5.3 Scout II

Discussion in 'The Skunkwerks' started by BO185, Jun 8, 2005.

  1. BO185

    BO185 High Wheeler

    Here's some of the info on the Gen III 5.3 swap into a International Scout II. It might help with other vehicles as well.

    This info covers the GM Gen III V8's: Vortec 4.8/5.3/6.0/6.2 and LS1/2/3/6/7/9. And is by no means complete It's just a guide and info for the cost benefit analysis for anybody thinking about the swap.

    RPO codes for Gen III/IV LS1,2,3, LQ4/9 etc...

    The list is for a Gen III truck engines. But the LS engines are the same basic engines.


    1) EXHAUST You will need stock F-body LS1 Camaro exhaust manifolds 1998-2002. The stock trucks will not fit the frame they kick out at the exhaust flange! I got mine for free a local shop had thrown them in a dumpster because they said they did not need them. Check E-bay, or locally. Don't pay more than 100 bucks more like 50 bucks for both! Oh, size at least dual 2.5'' back with a cross-over fwd of the transmission with (insert your mufflers here). Single exhaust will work I would do 2.5'' to muffler than a single 3'' or 3.5'' out. As for headers Longtubes are the way to go. But since nobody makes longtubes for the scout swap. I have been looking at some Jeep LT's for GEN III swaps in those they may fit with out mods. I have yet to see if they will fit though. UPDATE: Having yet tried I believe a set of F-body long tubes 98-2002 might fit.

    2)VSS The computer needs a Vehicle Speed Sensor (VSS) signal for shifting the 4L60E and to get the motor to idle right in certain conditions. If running a manual trans you need some type of VSS for the ECM as well for better economy and idle. The stock location for the VSS is in the transfer case on 4x4's. It uses the VSS for the computer and speedo. Options are the 1990 to 1991 NP241 right drop with VSS but you may have to change the ring and the sensor to the late model stuff just check to see if it has the 40 tooth ring on it. Just make sure that VSS is at the end of what ever gear reduction you have of the engine may idle funny and the trans not shift right when in low range! VSS information
    The engine can be tuned to run without a VSS but I wouldn't recommend it expect for off road use only. As it reduces and fuel mileage.

    3) Fuel The engine needs 60psi give or take to run. I made a custom tank out of Aluminum for the stock scout location and used the stock gm intank pump and sender truck pump for the same year as the motor. I had to shorten the sender float so it would fit the tank and read correctly. I wanted a little more than the stock 19 gals but the 33 gal is to big so the tank holds 25 gals. Options are a external pump mounted low on the frame rail with a return from the engine to the tank. The 2005 up truck fuel rails use a return less fuel system like the LS1 do, so you need a regulator like the Vette fuel/regulator or stock fuel sender. In the stock returnless fuel systems for the trucks the regulator is in the tank with the pump and sender. On the earlier truck manifolds just run a filter and a return line. Summit sells slip on fitting adapters to connect the rail to AN fittings.

    4) Emissions I don't run any kind of emissions on my engine. So if your state says you do than you most run cats and EGR valve. But if not than you can cap the EGR valve at the intake and exhaust and remove the valve on pre 03 engines the later engines don't have EGR on certain models. And I don't run cats or a purge canister for the gas tank. You most have some one remove the emissions codes in the computer or the check engine light will be on. O2 sensors the stock truck has four two in front of the cats (you need these) and Two behind the cats (can be removed and code turned off). The computer just uses those two behind the cat to see if the cats are working or not.

    5) Cooling I bought a universal Chevy style radiator from summit that fits the scout opening. I modified the stock GM truck hoses to fit the rad. There is a small hose than goes into the stock rad and a heater for the throttle body I removed for a cooler air intake. It Uses this to prevent throttle ice in cold air but round here it doesn't get that cold. Also on the LS motors you can cap the rear lines and just use the front steam ports. Fan I use an Electric fan because I mounted the engine low and the stock gm fan is to low plus the e-fan doesn't steal horse power! I also run a trans cooler and oil cooler under the AC evap.

    6) Computer and wiring I used the stock computer and had it modified with HPtuners to work for what I needed. It's reprogrammed for performance. You will have to go in to the computer and defeat the anti theft software (VATS) so the engine will run in the scout. VATS uses the stock gm ignition switch to tell if it's in the right truck or not! For wiring I interfaced the stock gm harness to my own home made harness for the dash with auto meter gauges. I also put a check engine light (yellow LED) in the dash and put an OBD II plug under the dash so I can plug up My laptop. Options are to interface the gm harness with painless universal. I would recommend pulling all stock scout wires if the are the original old ones not worth a fire! I will try to compile a list of codes to turn off and make a harness interface guide as to what pins do what from the computer I have see them on line but A good shop manual for the gm stuff as wire prints in them. Oh you must also wire the brake light switch up so the torque converter will lock and unlock. I also used the stock Gm Neutral safety backup light switch on the trans at the shift lever. Also if you get the under hood GM fuse block as well as the TAC box and gas petal, this will make swaps easier for DBW TB.

    Basically what can be removed or not needed

    -EGR: mounts in front of pass. head with a tube running from the exhaust manifold to the valve then into the intake behind the TB. This for 03 and earlier motors mostly.

    -canister purge valve/lines: These run from the charcoal canister to a valve above the drivers valve cover then into the intake on top.

    -Cats: catalytic converters you don't need them.

    -Rear O2's: These are mounted behind the cats (2 each) and tell the PCM if the cats are working or not. you don't need these.

    -Oil level sensor: It's on the pass. of oil pan. You can jumper the wires in the harness at that plug. I usually leave it hooked up.

    -TB heater:
    Coolant tubes in the TB that move coolant through the TB to heat it. Just remove the lines from the TB and reconnect underneath it.

    The harness can be reworked to remove these things and make it for a 3 or 4 wire hook up to the vehicle. Then have the PCM tuned to remove what you don't need.

    Sensor locations (Gen III truck motor)
    -MAP is on top of the intake, towards the rear.

    -Knock sensors are under the intake but the connector is just to the driver side of the MAP sensor on the intake. (Gen IV motors are on the each side of the block)

    -Coolant temp is in the front of the driver side cylinder head.

    -Oil pressure is right next to the Cam sensor at the back block behind the intake.

    -Low oil level mounted on the pass or oil pan

    -EVAP purge solenoid The cylinder sticking out of the intake right in back of the throttle body is the EVAP purge solenoid.

    -TPS and IAC are on the cable throttle body. IAC on top. DBW TB has no IAC.

    -MAF and IAT are combined in the MAF located on the intake tube.

    -Cam sensor Back of the block on Gen III motors and is mounted on the front of the timing cover on Gen IV motors.

    -Crank Trigger Located on pass. of block inboard of the starter. Gen III motors are 24x wheel and Gen IV are 58x wheel (save for the early LS2's 05-06 these were Gen IV motors with E40 ECM and 24x wheel's). Black color is 24x reluctor and grey one is 58X reluctor

    7) Engine mounts I used Advance Adapters universal small block Gen I adapters and weld to the frame and adapted the engine mount to fit the gen III with a plate. I was to lazy to make my own mount the AA stuff is great. The Gen I motors have Three mount holes on the side of the block. The GEN III has four. I weld a steel plate to their mount and used one hole and weld the rest to the plate and drilled the other holes and bolted all four holes to the engine, GRADE 8 Metric bolts are a must. I custom made the trans mount with a hump fro the front shaft.

    8) Driveshafts I used JB conversion slip yoke eliminator on the transfer case I run a cv front and rear. The rear shaft will be short with out the SYE like 24 inches but I gained 6 inches in the SYE conversion. Custom shaft rear and stock 86 blazer front lengthened a little.

    9) Air conditioner I used the stock gm 99 air compressor and adapted it to work with the scout stuff the compressor fits with just enough room to bolt the hoses on. I had to bend the stock hose to the run them right than adapt them to the IH stuff with adapters. it could still be use as trail air if you don't need the AC. Note the later Gen IV E38/E40/E67 ECM's won't control the a/c system. SO it to needs to be standalone if using 2007-up motor.

    10)Intakes The truck intake flow the same as the LS1 car and offers better low end over the car one. The LS6 flows better than the trucks but not enough to be worth swapping it out. The aftermarket FAST etc. flow really well but are expense! You can upgrade to a TBSS LS2 90mm TB truck intake or an LS2 90mm as well.
    The new L92 and L76/LS3 intakes will only fit the L92/LS3 square intake ports and won't fit the Gen III heads.
    Also the DBW intakes are alittle different than the cable ones as well with the PCV locations.

    11)Heads There are lots of choices now. From ported to stock. Stockers: The 317 stock 6.0L heads are based on the LS6 243 and flow pretty good. The 799 heads are basically 243. The L92 head will only fit a 4'' bore motor and will only work with L92/LS3 intake because of the different intake ports. YOu can add 243 to a 5.3l but it will increase CR as well. Then newer 5.3l actually come with 243 heads now.

    12)Oil Pans There are several stock pans to choice from for your application. LSx oil pans pictures and dimensions.

    13)Transmissions The Gen III/IV engine share the same SBC trans patterns as the early V8. So any SBC TH350/400/700r4 or Gen I 4l60 and 4l80 trans will bolt right up. You just need to correct flex plate and spacers for the earlier SBC trans. A spacer supports the torque converter nose. AND YES THAT'S THE WAY IT GOES!!! Some have even not even used the spacer. But, like i said it's to support the converter center.
    The Gen III converters for the 4l60 have a large center section than the Gen I and hence the dish. The spacers on the crank themselves are for the 4l80's with the 6.0ls behind them with flat flex plates.

    4l80 converter Note the middle used with flat flexplate and spacer on the crank

    4l60 Gen I/ 4.3L smaller center hub

    4l60/65/70 Note the larger center hub for the dished flex plate!

    Spacer from GM parts direct or local dealer
    GM PART # 12563532
    CATEGORY: Engine Flywheel
    PACK QTY: 1
    CORE CHARGE: $0.00
    GM LIST: $52.86
    OUR PRICE: $31.34

    GM PART # 12563533
    PACK QTY: 1
    CORE CHARGE: $0.00
    GM LIST: $6.86
    OUR PRICE: $4.06

    The later model 2007 trucks using the E38/E67 ECM's use a separate TCM for all transmissions. So you will need the TCM for the 4l65/70 and the 4l80 as well. GM did this because they need the new ECM to control things like VVT and AFM and the transmission controls really limit the computing power so they separated them.

    The new 6l80/90 will work, the TCM is internal to these, but the limiting factor with these is they require a 58x relutor wheel and new E38/E67 ECM controller. So these are only options for the Gen IV's now. Till some one makes a standalone for the TCM inside the trans.



    The Gm engine Gen IV Vortec L92 6.2L /L76 6.0L and LS2/3/7. The basic difference's of the new motors are the placement of the knock sensors on the side of the block, a 4x cam sensor mounted in the front of the cam now, some have VVT, AFM, and a 58x reluctor wheel (crank trigger). These engines are the same as the Gen III save for these changes and most parts inter change from both family's.

    That's just half of the info I have found, and will try to answer your questions! Anything to help!


    Attached Files:

    Last edited: Nov 16, 2009
  2. Eric Underriner

    Eric Underriner Binder Driver

    HACK THE FRAME---MAKE IT FIT!!! Keep us posted on the progress--those heads flow great so throw in a rowdy cam.
  3. wtrskiscout

    wtrskiscout Farmall Cub

    I have seen a Scout II with a Vortec installed.
    I don't have any pictures of more specific information, sorry.
    The truck was in the shop at Anything Scout in San Jose, CA.
    I don't think that they had installed the powertrain specifically, but the truck was there for some other work.
    This might not help you much, but I know that it can and has been done before.

    PS. I was very jealous of the owner. It was a very clean install and a great looking truck.
  4. BO185

    BO185 High Wheeler

    It fits the frame pretty good and my buddy gave me some 2000 F body exhaust manifolds this weekend.There not as wide as the trucks manfolds.
    And the fit like a champ. I thought about a cam but most cams made are for the LS1's which is a larger displacement and evern bigger heads. But I may make some thing work. But it is 300 horse bone stock at the fly well. with a flat toque curve.
    Last edited: Jul 20, 2005
  5. BO185

    BO185 High Wheeler

    Pictures of a Vortec 350 before the Vortec 5.3

    Last edited: Aug 13, 2006
  6. littlerock_82

    littlerock_82 Farmall Cub

    jegs and gm performance parts sells header flanges to make custom headers to fit the gm 5.3. good luck.
  7. BO185

    BO185 High Wheeler

    Here's some pictures of the Vortec 5.3 mocked up in my Scout II. It fits great with plenty of room! Don't have the finished Pics yet.


    Last edited: Aug 13, 2006
  8. mpowers

    mpowers Farmall Cub

    that thing looks tiny in there.
  9. BO185

    BO185 High Wheeler

    Well at least it ways less than the 345 that came out! I loss like 500 pounds during the swap!
  10. IHWillys

    IHWillys Farmall Cub

    I like what you're doing there. That will be a very nice power plant for the Scout. Light, powerful, decent mileage.

  11. BO185

    BO185 High Wheeler

    Last edited: Mar 23, 2006
  12. crazyscoutproject

    crazyscoutproject Farmall Cub

    I have a 72 scout 2 and just bought a vortec 5.3 and 4L60E for it. The np 241 that your running is right hand drop and out of a 1990-1991 chevy? Did it bolt to your 4L60E or did it require a conversion? How much effort did your driveshaft work require? Any ideas on all of this or additional thoughts that you think i should know would be great.
  13. BO185

    BO185 High Wheeler


    The NP241 Bolts to the stock transfer case adapter for the late model 4L60E. Is the transmission the 4x4 transmission it will have the short output shaft and a transfer case adapter on it!

    For the front depending on if it's SOA I used the stock Mid 80's blazer front drive shaft with the CV joint at the top. You will need to modify it to fit what ever you suspension is. This can be done cheaply for like $100 bucks most places. For the back I bought a JB conversions SYE for the NP241 and Had a custom driveshaft made with a CV at the top. I would recomend the SYE on a 100'' WB Scout II

    I would use aftermarket gauges completely. It will be easier to wire not to mention more acurate. Plus you will need a Check engine light and ODB II port under the dash.
    Any more questions let me know.

    BTW those interested in all things GEN III related.
    I just got a 6.0L for X-mas! Plans include a stoker kit to make it a 408ci torque monster plus new cam as well. I plan to dyno the engine and looking for 400HP and 450TQ on all motor small block.
    I will dyno it in the truck after the swap as well to see the total lost of the drivetrain is.
  14. crazyscoutproject

    crazyscoutproject Farmall Cub

    thanks for the great info. I now have some new questions, you mentioned a JB conversions SYE and i dont know what that means or where to find out what it is. Im new to working on trucks and have undertaken a very ambitious project so bear with me if you would. Also, what is a ODB II port and where do i get one? thanks
  15. crazyscoutproject

    crazyscoutproject Farmall Cub

    sorry, another question, for the np 241 case, does it have to be out of a 90-91 truck, or could it be from other years?
  16. crazyscoutproject

    crazyscoutproject Farmall Cub

    ok....last one for now i promise, you said you built a custom fuel tank, is that a must? or can i just get an external pump and return line?
  17. justscoutin

    justscoutin Binder Driver

    the right hand drop 241 comes specifically from a 88-91 k5 blazer or suburban.
  18. BO185

    BO185 High Wheeler

    Because the NP241 use a slip yoke on the back if you have a light on the scout you may need to install the SYE (Click link below). Because the rear drive shaft wil become real short without doing it because of the swap.

    ODB II is the what late model vehicals use to read the trouble codes and interface with the computer. It's monted under the dash on most cars. Shoud come from the donor truck or buy the plug at a junk yard and wire to the correct computer pin #. Check out LS1tech.com for info on the GEN III chevrolet engines.

    Slip Yoke eliminator (SYE)
  19. BO185

    BO185 High Wheeler

    Yes for one because you need the Vehical Speed sensor (VSS) to shift the 4L60E transmission correctly. The VSS replaced the speedo sender in late 80's of fuel injection and such. Two it's the only trans that they make a SYE for NP208 they do not make one for it for. If you don't use the SYE than you could use a NP208 and convert for the VSS.

    Yes, you can use an external pump rated at 58 psi min. and just ust the stock tank. I would put a filter before and after it as well.
  20. BO185

    BO185 High Wheeler

    the trucks are left hand drop on those years because of the body stule change. You best bet is to go to a local salvage yard and tell them you need a 1990-91 blazer or burbin' NP241 transfer case with the VSS. I paid like 300 bucks for mine. Which is not bad B/C they are hard to find!

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