3400 Revs faster than 3100?

[IsaacHayes]

I was checking out my friends 3400 Impala tonight because he had a whining noise coming from it. I gave it a rev expecting it to rev slow like my 3100 and the thing revved like I had it WOT!!!

Do they really rev that fast because of the bigger bore?
Or is the tuning different on the 3400 enough to cause that fast rev?

[mcgavinz26]

I have always thought the 3x00's have reved kind of fast for what they are. When I did my 3100 -> 3400 swap the one thing I noticed the most was the exhaust note had changed. I had ported the rear log (downpipe), but I don't know if thats what did it or the slight displacement increase... or both?

[IanSzgatti]

i had a 3.3 engine up at the farm and took off a manifold only to discover that it was like pipes sticking through the 'log' and the seams welded to seal it... is that what these things have too? It was pretty damn cheap looking.... anyway, I could definately see the point in porting them... i think that would be a big difference.

[IsaacHayes]

My 3100 never revved that fast really... Just about normal. My friends 3400 you just touched the throttle with your finger under the hood and it was like WOOOMP! It surprised the hell out of me to be honest, I wasn't expecting it... I was used to my motor.

[3100 MPFI]

You know, it is kinda weird.

My STOCK 3100 in my 1996 Grand Prix was slow to rev, but the 3100 I built up for my 1988 Cutlass Supreme would snap up FAST.

I know my 1988 Cutlass Supreme was not STOCK, but still.....

Maybe it has to do with the COMPUTER. The 1996 is a stock OBD2 PCM, but my 1988 was running with a 1993 3.4 DOHC ECM.

[Spankdamonkey]

Does he have an UDP on it? My 3100 seems to rev alot faster after I installed it.

But as was stated, it's probably all in the computer programming.

[Monzsta]

When I stuffed my 3400 in place of the ol' 3100 I noticed greater throttle response running the same tune. Same feeling you had. Slight throttle opening, the k&n bellowed WHOOOP! I was shocked. Now I'm in the middle of tuning it, so that's diminished somewhat untill I get after the timing, AE and PE tables.