Looking to do LS1 engine/tranny swap....info neede

[Firestorm91tt]

Hello,
Newbie here looking for some senior insight in regards to doing a engine/tranny swap (4.3L stock set up to LS1).

I have a 1994 GMC Sierra SL with 225,XXX miles. The stock 4.3L engine and automatic tranny are beat. Needless to say she is tired and a new engine/tranny install would be nice. I have access to getting several stock LS1 engine and tranny combos to include all accessories, ECM, harness etc.

My question is how much of a PITA is it to swap out the stock engine/tranny for a LS1 set up. Is there any difficulties in dropping in a new set up. What is all involved as far as possibly modding brackets, wiring etc. I really dont have a clue as to what what all would be neccessary for the swap. I do know that a bigger radiator and electric fans will need to be added if I go the LS1 route.

Is there any links that show a LS1 swap with pics and dialogue that may help me along the way during my install. I would like to research this project as much as I can before I actually purchase an engine/tranny.

Thanks in advance for looking.

[RedHeartbeat]

I would suggest checking into some back posts. There is a lot of good information here. I had a 4.3L V6 in my 92 before it went LT1 and now LS1. LS1Nica and Farmtruk both did the conversion, also. I know there are a few more here with the old body style trucks that now have an LS1 engine. I would suggest you contact Street and Performance, www.hotrodlane.cc, for a bunch of install information and some really cool parts and accessories. I believe they also have a video you can buy showing details of a conversion. Your V6 mounts should work with a set of their engine mounts or you can make your own from a sketch you can download on the site here. You can also download their full catalog, a great thing for reference.

[LS1Nica]

Hey guy theres alot of backposts regarding this swap throughtout the LS1 conversion forums. Anyways I have a 91 1500 it had the 4.3V6 with the auto tranny with the SHORTBED. I dropped a 02 LS1/T56 tranny combo in it. Its a really easy swap if you got the tools the time and money. For me the biggest pain were the clutch pedal and the wiring harness. Everyone will tell you the same get the motor, tranny, wiring and PCM all together.
Reuse the driveshaft, crossmember, wiring for the lights and accesories, I reused my radiator but Im going to upgrade soon just to be safe.

Buy a high pressure fuel pump (I used a vortech), fuel lines (hose shops will hook you up if you show them the fuel rail and filter for about 60 bucks), electric fan, motor adapter plates and thats about it. I reworked my own wiring harness and though it works its an awfull sight when you open the hood. Well good luck man anymore questions post.

[Firestorm91tt]

Excellent post....I was very curious on how the ls1/tranny combo fit in a truck very simular to mine. I was wondering if any cutting/welding had to be done to the frame as far as mounting both the engine and the tranny was concerned. Its good to know I can reuse the driveshaft etc.

When I finally get ready to buy an engine/tranny Ill make sure to get everything I can. I mean it will be a complete power plant/drive tranin assembly. I am still searching for additional post that will assist me with my future project. I will post more questions later after I do some more research. A couple questions I do have:

If I get a complete ls-1 to include assecories/harness how hard is it to intergrade with stock parts...will my speedo, coolant temp, oil pressure gauge work..any tricks with ignition?

Does the ecu have to be redone or is it as simple as dropping right in...........i have seen posts mentioning reburning them for correct tire sizes/gears etc?

How long did it take you to complete your swap?

Does your truck haul ass due to the fairly low weight of your vehicle....and is there a huge difference between the 4.3 and ls1?

[RedHeartbeat]

I don't know about anyone else but my LS1/auto in a 92 xcab dusts Mustang GTs all night long at the track. It's bone stock right now and the only stock truck that beats it is a Lightning or supercharged Harley Davidson. The stock LS1 is even faster than a dealer optioned whipple charged late model.

[GMCwantsLS1]

"If I get a complete ls-1 to include assecories/harness how hard is it to intergrade with stock parts...will my speedo, coolant temp, oil pressure gauge work..any tricks with ignition?"


Your speedo will work, any GM electronic speedo will work or any speedo that uses 4000 pulses per mile. You will need to get the PCM reprogramed by Allen to calabrate for tire and gear sizes, as well as remove VATS and other things you won't need. For coolent temp you will need the three wire sensor from GM PN 12551708. The third wire is for the coolant temperature gauge on GM's and the other two wires are for the PCM. For oil pressure you can use the LS1 sensor and splice in your orignal sensor wire that goes to your gauge. I don't know if there are enough extra relay and fuse slots under the hood on your truck so you might need to add some to run cooling fan relays, PCM fuses and relays, AC relay ect. I used a relay harness from a 1997 Z28 Camaro for mine. You will want the radiator fans from the donor car too. Another good investment is the LS1 Engine Installation Guide from GM PN 88959384 as well as http://www.alldatadiy.com/ to find out about the wiring harness pin outs ect.

Jeff

[Firestorm91tt]

excellent...........looks like i may take on this task here in a couple months. i need to keep her as a daily for a bit longer before i take her down. this will give me plenty of research time for the project.

[Firestorm91tt]

Well I ordered the DVD LS1 install vid, I hope this helps shed some light on the swap. It looks like I am going to be gaining the assistance of a local GM mechanic who I am gonna slide a few bucks.

Im hoping this install can be completed over a weekend or two. I have searched quite a bit..is there any other links that can be provided right off hand showing LS1 swaps / trouble shooting etc. I looked here but most posts are have a few replies. I did howevere read the one post that had 56 replies started by LS1Nica.

[RedHeartbeat]

Post what parts you have on hand for the swap and we'll sort through it to see if you have everything.

[Firestorm91tt]

Well unfortunately I dont have anything as of yet. However I am the kind of person who likes to buy stuff ahead of time. I wouldnt mind buying all the auxillary stuff first. I was reading some posts and see that some things are needed ie: headers/manifolds, radiator, electric fans, higher lph fuel pump, motor mount adapter plates etc. If you guys can suggest some parts and where to get them Ill start buying. Unfortunatley I live in a Condo Assoc. so I dont have anywheres to store an engine and tinker with it before the actual install. I could take it to my father-in-laws but it would be outside under a pole barn fighting the elements.

Also, I see that you suggest that the PCM gets reburned, but some things are needed for a correct tune. I see questions/perameters in regards to gears, tire size etc. I dont know a damn think about gears and am still undecided on tire size. I have the stock 15" wheels and may keep them at 15", but I do want some wider meats though. I want the truck to be respectable....if I can dust Mustang GT's I would be more than satisfied. I have been talking to my buddies at work about the swap and they are telling me heads and cam are a must....but again like I said I dont know much about stuff like that. The only thing I know my way around are 3/S's

I am very new to this truck modding so please bare with me