2007 GMC Sierra 4.8 to LS1 swap help

Discussion in 'GM Powertrain' started by ig109, Nov 23, 2009.

  1. ig109

    ig109 New Member

    I am the proud owner of a new body style 2007 GMC Sierra Single Cab, Short Bed, all black.. The truck is my daily driver, and my tow rig.. Only problem is that the 4.8 really hasnt got enough power for my towing / Fun needs.. I recently came to own a never fired 5.7 litre LS1 camaro engine, it is of the 1998 vintage.. I am really wanting to swap the two.. Externally they are the same right.. The LS1 is lighter, i picked it up and put it in the bed of my truck.. However i know that the crank reluctor and cam sensors are different.. I plan to update the cam with a TR220 cam, install some headers.. change the cam and crank sensors to work with the E38 ecm.. I was wondering if the flexplate will be the same, engine mounts, starter and such, i wish to also install a set of L92 heads.. Will my stock fuel system (including manifold and injectors) work with this engine? I was thinking about going all out and building a 383 out of it..

    I know you are all going to say that i should just get an L92 or LQ4 and swap that in but this engine was FREE..:party: So i am going to use it as my base..

    What do you all think?? Thanks in advance for the help and advice..

    Also will the 4l60 be ok with this engine in front of it..
    One final question.. This truck was ordered by me with the towing package, but i forgot to order the 3.73 gears, i have a new set of Richmond 3.73 gears for an 8.5 inch 10 bolt rear axle that i originally bought for my 79 Trans Am (no its not a BOP 10 bolt) so do you think these gears will work in my rear axle? I have the G80 diff in the truck that came with the towing package.. Yukon gears said they would,:gasp: i am not sure as to if the speed sensor in the axle will make a difference or not..

    THANKS.. ALL responses are appreciated..
  2. ig109

    ig109 New Member

    Oh yeah, and i am planning to have Wait4meperformance tune it.. He is only about an hour and a half from my house and said he could do it at his place for me.. Do you all think it will run at all without tuning it first?

  3. vncj96

    vncj96 Epic Member 5+ Years 1000 Posts

    the 4l60E is really at its limit in my old burban with the 330lbs of tq it puts out, which is part of the reason why GM lowered the TQ numbers on the LS engines for the trucks. I would get one built. I am sure you could have yours updated and a shift kit but i think what you are looking at you are just eventually gonna chew it up. i would also consider going up in gears possibly to probably a 4.10
    Last edited: Nov 23, 2009
  4. b_burdine

    b_burdine Rockstar 100 Posts

    What exactly do you tow?
  5. ig109

    ig109 New Member

    I often tow a 79 trans am, and i am currently building an off road toy.. a 74 Jeep CJ5 that will be a trailer queen as well (too much body is going to be gone to make it street legal) The trans am is an on going project that i have to drag to and from different shops getting different things done to it.. I will not have it forever but i am going to have to tow the jeep quite a bit.. I know what you are going to say.. Get a 2500.. that really isnt an option, and elbow grease is free so... Onward with this project..

    Adding to this is the fact that i have a thing for go fast vehicles.. I think that with this combination of engine and gears (?) and such should make for a fun truck.. Thinking of lowering it a little (2 inches) and adding some helper bags to the rear.. and a set of stock 20 inch yukon/sierra wheels.. make a good daily driving, tow when you need to truck...

    Thanks for the input..

    The trans will probably get replaced by a 4l80 later.. but for now im giong to roll with what i have..
  6. b_burdine

    b_burdine Rockstar 100 Posts

    I wasn't going to say that get a 2500 at all. I say turbo that bad little 4.8l. then you will keep your gas mileage when you're not towing and still have insane amounts of power when you need it.
  7. ig109

    ig109 New Member

    Ok or that...LOL. I looked at a STS kit for the truck.. Thought that would be pretty bad.. However i never got an answer as to how much that would cost.. I already have the LS1 sitting on my stand in the garage beconing to me to throw a cam in it and thrash on it.. Plan was to put the LS in the truck and put the 4.8 that is in the truck under a carb and place that in the jeep..

    Or at least that was the plan.. By the way, you are probably going to say that i should sell the LS and buy a turbo kit.. well that would work but i cant legally sell this particular engine.. that is why it was free (it isnt stolen, but it was supposed to be scrapped, lets just say i know people) And i would hate for that person to get in trouble for being a good friend..
  8. ig109

    ig109 New Member

    Has anyone done any kind of swaps in the new body trucks???
    I am looking for some wisdom and finding none (at least about the topic at hand) The STS kit would make it alot of fun to drive but i question the additional torque, i really need help when taking off from a light or starting up a hill.. A turbo seems like it would help on the highway but not on the hills and lights.. no replacement for NA displacement, and a 5.7 is bound to make more torque than the 4.8..

    Does anyone have any wisdom on swapping gears in these new body trucks? Where did you get your gears? How much were they? Do you think going from a 3.23 to a 3.73 will make a noticable difference or is it right for me to actually concider 4.10 gears????

  9. Project Reaper

    Project Reaper Rockstar 100 Posts

    If you want to swap that motor into your truck you can take the ls1 5.7 long block ( motor and heads ) and use the rest from your truck. as far as the couple sensors that are different you might have to use the ls1 sensor and wire it in or see if the 4.8's sensors will work. as far as the intake and the coils, it will work but it will perform differently than normal. once you cam it and increase anything it will run like crap untill it is tuned. once it is tunes everything should straighten out and run smooth.

    the biggest problem you would run into is the sensor issue and maybe a wiring issue. is the cam sensor plug the same config? i doubt it. youll probably have to rewire it and customize your wiring harness. alot of changes happened from the ls1 used in the 98-02 camaros and the newer model trucks...

    also i have 4.56 gears in my truck which is a large upgrade from stock and it made a noticable difference, plus i can still cruz on the highway at 80mph and 2k rpms.
    Last edited: Nov 24, 2009
  10. ig109

    ig109 New Member

    However you are running 35 inch tall tires.. Im have 245 70 17s which is about 30.5 inch tire.. I really dont want this truck to be wound out at highway speeds.. With 4.10 gears it would be the eqivalent of taking it out of OD and leaving in D with the current gears.. which is a bit much.

    The wiring harness on my truck will not have to be modified.. I will simply change the crank reluctor on the LS1 with a 58 tooth gear, and exchange the front cover with the one on my 4.8 along with the cam gear (and aftermarket cam) from an egnine with the 4x cam sensor.. No harness changes should be necessary..

    I was really looking for information on the rest of the truck, such as fuel system.. Transmission and such, and possibly someone that could assure me that the engine will bolt to my stock engine mount.
    I am concerned that the trucks returnless (supply on demand) fuel system will not keep up with the increase in displacement.. As well as the fact that i wish to use the truck intake manifold and TB to keep stock appearance and to keep torque as high as possible, i wondered if i would have to find different injectors or if my stock ones will keep up.. I could probably find a Cadillac or Denali 6.2 intake and injectors if needed, but i would like to know if that is necessary..

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