3100 Headers MPG

[FooBag]

My g/f has a 03 Malibu with a 3100 in it. I was curious if anyone has noted increased milage with the installation of headers with this engine. Also, from what I have read, the 3400 headers will match up with a 3100. Is this correct?

Also, does anyone have any idea if swapping the UIM/LIM to a 3400 or 3500 would help or decrease milage? I'm assuming decrease, but I don't really know.

[DEI37]

They would increase mileage if the tune was set up for it. With better breathing comes better efficiency.

[ikessky]

Also, does anyone have any idea if swapping the UIM/LIM to a 3400 or 3500 would help or decrease milage? I'm assuming decrease, but I don't really know.

You already have large port intake manifolds. No need to swap for a 3400. The 3500 would be beneficial, but is a little more involved that just a bolt on mod.

[SHOoff]

You already have large port intake manifolds. No need to swap.

Why does having large port intake manifolds mean that you don't need to install headers? It would benefit the intakes.... i mean if it can't shit, it can't eat.

[ikessky]

Why does having large port intake manifolds mean that you don't need to install headers? It would benefit the intakes.... i mean if it can't shit, it can't eat.

I was responding to the second part of his question. The part where he is wondering about swapping in 3400 intake manifolds.

[IanSzgatti]

Also, from what I have read, the 3400 headers will match up with a 3100. Is this correct?

that is correct, and i've been told that newer 3500 exhaust manifolds will go on as well, and are better than 3400. You can also port the 3400 manifolds before installing them.

as far as an increase in MPG, if your pulling in more air, the computer will still try to get that air/fuel ratio to be ideal, so more air equals more fuel. I guess theres the arguement that now everything is more "free", but it's really only a transfer of energy.

[IsaacHayes]

Improving the VE of the engine gives you more power and makes it well, more efficient so MPG can go up.

[IanSzgatti]

sorry issac... your right.... you should have pointed out the error in my thinking!
it's now obvious to me you'll travel farther because that transfer of expent energy I was talking about shows as milage... I always get confused when I hear "more power, more milage" it's kind of misleading.

[ikessky]

sorry issac... your right.... you should have pointed out the error in my thinking!

Don't sweat it. I went back and edited my post so as to not confuse anyone else. It was poorly written the first time!

[IsaacHayes]

Yup. Think of the 3.0 ford motor, its less power than our 3100's AND gets worse mileage!