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LSx conversion questions

This is a discussion on LSx conversion questions within the LS2/LS3/LS4/LSx forums, part of the Vehicle Specific category; Hey fellas. So got out of the diesel game and looking to do a variant of the LS swap. Right ...

  1. #1
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    LSx conversion questions

    Hey fellas.

    So got out of the diesel game and looking to do a variant of the LS swap. Right now thinking either a LM7/LS3 depending on price into a Chevy Apache. But that could be some time off.
    Some questions I have around different approaches/options -- basically around wiring/modules to link everythign together.
    Appreciate some clarification or insight.


    ************************
    Approach 1 - Full EFI harnessed Conversion (donor harness worked or aftermarket)
    ************************

    LSx engine and full wiring harness (ECM/PCM) and DBW pedal and TCM. Painless aftermarket harness or Harness reworked and wired accordingly.
    eg

    painlessperformance.com/webcat/60524
    or
    painlessperformance.com/webcat/60221
    or
    ebay.com/itm/LS1-5-3L-6-0L-Engine-Wiring-Harness-and-PCM-Stand-Alone-Modification-/252448487636?hash=item3ac71a38d4:g:tMoAAOSwCypWmWS X&vxp=mtr

    4l60E/4l65E engine with valve body work.

    Essentially those are the main components required to make this work in a classic (accesories, fuel supply, gauges etc withstanding)

    Between $300 and $900 in wiring/modules if you have the ECM/PCM and TCM etc from donor vehicle


    Q1) Is there anything I am missing or not understanding here.

    - - - Updated - - -

    ************************
    Approach 2 - Full EFI aftermarket conversion (aftermarket harness/ECU/PCM/TCM)
    ************************

    Same as above ........ but with regard to the harnesses you now run something like

    fuelairspark.com/fas/gm-ls-ez-efi-2-0tm-self-tuning-engine-control-kithtml/ EFI and ignition control. approx $2k
    or
    superchevyperformance.com/19171130_LSX_Ignition_Controller_p/19171130.htm plus EZ EFI 2.0 EFI and ignition control) approx $2k

    then

    summitracing.com/parts/tci-302820 (transmission control) ~$600


    So around $2500 additional to the engine/trans costs (then add accessories etc)


    Q2) - Any advantage in going aftermarket here ??? Its pricier and then you have a bunch of compeonents working together. you would have support from that one company - but you know

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    ************************
    Approach 3 - Non EFI aftermarket conversion (carburated)
    ************************

    eldebrock EDL-91238 $540

    1413-edelbrock-performer-series-eps-800-carb $427

    summitracing tci-302820 (transmission control) ~$600

    So around $1500 addtional (then add accessories etc) but now you are drive by cable.

    Q3 ) What is the value in going this route over option 1 - unless your a carb fan ?

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    Q5) What are the best "bang" for buck heads on a LSx 5.3 or 6.0 engine if you are planning ~400-450 hp. Some of the heads are pricing out at $1200 each.

    Q6) At what point do you need aftermarket head studs Rule of thumb ? NA and FI.

    Thanks guys
    Have read and continue to read the books and forums - but these are some questions I have that aren't clearly answered.

  4. #4
    Spaz is My Mentor SMWS6TA's Avatar
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    Navy Blue Metallic
    98 T/A w/a little mods...

    Each route you take has pros and cons as well as costs. What's you end goal? street, track, cruiser?
    There are many ways to skin this...

    For a 6.0L:
    High output/flow look to LS3 heads. 6.0"s are the only GEN III/IV blocks that can use both cathedral (LS1/2 style) or rectangular (LS3 style) heads. Just need to match it with the intake, TB & injectors. LS3 will not work with 5.3 blocks. Ported & polish 243 heads can't go wrong if you stay cathedral, plus Trickflow has some bad ass heads for cathedral in both 5.3/5.7 & 6.0L

    5.3L - heads depends on what you're building. For boost (FI) everyone I know that has done a budget build running boost is using 317 heads. With aftermarket comes a need for deep pockets.


    Studs - always ARP. Make sure a machine shop verifies if it needs a line hone for the crank.

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    Quote Originally Posted by SMWS6TA View Post
    Each route you take has pros and cons as well as costs. What's you end goal? street, track, cruiser?
    There are many ways to skin this...

    For a 6.0L:
    High output/flow look to LS3 heads. 6.0"s are the only GEN III/IV blocks that can use both cathedral (LS1/2 style) or rectangular (LS3 style) heads. Just need to match it with the intake, TB & injectors. LS3 will not work with 5.3 blocks. Ported & polish 243 heads can't go wrong if you stay cathedral, plus Trickflow has some bad ass heads for cathedral in both 5.3/5.7 & 6.0L

    5.3L - heads depends on what you're building. For boost (FI) everyone I know that has done a budget build running boost is using 317 heads. With aftermarket comes a need for deep pockets.


    Studs - always ARP. Make sure a machine shop verifies if it needs a line hone for the crank.
    End goal is really street/DD.

    On the engine build though ....

    Lets say you build a 5.3 ....... so ballpark $1k for good condition. Then add on $400 per head. Now a $200 cam, springs and retainers.
    your at a ballpark $2k ........ versus buying a 5.7 true LS at say $2.5k.

    So wondering where the savings is here unless you just run the 5.3 as is (meaning ~300HP versus closer 400 hp).

    Seems like just better getting a LS1.

    The 6.0 definitely looks interesting eg LQ9 at 345HP - so thinking with a cam and heads closer 400. But these are priced higher also.

    Guess the best way to phrase the question with so many options as a base would be.........

    1) most cost effective wiring/interoperability with engine
    Rework of existing harnes/PCM and use DBW ...................... ballpark $500-$1200

    2) Engine
    ???

    Essentially bang for buck for HP on a street/DD.....circa 400hp. But able to grow.

  6. #6
    Spaz is My Mentor SMWS6TA's Avatar
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    Differences between a LQ4 & 9 are just the pistons. 9's are flat top and 4's are dish. 9's have higher compression ratio over the 4's.

    Newer 9's have the 243 or 799 heads (Both same casting, true 243's off a Z01 Vette have the Sodium filled valves, if off a truck they are regular valves like the 799's. You have to weight them to know for sure which valves you got.)



    Best bang for the buck IMHO is a 6.0L. Wither you stay stock or bore it out you have plenty of potential over the 5.3 or 5.7 blocks. 6.0L hold more boost, can be bored out more, handle more N20, and are all around stronger then Aluminum.

    I paid $250 for my 6.0L block. It had hydrolocked and only needed to be bore 0.005". I could have gone 0.030" over and made it a 408, just ran out of $$ and needed it up, so I'm happy for now with it being a 403ci.
    http://www.ls1.com/forums/f7/my-6-liter-build-174257/

    http://www.ls1.com/forums/f8/my-8-8-rear-build-165553/

    6.0L Block - Forged 403 built, breaking it in , Polluter Stg3 Cam, FAST 102mm Intake, NW102 TB, MSD wires, NGK TR6 plugs, Truck Coil Packs, LS3 Fuel Injectors, CC Pacesetter LT Headers, TS&P ORY, QTP e-Cutout, Magnaflow Muffler, 104mm Air Lid & Line Lock, Catch Can, Stage 2 T56 w/Viper shaft, PRO 5.0 Shifter, Tick MC, Monster Stg 4 Clutch, QT SFI BH, MWC DSL, UMI: SFC, PHB, LCA's, LCA Relocation Brackets & TA, Hotchkis Springs (1" Drop), YR1 Snowflake Wheels wrapped in NT555 tires & Custom Fab Ford 8.8 rear w/4.10 Yukon Gears, WSQ Hood, 3"CM Strange Eng Drive Shaft.

    Horsepower never lies, but is often lied about!

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    Hey guys.
    So some more questions ...... been researching on non engine stuff .... back to some engine stuff.
    This is for a conversion into a 57 Apache.

    How to determine correct offset/design of motor mount to ensure correct alignment of block and transmission in both the engine bay and driveline angle.
    How to determine if I can fit a certain transmission in. Meaning would a 4L80E even fit in my truck ..... and how to work that out. There are some schematics floating around ...... but this partly depends on item #1 correct ?

    A lot of the used engines for sale have obviously been wrecked. What tests would you do to get best idea engine is ok. Obviously compression and hearing it running (where possible) - but what else ?

    VVT - do I want an engine with VVT - can it be turned off - do I want to turn it off on said build ?

    Are there any engines I want to stay away from on this conversion ? For what reason - eg VVT .... *shrug*

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