Make 1991 Caprice Wagon faster

I have a 1991 Caprice Wagon with a weak 305ci TBI V8 (my friend's 1995 escort is faster). I have two questions I guess.

1. How much would it cost me to upgrade to a 350ci TBI V8 and how much performance would I get out of it?

2. If I were to upgrade the TBI to a multiport injection like the LT1, how much would that cost and would it increse performance more than installing a 350 TBI?


My old car was a 1992 Grand Marquis and I'd like to get my Caprice to outrun that car with a $1,000 budget.

forget the LT1 swap for 1k. the electronics alone will drive you insane. I have a 1991 caprice sedan 305. here is what i suggest:

1: cut a hole in the passenger side of your airbox and rig up a second cold air tube: my unique "L03 H.O. dual snorkel"

i also have K&N and a 160 degree stat

these small mods i felt gave it better pull

however, the mod im most pleased with is this one:

http://www.holley.com/HiOctn/ProdLine/Products/NOS/NOSNS/GM1.html

right now im running a 135hp boost
my numbers now are about 300hp and 400 ft lbs w/o the intake/stat mods i listed above.

i had a little trouble with the electronics when installing it, but i got a shop to finish what i had done in about 2 hours saving me a lot of money (i did 90% of the work myself)

the kit was $560 and the labor was <%200 bottle refils are about 40-50 dollars and are good for 8-10 quarter runs. right now i would guess it's in the high 14's but only one way to tell... also you have a wagon which is about 500lbs heavier than the sedan.

You could cam it up, port the heads, edelbrock intake, and swap to a carb if you don't have emissions where you live. A mild cam like one or two small steps up from stock would still let you run stock heads and valves with new springs. I can't estimate how much power you'll get, but it will be a very nice bump. You'll really be able to feel it. Use a performer intake and a 500 cfm edelbrock 4-barrel and I'll bet you will even pick up a couple MPGs. That budget will probably be over $1000 but not much.

You could buy and install a 350 with your stock (reworked) TBI, but without a core you might be looking at more than $1500.

An LT1 can be bought for not much money, but unless you're installing it yourself, forget about it for a grand.

Try some more mechanical things. Instead of getting more engine, take a look at your chassis options. Even the "tow package" wagons had 2.73 rears. Find a 3.73, I guarantee you won't be disappointed. It sounds like a big difference and it is, but we Impala SS guys often run 4.10s and that's not too much. At least 3.42s, but no less. Your car has a 4L60 in it (or some prefer calling it a 700r4). It has the widest ratio spreads of any tranny, so whatever you do, don't kill torque. If you cam it up too far, you'll not be happy. Swap to a 2300-2400 stall converter and make your shifts a little firmer. A gear swap and tranny doctoring will make a world of difference in that car. If your car has 2.73 rear, right now adding power to the engine may actually hurt performance and streetability. Its all about a matched set and chevy made that one at the extreme edge of what I would call "matched."

If you want, post all of your RPO codes that start with "G", "M", and "F" and I'll tell you what tranny, rear, and suspension options you have so we have a good base from which to start.

Also, I don't wish to be contrary, but I advise strongly against the 160 stat in this engine. Its a common modification for LT1s but that is because they are reverse cooling. In standard flow cooling, the stat opens when the engine water reaches a certain temp like 190. It sends 190 degree water to the radiator to be cooled off and returns as cool water. In a reverse cooling engine like an LT1, a 190 stat opens up at 190 and sends water to the engine, not the radiator. That means that it starts as 190 degrees and gets hotter. It goes to the radiator and comes back as 190 degrees. Switching to a 160 stat keeps "normal" operating temps in an LT1. Using a 160 stat in a standard cooling system doesn't let the engine get hot enough and oil won't be able to burn off the acids, waters, and contaminants that it needs to and oil condition will suffer dramatically. Plugs will foul faster, heaters won't work as well, fuel mileage will drop, and catalytic convertors can clog. Cylinder washing/scoring and bearing failure have been extreme and rare results and performance won't be helped in TBIs. In fact, the PCM compensates for the cold temperature by richening the mixture. Closed loop operation is already richer than optimal, so power will drop. In LT1s, power increases because they use a Knock sensor. The cooler heads allow for more ignition lead. Many drivers switched to a 160 because their car overheated. This is not an overheat cure. It just postpones it. Heat increase in the coolant is caused when the heat being added to the water is greater than the cooling system can remove. Even if you take the thermostat out, it won't cure over heating. Something else is wrong if your car is overheating.

That's all... off my soapbox now :sunglasse

I do live in an area with emission standards (chicago) so I guess a carb would be out of the question. Where can I get my RPO codes? I don't have a full jack here (I'm a college student) so I can't get under my car. I dont know a whole lot about things like that. I know enough to do basic stuff like a brake job, changing plugs, filters, etc. My dad is a mechanic by profession so he would help me do all the work. Would you reccomend changing the rear-end and modding the trans or swap the 305 for a 350 to gain power? I use the car as an everyday driver so I can't install nitrous or anything like that. What I'm really looking for is more passing power and better acceleration. I'm not overly concerned with mileage otherwise i wouldn't have bought a V8 car.

I'm not well-versed in Chicago's smog laws, but if they comply with Federal or CARB rules you can do a few things. You can swap out for a 350 without issues IF that was an option in that car. For instance, you could remove a four cylinder in a Mustang and replace it with a 5.0 and still be fine as long as all of the emissions equipment for that year or newer is intact. Your other legally easy choice is to select an engine from a newer car and keep all of its emissions intact. A good example of that would be the LT1 swap. The important thing is to get all of the emissions equipment from the donor car. Swapping from the same year will most likely be the easiest since there is a great chance that all of the emissions equipment is identical. You would only have to replace the engine itself. The limitation there is you would be limited to what that year had to offer unless you want to modify it with a cam/head/intake package like I talked about before. Then you are getting into possibly some parts that won't pass emissions.

The benefit to a late-model engine swap (like an LT1) is that you can get 300-hp easily and legally with a stock engine, but you have to retrofit all of the emissions stuff including the computer and seemingly 6 million wires. Its not easy, but can be done. The other drawback (which isn't too big of a deal) is getting a new emissions clearance. I'm already getting long-winded on this, but this website will explain it better. The example they use is an S-10 V8 swap in CA, but it is pretty applicable most places. http://www.tdl.com/~jags/Pages/Chevrolet_S-10_V-8_Smog.html .

The RPO codes (which stands for Regular Production Option) are on a sticker in one of a few places. Sometimes they are in the glove box, on the spare tire cover, on the inside of the trunk lid, or on tailgate. They will be three-digit codes. You've probably heard of a few of them but didn't know they were RPOs. For instance the F41 suspension, Z28, Z71, and ZR4 option packages, and one you already know, LT1. codes that start with G are rear axle related. M codes are transmissions (like the muncie "M20") and F are suspensions.

i would suggest selling it and getting a sedan unless you want your groceries really fast. ha ha just kidding. i agree with akbar347

Thanks for all of your advice guys. I guess fate just kinda made my decision for me as my trans is starting to slip so I gotta replace or rebuild it. It has 111k on it so I think its earned a retirement. I think I am just going to install a new trans and rear end. Any specific transmission/rear end combo you guys would reccomend?

P.S. I need to show up little foreign four-bangers faster, not get groceries