3.1 or 3100

[bashmanx]

Hey Forum, I am building a 3.1 turbo from the ground up and before I sink all the into machine work, I have to make sure that the block that I was given is truely a 3.1 and not a 3100. I guess my first question is, is there a difference between a 3.1 and a 3100 block? If there is, what on the block will tell me which one it is? The dealer was no help in this situation. Thanks for your help. Brett

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[bszopi]

Welcome to the site! Do you just have the block or do you have the rotating assembly as well? If you have the rotating assembly, the main caps on a 3100 will have bolt holes going into the side of the caps. The block will also have a spot for a cam position sensor.

Brad via Tapatalk

[bob442]

a 3100 will be more ideal for the valve train, stronger bottom end, and intake design. as brad mentioned the main caps have what is like a 4-bolt main. the lifters are roller hydrolic, and the rockers are rollers as well. as long as you dont have your heart set on using a 'MFPI 3.1 intercooled turbo' plenum, i would suggest snagging a 2000+ 3x00

but other things to consider is what this is going into aswell as there is some modifications required to drop in the newer motor.

[zinX11]

I haven't been keeping up with all the ins and outs of these engines so I'll have to ask what difference does it make which block is used? Is one stronger than the other? Or is there an incompatibility that dictates one over the other?

Mike

PS I'm also contemplating turbocharging, and am curious if there is a block that would be preferable, given a choice. I'm looking at the 3.4 from the F-body...

[bob442]

again, what is this going in, and what do you have in it.

[bashmanx]

I'm contemplating changing the motor now. I had my heart dead set on a 3.1 turbo (1990) liter because I bought forged pistons for it. After I bought them, I was told that the 3400 would produce more power. I'm still on the fence. Would the 3.4 be the better choice? I'm putting this into my z24 and I have a turbo set up already to go with a haltec computer. If you guys know Curtis Walker, I bought his 91 turboed z24. Thanks, Brett

[bob442]

well you could still use a 3.1 block and make it a hybrid....

[Superdave]

I'm 99% sure that block came out of a 91 Z24, I did text the original owner and his wife however neither responded. They live in Kentucky now and seem to be hard to get in touch with.

If memory serves me correctly, they had a red 91Z auto, the 3.1 started to knock so he pulled it and swapped it out for a 2.8 from an 89 Z24. Our plan was to use that 3.1 and build a beast gen 2 however his situation changed and the parts ended up in my garage for a few years.

I am 100% sure that is a Gen 2 block, the original flat tappet cam is still up on my shelf and it's original rods and crank are in a 3400 that i rebuilt for my old 91 Z24 a few years ago.




The heads i gave you are ported pretty well but you'll be limited by the 3.1 LIM and UIM.. Here is what i'd do in your situation.. and why.



Grab the newest 3100 you can, year 2000 or newer. It's got the same exact rods and crank as the older 3.1 and your new forged pistons will fit once the block is bored out. You'll get a stronger block with improved oiling, much better flowing heads than stock and a much better flowing top end. The cam is a roller that's similar in specs to the stock gen 2 cam however there are aftermarket ones from wot-tech that you can use to pull even more power out of it.


With a built 3100, the right turbo and traction you'll have no problem beating his old 12.2 record.

[bashmanx]

Dave, that sounds good. Question, would I be able to use the same wiring, water pump p/s pump etc.? My guess is no, but I just want to make sure. Thank you all for being patient with this newbie.

[bob442]

you should be lucky with all the accessories, you might have to get a alt. braket from a 96 3100 to use yours, and yes you can use the wiring harness. you will need to aquire a 1/2" NPT tape for the heater core line unless you can score one thats similar to your cavalier. if you can borrow that tap your set. its on the lower intake by the thermostat