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Enlighten me please! 3.1 vs. 3100


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Posted

What are the major differences? What's interchangeable? Why would you want to interchange it?

 

Thanks.

Posted

Differences? altered/modified heads, lower and upper intakes, exhaust manifolds, throttle body, the block is somewhat different. The intake ports are different shaped and bigger, one of the reasons why it has a bit more HP than the "3.1" there are more details than this, i just dont want to get into it :)

Posted

So, in other words, nothing is the same except the displacement and the alternator?

 

There is a guy who is offering a complete set of heads, gaskets, and misc. stuff that goes with that. The trouble is, he can't tell a 3.1 from a 3100. I have a 3.1, and I don't want to get something I can't use...

Posted

you can bolt the 3100 heads, manifolds, etc no problem to a 3.1 block. I think the main difference with the block is with the camshaft.

Posted
you can bolt the 3100 heads, manifolds, etc no problem to a 3.1 block.

 

Yea, but do I want to? Will that get me anything special as far as performance? Will that throw off my ECM?

 

 

Damn, I''m full of questions today..... :roll:

Posted

the 3100 has better flowing heads, intake, and the exhaust manifolds are a little better (though handrails still suck as exh manifolds) so yeah if you can get it tuned correctly, then you'll gain from it.

Posted

The crankshaft, water pump, and I think some of the pulleys are exactly the same. :)

Otherwise, everything else is different.

I think you will lose some low-end by going with 3100 heads and intake, but gain mid and higher band power.

 

It's not as easy to squeal the tires in a 3100 as it is in a 3.1L. In fact, in the 3100 Chevy Malibu I drove, it was pretty much impossible to squeal the tires. The thing felt like a 4-cyl from a standstill.

Posted

All the 3.1 cranks are primarily the same. 981 casting on most of them. The only ones I'll question are the Twin Cam and the Turbo cranks but when I try to look form them all I come up with a 981 casting so i think It's all B/S and GM made it relatively strong from the get go. You'd really have to take its out of the engine beat the shit out of it for the the crank to break....Same goes for the 2.8 cranks '85+.

Posted

I think the 3100 block uses cross bolted main caps too. I'm not positive on that though.

 

Jason

Posted

one thing to watch out for though, is with the roller rockers, and lifters. The 3.1 CAN NOT use them. I am not certain when the roller rockers, and lifters were introduced, but if you are putting the heads, and intake from a 3100 onto a 3.1 block, then there is no way to oil them. you will have to use the standard lifters, and rockers. At least until someone develops a way to convert them.

 

also, the front cover is the same between the 3.1, and the 3100 with the exception of the power steering pump. that is where the differance is.

Posted

slight corretion to that. What is differant with the front cover is the mounting area for the power steering pump.

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