L18 8.1L swap resource thread

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

  1. wheels87k5

    wheels87k5 24 Karat Premium Member GMOTM Winner

    Joined:
    May 1, 2007
    Posts:
    1,878
    Likes Received:
    1,746
    Location:
    Goddard, Ks
    Build(s):
    2
    This is what I'm needing to find out. If what I have now will not work like needed, what do I need to do to correct it?

    Do I need to add something to the NP241 so that it will be in sync?

    Since my NP241 is the mechanical speedometer, will I need to convert it to electrical?

    Maybe it's best to put this in the Garage section.
     
    Last edited: Jan 15, 2019
  2. Larry

    Larry Chupacabra Rancher & Tumbleweed Farmer Premium Member GMOTM Winner Author

    Joined:
    Jul 18, 2000
    Posts:
    1,547
    Likes Received:
    1,431
    Location:
    A windy corner of a dirty street: Pueblo West, CO
    Build(s):
    1
    Sorry for the late bloom as my laptop threw a rod and I have been confined to watching from afar on my phone. It is my understanding the two speed sensors on a 4L80E are to measure turbine speed and slip or something like that. You would still need a speed sensor on the actual output of the transfercase to work correctly. Howell Engine Development sells a speed sensor that screws into the speedo cable port to gain a VSS signal. You're in good hands working with Team208 so you probably aught to get with him and get his imput on that question. I don't mess with automatics to be able to give good solid advise

    Not sure if something like this would work or not but I'd research this before digging into a VSS swap on your 241
    [​IMG]
     
    SpeedlabDan likes this.
  3. wheels87k5

    wheels87k5 24 Karat Premium Member GMOTM Winner

    Joined:
    May 1, 2007
    Posts:
    1,878
    Likes Received:
    1,746
    Location:
    Goddard, Ks
    Build(s):
    2
    OK...thanks for the input. I just sent Howell the question at hand.

    I also started a thread on this in the Garage.
     
    Larry likes this.
  4. ashman

    ashman What's a pigeonrat?? Premium Member GMOTM Winner

    Joined:
    Mar 1, 2011
    Posts:
    5,199
    Likes Received:
    4,669
    Location:
    salt lake city
    Build(s):
    3
    Dakota digital makes an adapter to get vss from a mechanical speedo as well. I used it for awhile and it worked great. Only like $30 too.
     
    wheels87k5 likes this.
  5. bigblock72

    bigblock72 Elmer's glue taste tester Premium Member GMOTM Winner

    Joined:
    Oct 18, 2005
    Posts:
    1,419
    Likes Received:
    214
    Location:
    American Fork, Utah
    You don't need to have the VSS read at the transfer case, the output speed sensor in the trans will do everything that you need and you will be able to keep the original mechanical speedo. My Blazer has been this way (and most of the swaps I do) for many years with no problems, in fact I like having the converter lock up in low range 20 mph as it helps keep the trans cool. The only negative about not having the VSS in the t-case is the trans shifts a little slow when in low range, but it certainly isn't a deal killer, I'm just a little easier on the throttle.

    When using a 4l80-70-65-60e trans you must have a 40 pulse signal for the computer to be able to shift the trans properly. All of the speedo cable sensors are less than 8 pulse and work fine for a manual trans or old school automatic transmission.
     
    SpeedlabDan and Larry like this.
  6. SpeedlabDan

    SpeedlabDan Keepin it trashy never classy Premium Member GMOTM Winner

    Joined:
    Aug 3, 2017
    Posts:
    4,566
    Likes Received:
    6,745
    Location:
    SWEDESBORO New Jersey
    Build(s):
    2
    I agree I'd rather have the. Vss in the body of the trans not the tcase. For my Allison it would fix the low range issues especially having double low and come to think of it if I drop the rear shaft I would have no vss signal in front drive hi/low. Now if I cold just figure out where to put the vss in a 4wd trans.
     
  7. NTXJIMMY

    NTXJIMMY Now that's thinking with your dipstick JIMMY! Premium Member

    Joined:
    Oct 14, 2009
    Posts:
    556
    Likes Received:
    412
    Location:
    Whitewright, TX
    Build(s):
    3
    Larry
    Great info! I appreciate all the support for this

    I recently purchased a ‘88 K30 Crew Cab and a workhorse 8.1 in the pics below

    I have a quick question and I might have skipped over it somewhere in the thread but here it goes

    When you swap the drive by wire to the 7.4 drive by cable throttle valve What brackets are you using for the throttle and cruise cables ?

    Thanks!!

    BC18097B-9A6A-4C86-A2D1-2FCDFB7BCCB8.jpeg

    53377725-6E45-4B3C-B70D-35C896F34CA0.jpeg

    658BE459-9F68-404A-8395-3326FD05C745.jpeg
     
    Big Ray, SpeedlabDan, 72gmck5 and 2 others like this.
  8. Rick Capito

    Rick Capito Registered Member Premium Member

    Joined:
    Dec 7, 2017
    Posts:
    66
    Likes Received:
    116
    Location:
    Prescott,AZ
    I made my own . Welcome to the 8.1 club IMG_0927.jpg IMG_0926.jpg IMG_0926.jpg
     
  9. Kay86K5

    Kay86K5 1/2 ton status Premium Member GMOTM Winner

    Joined:
    Mar 9, 2012
    Posts:
    3,753
    Likes Received:
    4,392
    Location:
    Emmett, ID
    Build(s):
    4
    On my old 8.1 that I was using mech throttle on, I actually just picked up a throttle cable and throttle bracket from a 97 Tahoe with a vortec 5.7, and then modified the bracket just a tad, and bolted it to the same intake bolt as shown just above. Seemed to work just fine
     
    SpeedlabDan likes this.
  10. Larry

    Larry Chupacabra Rancher & Tumbleweed Farmer Premium Member GMOTM Winner Author

    Joined:
    Jul 18, 2000
    Posts:
    1,547
    Likes Received:
    1,431
    Location:
    A windy corner of a dirty street: Pueblo West, CO
    Build(s):
    1
    Yeah, I just made cable brackets too. Don't have access to any pictures at the moment but can try to get some tomorrow
     
  11. NTXJIMMY

    NTXJIMMY Now that's thinking with your dipstick JIMMY! Premium Member

    Joined:
    Oct 14, 2009
    Posts:
    556
    Likes Received:
    412
    Location:
    Whitewright, TX
    Build(s):
    3
    Thanks guys
    I think I have one or 2 of the 5.7 Vortec brackets laying around I will see what I can do with those

    Anybody have more pics I would greatfully appreciate them.

    I will start a build thread on this one as soon as I start on it and get done with my Jimmy.

    Right now gathering parts
     
  12. NTXJIMMY

    NTXJIMMY Now that's thinking with your dipstick JIMMY! Premium Member

    Joined:
    Oct 14, 2009
    Posts:
    556
    Likes Received:
    412
    Location:
    Whitewright, TX
    Build(s):
    3
    Wondering if this would work

    Holley 20-147
    Summit sells it for $33
    Just wondering if it would work with the 8.1 due to the angle of the throttle valve


    E7BED1F2-38DF-4886-84A6-990CFC6D5C28.jpeg
     
  13. Larry

    Larry Chupacabra Rancher & Tumbleweed Farmer Premium Member GMOTM Winner Author

    Joined:
    Jul 18, 2000
    Posts:
    1,547
    Likes Received:
    1,431
    Location:
    A windy corner of a dirty street: Pueblo West, CO
    Build(s):
    1
    Both bueno... the 8.1 has a three bolt throttle body
     
  14. Rick Capito

    Rick Capito Registered Member Premium Member

    Joined:
    Dec 7, 2017
    Posts:
    66
    Likes Received:
    116
    Location:
    Prescott,AZ
    And as Larry said in his article you'll need a throttle body spacer at least I did.
     
  15. Larry

    Larry Chupacabra Rancher & Tumbleweed Farmer Premium Member GMOTM Winner Author

    Joined:
    Jul 18, 2000
    Posts:
    1,547
    Likes Received:
    1,431
    Location:
    A windy corner of a dirty street: Pueblo West, CO
    Build(s):
    1
    Back home finally. Here are some cable bracket pictures from mine.

    This one is the K10. Both trucks use a Lokar TC-1000LS1U throttle cable
    [​IMG]

    [​IMG]



    Suburban
    [​IMG]




    Exactly, mine needed the throttle body spacers in order to route the cable in the most direct and smooth fashion as possible. Others have commended on FB groups they were able to use the L29 TB without a spacer but I haven’t seen pictures or how they’re routing their cables. They must be routing them very low and around the fuel rail with a ton of curves and potential bind spots
     
  16. NTXJIMMY

    NTXJIMMY Now that's thinking with your dipstick JIMMY! Premium Member

    Joined:
    Oct 14, 2009
    Posts:
    556
    Likes Received:
    412
    Location:
    Whitewright, TX
    Build(s):
    3
    Thank you guys for the info!
     
    79rustyk10 and Larry like this.
  17. Larry

    Larry Chupacabra Rancher & Tumbleweed Farmer Premium Member GMOTM Winner Author

    Joined:
    Jul 18, 2000
    Posts:
    1,547
    Likes Received:
    1,431
    Location:
    A windy corner of a dirty street: Pueblo West, CO
    Build(s):
    1
    Good news for those looking for alternatives for the 12558927 driver’s side high mount A/C compressor and P/S pump bracket. As many have you have found by now, that bracket has become extinct from GM parts for a few years now and used brackets are getting harder and harder to find every day.

    Well, necessity is the mother of all inventions! I’ve ran across a talented guy on one of the 8.1L Facebook groups that has created a nice fabricated bracket as an alternative to the 12558927 for use with the Saginaw Power Steering pumps and HT6 (or equitant) air compressors.

    Now, some people have reservations about fabricated accessory brackets compared to cast pieces but given the parts availability situation, a fabricated bracket looks pretty appealing to me! I’d also like to add that in the big rig world fabricated brackets are very much the norm even still today. In my world, we use fabricated brackets on Cummins L9 engines in our IC Bus RE series rear engine school buses to mount huge air compressor for HVAC, air compressor for brakes, alternators big as water melons and we never see issues.

    As a reminder this is what the 12558927 looks like
    [​IMG]


    Here is the Amos bracket…
    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]


    The next questions with will come to mind is the availability of the matching alternator bracket. As this moment, everything points to the fact GM is still stocking the 12559613 passengers side alternator bracket although Amos has plans to fabricate that bracket in the future as well (and possibly even alternative coolant crossover combinations). There is also the dual alternator bracket 12563070 that has been discontinued by GM although some people have stated a few of these brackets can still be found on dealers shelves from time to time.

    Lastly, keep in mind the water pump and crank pulley still must be changed to match this bracket configuration if you’re using an engine from a pick up truck. Part numbers for the water pump and pulley are listed on post #9 on the first page of this thread. Both of those are readily available

    If you’re interested in this bracket the contact to have one made is:

    Amos Garcia
    AmosPGarcia@gmail.com
    520-490-0580
    8.1l496vortec on Instagram
    Amos Garcia on Facebook

    :thumb:
     
    Last edited: Apr 6, 2019
    Rick Capito, Kay86K5, 72gmck5 and 4 others like this.
  18. Kay86K5

    Kay86K5 1/2 ton status Premium Member GMOTM Winner

    Joined:
    Mar 9, 2012
    Posts:
    3,753
    Likes Received:
    4,392
    Location:
    Emmett, ID
    Build(s):
    4
    I saw this on facebook too. I’m planning on picking at least one of these up from him
     
  19. Capt Ron

    Capt Ron Minus .7 liters Premium Member GMOTM Winner

    Joined:
    Nov 17, 2015
    Posts:
    1,700
    Likes Received:
    2,721
    Location:
    Lakewood Co
    Build(s):
    2
    I am once again a member of the 8.1 owners club! I picked up what appears to be a 2003 with a claimed 30k miles from a
    Schwan's truck. While reading one of ktmoutfront's build threads he mentioned having an 8.1 and I knew he had a cross country move coming up so me being the kind guy that I am I offered to take it off of his hands to lighten the load while moving. After some thought he got back to me with a price and the rest is history. It is missing the injectors and fuel rails so I am on the hunt for those.
    I really got to get better at taking pictures.

    IMG_20190504_133116627[1].jpg

    IMG_20190504_133140663[1].jpg

    IMG_20190504_133159096[1].jpg

    IMG_20190504_133233937[1].jpg

    IMG_20190504_133210316[1].jpg
     
    Last edited: May 5, 2019
  20. ZooMad75

    ZooMad75 #crawlabago Premium Member GMOTM Winner

    Joined:
    Apr 5, 2003
    Posts:
    5,440
    Likes Received:
    10,564
    Location:
    Pueblo, CO
    Build(s):
    1
    Nice. It's got the right brackets too. Good pickup. We were probably running north at the same time this afternoon. I was going up 105 instead of I-25 though.
     
    Capt Ron likes this.

Share This Page