OK so I got a bone stock 1991 Trans Am convertible right now with 99,000 miles. 305 Tuned Port engine, 700r4 transmission. 0-60 in 8 seconds really isn't doing it for me.
I don't have the money or resources for any sort of engine swap, and considering that my car is a bit rarer than others, I'd like to keep the factory "flavor."
Here's what I wanna do:

*Swap out the stock 2.73 with a 3.42 or 3.27 (which would YOU recommend? the car is gonna be a driver in the warm months btw)
*full exhaust, headers to muffler.
*bypass smog pump and gut the cat (car is due for emissions in 2 years so I'll worry about it then) (https://www.thirdgen.org/serpentine)
*most or all of the TPI mods in the technical articles section. (https://www.thirdgen.org/tpimod1)
*cold air intake (http://87tagta.tripod.com/coldair.htm)
*shift kit in the 700r4, probably a TransGo unit.
*some aftermarket TPI intake or runners (good idea for 305?)
*ECU performance programming (is it worth it?)
*maybe a bigger cam (any good ones for the 305?)
*and maybe, MAYBE a supercharger or turbo later on if money allows it.

Now what kind of improvements in 0-60 and the 1/4 mile should I see if I do everything except the last two? What about including the last two?

And here's a couple videos of my car...
stock 0-60 run:
http://www.youtube.com/watch?v=Ww-MhE6Lu5I
and just a walk around:
http://www.youtube.com/watch?v=F_p7rvYcg7k

 

I'll be honest with you, aside from the gear change, exhaust, and the last two on the list, you're not talking about anything that's going to make much difference. The shift kit is a good idea but it's not going to shave a bunch of time off a 1/4 mile pass.

The smog pump doesn't really cost you anything. It's a couple pounds of weight, that's about it. The TPI mods in the article, are all the little tricks and tips that have been around forever. No one has ever shaved a second with those mods. The cold air intake in that article is no better then just removing the air filter canister and running the filter element open. Aftermarket intake and runners are worth something, but they're expensive for the gains. Tuning would help, but again it'd do the most after mods, and if you're talking about something like a Hypertech or JET chip, it's a waste. A custom chip would probably help a little.

I think if you did all of that minus the cam and a power adder you might shave second in the 1/4. But just doing the gears, exhaust, and maybe some intake work and some of the free mods I think you'd get the same results.

The thing about most of the easy/free mods is they don't really do anything. After opening up the air intake, and uncorking the exhaust, you'll be best served by thinking about heads, cam, and intake. At that point, the 305 is only going to carry you so far. There isn't much better heads and intake for a 305 then what you have already. You might see small gains, but nothing like you'd see on a 350. Just swapping from the 305 to a 350, changing over to stock 350 parts would be a much more obvious improvement, and it'd have more potential.

 

Wow I'm kinda disappointed if that's true. I know that removing the smog pump would shave only a little weight but wouldn't the reduced drag on the serpentine belt pay off?
How do you think those mods I listed would help 0-60 times? Considering you said they'd help the 1/4 by a second I'm assuming that would cut 1/2 a second off of my 0-60, which for that money isn't impressive. Can we get any more opinions in here?

How much do you think a 350 swap with a used (but healthy) engine might cost? I was always thinking about it but I was afraid to spoil the factory "originalness" in my car.

 

there are some engines for sale in the classifieds for around 3000 and they are said to run mid to low 11's and make close to 500 hp. if you want power thats going to be the cheapest way

 

3 grand?! I'm not looking for a 500 horse engine. I just want a car that is more respectable is all. I'd be fine with a stock 350 engine out of a thirdgen or something. High 200 hp to low 300 hp is fine for me.

 

Don't gut the cat Do it right and buy an after market Hi-flo. Then sell the old cat to the local scrap yard and get some of your money back. A good cam if you stay 305 would be an LT1 cam. All the other B.S of by-passing, Shaving, and removing is pretty much a waste of time and effort. I'd go with 3:42's. Infact I did...... I like them fine. I also bought a junk car that happend to be a G92 car so I swapped out the duel cat y-pipe. I noticed a differance in the way the car rev'ed but it seemed to have no effect on my time slip(However I do have a bad injector and that could explain the lack of gains) I have done several of the "Free Mod's" and felt(and if you cant feel it.....it might as well not be there) no differance. Gears,exhaust and cam are your best bet.....unless you want to drive to Va and pick up this 350 I wanna get rid of.......... Oh! Also look around and try to find a good used intake

 

OK you made me feel a little better haha. Yeah I totally forgot about the dual cats some of the thirdgens had. Yeah I'd like to get that. What kind of diameter exhaust tubing would you guys recommend? And since you recommend a hi-flow cat, I might as well put in an emissions-compliant one. Do they ever give problems with smog testing?

And according to this video, the stock 0-60 of a Trans Am convertible with the 5 speed is 7.8 seconds and 1/4 mile is 16.2 @ 86 mph. I guess an automatic car like mine would hit those in a couple tenths more (am I right?).
http://www.youtube.com/watch?v=E6Z63CyMCrU

If this makes sense (I don't know too much about speed numbers yet), I'd be happy with a car that hits 60 in the mid to low 6s and the 1/4 in the 14s. Possible with a 305?

 

^
www.ProCharger.com

 

With what you are looking at running as far as mods you can get a great sound and performance from headers to a Y into a single 3" pipe with a single or dual dumps.

 

Oh ok, I was thinking of possible a true dual. Is it worth it or is a 3" single recommended? But regardless I'd like two exhaust tips. And what would I see with a cam upgrade? What kind is recommended for my engine?

 

An Lt 1 cam is not much bigger than an L98 / lb9 cam from 1990 - 1992. Replacing the stock cam with one will not gain you more than just a few horses.

 

I've always heard that the best bang for your buck is to have a cam custom made based on your setup. Spend some time looking at the exhaust threads - there is some great info in there explaining the ups & downs with single vs. dual pipes...

 

There are cams from comp cams and and other manufacturers like crane, that work pretty well with stock intake and head setups. For everyday performance picking up a good aftermarket cam that is well matched to the rest of the motor is well worth it. Custom grinds would probably be more suitable for higher power goals, where there have been substantial upgrades to head ports, intakes, exhaust, perhaps power adder and such, and the aftermarket doesn't offer precisely what one needs.

 

Yeah I was thinking of maybe getting a set of better heads if I can find em at a good price. I heard good things about the Vortecs... any thoughts?
That plus the exhaust, cam, and make aftermarket intake. What kind of combos do you guys run/recommend?

 

I agree that it would be an improvement over stock - no doubt about that!

 

Oh and I forgot to mention that I'd definitely like stuff that can be swapped over to a 350 later on assuming I ever get one, so I'm not wasting too much money lol.

 

$3000 for an engine swap is laughable. Check around with your local machine shops and see if you can find a rebuilt roller cam 350 block with flat top pistons. Find a good used set of L98 heads, and you should be able to get a long block that will bolt right in place of your 305. You'd have to change the injectors, knock sensor, and computer chip to get the most out of it. I think if you bargain hunt a little you could probably get it done for under $1500. It'll have a ton more potential then a 305 and it'll still LOOK stock. If you're worried about the value of the car in 20 years, the free mods will hurt it more then upgrading the engine. You can always throw some dessicant packs in the lifter valley, wrap your old engine in saran-wrap, and tuck it in the corner on an engine stand for a rainy day. But I'd be willing to bet the car would be worth as much or more with a clean 350 swap then it'd be with with the stock 305.

Do a 350 with a mild cam, and upgrade the exhaust. You'll have less invested and it'll make an obvious difference that you WILL notice.

 

I swapped in a 350 b/c they have MORE potential. You can make a 305 pretty nasty too though(Costs a little bit more) but hey you'd be one of the very few nasty 305's out there. I've seen plenty of 500+hp 305's. My first 350 swap cost me $200 for a motor with 60k on it and some misc parts. Very cheap, but i got lucky. If your worried about value keep your 305 in the corner with the original parts don't mess with it and change stuff. Look at the old vettes/Camaros for example, gorgeous resto mods are nice but don't get half as much at auction as say an old whooped looking car with ORIGINAL PARTS... keep that in mind. Another problem is that you need to choose one or the other, 305 or 350.. most parts do interchange BUT a "big" cam for the 305 will be a milder cam for the 350.... Its all about what you want...

 

You said it!

 

That i WILL agree with. The 350 is quite a difference right off the bat. Then if you open that thing up its like a whole different world.

 

Well I am in a similar in spot but is a mine is an 88 firebird t-top not a vert. I have already decided that besides I am leaving the engine alone besides the exhaust because I am gonna save for a 350 crate motor. I was thinking about maybe buying a setting of gears to help performance while I save up the money. I was thinking maybe between 3.11 and 3.53 for gears since I do drive the car on a regular basis. Besides the exhaust I do have new tires and rims on the way. If somebody could let me know if I should go for gears or wait util after I get the motor.

Thanks in advance,
Seth

 

.311? .353? You mean 3.11's or 3.53's?

 

yah my bad hit the button at the wrong spot, didnt notice

 

My fellow CT third genner. PM me if you need some help or have a few questions. I cammed and built my old 305 TPI and have a ton of experienece with these cars as well as lots of parts lying around. When my 305 was stock, I did 0-60 in about 8-9 seconds. I put on edelbrock shorties with no cat and a flowmaster exhaust and it went to about 6.5 seconds. Big improvement because I found out my original cat was melted and blocking half the exhaust!!

Anyways, I can help ya out if you want to do a few things. Being a convert, I can see why you'd want to keep it original looking. I have a custom made 3" cat delete pipe that has the correct flanges on it and should bolt right in with no modifications to exhaust if your interested. Anyways, talk to you later.

 

Thanks man! I sent you a PM btw.

 

their is a guy here that has a complete l98 350 swap for 450 bucks just needs rings and bearings and reassembled how that for shaving 3k down to under 1500