fuel injection system is different. On the 3.1L MPFI, the fuel injectors are at the base of the lower intake manifold and the fuel is injected there. On your SFI, the injectors are in the same spot, except the firing of them is sychronized with the opening of the intake valve, hence the name Sequential Port Fuel Injection

3)Your compression ratio is 9.5:1 where as the 3.1L has 8.9:1

4) Your cam is a rolller cam, and the 3.1L is a flat-tappet cam

5) Yes, your heads flow better, and your exhaust port is D-shaped and the 3.1L is a circular shape

6) Your motor has 160 HP and 185 ftlbs of torque, 3.1L has 140HP and 180ftlbs.

There is more on a post I posted a few days ago, it should be near the top of one of the areas. Here it is: http://www.w-body.com/forum/viewtopic.php?t=3783

 

Robby

Posted

Thank You. That really clears stuff up for me. :D

 

P.S. I really like all you people and the board itself. The help is almost instant.

Posted
The help is almost instant.

 

Thats cuz Im a sad, lonely man, who sits around and stares at the computer all day, usually half-naked, cuz Im too lazy to put clothes on. :joke:

 

Robby

Posted
The help is almost instant.

 

Thats cuz Im a sad, lonely man, who sits around and stares at the computer all day, usually half-naked, cuz Im too lazy to put clothes on. :joke:

 

Robby

 

oh dear god no get that image out of my head :yikes: :bash:

Posted

robby after what you just said ...you have defenalty confirmed my hetrosexuality....I was like this :puke: for like 5 minutes after you sent tha.....muhaha

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