The bottom end of my 2.8 is smoked no chance on salvaging it. Friend smoked the cam and head on his 92 cavalier z24 3.1 v6 and is willing to sell me it for $50 bucks to make up for his new engine purchase which is fine and can get that back by scrapping what's not needed. I've been trying to figure out from the forums here with not a whole lot of luck or maybe overlooked it to get everything needed for a 3.1 stroker engine using my 86 gt 2.8 block and top end without anything crazy like a turbo or supercharger. I have a nice machine shop nearby at reasonable prices and parts if needed. What will I need to put her together and will I need to change the pcm at all?
As for the donor car its an 92 cavalier 3.1 z24 engine mated with a 5 speed manual with DIS and about 120k and unfortunately I don't get the tranny.
Any and all information is appreciated also what would be the expected power or a stock 3.1 stroker assembled?
3.1 crank and pistons, harmonic balancer and flywheel/flexplate, and '87 Fiero timing cover and pan. I have a pan and a set of .030 over Silvolite 3.1 pistons for $60. You need the cover because the Cavalier's water pump runs the wrong direction and the '86 pan won't work with the '86 cover.
[This message has been edited by raysr11 (edited 08-05-2011).]
If you have both engines you will likely have every thing you need. Depends if your flywheel is the internal or external balanced one, the new crank will need the neutral ballanced FW if your 87 does not have it. I am doing one from a 94 Olds into a fiero, aluminum heads, use the iron head pistons with the aluminum heads and you end up with about 12 to 1 compression. Mine looks like this right now. Larry
To stroke your 2.8 to 3.1, you will need the following parts:
-- Crankshaft (with matching bearings) -- Pistons (with matching rings) -- Flexplate or Flywheel (depending on transmission)
The only parts you need from your buddy's 3.1 are the crankshaft and flywheel (or flexplate, whichever it uses). But since your friend's engine has aluminum heads, his pistons will not work (unless you want super-low compression). You will need pistons from a 1990-92 Camaro with 3.1 V6. Or if you want new pistons, look up Sealed Power part # ZH562CP. Summit Racing sells them for about $29 apiece.
I have a manual transmission in my car haven't looked at my crank to see if its balanced yet. For compression if I were to buy new pistons how would I achieve somewhere around 9.5/1 and with the cast head pistons from a 90-92 camaro what's the compression from that? Also which connecting rods do I use or are they the same?
[This message has been edited by MeAndMyFi (edited 08-05-2011).]
.... Friend smoked the cam and head on his 92 cavalier z24 3.1 v6 and is willing to sell me it for $50 bucks to make up for his new engine purchase....
You do realize that if he smoked that, then there is a HIGH chance the crank is smoked as well.
A rocker broke causing the cam to get burned out and for $50 if its shot scraping the engine block woe basically buy another crank so really im thinking its worth it to me and especially for extra parts.
Like they've said, the crank and flexplate/flywheel plus pistons is what you need. GM made the 3.1 from the 2.8 by putting in 8mm longer stroke, and to keep the same connecting rods they moved the wrist pin up 4mm in the piston. The aluminum head motor is completely different in head design so the pistons for it will not work at all with the iron head.
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09:00 AM
Francis T Member
Posts: 6620 From: spotsylvania va. usa Registered: Oct 2003
If you use different pistons and harmonic balancer than what was with the crank, you'll need to have it all balanced. Swapping pistons may/will require a clean up bore, new rings. Also, since the engine saw internal damage, you should have the block tanked, All and all, it may be cheeper and easier to just pickup a good low millage 3.4.
as many above - and as someone who did this: it is cheaper to just get a proper 3.1 (or better - 3.4) iron head short block
but - I also understand the joy of doing it yourself, and working with what you have. so: what you need is the actual pistons. Iron head & Alum head pistons are different. so - you will take the 3.1 block, crank & rods. put 3.1 pistons from a 3.1 Firebird. use cam of choice. put yer heads on top. and use the Fiero intake system. it will all look original.
options: the 3.1 also has a knock sensor & crank position sensor. these are hany for doing the 7730 ECM swap. something thats easy to do while you have the engine out & the harness removed. you can even add DIS (remove distributer, and use coil block)
If you use different pistons and harmonic balancer than what was with the crank, you'll need to have it all balanced. Swapping pistons may/will require a clean up bore, new rings. Also, since the engine saw internal damage, you should have the block tanked, All and all, it may be cheeper and easier to just pickup a good low millage 3.4.
Harmonic dampeners are the same for all models other than the indexing of the timing mark. The dampeners are neutrally balanced and as such have no effect on crank balance. The flexplate/flywheel balance is standardized, and on the 3.1 is neutral balanced anyway so there's no need to rebalance the rotating assembly unless you were building a high-rpm motor. Even then it wouldn't e critical.
I was planning on using the 2.8 block since its in great condition as for the 3.1 its iffy also only the crankshaft on the 2.8 was shot along with a connecting rod. And as far as another 3.1 or 3.4 if they landed at me for about what im paying that'd be my way to go but id find this fun and fun learning combining the two together and completely doing it bottom to top
Unfortunately that 3.1 short block wouldn't help me for many reasons. But for someone who wants it it could. I will still be going the same route I was planning and will cost around the same regardless. My block is in great shape without and problems beside the cranks and 1 connecting rod. I could simply just buy a crankshaft for $200 but for a little extra buck I can get somemore power. Not really worried on final cost really and like I said it will be a fun experience to rebuild the engine myself. Also are the 2.8 injectors the same as the 3.1? If not is the 3.1 a better choice?
With a stock setup you should be able to keep the Fiero injectors. I don't know if the 3.1 injectors are electrically compatible. The worst case is that you would need to get an adjustable fuel pressure regulator and bump the fuel pressure a hair.
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07:11 PM
Blacktree Member
Posts: 20770 From: Central Florida Registered: Dec 2001
Originally posted by MeAndMyFi: I have a manual transmission in my car haven't looked at my crank to see if its balanced yet. For compression if I were to buy new pistons how would I achieve somewhere around 9.5/1 and with the cast head pistons from a 90-92 camaro what's the compression from that? Also which connecting rods do I use or are they the same?
With the Camaro 3.1 pistons, your compression ratio should be around 8.5:1. On my old stroker engine, it actually came out to 8.3:1, because the block deck on that engine was a little high. You can increase compression by having a machine shop shave material off the bottom of the cylinder heads. Although, it will take a lot of shaving to go from 8.5 to 9.5 compression ratio. And FYI, when you shave a lot off the heads, you also need to shave the lower intake to match.
The 2.8 and 3.1 V6 engines (and even the Camaro 3.4) use the same connecting rods. So you can mix and match them. Although, you may want to double-check the weight of the rods, if you decide to use rods from two different engines.
Since I've gone both routes (I built a 3.1 stroker, and later installed a 3.4 crate engine), I have to say that I like the 3.4 V6 better. But if you don't have around $2500 for the swap, then I guess it's a moot point. The irony is that I spent close to $3000 and over a month building up the 2.8. And the 3.4 performed just as well "out of the box".
[This message has been edited by Blacktree (edited 08-05-2011).]
Thanks alot blacktree you're very helpful. I wish I had money to put something better in it. This will do for awhile though. Which cam lifters and rockers did you go with? Just looking for mild performance
Thanks alot blacktree you're very helpful. I wish I had money to put something better in it. This will do for awhile though. Which cam lifters and rockers did you go with? Just looking for mild performance
I used the Edelbrock Cam & lifter kit, with Comp Cams 1.52:1 roller-tip rockers. I also ported the intake manifolds (from the throttle body all the way down to the heads), and ported the heads. Plus, I installed a set of Trueleo exhaust headers.
The end result was really nice mid-range torque (from 2000-4000 RPM), and good fuel economy. With a 5-speed Getrag, it got about 21 MPG around town, and around 30 MPG on the highway.
You've got the right advice on parts needed - just pistons and crank. You don't need to balance the bottom end, but you will need either the 3.1 flywheel or to balance the pre-88 flywheel - easy to get it neutral balanced for use with an internally balanced 3.1/3.4 crank.
as many above - and as someone who did this: it is cheaper to just get a proper 3.1 (or better - 3.4) iron head short block
+1
It would be best to find a nice condition 3.4 from a mid 90's Camard/Firebird... This is the cheapest motor "swap" you can do in the Fiero while still gaining a noticable HP increase... I heavily modified/built my 3.1 stroker and the power is only marginally better then a stock 3.4. Cost wise, I could have went with a 3.4 (but at the time, the 3.4 were very ecpensive to aquire) and had about 10-15 less HP but would have cost me about 1/4 the cost to build my 3.1 (by todays prices; not 97 prices when I started my build)...
