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Discussion Starter #1
if this is in the wrong spot please tell me. i am going to be restoring this car and am studying ways to get more power. theres not much in the way of mods for the 4.5l. i thought about a 4.9l swap but i dont think that will give me the power i want. how difficult would it be to swap in the engine and trans from say, an impala ss or other front wheel drive car? as far as bolt patterns go what would i run into there? please dont tell me to buy a sports car or seek more power elsewhere. i want to make this car fast because you dont see it much, if at all. what options do i have for swaps? compatible engines and trans axles? would love to swap in a ls engine, or lt1. possible? i know the weakest link would be the trans, so is there another trans that will bolt in, or is it possible to beef this one up?
thanks in advance.
John
 

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'99 Eldorado 77,000 miles
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291 Posts
Which Impala SS are you referring to? The new V8? or the 3.8L V6 Supercharged? I'd say go with the new N* and figure out a way to fit the thing on the car haha!
 

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1998 Seville STS / 2013 Chevrolet Impala
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1,889 Posts
The 4.X series are VERY mod-able, just about anything you can do to a SBC you can do to a 4.x.

Of course, unlike the SBC, everyone and their uncles don't make parts for a 4.x, so most of the work will be custom jobs.

If you're up to the task, you will have yourself a very challenging, yet fun experience. If you're not, getting a new LSx in there would be as easy as jacking up your old antenna and running a new car under it. :D
 

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1994 Cadillac Eldorado Touring Coupe
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821 Posts
Definitely won't be putting an Impala engine in there (2000+), unless you are bringing along someone from GM's electrical team.
You're in for the biggest pain in the ass imaginable. Good luck.

(Buy a new car if you want speed! FWD is not the greatest drive layout for high HP output anyway!)
 

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Discussion Starter #5
wiring is not a big deal, thats what i know the best. i am swapping a 6.0l vortec lq4/4l80e into a 66 chevy pickup and i did all the wiring myself. my problem is fabrication, i can do minor stuff but major fabrication is not my area of expertise. thats why i was wondering what would bolt up with minor metal work, cause i can do the rest. if anybody can tell me what would be closest to fitting with the smallest amount of fabrication i would be grateful. im not going for high horsepower, just something in the area of 300-350hp. what i would really like to do is build a custom chassy and integrate a trans tunnel into the floor and make it rwd, but appear stock, or as close to stock as possible. but i dont see that in my budget. lol
thanks,
John
 

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Discussion Starter #6
my car being a 90 model with pfi, is the tranny a 4t60 or is it the 4t60-e electronically controlled tranny? could i swap in a 4.9l and just swap my intake and accessories from the 4.5 and use my stock computer? . my current tranny is slipping and ive changed the filter and fluid, modulator valve, and ran some lucas and it hasent helped so i need a new trans. the engine has a furious oil pan leak that needs fixed but from what ive read its gonna be a pain in the a$$. being the car has 170,000 miles i would like to just build a 4.9l and find another trans and just swap them instead of messing with the current drive train.
thanks,
John
 

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90 Eldo -SOLD-, 98 ETC -SOLD-, 86 XR4Ti Track Car, 07 Ranger
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963 Posts
Dude, forget a swap, tear your engine down, port the heads and get oversized valves, look into a custom ground cam, get forged rods and pistons, better headgaskets, slap a turbo on there with an intercooler and install any of the many piggybacks for OBD-I engine management and leave the trans controller alone, for simplicity, or go MegaSquirt and get a manual shift controller for your trans, also look into getting an 4T60E or HD trans (have no idea if this is even possible) or upgradethe 4T60 with a limited slip and a higher stall torque converter.
 

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Discussion Starter #10
well i fixed a few problems. i bought a few feet or rubber hose and replaced every rubber vacuum hose i could find. put a new air filter and pvc calve, and changed the oil. its running alot better. next up is the trans filter and fluid. still would like to swap to a 4.9l and a 4t60e or maybe 4t80e. i was hoping someone had done something similar or maybe had some pointers but i guess ill just have to compare the trans mounts side by side somehow. could someone tell me how a 4.9l would run with the pfi intake, stock computer, and all accessories from my 4.5l bolted on it?
thanks,
John
 

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02 Eldorado ESC, true 2.5" duals, 18X10's & 275/40ZR18's, 14" rotors, C5 Vette brakes
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254 Posts
If you check in yahoo groups, there is one called Cadero Owners; it is for Fiero Owners who have put the 4.5 or 4.9 into their Fieros. They may have some valuable swap info and modification information on file since that engine is their specialty.

If you do a 4.9 swap into a 90, please let me know how it all works out. That is what I was thinking about doing with a 90 Touring Coupe that I almost bought. If one comes available again cheap enough, I may consider it again. If it wasn’t for the Body Control Computer (and my bad experiences with them & the related electronics in my wife’s 91 Toro, I’d hold out for a 91 Touring Coupe. But I think a 90 with a 91’s engine is a possible way of avoiding those headaches.

For handling, consider swapping in Toronado Trofeo springs/struts or (if they will fit) Grand Prix struts & springs from a sportier model. There should be a 12” disc brake upgrade available from a late Grand Prix as well.
 
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