3400 Intake (upr & lower) swap on a 3100

[Dean]

Okay, I am new to the site and read through some of the cool things others have doen on their 3100s and 3400s.

Currently, my '96 GP with the 3100 motor is torn apart in my garage. My everyday car. I like to do some of the suggested mods.

I have a question, when you swap the intake manifold, and exhaust headers from the 3400.

What model year motor 3400 would be good to use? I saw some references to using '99 3400 intake...2000 Model Year!?! And I also saw the use of the exhaust manifolds from a the minivans (since they are slightly bigger)!?! Or where can I get set of those headers I saw in a picture?

Just wondering with model year to use for my swap intake swap and exhaust manifolds?

Thanks!

[ikessky]

RE: 3400 Intake (upr & lower) swap on a 3100

You can get headers from S&S, but you will need to modify the rear one to clear the firewall (they were designed for ~'99 Grand AM's). You can use any year 3400 or '01+ 3100 intakes, which flow the same as the 3400 stuff. Depending on the year of intake you get, you may need to get an EGR adapter plate to keep your current EGR setup and not have any codes thrown.

[Dean]

Re: RE: 3400 Intake (upr & lower) swap on a 3100

You can get headers from S&S, but you will need to modify the rear one to clear the firewall (they were designed for ~'99 Grand AM's). You can use any year 3400 or '01+ 3100 intakes, which flow the same as the 3400 stuff. Depending on the year of intake you get, you may need to get an EGR adapter plate to keep your current EGR setup and not have any codes thrown.

Then I am best off getting a 3100 intake off of '01 model year to present from the junkyard. Then don't need to do any porting and polishing.

Another question, what about bigger intake and exahust valves. What would I gain, besides better flow. Have others benefitted greatly in doing this mod?

[ikessky]

RE: Re: RE: 3400 Intake (upr & lower) swap on a 3100

There is still room for porting and polishing even on the new intakes. They just flow better than your '96 style.

[TheDirtyBen]

RE: Re: RE: 3400 Intake (upr & lower) swap on a 3100

if i'm right, i believe the 2000+ 3100 and 3400s both have larger valve (intake) over the 94-96. anyways, if you use anything other than 94-96 Upper intake manifold, your stock EGR will NOT mount to it. you will need an adapter plate or block off the port and re-program ECM to prevent CEL occurences.

[Rhedalert]

RE: Re: RE: 3400 Intake (upr & lower) swap on a 3100

actually, '96-99 used the same EGR. Get your hands on '96-99 3400 intake manifolds and you won't have egr issues.

[TheDirtyBen]

RE: Re: RE: 3400 Intake (upr & lower) swap on a 3100

ok wait. i was told that 97 3400s had digital EGRs, but i know that 99s had linear EGRs.

[Rhedalert]

RE: Re: RE: 3400 Intake (upr & lower) swap on a 3100

'96-99 EGR's are the same as '00+ but mount differently. '00+ mounts sideways whereas '96-99 was flat.

[Guest]

Re: RE: Re: RE: 3400 Intake (upr & lower) swap on a 3100

'96-99 EGR's are the same as '00+ but mount differently. '00+ mounts sideways whereas '96-99 was flat.

This is true, but all you need to do is get a newer EGR and tube, if you get the newer UIM. Electrically they are the same from '96 to '04 (maybe even '05).

[Dean]

Intake Manifolds swap

If you do this swap, putting the 3400 intake (upr and lwr) onto the 3100. What kind of horsepower gains are you going to get?

Or instead of doing the swap, couldn't I just buy the ported upper and lower from the 60DegreeV6 store?

[bszopi]

RE: Intake Manifolds swap

Going to the new, larger bore (port) intakes will probably gain you 5-7hp by allowing more air to get into the cylinders. Not that big of a difference if that's all you do, but makes a difference once more (internal) work is done to the engine.

If you choose ported old-style 3100 plenum and manifold, it will still be less than a stock 3400 (or new-style3100) setup because there is no way to increase the size of the older ports to that of the newer ports. Porting will smooth out the walls of the ports which may help velocity and decrease the possibility of turbulence in the port, but I don't think you'd gain much more from it.