First_Formula

Hey everybody, I've decided against keeping the 305 in my car as its a bit of a dog and I've been told the 5.3 is a much quicker engine that gets better gas mileage. Anybody who has a 5.3 I wanted to ask what kind of MPG you guys are seeing out of curiosity.
I'm going to go as stock as I can for the truck engine. No heads cams I just wanted a little more go and I hear these get better MPG too so Bonus!
Anyway i'm making the parts list as i'm a firm believer that preparation is always a good thing and i wanted to run it by you guys and see if anythings missing or incorrect as this will indeed be my first engine swap so sorry if i've got alot of questions but here we go.

1. 5.3 litre lm7 engine
2. wiring harness from same engine
3. t-56 tranny from 94 and up camaro/firebird
4. adapter plates for engine mounts?
5. ECU from truck (or have mine flashed, One of my very gray areas)
6. Intake manifold from an LS1 i believe
7. Fuel pump from truck
8. LS1 oil pan (or will my stock 305 oil pan work...)
9. Custom headers (or ls1 headers?)
10. Use my stock 305 accessories (alt, PS pump, brake booster etc)


One question I had about the accessories... Will my stock accessories bolt in to the lm7 engine block or will there be some custom drill work involved in that. Also as far as driveshafts go do i need an ls1 driveshaft or am i good with my stocker?

INTIMIDATOR Z

iTrader: (4)

dont think the 94 t56 will work.
i used the 1" set back adapter plates off fleebay
have the trucks ecu flashed (your 3rd gen one wont work)
yes you would need a LS1 manifold
get a 255lph fuel pump
ls1 oil pan (3rd gen one is completely different)
you can use LS1 stock exhaust manifolds
cant use any of your 3rd gen accessories.
you can use your stock driveshaft


pretty much almost everything motor/trans/harness wise on the 3rd gen you wont use with the exception of some plugs.

Guest

You need the '98-'02 T56, and flywheel
You need the LS1 fuel rails and injectors
Be sure your donor has a cable TB, not DBW.
The engine, computer, TB and harness should all come from the same donor
That Walbro 255 LPH pump is mostly sold as an upgrade replacement for TPI 350. But it's the way to go.
I don't see much point in spending $900 on headers when the goal is MPG, and your cruise rpm is so low that the headers aren't helping, and the stock '98-'02 F-car exhaust manifolds aren't any restriction.
For a stock 5.3, conventional wisdom holds that some 1.625" long-tubes should help your mid-range and top end. But cruising at less than 2000 rpm, and less than 1/2 throttle, they're no help at all.
The truck oil pan and exhaust manifolds won't work.
The FEAD is becoming a challenge, the supply of '98-'02 F-car parts is drying up and hotly contested. Everyone wants that stuff for every swap out there, not just us third gen owners. The truck stuff can be made to work, but brings another set of challenges.
The CTS-V stuff isn't cheap, and the GTO stuff is slim pickin's, as well.
The Kwik Perf. stuff is also spendy.
If you want to low-mount the a/c compressor, like the '98-'02 f-car, then you can't use the cheap brackets, you have to switch to the Spohn mounts.
When you get the correct oil pan, you also need the matching dipstick, and the matching dipstick tube.
The LS1 injectors flow more than the LM7 injectors. The LM7 injectors are too short to go between the LS1 manifold and the LS1 rails. And the LS1 injectors seem to take a different connector ( electrical ) than the trucks. IDK.
You may find it easiest to just keep the truck stuff, and change the hood.
Otherwise, whoever removes the VATS from the LM7 computer will need to know which injectors you use.

First_Formula

So to my list I need to add LS1 injectors, the t56 has to be 98-02, I can use stock ls1 oil pan, intake manifold and exhaust manifold.

INTIMIDATOR did you run into the problem of the different electrical connectors for the fuel injectors?

ronnjohn what is FEAD and VATS? when i have the trucks ecu flashed will that flash vats too?

Guest

VATS is Vehicle Anti Theft System. Your donor truck has it, your third gen does not.
Front Engine Accessory Drive. GM's current terminology for the alternator, p/s pump, a/c compressor, AIR pump, brackets, water pump, damper and such.
You can't use any of your original stuff.

First_Formula

So I have to get new accessories, What can they be off of? Do they have to be LS1 accessories or can I relocate the trucks?
Also does that require drilling out new holes for mounting everything or are the ls1 accessories a direct fit?

Guest

Now that you know what the FEAD is, please re-read what I already typed about it.

INTIMIDATOR Z

iTrader: (4)

yeah i had to change the injector plugs. i just went to the junkyard and got some off of fords.

one92rs

iTrader: (5)

just run the ls1 injectors and get it tuned. you will have to have things tuned out anyway. not sure on the vats. i know my 92 camaro has vats. that is why there is a chip on my key. on gas mileage do as instructed before. 2000 to 2002 manifolds. the 02 sensor will have to be relocated. no problem though. you can pick up even small cams used for really good prices.

First_Formula

Fords have the proper plug wires for ls1 injectors? weird. why not use LS1 plugs? Do the fords have the same wires going to them or how'd you splice them in?
Also what kind of gas mileage are you getting Intimidator?

First_Formula

So 98-02 ls1 accessories. I'll have to junkyard search a bit.

INTIMIDATOR Z

iTrader: (4)

yeah theyre the same style plugs. i like how they clip on instead of the GM style. dunno my mileage its not tuned right right now and plus im havin a cooling issue so i havent really been driving it much lately.

First_Formula

So updated parts list:

1. 5.3 litre lm7 engine
2. wiring harness from same engine
3. t-56 tranny from 98 and up camaro/firebird
4. adapter plates for engine mounts
5. ECU from truck
6. Intake manifold from an LS1
7: 255 lph fuel pump
8. LS1 oil pan
9. Ls1 headers/exhaust manifold
10. LS1 FEAD
11. LS1 or Ford injector plugs with LS1 injectors


Sound good? Thanks alot guys! And good luck with your cooling problem intimidator

one92rs

iTrader: (5)

put custom tune in there to turn off emissions and possibly do some tweaking.

INTIMIDATOR Z

iTrader: (4)

sounds about right. um gotta look into trans mount too. also if you dont have anyone local to tune your ECU i hear there are some decent mail order tune companies.

and thanx i hope to have it fixed soon. hopefully

First_Formula

I think I'll look into that EBL flash tuning stuff that I can tune on my own so i don't have to worry about them messing up my tune.

Thanks for all your help everybody!

one92rs

iTrader: (5)

you cannot use your ecm. so ebl flash is not going to help you. you need to invest in hp tuners or order a mail order tune.

INTIMIDATOR Z

iTrader: (4)

when i did a previous swap i used this company called spareecm. you just tell them what your car has and what you want and theyll send you a ecu with a decent tune in it.

NemeSS-TyranT

iTrader: (1)

will also need the truck maf.
the injector plugs are called ev1, many vehicles use the same type plug for injectors.
ford and gm cars of all yrs and engines.
what acesory setup u plan on running?

First_Formula

I've never had A.C. in a car so i'd like to keep that lol.

I plan on running a full on setup. After all its not a street/strip car its my D.D. with a little extra play power lol. Do you have any suggestions on unnecessary parts or anything?

Will a stock LS1 accessories setup bolt right in to the lm7 block? or will I need to have new holes machined into the block..?

85T/A350

Yes LS1 accessories will bolt right up. As far as mpg, I dont have one in a thirdgen but my 04 ecsb Silverado has the 5.3 and I can get 21-22mpg on the highway. So Id say in a car that is 1000-1500 pounds less it would be quite a bit higher.

Guest

By '99 there were lots of owner reports of LS1 / T56 F-cars returning 30-32 MPG on the interstate.
But they had 346 cubic inches, not 325. You might need more rear gear to make up the difference.
Maybe a 3.73:1 with the T56, since they had 3.42:1

88FormulaKiller

iTrader: (8)

I just wanted to Add this to give you another option on the T56, you can use an LT1 style T56 but you must change out the input shaft, front plate and bell to use it with an LS motor, the good thing about this is all the LT1 T56 parts you swap out of the T56 can be sold off and in some cases you might break even.

The same can be done with a C5 vette transmission but with more parts needing to be swapped out.. but you'll have a better "stock" T56 in the end but it can get costly.

Ive learned alot in the past month about the T56 trannys, because ive been looking for one! lol

First_Formula

So i can either use a fourthgen LS1 t56, or a LT1 t56 with an ls1 t56's bellhousing and all the other parts you mentioned OR do the same thing with the vettes t56 with more parts?
Neat. Just so you know My car is knocking from the lower half and the 305 isn't worth rebuilding the crank up for. Thats why i'm doing this swap. I'm gonna drive it till it dies and in the meantime be haulin *** to get this 5.3 up and running in a nother F-body so in a bout two weeks to a month I'll be asking a LOT of questions on here lol. I'm a newb to engine swaps. Never done even a direct bolt in so the LSx swap is gonna be difficult for me to say the least lol.

88FormulaKiller

iTrader: (8)

The corvette T56's get alittle deeper into the tranny, AFAIK, you need to change the input shaft, mid plate (front plate) Add an LS1 bell, change the output shaft, tail housing and find and i stress FIND a shift rail from an F-body. Its going to cost as much as a new remanned T56 for an F-body, i only mentioned it becuase it IS still an option and to some people money doesnt matter. i suppose if someone lucked out on all the above parts (all that are needed) and sold off the vette parts and got a low mileage vette T56 for cheap money it might be worth it in the end but thats a big IF.

Check out LS1 Tech, theres alot of T56 Guru's over there that will help you out with anything T56 related.

Also, the LT1 T56 is a viable option if you can find one with relatively low miles without a bell/etc because the cost of a low mile or built Lt1 T56 is generally the same price as the LS1 version, so its only worth it if you can buy one for less than the average price and do the swapping yourself.

88FormulaKiller

iTrader: (8)

This should be of use:

http://www.ls1tech.com/forums/manual...-pictures.html

Guest

EVERYONE wants a T56, that's why they cost so freakin' much. If I was king, I'd behead anyone who tried to use fourth gen F-car parts in anything but a third gen. There ain't enough to go around, so that drives prices up.
You know, if you go 4L60E, the savings will more than cover the cost of a paddle-shift kit, put shift control at your fingertips, literally, without taking your hands off the wheel. That might be fun enough to make up for no T56?
As for MPG, a T56 with a 3.73:1 axle should equal a 4L60E with a 2.73:1 axle, then the right converter could make up the difference from a dead stop.

88FormulaKiller

iTrader: (8)

its kinda 50/50 with the demand vs versatility of the T56, it makes a nice retrofit 6speed in anything with an LS1, so with such a broad spctrum of LS1 vehicles being swapped it increases the usual demand 10 fold. its too bad GM wasnt smart enough to use the same T56 for 93-02 F-bodies requiring no conversions, they would be somewhat more available in used form and probably a few hundred dollars cheaper.

First_Formula

So a t56 will cost me quite a bit lol. I'm not too worried about it for now, I'll deffinately look into the auto ls1 tranny but i love me a good ol stick lol.

I pick up the body tomorrow! 500 bucks for a car with just a little surface rust on the quarters which i will immediately sand and primer and TTops. Currently a v6 t-5.
then I gotta wait two weeks for a paycheck to pick up the engine from a junkyard. Gotta try to find an engine with a wiring harness and ecu.
First engine swap.... I really should have picked a direct bolt in lol. I'm sure I'll be buggin you guys quite a bit lol. I'll do my best tho

First_Formula

Also Intimidator I had a few questions for you regarding the wiring harness but i guess i can save them till i actually get the engine.