ok, is the 3.1 a bored 2.8 or a stroked 2.8??? i've heard both but i think it is a stroked 2.8. dunno???

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Dan
100% stock 1990 RS 3.1L
and VERY slow

 

All it has is a bigger crank ive herd

 

that'd be a stroker then. my next question....is the 2.8 block identical to the 3.1??? for example: main seals, crankshaft journals???

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Dan
100% stock 1990 RS 3.1L
and VERY slow

 

In all respects, they should be identical, as with the 3.4. I've heard there is a slight difference that can be ground out on the journals though.

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Reno
'88 Firebird LB8
"Cerberus"
Now: rusting on a side street til I get out of college

Plans: BUILT 3.4 motor with B&M racing tranny, Hotchkis suspension all around, lowering 1", Accel ignition all around, Splitfire plugs, 88 front bumper, ASCD Ram Air I hood, 91 GTA spoiler, formula wheels, Firehawk tires, restored interior (first on list)

 

thanks reno

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Dan
100% stock 1990 RS 3.1L
and VERY slow

 

the 2.8 3.1 and 3.4 blocks are all the same with the exception of each has a bigger bore than its predecessor..

 

Is the 3.4 block's external dimensions the same as a 2.8's? I thought a 2.8 couldn't be bored out to become a 3.4 because the walls got too thin.


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-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards

 

Tom, did you get that info off that old board that had all the mods for the 60 degree v6. I think they said something about boring the engines, and said that once you got to 3.4 litres, you were way in the danger zone. But, i'm sure Chevy could have devised a way.

 

I;ve read where the 2.8 and 3.1 have the same 3.5 inch bore, but the 3.1 has different pistons and crank. The 3.4 has a 3.6 inch bore. You can bore a 3.1 about .040 or .060 over , cant remember which, and come out to a 3.2. Nick Norris said his 3.4 heads will work on 2.8/3.1's and my 3.4 headers fit my 3.1, so I'd say its safe to say the heads are about the same( except 3.4 heads have the big valves).

 

so if you were to build up a 2.8/3.1....would you recommend stock 3.4 heads?? does anybody make performance heads for a 2.8/3.1???

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Dan
100% stock 1990 RS 3.1L
and VERY slow

 

2.8
3.1 = stroked 2.8
3.4 = bored 3.1
3.4 = stroked and bored 2.8

Got it?

Good.

-Reno

 

but......you cant bore a 3.1 to a 3.4. You'd have to bore it .1 over! you can only safely bore a 3.1 .040-.060 over tops. The 3.4 block has a little more iron aound the cylinders.

 

85f-bird, I don't know what website you're talking about, never saw it...

3.1Firebird, how'd they swing that then? Is the 3.4 block bigger externally? Or did they make the water jackets smaller? Hehe, someone's gotta cut open a 3.1 and 3.4 block!

Also if the 3.4 heads have bigger valves, can the 2.8/3.1 heads be modded to take those same valves? Oh wait then the motor'd probably need extra fuel... AFPR? Woah.


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-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards

 

http://www.foothill.net/~terryk/X11Z19.HTM

The 2.8L and 3.1L share the same block, (except for earlier 2.8Ls that had smaller main journals), and a 3.4L block is a beefed up version of a 3.1L with a slightly larger bore.

Read all about it at the URL above. Very good basic info on our engines.