i was curious on which would be more good on gas,the 3.4 or the 2.8?

If i did the 3.4 lwerend witht he 2.8 top,would that mak a differance in gas use as well?

holy crap, a car that looks worse than mine j/k

I would think the 3.4 would, more power from roughly the same size motor. Also one of those screwy things like the 8cyl cars getting as good or better milage than our 6's

3.4 will burn more gas than a 2.8, all things being equal.

Our V8 cars of the same year get better gas mileage, because of the gearing. You want mileage? 20mpg out of a 4bbl 354 Pontiac Firebird. How? 2.41 rear gear. Cruised like 1700rpm.

Well Doward, you're partially right.

Out of the car, both fresh...the 2.8 WOULD have better fuel economy, however, the MPG difference IN car if he did a swap would be better with the 3.4. Why? 2 reasons. A: It's most likely a fresher block. It would have fresher seals, and would be more efficient in creating power. B: In these cars, because of the weight, there is a problem with the 2.8 being underpowered and "straining" to get the car moving. Once it's moving isn't that much of a deal unless you're cruising over 70 (15MPG in my V6 @ 85, 23MPG @ 94mph in my V8). You kinda of have to find a sweet spot where power, gearing, and weight all click just right in order to get the maximum MPG. But I'd bet money that after a 3.4 swap, he'd get better gas mileage.

One more thing. Put 2.73's in a V6 and see how the gas mileage is. I'd bet it's worse. My in town mileage with them on my V8 sucks. It's one of the reasons I'm switching to 3.42's. The 2.73s are just too low geared to get to speed easily.

The gas milage in my 1985 Firebird JUMPED SO HIGH AFTER THE 3.4 SWAP!
I got close to 30 MPG doing 85MPH the majority of the way with the car loaded with me wife & baby & baby stuff.
TORQUE BABY TORQUE
Only assemble a 3.4 bottom end to a 3.4 top end (heads).
Don't waste your time on the 2.8/3.1 heads.
Read the GM Performance Parts book (a measly $6.95 at any GM dealer) to see why the 3.4 heads are superior.

Thanx for the help guys

Would the intake stuff from the 2.8 bolt to the 3.4 stuff? And would i have tto swap out the computer and all that jazz too?

Personally right now im tryin to keep things as simple as i can til i get more familiar with the car(its my first F-Body and FI V6).

1. Read Karls tech article on 2.8-3.4 swap boogie.
2. Here are some pics of my 2.8-3.4 conversion My cardomain site, scroll down for engine shots
3. Decide which version or the swap you cando/afford to do:
a) Karls, follow Karls article
b) Use mine: keep long block & swap intakes & little things
c) Dale's swap,, everything including the 3.4 ecm & harness

hardest part may be fing\ding a reasonably priced 3.4

good luck

Ive read his article before
ive seen you pix,VERY nice,BTW Camaros are good for alot of other things as well

Id probably go witht he 3.4 lwerend and heads and use my intake and what not. But if i go that route with it can i keep my all my original electronics? I really dont want to mess with that stuff

Yes, it's all in Karl's article. Think of dropping a 3.4 in as dropping a 2.8 in. That should clear every question up. If you dropped a 2.8 in, you wouldn't change anything, right? Same deal with the 3.4.

Yeah, that's true - didn't take weight into consideration

Have any of you guys weighed your cars? I'm 2950 without me, and 1/2 tank of gas. My 2.8 seems to putter along nicely. Honestly, if I had a 3.4 in mine, I'd want 3.23's for best mileage, instead of my 3.42s.

Torque is good. 320 ft/lbs @ 1800rpm is why my Firebird with the 354 Pontiac and 2.41 rear end got 20mpg with a 4bbl Qjet.

V6=3600 w/ me.

V8 Vert-3760 w/ me.

It's really a very simple very detailed mix of parts to do the 2.8-3.4 Long Block Swap Boogie!
In the end, you use your current induction/ignition/pulley/ecm-sensors-computer system & place all that onto the 3.4 LONG BLOCK.
Retain from the 3.4 the INJECTORS, Exhaust Manifolds, Balancer & Flywheel. Insert 3.4 injectors INTO the original 2.8 fuel rail on the old 2.8 MPFI set up.
Reassemble to make the stuff look like you started with the original day one engine.
In the end, it is a very boring looking swap.
Until ya mash the go pedal.
My Firebird pulls like a freight train.
I love torque.
I didn't build the car for speed.
Only as a way to keep using the good body with a cheap engine alternative (I blew my engine-lower hose came off-opps!).
AND I had to be sure I passed CA Smog testing.
All the extras were only perks.
I really enjoy this Firebird, alot.
I've ended up with a very well balanced ride for pretty cheap.