L18 8.1L swap resource thread

Discussion in 'The Engine Bay' started by Larry, Jun 14, 2013.

  1. Kay86K5

    Kay86K5 1/2 ton status GMOTM Winner

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    Yeah, I know Tilden Motorsports out of Cali will ship a complete motor from intake to oil pan even with all accessor brackets, alternator, pullies, and even a p/s pump (no a/c compressor but the bracket is there) with complete reworked harness and a tuned ECM to whatever you want for $3500. Pretty steep but when you look at what you are getting it's not that bad. I guess that is always an option if I can't find a junkyard one. But it's harder to drop 3500 plus shipping all at once instead of bits at a time while getting a junkyard one to work for your needs...
     
  2. y5mgisi

    y5mgisi 1 ton status

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    Lol I guess I didn't think it all the way through. I guess I expected most would do what I intended on doing and just sitting back and looking at the two charts all while saying "interesting" several times over in my head.
     
  3. Kay86K5

    Kay86K5 1/2 ton status GMOTM Winner

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    Are the 1987 and up TBI tanks/sending units all the same? For example, is a 1989 TBI tank/sending unit the same as an 1987? My thought is yes but didn't know if they made small changes to them in the late 80's, so thought I would check
     
  4. y5mgisi

    y5mgisi 1 ton status

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    I believe they are the same 87-91.
     
  5. Larry

    Larry 1/2 ton status Premium Member GMOTM Winner Author

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    Yep
     
  6. Kay86K5

    Kay86K5 1/2 ton status GMOTM Winner

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    Perfect! Thanks
     
  7. Kay86K5

    Kay86K5 1/2 ton status GMOTM Winner

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    One more quick question for Larry (as I know he did this a while ago) but if I should already have a round pattern 205 in my truck behind a th400. Do I still need to get the aa adapter to mate to a NV4500 or will it just bolt right up behind it?
     
  8. Larry

    Larry 1/2 ton status Premium Member GMOTM Winner Author

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    No, you don’t really need the AA adapter as long as you swap in an earlier TH400 short input gear. ORD sells them and might even work you a partial trade for your long input. Doesn’t hurt to ask. Without swapping to the short input you would need the AA spacer/adapter, which I would not recommend.

    Pictures and story of the NV4500 redo in the K10 starting at post 211.



    [​IMG]
     
  9. Kay86K5

    Kay86K5 1/2 ton status GMOTM Winner

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    Thanks for the link Larry. It looks like some minor mods to get everything to fit up well. I am seriously considering an NV4500 with an 8.1 in my rig now. Looks a lot simpler and really awesome! Thanks for the info
     
  10. efituned

    efituned Registered Member

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    It's almost finished...waiting on the pcm. I've got to wire the TB connectors and the warning lights in the cab. I prelubed the engine, then spun it over without the spark plugs, built about 35psi of oil pressure.

    [​IMG]
    [​IMG]
    [​IMG]
     
  11. Kay86K5

    Kay86K5 1/2 ton status GMOTM Winner

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    As far as fuel lines go, for you guys who just purchase the motor and not a donor truck to rob the lines from, what are you guys using for lines? Are you going and purchasing new factory fuel lines from the correct year motor and fitting into your square body? Or will the factory TBI fuel lines work?

    Oh, and on a side note from anyone in areas where you need to pass emmisions/inspections before you can register your vehicle...I know they discontinued EGR in 2004, but if you have a motor from 01-03 with EGR, have you removed it and still been able to pass emissions/inspection?
     
    Last edited: Dec 4, 2015
  12. efituned

    efituned Registered Member

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    On my 86, I used the factory feed line, which is routed up in to the engine bay from the passenger side wheel well. I used 5/16" brake line hose for the return and clamp/zip-tied it right along the feed line. I used an inline 3/8" fuel injected filter near the fuel tank. It's mounted in a spot right above the rear drive shaft. So far, I haven't had any leaks.

    On a side note, I started the truck last night. All seems well, except for the iacv. I think I wired it wrong. When it's unplugged it idles around 780, but when its plugged in I get 1900.
    It's hard to hear much with the open headers, but sounds good with no leaks or funny stuff.
     
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  13. Kay86K5

    Kay86K5 1/2 ton status GMOTM Winner

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    I have been asking Larry some questions over on his Polar Bear Burban thread and someone asked I would bring these over here so when people are searching about 8.1's they can find the answers here.

    Me: "What year 8.1 did you end up putting in this thing (referring to Larry's burban)? I know you said multiple pages back that you had a couple motors that your were making into one, but what year block did you end up using? Also, and more what I'm interested in, what fuel rail/fuel lines did you end up using (01-03 or 04-up)? And did you use your factory 89 TBI fuel lines?"

    Larry: "The engine itself is a later one….I’m thinking 2005 to 2008, maybe even 2009. It looks older because I didn’t like the bare aluminum valve covers and put 2002 valve covers on it (once again, referring to the 8.1 he swapped into his burban).

    Everybody has a preference, and my preference is the earlier style return type fuel rail as I like having the ability to adjust the fuel pressure up on the rail whereas returnless gets more complicated where you must rely on aftermarket BS to regulate the fuel pressure. I just purchased a brand new return type fuel rail for it through work (pn 12575055). As far as fuel lines, I do use the factory TBI lines up to the fuel filter area on both the supply and return side. As far as the fuel lines themselves I am also running Workhorse fuel lines (pn W0000540 Return, W0000539 Supply) then I use a Napa 3623, which has a threaded connection on the tank side and a quick connect fitting that perfectly matches the Workhorse fuel line. The return line gets a little more complicated where you need to cut off a piece of the quick connect tubing from something at the junk yard so it will fit in the Workhorse return line. I find the return line at the fuel rail on 1999-2003 LS engines work great. Just cut it off a donor fuel rail and use it. Hard to explain. If you’re ever down in this area I can show you.

    Hope that helps."
     
  14. y5mgisi

    y5mgisi 1 ton status

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    Thanks Kay! And Larry for providing the info!
     
  15. Kay86K5

    Kay86K5 1/2 ton status GMOTM Winner

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    As a request, whenever you have some time Larry, would you take some photos on your K10 for the transfer of fuel from one dual tank to the other? I think I read on the other forum that you changed it up and are now running a factory TBI fuel pump in your "storage" tank and just have that being pushed into the "feed" tank through the vent. Is that correct? Did you just wire up a switch to turn the pump on when you want (or use the factory dual tank switch on the dash)? I am sure others would be interested in your set up with some pics, if you have some time :thumb:
     
  16. Larry

    Larry 1/2 ton status Premium Member GMOTM Winner Author

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    Well, I don’t have much to offer up other than the picture below is how the fuel gets moved into the main tank. I just added a T into the fuel fill vent line where the fuel shoots straight into the main tank. I have an EP241 (because that is what I had on hand) in the passenger’s tank that works like a storage tank. The EP241 moves fuel to the driver’s tank which is the main tank to feed the engine via an EP381 pump, in-cab switch and relay.

    I’ve read where a lot of guys have had good luck with LS swaps with using two tanks, two pumps, and the stock switch valve ( the later version of the valve). I don’t know why it wouldn’t work for me but I may take another stab at it someday to see if I can get mine to work. The transfer solution works okay but it is easy to forget the switch on and overfill the tank. I’ve done that a few times.
    [​IMG]
     
  17. Team208Motorsports

    Team208Motorsports Its Magic Bitch Vendor

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    You know the stock ecm has a fuel transfer function........... Automatically do it for you. :pimp:

    Yeah it would require senders but it would be cool. LOL
     
  18. Larry

    Larry 1/2 ton status Premium Member GMOTM Winner Author

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    That is correct, GM medium duty and Suburban had dual tanks where the ECM automatically transferred fuel to create the illusion there was one large tank. I’m not interested in doing that personally but it is always an option for someone.
     
  19. wetoolowdingbangow

    wetoolowdingbangow 1/2 ton status Premium Member

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    Would a 8.1l work with the diy4x poly engine mounts? I'm thinking I'd have to make my own motor plates...

    Is there an alternative to the low hanging oil pan?

    I found a 8.1l with 12k on it for $1000....
     
  20. Larry

    Larry 1/2 ton status Premium Member GMOTM Winner Author

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    Sure, don’t get hung up on 8.1L engine mounts just because it is an 8.1L. The 8.1L mounting is no different than any other BBC or SBC for that matter. Those type of engine mounts your talking about look like a great way to introduce engine harmonics into the rest of the vehicle but that is just my opinion. I personally wouldn’t use those on anything other than a trail only rig. The Energy Suspension inserts into factory GM saddle brackets work great.

    The big oil pan usually isn’t a problem when installing into a GM truck (need the ORD HD Xmember for 4x4 67-72s and 73-87) but there is a company that sells a smaller L18 oil pan for swapping into cars. It’s like $800. Can’t remember the company name but someone here probably knows….or on the 8.1L Facebook group.

    A 12K mile 8.1L for $1000 is too good to pass up. Several have popped up lately on the 8.1L Facebook group. Guess guys are learning there is a lot more expenses involved in a late model engine swap aside from the cost of buying just an engine off Craigslist than they expected :haha:

    Figure for a $1000 engine it will probably cost at least $2000 to $3000 on top of that for install bits to do the swap right.
     
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