L18 8.1L swap resource thread

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

  1. Larry

    Larry Chupacabra Rancher & Tumbleweed Farmer Premium Member GMOTM Winner Author

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    Yeah, a grand (or less) sounds decent for an L18. The G-van L18 has the correct accessory brackets for ease of swapping into older trucks too (providing you want to run A/C). L18’s were not known to have piston slap like the early Gen III small block. 120K isn’t many miles in the grand scheme of things. I would be curious about the maintenance history on this engine. Both my 8.1Ls rattle but the noise is the trans release bearing more than anything, which would not be the case with a G-van with a 4L80E.
     
  2. -stew-

    -stew- Banned

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    Synthetic oil changes every six months since it was new. In the winter time this truck was started in the morning, and not shut off until the end of the day. I'm sure this truck has run 20 hours straight many, times. I'd like to get into the pcm with and see if there's an hour meter. And it's worked every mile it's ever driven. The van was rated for 12k pounds and scaled in at 14+k pounds since new.
     
  3. -stew-

    -stew- Banned

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    Van is currently on the auction block. Ends Monday morning. Wish me luck!
     
  4. kcpeltz

    kcpeltz Registered Member Premium Member

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    Does anyone know anything about converting the 8.1ls that were in kodiacs running on lp back to gas?
     
  5. Larry

    Larry Chupacabra Rancher & Tumbleweed Farmer Premium Member GMOTM Winner Author

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    GM did not build any propane equipped trucks or propane specific 8.1L engines. Most of those propane fuel 8.1L engines were found in Schwan’s Foods trucks and were equipped with an aftermarket Landi Renzo or Baytech propane system. Those can be switched back to gasoline by replacing the fuel rail and injectors.
     
  6. kcpeltz

    kcpeltz Registered Member Premium Member

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    I knew they were conversions, didn't think to put that.
    So just fuel rails and injectors? I assume it's the same ECM,just with a propane tune? And it just needs to be reprogrammed for a normal tune.
     
  7. Larry

    Larry Chupacabra Rancher & Tumbleweed Farmer Premium Member GMOTM Winner Author

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    The propane converted engines I’ve seen use an independent ECM to run the propane system and the engine ECM is left original. In fact, the company I work for built around a 1,000 UPS trucks with 4.8 and 6.0L engines for Canadian market running on liquid propane. Those actually run two propane ECMs per truck as the ECM’s could only handle 4 cylinders so a V8 required 2 4 cylinder ECMs to make them work. Quite the mess.

    Regardless, you’d want to have a tuner rework the 8.1L ECM anyway to remove Torque Management and do any other stuff that you want changed anyway.
     
  8. Larry

    Larry Chupacabra Rancher & Tumbleweed Farmer Premium Member GMOTM Winner Author

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    I was talking to Larry from RayLar Engineering (Corvette Shop San Diego) this afternoon and found he has a neat hotlink to this thread on CK5 posted on his website. For those unfamiliar with RayLar, they are the experts on all things related to building big power 8.1L engines for marine, RV, pickups and hotrods. Pretty cool :waytogo:

    I am splurging on some RayLar goodies for the 8.1L engine that I am currently building for the Polar Bear Suburban. Can’t wait to see how an 8.1L runs on a decent cam as the stock stick is about as flat as a broom handle. They run great with the stock cam....should be very impressive with the RayLar cam. Stay tuned on that :popcorn:

    [​IMG]
     
  9. y5mgisi

    y5mgisi 1 ton status

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    Nice! What I wouldn't do to have a few extra bucks freed up!
     
  10. IGOR

    IGOR 1/2 ton status Premium Member

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    I will be curious to see how that cam works out for you Larry! Raylar has some neat (& $$$$$$) stuff.
     
  11. gonefishin

    gonefishin 1/2 ton status Premium Member

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    Which cam are you going with? I am considering their bp203 cam. I would love a set of their aluminum heads and to have my intake ported
     
  12. Larry

    Larry Chupacabra Rancher & Tumbleweed Farmer Premium Member GMOTM Winner Author

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    Me too! Boy am I glad I decided to throw a cam in this engine! Let me tell you why….. This engine was a warranty core that has been laying around for 7 to 8 years. The causual failure was the oil pump drive, which breaks the drive shaft when the drive locks up. The pump drive basically takes place of the distributor where it supports the top side of the oil pump drive shaft. Same design as a 6.2/6.5L diesels. Back around 2006/2007 these oil pump drive failures were pretty common due to a supplier issue and the drives were on intergalactic back order so many engines were swung to avoid Lemon Law for days out of service. Anyway, knowing this engine had suffered the oil supply issue I dropped several rods and mains. All of the bearings looked great so I hoped the cam bearings would be too. Then I decided to add the RayLar cam and when I yanked the old cam I found the cam bearings were toast! They have huge burn out marks on them, especially the center bearing. They did not spin in the bore but the surface of the bearing look like crap. So it is a damn good thing I decided to install a RayLar cam otherwise I wouldn’t have known the cam bearings were toast until I fired it up and found low oil pressure. Also found one phuckered up roller lifter as well. The roller won't even roll till you tap on it on the bench.

    The bitch of it is now is finding all the bits and pieces. The rod nuts are one time use only and so far I can only find 5 new nuts. I still need 11 more and GM has them on a 8 week lead time. Hopefully, I can find some on dealer’s shelves. I see Scoggin Dickey has some but they want a left nut for each rod nut. Lifters are easy to come by on Ebay but I played hell finding the right cam bearings as the Sealed Power M1404 (?) bearings Napa lists are not right. GM actually lists 3 different bearing part numbers to make up the 5 positions. The Sealed Power cam bearing kit uses one bearing for each position. That may have worked out fine but I don't want to take my chances running a high dollar camshaft on questionable aftermarket cam bearings.

    12508996 Front cam bearing behind timing chain
    12508997 Position 2 and Rear
    12508998 Position 3 and 4

    I also bought a set of head gaskets, 5 rod nuts and all of the seals/gaskets from work but I still need to buy head bolts providing we remove the heads while replacing the cam bearings. We’re hoping we can sneak the cam bearings in without yanking heads to pull pissers out of the way. If we end up pulling pissers at least I have the head gaskets here if we need them. We’ll see! I was hoping to get this engine installed over Christmas but this latest delay skewed that plan. Prolly be sometime the first quarter of 2015 by the time it is installed.

    Oh, I also got a set of shortly Sanderson headers for it too. I am really anxious to see how it runs with a cam and headers compared to the blue trucks stock 8.1L. I am a 100% header hater so I hope these Sanderson’s make me a lover because I haven’t found a friggen header that I ever liked. I hate the leaks, burnt wires and fried starter motors that headers are so often responsible. We see how these work out. The headers on the 396 on my little hot rod 68' GMC have pretty much ruined me of headers :haha:


    Oh, me too. I would love a set of their heads and a reworked intake. RayLar Larry talked me in to a 202 cam as I wanted low end grunt with a strong midrange pull as well. The 201 is a major stump puller according to Larry at RayLar. It sounds like the 203 and greater are more hot rod cams, which would be cool but I believe those require an $adjustable valve train$ and possibly different springs. I don't even want to mess with adjustable rockers....the 396 in the '68 ruined me of that BS too. It is so nice just to torque a rocker bolt down and walk away like late model 7.4 and 8.1Ls.
     
  13. offshore

    offshore Registered Member

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    I have no automotive experience with Raylar but I have installed their Marine parts including a couple of full kits, heads, cam, intake and I can tell you the power gain was always as promised. Nice Quality stuff!
     
  14. Mark1968

    Mark1968 1/2 ton status

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    So I suppose if we are shopping for a motor we should find one as complete as possible.
     
  15. Ten_Bucks

    Ten_Bucks 1/2 ton status

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    Larry, just wanted to say congrats on your K10 being featured in the latest issue of Petersen's 4 Wheel magazine. Your truck looks great!

    Scott
     
  16. Larry

    Larry Chupacabra Rancher & Tumbleweed Farmer Premium Member GMOTM Winner Author

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    Thank you Scott! I know I was pretty excited about it.. so much so that I bought this when they called to offer the plaque for $255 :laugh:

    [​IMG]
     
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  17. Ten_Bucks

    Ten_Bucks 1/2 ton status

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    That plaque turned out really nice. When my rig was featured in an issue of Four Wheeler a few years ago, I did the same thing. I plan on hanging it up when my wife and I get our house in Nevada next year.

    Scott
     
  18. y5mgisi

    y5mgisi 1 ton status

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    Awesome!
     
  19. Larry

    Larry Chupacabra Rancher & Tumbleweed Farmer Premium Member GMOTM Winner Author

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    Cool. What issue was yours in? I'll have to dig that mag out. Congrats to you too :waytogo:
     
  20. Ten_Bucks

    Ten_Bucks 1/2 ton status

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    I dont remember which month, but it was a 2012 issue.

    Scott
     

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