I'm not sure quite what that means.. that's from my "rebuilding the GM V6/60 degree" book. It almost sounds like he was trying to say "forged pistons" when he says lathe-turned.

What gets me is, there's no specific "89-up" piston kit for a 2.8! At least according to the PAW catalog, that is... seems all years 2.8/3.1 MPFI motors get the same piston kit.

Anyone know if GM offers a rebuild kit?


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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
---Think your car could be pic of the week? Visit http://www.f-body.net for details!

 

yep...a friend i know worked in the Van Nuys factory and he said before they went to the 3.1 they tried the 89 2.8's with forged pistons, and they gained something from it (dont recall...possibly hp? i doubt it though) just the benefits of owning an 89..!

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" I'd rather run last in a full out race, than to NOT run at all ".

 

I know the piston weight was also reduced; maybe the forged piston let them run the lighter piston? Hm. Thanks for that confirmation!


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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
---Think your car could be pic of the week? Visit http://www.f-body.net for details!

 

I'll buy that they improved the pistons on '89s (yipee!! ) as GM makes odd little advancements in almost every engine every 2 years or so.

But WHY would they put forged pistons in a 135hp 2.8??? Doesn't add up...hell, LT1s don't even have forged!! Why would they do that?

BTW, there was no noticeable HP gain from this change, as all 2.8s '85-'89 in Fbodies got 135hp.

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Jason E
'89 Camaro RS 2.8
Hypertech chip/K&N filters/Accel 8.8 wires,coil/RapidFires
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JasonEE98 on AOL IM

 

Maybe that was why my 89 RS was more peppy than your run-of-the-mill 2.8? Now it makes me more angry I got rid of it...this Toyota POS is making me regret selling the 89!!!!!

Vman

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1969 Camaro
383, Corvette heads, 700R4
Resto is in progress

1988 Toyota 4-Runner
aka the Parts Hauler

 

True.. isn't it such that when you lessen the weight of the rotating mass, the engine rev's up faster? I'll check that book tonight to see when they lightened the pistons.


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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
---Think your car could be pic of the week? Visit http://www.f-body.net for details!

 

Indeed Tom is correct...any time you lessen rotating mass, an engine will rev up quicker. Whether it be valvetrain or pistons, lighter is better.

So lathe-turned = lighter?

 

you know those ricers that always say their engines have "mad revs yo"???? those dip$hit's don't realize that, obviously, 4 pistons wiegh less than 6 or 8. less rocipricating mass= "mad revs yo". no pushrods help too......f**k ricers.

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Dan
1990 3.1L RS
80 Series Flowmaster
It's fast(er than a 3 cyl metro)

 

Well, I checked the book, but forgot the paper with the specs! OOps- anyway, the pistons were lightened twice in 1989. So I bet that the stronger forged piston was just as heavy as a cast; but since the forged is stronger, they could lighten it.

Good point about the same HP! Looks like it's not something to bother hunting down... or is it? Could a machine shop lighten a cast piston for cheap?


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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
---Think your car could be pic of the week? Visit http://www.f-body.net for details!

 

Mad Revs Yo! also means cam profile+ ,more valves, A bottom end that can andle it also and means you can gear lower because you have a higher powerband. YOu are correct though that some of it has to do with fewer cyl. and no push rods. Hey don't forget though the extra cam does add weight.

 

Tom, is there any way to figure out which pistons my '89 had? How could I figure out which version they are?