3.1 vs. 3100/3400 help

[jackflat0021]

its been a while but im back at it again and i have found alot of parts and havenoticed tha they can be installed minor modifications but i nee to know what the differnces are between the engines

[IanSzgatti]

3.1 engine? not really anything I think you want to do with that.

3100 engines got better flowing heads, roller-rocker valvetrain, better intakes...

2000 year+ 3100's have bigger intake valves in the heads, and the plenums flow better because of bigger runners...

3400 upper and lower plenums + heads can be put on your 3100 engine, requiring more modifications than if you used only the 3400 intakes on the 3100 heads...

2000+ components could be swapped as well to pre 2000 3100 blocks as you might have suspected... but there are some small design changes to overcome depending on what your starting with.

Everything I've listed off here I learned here.... but I'm still no guru... there is lots of info here http://60degreev6.com/Family_Tree .
and... http://60degreev6.com/forum/showthread.php?t=24944 will show you some visual difference between the parts your asking about...

what is it your planning to do, and what parts do you have?

[powerdoctor]

I would want to know what skills you have as far as fabricating goes.
You can shave h-beam rods to the right width, add a "z" vin steel crank,
go with arais forged pistons with floated pins, ect....
I would go with a newer block, as they have a much better oiling system plus roller lifters.
It really would not matter to much which block,I:E 3100, 3400, 3500, 3900, unless you have a specific bore in mind.
If you plan out you piston selection right you would be able to use the heads from any pushrod v6, with the compatable intake, or fab one up.
So it really depends on you.

[Jbrogan]

3100/3400 engines are much stronger and more powerful. 3400s only 10 more hp than 3100s. 3.1 mpfi engines have weak bottom ends (rod bearings go out) 2.8s are even worse. the stock intake manifolds on 3.1s suck, 3100s are that great eather but you can swap them for 3400s real easy. I got a 16.2 out of my old beretta with a 3.1, and everything was stripped out of the car. my beretta with the 3100 ran 15.7 with just a warm air intake.