3400 Lower Intake Manifolds

[FromTheInside]

I have searched the entire internet and mainly this forum all night. I am curious what the changes are between the 3400 lower intake manifolds from 1999-2005 (I have a Grand Am GT). I know that the injectors changed after 99 but I am talking about the bare manifold itself. I have read something about the heater hose using threads rather than being a push-in type. I assume that this is the black hose that goes into the thermostat housing. I haven't read any concrete information regarding the differences. I also saw a thread where someone had a 02 manifold and it was a push-in. My 99 has a push in as well.

My LIM has 99 written on it obviously. I have seen others with 00 on them but they look exactly the same. I'd like to know what has changed and what year the changes were made.

Furthermore, I know the 3100 changed manifolds in 2000, so what years will these fit in the 3400? Thanks =]

[SappySE107]

You want a 00 or 03 lower. These are all compatible but the casting flows better on 00 and 03. Your 99 upper is easiest for the EGR, but 00+ are best for flow. Rail/injectors are all compatible as well so that won't matter if you keep what you have, or upgrade to 00+ rail and injectors along with your tuning. They are less prone to clogging.

Only small ports are threaded (93-99 3100). 00+ 3100 is the same as a 3400 other than what it says. The above all apply.

[FromTheInside]

You're the man! I can see that the 2000+ 3100 upper is the same as the 3400 upper.

So basically all 3400 manifolds between 99 and 05 can be changed out with no problem. Nice. You mentioned flow as well. Is the 00 LIM ported slightly more the 99?

..Just wanna learn everything I can about this so I can help others with the same question.

[SappySE107]

http://wot-tech.com/shop/articles/choosing-3100/3400-manifolds/cat_64.html

That explains the manifolds a bit more. The lower isn't ported stock. The 00 lower is just a different casting. Close to the same but different enough to have an increase in flow.

[FromTheInside]

Thank you for your wealth of information and help. I am surprised that I didn't come across that during my hours of searching.