Lee7

Well, since i have my whole top end taken apart, i am thinking about porting/polishing the heads while im at it.

And then i got to thinking maybe i should get a Stroker kit and have the engine block bored.

Or should i just go with a 3.4 block?

TomP

Don't think of overboring as too much of a power adder; there was a guy on here... can't remember his nickname for the life of me... but he had his overbored and it came out to a 2.9? KevinS.. that was his name on here. I guess I can keep my life; I remembered. Anyway, overboring is mainly used just to clean up the holes after excessive wear. Plus, if you overbore to the max, you'll never be able to rebuild the motor again. I -think- max overbore is 0.040... been a while since I looked at that stuff. Plus the more you overbore, the weaker the cylinder walls get.

Quick_Trans_Am

iTrader: (2)

I always thought the max was .060, but I think that may change depending on the engine block itself. I had a V8 before with a .060 overbore, and TomP is right, if anything happens to that block after that, it's usually time for the scrapyard, unless you choose to get the cylinders sleeved, which can be an expensive process. One engine shop quoted me around $400 to sleeve a SBC, roughly $50 per cylinder. The same shop wanted $230 for a completely cleaned, crack free, .030 overbore, 4 bolt main block. They had already prepped it, and it was ready to be built.

V6camaroman

i think the max on the 2.8's and 3.1's are .060 over. when i rebuilt my motor about 30,000 ago i had the block done .040 over. i recomend that to anyone who rebuilds their motor. if u do a small bore like .010 or .020 over u wont feel a difference but if u do .040 u will feel a difference through the rpm range. i did anyways.

Project: 85 2.8 bird

and remember, the smaller the first overbore, the more overbores available down the road

Doward

Exactly... Don't overbore for the intention of lots more power.

I say .040 is max on any engine - .060, I'd recommend sonic testing the walls to be sure of their strength. I have seen Poncho blocks punched .090, before!

If you can, just hone the cylinders, and go with new rings...

AGood2.8

Here's a handy chart for y'all.

http://users.spec.net/home/emxjc/block.html#Boring

Gumby

10051141 Bow Tie Aluminum Block
This heavy-duty aluminum block is 47 pounds lighter than a production rear-wheel-drive cast iron block. It has extra-thick cylinder walls with dry nodular iron sleeves. The head bolt bosses are reinforced to improve head gasket sealing. This block has wider main bearing bulkheads than a production cylinder case; four-bolt caps are installed on the two intermediate main bearings. These billet steel main caps have splayed outer bolts that provide additional bearing support. The aluminum Bow Tie V6/60º block features a revised lubrication system. The "priority main feed" oiling is similar to a Chevrolet small-block V8, with three oil galleries above the camshaft; production V6/60º blocks have only two oil galleries. Oil is routed directly to the main bearings in a Bow Tie block to ensure proper lubrication at high rpm. The main bearing saddles are grooved to increase the flow of oil to the crankshaft journals through additional feed holes drilled in the upper bearing inserts. Block weight is 59 lbs.

Technical Notes: Aluminum Bow Tie V6/60º engine blocks have rough-bored 89mm (3.504") cylinders which can be safely overbored to 91mm (3.582"). Light alloy Bow Tie blocks have bosses for both front-wheel-drive and rear-wheel-drive engine mounts. The starter motor can be installed on either side of the block. The cylinder walls are non-siamesed, and the cylinder deck height is 8.820". Cylinder bore range is 3.525-3.582"; crankshaft journal diameter is 2.65"; all sump type is wet. This block has a 2- piece crankshaft seal and a design maximum stroke of 3.20". It is bossed for front or rear drive engine mounts. Intended for professional competition.

KED85

COMPLETE INTACT USED RUNNING 3.4 MILLS CAN BE HAD FOR AS LITTLE AS $210.
Why are you wasting your time when ya already know the answer.
Spend the time seeking the right solution.
All 2.8 blocks are good for is scrap metal.
Go find a 3.4 today!
Ebay, local yellow pages for wrecking yards.
Insurance companies, ask them for a good wrecking yard source for late model cars.
I paid $800 (44K miles) & $900 (50K miles) for mine, added a some gaskets had a 160 HP, 200 Foot Pound of Torque standard bore mill with zero break in problems.
Shortest time frame was only about one month of solid work on all details to make swap 100% proper.

GO FIND A 3.4 USED RUNNING LOWEST MILAGE YA CAN FIND & have fun cheaper & sooner than playing with that 2.8 paperweight.

This swap in pic in my ride?
Total cost was about $900.
I sold stuff had to buy stuff to reach that total.

Try doing that to a 2.8 & get same cost & HP results.

Project: 85 2.8 bird

FYI: that aluminum block is $3k

bes217

Why don't you just get your block sonic checked to know for sure how much you can bore it out.

Lee7

I will probably run my current 2.8 into the ground, when that breaks i will get a cheap 3.4 from the junkyard and rebuild the bottom end. Then use the top end that i am rebuilding now.

KED85

Two things
Spring pockets on 3.4 heads have MORE MEAT to handle the larger springs for higher charge for the RPMS
Second.
I DO BELIEVE
the compression from a 3.4 head will be larger than a 2.8/3.1
FOR SURE go BUY the MEASLY $6.95 GM Performance Parts Catalog.
It lists exactly the diff between the 2.8/3.1 & the 3.4
There is a world of diff all in the favor of obtaining a 3.4 used running mill for less moola to play with
than wasting the time on a the 2.8-3.1 set up.

82-T/A [Work]

Well, you have a few options, but it all depends on how much you want to spend, and what your intentions are.

If your looking to get a LOT more power, swap to a V8.

If you want to keep your car completely stock, then have the block rebuilt as it is.

If you want to keep your car original, as in.. the original block, but you want a lot more power, you can go with several stroker kits. ARI Racing sells a $500 dollar stroker kit to upgrade your motor to a 3.1 liter engine.

Personally, this is what I did to my 1987 Fiero V6. I wanted to keep the engine looking original, and I wanted it to be the matching engine block.. so I rebuilt my old block. Total cost for all the parts, and to have it machined and assembled.. probably close to about $1,700 bucks.

But keep in mind, I'm putting out about 180 horsepower and 220lbs of torque. Also, it looks factory original.. if you look at the motor, you CAN NOT tell the difference. I had the exhaust manifolds professionally bored out and re-enforced, they are basically like headers (just not equal length). The Y-pipe was jet-hot coated inside with all the restrictions removed. I have a high performance cat.. the factory exhaust piping (it's mandrel bent) and a Borla muffler with the factory exhaust tips.

Even the top of the engine is all original. Unless you take the throttle body air tube off.. you can't tell that the throttle body has been bored out. I've got an aftermarket accell ignition coil, and I painted it black. The only thing I didn't mess with were the fuel injectors. I purchased new 17lb injectors, but I decided not to paint them. So if you look really hard, you'll see the yellow injectors instead of black.


Anyway, that's one option. Or you could go out and buy a used 3.4 like Ked said.. however, then you're buying someone else's problem. You might get lucky, you might get a piece of crap. Either way, at least you'll have a 3.4 block at that point.

KED85

You notice ALL OPTIONS take effort & research for the best end result.
LOW MILAGE USED RUNNING 3.4 are leaving this earth at a very fast rate.
YES YOU COULD BE
buying a problem from another.
My two examples are stellar in lack of problems dept.
Lucky?
I had a good source to score me the best for my meager orginal funds.
BEST OPTION THESE DAYS IS A NEW 3.4 mill from GM at $1800.
Research before you even pick up a wrench.
REALIZE ALSO
Number matching in a Fiero is WAY MORE IMPORTANT THEN
number matching in an F body (the v6 examples).
BESIDES these days ya can't "even find the stamping VIN number" on a 60* mill, unlike the old days of GM (it's upfront on a V8).
EITHER WAY money is money
Hate to hear it wasted.
That's what I heard from a guy that rebuilt a 2.8 (I chatted with guy in person)
That conversation also lead me to the 3.4 higher power mill decision.
Can't argue with MORE cubic inches at a cheap price!

82-T/A [Work]

KED85, yeah.. I completely agree. For most people, a numbers matching block really isn't THAT important. For me, the V6 in the Fiero IS the big engine... it's like having a 350 TPI stock in the Camaro or Firebird (not in performance, but relatively speaking).

But personally, if I owned a 2.8 liter V6 Camaro or Firebird.. the first thing I'd do would be to buy a V8 and swap it in.

For those that want to keep the engine a V6, want as much power as they can get but don't feel like changing anything else... a 3.1 block or a 3.4 block is the way to go. And you're right... 3.4 blocks ARE becomming rare.. at least the ones that we use. The cast iron blocks were only used in.. what.. maybe 3 cars? The f-body and a handful of minivans.

Those are direct swaps for our cars (Fieros and 3rd gens).

The one thing people need to remember when swapping motors is... they have to also swap the fuel injectors. When you upgrade to a 3.1 V6, you need to get 15lb injectors (when upgrading from a 2.8 in a Camaro / Firebird). When going to a 3.4, you need to get 17lb injectors.