3400 Horsepower rating

[KNTRDR]

Here's one that I've been scratching my head over. My 1996 Lumina APV with the 3400SFI engine is listed to have 180HP. However the later 3400s such as used in the 1998-up Ventures, Aleros, etc. all seem to show as having 185HP, even though they appear to be the same engine. Anyone know what the change in power is caused by?

[gboogie99]

different flow on the intake manifolds, it was a minor revision by GM that added the HP. Also head are slightly different.

[bszopi]

different flow on the intake manifolds, it was a minor revision by GM that added the HP. Also head are slightly different.

All 3400 heads (96-02) are the same, so I'd have to shoot you down on that one. I will agree with the flow through the plenum though, as the plenum internals changed slightly over the years. There have also been revisions to the exhaust manifolds over the years that could cause the slight increase. And finally, it could easily have to do with PCM programming changes.

[TheProfessor]

im leaning heavily towards a change in the PCM

[gboogie99]

correct me if I am wrong but doesnt the 3400 flow a considerable amount more air than the 3100 which also causes a difference in horsepower although it is practically the same engine?

[GutlessSupreme]

The 3400 has a larger bore than the 3100.. besides that yea they're pratically the same engine. Up until I believe '00, the 3400 had larger-port intakes and heads. After '00, 3100s started recieving heads/intakes with the same big ports the 3400s have.

[Syn]

The 3400 has a larger bore than the 3100.. besides that yea they're pratically the same engine. Up until I believe '00, the 3400 had larger-port intakes and heads. After '00, 3100s started recieving heads/intakes with the same big ports the 3400s have.

QTF!

00+ 3100 is the same as the 3400 top end