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Differences between the 3.1L and the 3100??


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Posted

I saw someone said that there are differences between the 3100 and the 3.1 engines. Is this true and if so what are they?

 

Did the 95 base Luminas have the 3100 in them?

Posted

the first 3100s jumped up to 160HP, and then the second up to 175. a 3.1 was 140.

 

Also...correct me if im wrong...the 3100 went to Sequential Fuel injection than MPFI.

 

 

jon

Posted
the first 3100s jumped up to 160HP, and then the second up to 175. a 3.1 was 140.

 

Also...correct me if im wrong...the 3100 went to Sequential Fuel injection than MPFI.

 

 

jon

 

Yeah, there basically completly differant engines. The 3.1 is pretty much the same as a 2.8 but with a differant bore.

Posted

From what i have heard, the 3100's are only sfi for a few thousand rpm's, then turn into mpfi or vise versa. 3100's have been made to run mpfi and on 3.1 comps for people to mate up 5-speeds to them.

Posted

Everything is different.

It would be easier to list what's NOT different.

 

I know the water pump is not different. My memory isn't the best, but I think the crankshaft may have been the same too. Maybe the starter too? Anyway, most of it is different.

Posted

They are very similar, but very different engines. The block is the same, but all the internals are different. The heads are different, the intake manifolds are different, the throttle body is different. It is SFI instead of MPFI, and many many many other things.

 

BTW...that is a badass GTP.

 

Shawn

Posted

arent the 3100 9.5:1 compression as qopposed to the 8.something for the 3.1MPFI???

 

- Justin

Posted
arent the 3100 9.5:1 compression as qopposed to the 8.something for the 3.1MPFI???

 

- Justin

 

yeah, the 3100 is 9.5 or 9.6:1 compression wheareas the 3.1L has 8.9:1 compression.

 

Shawn

Posted
The block is the same, but all the internals are different.

 

No, the block is not the same. They are very different.

The 3100 block is designed for roller cam and was redesigned for increased stiffness. It also has a hole for cam position sensor.

Posted
The block is the same, but all the internals are different.

 

No, the block is not the same. They are very different.

The 3100 block is designed for roller cam and was redesigned for increased stiffness. It also has a hole for cam position sensor.

 

I thought it was the same block but modified for the roller cam?

 

Shawn

Posted

Nope, different. The 3100 block has more "webbing" cast into it for stiffness. Something about the oil filter mount is different as well, because you can't use a 3.1L oil cooler on that block, you have to get one for a 3100.

There's a lot more different than just that, I just can't remember right now.

Posted
related question - what is the difference between MPFI and SFI?

 

MPFI fires a bank of injectors (3) at a time. SFI fires each cylinder's injector to coincide with the opening of that cylinder's intake valve on the intake stroke.

Posted

Yup, starter is the same, Curtis tipped all us TGP guys to the fact. The 3100 starter is a mini Hi-Torque compared to the 3.1.

Posted

Here's the low down on the 3.1L MPFI...

Displacement: 3135cc

Compression Ratio: 9.0:1

Peak Horsepower: 140

Peak Torque: 185

Redline: 6000 rpm

Valves: 12

Cylinders: 6

Type: Generation II

 

Here's the low down on the 3.1L "3100" SFI...

Displacement: 3130cc

Compression Ratio: 9.6:1

Peak Horsepower: 160

Peak Torque: 185

Redline: 6000 rpm

Valves: 12

Cylinders: 6

Type: Generation III

Posted
Here's the low down on the 3.1L MPFI...

Displacement: 3135cc

Compression Ratio: 9.0:1

Peak Horsepower: 140

Peak Torque: 160

Redline: 6000 rpm

Valves: 12

Cylinders: 6

Type: Generation II

 

 

Where the hell did that info come from? 160 torque?? 9.0 compression? Man come on....

Posted

Thanks for all the information. Does anyone know which engine would usually last longer?

 

 

Someone ought to get pictures of a 3100 and a 3.1 block side by side.

 

Yeah that would be cool.

Posted
Here's the low down on the 3.1L MPFI...

Displacement: 3135cc

Compression Ratio: 9.0:1

Peak Horsepower: 140

Peak Torque: 160

Redline: 6000 rpm

Valves: 12

Cylinders: 6

Type: Generation II

 

 

Where the hell did that info come from? 160 torque?? 9.0 compression? Man come on....

 

Yeah, really, try 8.8 CR and 185 Tq

Posted

160 torque is like....the 2.8 in a J body or something. Info you find on sites is some the times inaccurate, including this one. 60 degree is the most accurate besides GM sites

Posted

i dunno any differences in them but i had a 94 beretta and it had a 3100 sfi and i have a 94 lumina and a 91 regal with the 3.1 mpfi and they are more dependable then the 3100 was, again just my opinion, and experience with the 2 motors

  • 10 years later...
Posted

Can the fuel regulator from a 3100 fit a 3.1?

 

Thanks for all the information. Does anyone know which engine would usually last longer?

 

My family's experience would yield the 3.1 more reliable.

Posted

Not likely, even if it fit i imagine thered b psi issues

Can the fuel regulator from a 3100 fit a 3.1?

 

 

 

My family's experience would yield the 3.1 more reliable.

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