3.1 MPFI Intake Manifold-Is It a Restriction?

[95oldsVan]

My 91 Lumina has the boxy looking mpfi Intake set up that many of you are all so familiar with.I wanted to know if there was a HP restriction due its design,runner length or height?Is it aimed at torque more than HP?

 

Are the later models with the 3100 spidery looking manifolds better for flow?

Just wanted to know what some of you think or know about it.Thanks.

 

[stockgp]

i believe they are aimed for torque, as he 95 era 3100 only has 5 more ft/lbs of torque, but 20 more horses than the 3.1.

[95oldsVan]

i believe they are aimed for torque, as he 95 era 3100 only has 5 more ft/lbs of torque, but 20 more horses than the 3.1.

 

Cool...but would you know exactly why the newer engine makes 20 more HP? what rpm does it do that as compared to the older 3.1?

I know cam and head design can also contribute as well as a better flowing intake manifold.Was just wondering a bit more about the specs to get an idea how much of a difference the 2 had.

 

[stockgp]

i'm not sure about the rest, but i know the 3x00 intakes are better flowing than the 3.1. and i think the 200+ 3x00 intakes are the best flowing of all.

 

check the w-body main page for hp@rpm numbers. i think they are there

[Prospeeder]

2000+ 3100 heads flow very well, they put out like 175-185 hp or so, and you cant forget they got Timed Injection, SFI

[TeeJay3800]

http://www.60degreev6.com would be a better place to ask this question.

[sl3196]

What's with trying to send people to another site for info? Plenty of people know their shit here.

[THe_DeTAiL3R]

What's with trying to send people to another site for info? Plenty of people know their shit here.

 

This topic isn't THAT technical to send them somewhere else...

 

 

Anyways I noticed that my 3100 seems to have nice smooth torque all through the RPM band compared to older 3.1s (and especially my old 2.8 GP).

[Robby1870]

i believe they are aimed for torque, as he 95 era 3100 only has 5 more ft/lbs of torque, but 20 more horses than the 3.1.

 

Cool...but would you know exactly why the newer engine makes 20 more HP? what rpm does it do that as compared to the older 3.1?

I know cam and head design can also contribute as well as a better flowing intake manifold.Was just wondering a bit more about the specs to get an idea how much of a difference the 2 had.

 

 

The overall runner length....(plenum runner length + lower intake runner length) is more even on a 3100. Cyls 1,3,5 on a 3.1L have shorter overall runners...just look at the back of the plenum. The heads on a 3100 flow better....the exhaust especially, the ports are D-shaped. 3100 is a roller cam, 3.1L is a flat tappet. 3100 is SFI and has a ~9.6:1 CR and a 3.1L has like 8.8:1.

[TeeJay3800]

What's with trying to send people to another site for info? Plenty of people know their shit here.

 

This topic isn't THAT technical to send them somewhere else...

I see you're point. I guess you're right...

[1QUICKHATCH]

the higher HP is mostly due to the better flowing heads and intakes, but the roller cam helps alot too!

[gp90se]

The runners/ports on a 3.1 plenum are pretty small where as the intake on a 3100 are a whole lot bigger. I just ported out my 3.1 plenum but have not driven the car with it yet but I can imagen it picking up a little more higher end HP.