I have a 1991 firebird. It's got a 3.1 with a 5 speen transmission. I was wondering, is there alot i can do with this motor to get good sound, speed and gas mileage? Or should I try to swap out for a 305. I have been lookin for a 305 H.O that is fuel injected and would bolt into my car. Would that bolt to my trans as well? (920)493-8495 TEXT or CALL!

 

wont bolt to the car or the trans for that matter, there is a lot of wiring involved as well as moving the motor mounts on the k-member. You need the v8 t5. If you are going through all that hassle, might as well just swap in a ls1. Its a v8, makes a heck of a lot more power than a 305, is lighter and gets much better fuel milage than you get now with the v6. the 305 wont increase milage over the 3.1.

 

If you have a good, running, 3.1, leave it alone. They make decent power and there is an aftermarket for them. Very relieable too, all of the weaknesses on the early 2.8's had been worked out by the time they stroked it to 3.1L.

 

I sure wouldn't put a 305 in it. I know some people will not like me saying this, but, you'd be down grading in my opinion. Heavy motor and slightly more power. I have out run a bunch on 305s with my v6. Now, a 350 or an LS motor is another matter.

 

I tend to agree, the 305 is not that great, if you go v8, get a 350, otherwise your v6 will make at least as much power as a stock 305, if you put some money into it, you can also always do the 3.4 block swap.

 

Ok thanks guys, i will definately look into these ideas especially the LS1 idea if you have info on what i would have to all change to put that in that would be great too.

 

New engine, trans, rear end (if you want to connect), whole wiring harness, relocate motor mounts, radiatior/fan... probably more.
IMO, of you want a V8, why not buy one and save yourslef alot of grief. Sell the V6 car to someone who can enjoy it without chopping it up. Buying a TPI to start with will end up being alot cheaper than doing a swap.

 

If i decide to stick to the 3.1 what can i do to it to tune itu up and get some more quality form it? it's got 120,000 miles and I have never rubulit anything though i would like to. If I could fix this up and get a little more power from it and save some green i would love it. Anymore advise?

 

There's lots of threads about increasing the output of a V6, so a search and you'll find a lot.
Some basic bolt that are available for the 3.1 are headers, exhaust, UDP, K&N filter, etc. If you're gonna be rebuilding and getting more advanced then there's cams, 1.6 roller rockers, head porting or a 3X00 top end swap. There's really no shortage of things you can do to these engines.

 

.... lmao at some of these 305 comments.

 

It's not that they can't be fast, mod for mod they will easily beat a v6 yes, the problem with the 305 is GM didn't intend it to be a performance motor, they built the 350 with that, and the thing with 305 vs 350, is the 350 doesn't weigh that much more but has gobs more stock power and potential. Mod for mod, stock for stock, yes the 305 is better than a v6, but the fact is the 350 is much easier to find parts and upgrades for and has more potential. So if you don't already have a v8 you might as well go straight for a 350, for all the trouble it is to put one in.

 

What it all boils down to is just how fast you wanna go, and just how far you'll take it to get you there. In a naturally aspirated situation, then the right bore and stroke (not necessarily cubic inch displacement) is of course always the way to go, not to mention overall vehicle weight. In power adder applications, it becomes an entirely different story. I used the 305 in my sig to mock up a turbo setup for a 355 I have sitting in the garage, waiting, for when the turbo 305 eventually blows a head gasket. Do you wanna know how long it's been waiting to go in lol? The 305 runs consistent, and it takes me right where I want to be w/out a rollbar, and I would never consider it a downgrade from a 3.1....

 

can i get some more info on this turbo 305?

 

The reason I called it a down grade is because it takes a minimal amount of work on the 3.1 (from stock) to out run a 305 that is stock. The way my motor was built, I put a hurtin on many 305s!! I was at the 1/8 mile strip one night a few years ago and got to talking to a guy who had a 3rd gen with a 305 in it. He was goin on and on about how he bought it so he could bring it to the track and let his 13 year old get some seat time cause it didn't have as much power as a 350,... Anyway, he knew my car had a v6 in it, once we ran...he didn't talk to me at all after that. I don't think he liked gettin beat by the v6!
Too, if you want to build the car to handle, I'd build the v6 for it long before I'd build an iron SBC! An LSx might be a little different story but, the v6 is still going to have better weight distribution front to rear. So, from those stand points, I consider a 305 swap a down grade.

 

Honestly, if you are going to put in a 305, youre better off dropping a TPI 350,LT1,or LSx engine. The 3.1 engine can be made to run real well and it is true that a 3.1 that is lightly modded can smoke a stock 305. All told, what i would do in your situation is either stick with the 3.1 or drop in an LTx\LSx engine. Even a TPI350 is better than a 305 lol

 

TTT

Okay, so there is a huge range of possibilities. What is your goal and your budget? I did my V6 build (2.8 stroker) coupled to a 5-speed. I'm still learning the tuning aspect but could probably put a serious hurt on a 305. I'm not downgrading 305's either as my GTA runs a 305/5-speed.

But as others have said, if you want the V8 route, 2 points: 1) buy a V-8 car (the change over from a V6 is work!!!!) and 2) go for the 350 vs the 305. The 305 can be made to perform, but the money goes further and the end result much faster with the 350.