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LS3 swap in 96 with 6L80E tranny NEED HELP!!!

10K views 16 replies 7 participants last post by  threeimpalas 
#1 · (Edited)
I'm planning on buying a conversion kit from brphotrods.com, it comes with tranny crossmember and mounts, motor mounts and frame brackets. Pulling the LS3 from a 2500 Sierra with 82k on it... Came with motor, wiring harness, pcm, and accessories. I will need to get my 6L80E. I am looking for 450hp to the wheels. THATS IT for now. It's an everyday driver and my main focus with this car will be reaching 30+mpg.... Swapping literally for gas mileage and the LT1 opti design issue(I have replace opti too many times). What all should I need to know before I start this project. I have read many threads and they started to get overwhelming with info not specific to this set up. My mechanic is charging $1300 for the swap if I buy all parts is that fair? Any unexpected large purchases or hard to locate items that I will run into that may cause issue mid-swap? I'm begging for info at this point as he is suppose to start the swap this weekend and i don't want to be out of my car for weeks because we run into issue... I have someone to tune out vats and do any tuning that's needed at tuners Inc in Jax,fl. Any help would be so greatly appreciated. Also I was looking to spend about 3k total on this swap if possible. I paid $800 for what was pulled from the Sierra, the kit is $500, and I still need to buy a tranny plus labor.. Am I going to make it under budget and if not explain why PLEASE!!!! Thanks for the knowledge in advance
 
#2 ·
You are probably not going to make 2 of your goals. The 30 MPG, and the $3K pricetag.


The 30 MPG is tough to get to with a 450HP to the wheels, no matter what.


The trans will probably cost you at least $1300-2000 to have rebuilt to take the HP you want to make. You will need another TC with about a 2500-3000 RPM stall and that is not included in the trans rebuild. You may also need some tunnel work to make the 4L80 fit, plus a new drive shaft. That would also require new universals for the drive shaft


If you have your 4L60e built to handle the HP, you should be able to skip the driveshaft, but you may need a flex plate to mate the two. You can make the LS computer work a 4L60e. The cost of the trans will be about the same. Make sure you get a TC that will handle the HP.


Is your mechanic going to do the wiring harness? If not, you need a harness, and that will cost you about $200.


I just did a 454 BBC swap into my OCC, and I planned on $2500...it cost me about $6500 when all was said and done, but then, I rebuilt the engine, and bought a MPFI system to the tune of $1500 (half price) plus injectors for $250, and aluminum heads for $1000, roller rockers, etc. I put a lot of go fast parts in the engine as well. It has been kicking me in the wallet on little stuff too. You can spend a lot of money fast when you start making mods. If you are looking for $450 HP, plan on about $250-300 for a cam. You probably want headers, and that is another $150-400. The intake may not be sufficient to deliver 950+ CFM to the engine, and you need bigger injectors for another $300. You can get a FiTech MPFI for about $1799 that will work for about 600-750 HP at the crank. It is a self contained system that can control the trans (you would only need to hook up the gauges).


I did all of the work on mine except for machining the block, installing the pistons on the rods, and turning crank. The only way you are going to get near your goal is to do everything yourself. If you make it under $5000 I will be surprised, even without rebuilding the engine.


I could probably list more issues, but the list I gave you is pretty long already.
 
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#3 ·
You are probably not going to make 2 of your goals. The 30 MPG, and the $3K pricetag......
Yeah.......ain't no way either of those things are gonna happen.

Since you already have the egine, transmission and ECM, you'll come closest to the $3000 mark if you can do ALL the install and tuning work yourself.

But 30 mpg from a LS3 that's been modded to 450 HP? No freakin' way. You might be able to squeeze 23-24 mpg on the highway with 3.08 (or lower) gears. But your city mileage will be in the low to mid-teens.

KW
 
#4 · (Edited)
......Any unexpected large purchases or hard to locate items that I will run into that may cause issue mid-swap?.......and I still need to buy a tranny plus labor.......
What. You DON't have a transmission yet? :eek:

OK.....a good 6-speed tranny's gonna cost you $1500 or more. Then......you gonna need a custom drive shaft (at LEAST another $500). And, oh yeah.....the tranny cross member from BRP WILL NOT work! Their cross member is for a 4L60E transmission.....your 6L80 transmission is an altogether different animal. You'll have to make mods to your floorboard JUST to get it to fit in a B-body.

With your budget constraints, I would recommend that you stick with the 4L60E tranny.

Better yet, just rebuild the LT1, go with a 24x conversion (I have a TorqHead kit going on my '96 SS) and call it a day.

But then......that's just me.

KW
 
#6 ·
I was exaggerating a bit with the mpg... I have the 6.0 in my garage now from a 2004 2500 HD... I'm now planning to build my tranny to withstand 600HP... The only thing I will be doing to the engine is LS1 intake manifold, 90+mm throttle body, 1.8 roller rockers, headers, and will be tuned. I am running 24 inch wheels and 3.73 gears. Obviously I will still need to change my TC but anything else major?
 
#5 ·
...my main focus with this car will be reaching 30+mpg.... Swapping literally for gas mileage and the LT1 opti design issue...
Swaps for fuel efficiency are a poor way to save money. You're going to need to drive a LOT of miles to get a return on your investment. You'd be better off giving your LT1 a tune-up, and finding a new Delphi or Delco optispark - not one of the cheap aftermarket replacements - and be done with it.

To back up KW, you will not be getting 30 mpg out of the LSx. If maximum MPG is your goal, you'd be better off going with something like an Ecotec.

FWIW, the engine you'll be getting from the 2500 also isn't an LS3. For $800, it's probably an LQ4. It may be a Gen IV engine, but I'd suspect not. You should confirm what exactly it is that you've purchased.

Additional costs will include exhaust, engine mounts, fuel pump and regulator, fuel lines, misc. wiring. Little odd and ends will quietly add up and eat away at your budget.
 
#8 ·
Gotta agree with these guys on this with the 30mpg and budget you have planned. I like the optimism, it may help you cut some costs during the project. I'm getting into the same project, but an LS2 with LSA supercharger, cam, headers, trans...etc and hoping for 700hp out of a 9C1. I already know my budget is around 12k, realistically. All I have already is the LS2, but selling unused parts help and I've got 2 parts cars worth of stuff to help fund it. Good luck to you on your project!
 
#9 ·
"My mechanic is charging $1300 for the swap if I buy all parts is that fair?"

yea id like to know the answer to that too....i assumed that the labor for an ls3 swap would cost alot more these days....i coulda sworn ive heard from several people that it probably would be around 3k for labor?....probably has some to do with what part of the country too though....
 
#11 ·
Since what you do have is an LQ4, which is 300 hp, to reach a crank hp of 550(450ish at the rear), you'll need the heads done, cam, intake, exhaust. The BRP kit, don't get the parts til you know which trans your using for sure. It would be best to find a built, or build a 4L60E to stay on a budget. Realistically though, for heads, cam, intake(i'd go with an LS6) and exhaust, that alone could cost a few grand. I think $1,300 seems fair for the swap though, if you aren't having to do any of the labor.
 
#12 · (Edited)
Just find a stock 4L80E and transgo2 HD it. You will be way further ahead of the 4l60e and the tuning would be much less of a headache from the 6L80e. You can find used 80e pretty cheap also
 
#13 ·
Im back!!!

Ok, so thank EVERYONE for all the help. With your guideance I have altered my budget ratger tgan alter my desires for the car. I will NOT use my LT1 tho. So with the swap this is where i am... my engine LT1 is out of the car (and for sale with 87k miles if someone wants it in Jax,Fl). I have purchased a 6.0L truck engine that HAD cathedral port 317 heads. I have sent my wiring harnesses off to current performan e for them to graft them for me. I bought casting #0821 corvette aluminum heads COMPLETE($1000), im using an LSsimple.net bracket hit with high mount ac that allows me to use my stock ac feom my lt1 set up(625). I also bought an LS3 intake complete with fuel rails and injectors ($400). ALL PARTS ARE BRAND NEW. I was thinking of getting the mounting kit, cross member, fuel lines, fuel pump, fuel regulator, and headers all from brp if there are no alternatives with the same convenience. Am i forgetting anything? Any objections or opinions regarding my set up that will save me from kickin my ass in the long run? Besides the grand it is costing for the wiring harness im not too far away from my ideal budget but i think i will be at around 7k total but will still have an LT1 to sell and make a couple bucks back. Last but not least i have 2 desires that i would like to be put into perspective. Is it too much to add the electric power steering in newer cars (vettes) and also i want an electric pedal i believe i need to choose my throttle body accordigly any suggestions for TB size? Brand? After all this i believe i will be done. Also purchasing a Dakota dash if anyone knows somewhere i can get one for less than $500 i would like to purchase asap. Thank for all the help ISSF
 
#16 ·
.....Am i forgetting anything? ......Is it too much to add the electric power steering in newer cars (vettes) and also i want an electric pedal i believe i need to choose my throttle body accordigly any suggestions for TB size? Brand?.....
Throttle Body === Go with a Nick Williams TB or a V-max TB. 90mm is really all you'll want with a stock intake manifold. Google will yield results.

I would've recommended a NEW Speartech wire harness.....but get with the guys doing yours and find out if they are setting it up for a drive-by-cable (like in the B-bodies) or an electronic drive-by-wire. This will determine what type of throttle body you'll need.


.......Is it too much to add the electric power steering in newer cars (vettes)......
More stuff to go wrong IMO.


.......and also i want an electric pedal i believe i need to choose my throttle body accordigly......
Don't need the electric pedal if you go drive-by-cable. Jus' sayin'.....


.......Also purchasing a Dakota dash if anyone knows somewhere i can get one for less than $500 i would like to purchase asap....
No idea what that is......



BTW.....do you have a cam in mind, yet? Don't need to go too wild.....anything more than 230*/242* duration with less than a 114* LSA is not necessary and will nagatively effect drivabilty. LS3 heads don't like more than about 10* or 11* degrees of valve overlap......

KW
 
#14 ·
Let us know how the harness works out in the end. I know I'll be looking for input on who to go with for the custom harness. Thanks for the update.
 
#15 ·
Look into hydroboost for your steering. It is relatively easy to install, and uses your power steering pump to supply the boost. You can use a Y to get both the brakes and steering to return to the reservoir.
 
#17 ·
Huh? I think there were some wires crossed in your post.

The OP doesn't seem to have a desire to change to his power brakes from the current vacuum-assisted system to a hydraulically-assisted one.

Changing to an electric power steering setup would be a major undertaking and a first for a B-Body. There's a lot of tuning to the feedback loop that would need to go into it to ensure proper steering response; not really something a guy in his garage would be equipped to undertake.
 
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