I got a 91 bretta this weekend and before i got this car i was planning on rebuiling my 2.8 into a 3.1. So my question is what can i use from this 3.1 FWD car in my 2.8. ( crank, pistions, heads, injectors, PCM or ECM, etc....). If i put this post in the wrong area, would a mod please move. Thanks

-William

 

is it a 3100 or 3400 series engine? or is it just a normal MPFI? (iron head)

If its just an iron head 3.1, all you could really use to help performance is the crankshaft. If you use a 3.1 crankshaft in your 2.8 with the 2.8 pistons, you will have a compression ratio of about 9.7:1, this compression ratio is alot better than the stock compression of the 3.1 or 2.8 engines, and would give you a decent boost in HP, along with whatever horsepower gains the crankshaft gives you, but you will probably have to use midgrade gas.

If you have an aluminum head engine in your 3.1, you would also need the 3.1 pistons as they have a smaller combustion chamber and would give you an ungodly amount of compression if used with iron head pistons.

EDIT: if forgot to mention that if the engine in your berreta is a 3100 or 3400, there is ALOT of work that must be done if you want to swap the parts to the 2.8 block, it would be much easier just to use the whole engine from the Berreta

For more information i would head on over to http://discussions.gmforums.com/foru...s=&forumid=263 , they know alot more about this subject than these forums.

 

You might mention the fact the wrist pin offset will send the piston right into the head. You need to take the 3.1 pistons, rods, and crankshaft, and put them in your 2.8.

I would recommend having the crank turned, and new rod/main bearings put in at that time, so that you won't have to worry about spinning a bearing later.

 

oh yeah. You would have to get the wrist pin relocated and bushed at a machine shop, but it would not be that expensive. But then again that would lower the CR, but i still think it would be higher than the stock 3.1 CR. I was not thinking everything out in my head.

IF i was going to use the 3.1 pistons, connecting rods and crank in a 2.8, i would not even do it. The extra stroke wont even help much at all. I would at least try to raise my CR somewhere near 10:1, its not worth it if you leave it at a low *** compression ratio of 9:1, because you will never make any power that way unless you run a power adder. The benefit of turning your 2.8 into a 3.1 would be minimal if you were only using stock parts.

 

i know this is kinda off topic but can you actually drop a engine from a front wheel drive car into a rear wheel drive car,
arent the angles different

 

No you cant put a tranverse motor in a RWD car but you can use the internals from the motor. I have a question:

What rasies the C/R? Is it the heads or the pistons? And how does it do it? Also how does the cam being taller help? More gas in more exhaust out or what?

-William

 

c/r can be caused by alot of things. Style piston, style head, stroke of crank, milling the head.

cam being taller yes, allows more air in and out, HOWEVER, just because its taller doesnt mean its better. You need to pick a cam per your application/use, injection/air system, and drivetrain.

I belive that the 3.1 cam from the beretta will swap fine into your 2.8. You will need to bring the pistons over also. Also, someone stated asking if it was the aluminum 3.1. If it is, I again belive that the aluminum fwd heads do make more compression.

 

I'd triple check everything before trying to put a FWD into a RWD... the intake is totally different, and you need to be sure of the mounts, and the starter, locations.

You can't change the wrist pin of the piston... you'd have to re-drill the hole, weld up the hole that was already there, then re-balance everything. You'd evd up with a custom piston, that's been hacked together - just get some forged customs for that price.

The stock 3.1 has an 8.5:1 cr.

CR is determined by volume at BDC / volume at TDC of the piston, IIRC.

You can - use pop-up style pistons to increase compression ratio... or, easy way is to mill about .050" off the head, then recheck your valvetrain geometry (shorten the pushrods a like amount, then check the angle... might need to 'hog out' the pushrod holes in the head)

To say it wouldn't be worth swapping out the 2.8 internals to the 3.1 is You've already got the parts - and for a little work, you can have 10 extra hp, and 20lbs/ft of torque. I firmly plan to get a 3.1's internals, for the lower compression, for the turbo setup. 8.5:1 cr + 15psi on a 3.1 = fun!

 

Sure you can, WHO says you can't put a transverse motor in a rear wheel / longitudinaly driven car? (Lets make sure we say longitudinal, and not just RWD, cause there are about 6-7 cars I can think of off hand that are Transverse, but rear wheel drive).

The ONLY thing that's different, from say.. lets take an early 90s.. 1991 Oldsmobile Sillouhette Minivan. It has a 3.1 liter V6/60. All cast iron head block. You can take that motor, and DIRECTLY swap it into your 2.8 Camaro. The ONLY thing that's different, is the bolt hole location for the starter, and the motor mounts. So you get the bolt holes for the starter drilled and tapped at a machine shop, and you just use the motor mounts from your old motor. (or buy new ones, which you should do anyway).

The Fiero is transverse, and one of the most common swaps is to take a 3.4 V6/60 from a 4th generation Camaro / Firebird, and drop it RIGHT into the back of a Fiero. Everything bolts up.


Just an FYI. But yes, as everyone else has said, if you want to use the 3.1 block and heads, you can. Just make sure it has the same intake, otherwise the only thing you can use are the crank and the rods.

As much as I'd like to say you could use the pistons, you actually really can't. The pistons will hit the cyl head (they're too tall with the 3.1 rods).

The standard set of hyperuetectic pistons for the 3.1 conversion will bring your compression down from 8.9:1 to 8.5:1.

However, you can have a custom set made that will give you whatever compression you desire.

 

Let's take a different approach to the "problem" at hand......

The '91 Beretta 3.1 is a genII MPFI, aluminium head design, and yes, most or all of it can be used.

I did something VERY similar with my swap, here's the skinny:

I started with a S-10 2.8L block, for limited down time on swapping the engine in, (and pretty easy to come by) I didn't want to have to make a left side engine mount as it was going in, I knew I'd have other things that were going to need to be addressed at that time.
Because I used an S-10 block, it has no provisions for the crank trigger sensor, my grandfather and I designed a front mount crank trigger, that mounted behind the crank pulley, this also lets me adjust base timing, much like a distributer based ignition system. This could be costly, depending on if you can make one yourself or know someone that can make one.
I used a FWD 3.1 crankshaft from a '92 Cutlass, this was a drop in for my '86 block.
Pistons are stock replacment aftermarket Federal Mogul hypereutectic .030" over.
Rods are original to the 2.8 block that I am using.
For heads I decided to use a set of '95 3100 heads, these are genIII design and differ slightly from the genII heads, they have better flowing D shaped exhaust ports and redesigned intake ports.
Intake is also 3100 from same year, so that the intake ports match.
On to valve train:
Cam shaft is a GM Performance equivilant to the Crane 260-2, lifters came with the cam.
pushrods are gen2 3.1 MPFI pushrods, as they were the right length for my combination, being a flat tappet hydraulic cam, and the splayed valves.
I used stamped steel rockers, I actually swapped to genII rockers as I had a set, and looked a little beefier than the genIII stamped rockers, I also used the iron head adjustable rocker studs.
Exhaust is custom, as the aluminim heads differ slightly from the iron head, the genII retains the O-shaped ports but the bolt pattern was widened by about 1/4" or so, making it difficult to use the iron head manifolds, plus mine as previously mentioned actually has D-shaped ports, and then I also added a turbo, so custom was the best/easiest route for me.
The bolt pattern in the end of the heads is just enough different that an adaptor braket needs to made to retain your existing belt driven accessories, this is also where the crank pulley mounted crank trigger helped, as I had to space everything out anyway.
I retained the S-10 timing chain cover and water pump, but used a newer '87 serpintine type, I wanted to completly update under the hood.
The genII and genIII intake designs do not allow easy retention of the distributer, the lower intake #6 runner (engine, not intake, on the intake it is marked as #1, this is due to the intake being turned around 180* ), so because of the interferance, I swapped the DIS ignition in, and it works well.
I also used an ECM and highly modified wire harness from an '88 Cavalier, that supports the use of the DIS ignition and MPFI.

I'm sure there are some small details that I am leaving out, if you have any questions let me know.

For some pics go here:
Look under "hybrid pics" and "engine swap"

 

Oh BTW the FWD 3.1 uses a static compression ratio of 8.9:1, when used with the .060" thick aluminium head gaskets.

The 2.8 and 3.1 rods, regardless of being from a longituduly mounted or transverse mounted are the same 5.7" long length, the pin hight is changed in the pistons to accomidate the longer stroke.