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86 k5 4x4 6.0 swap discussion

rileymurph41

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Ok everyone. My 454 just took a dump and I happen to have a LQ4 6.0 with a 4L60E ready to go from my Yukon. Have the complete Yukon. Anyone ever done a swap? Curious as to what issues I will run into like motor mounts, crossmembers, power steering pump lines, radiator, blah blah. Blazer has a 4L80E already in it. Looking for some tips and if anybody has an idea of a specialty parts list that would be great. Thanks everyone!
 

ZooMad75

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It's been done quite often around here. The basics needed are adapter mounts, harness (reworked original or new aftermarket stand alone) stock truck manifolds work for the exhaust. The fuel pump needs to change for a unit capable of delivering 55-65 psi. Delco ep381 is a common pump used that replaces a stock tbi pump. Speaking fuel, you'll need a tbi tank and sender.

There are part numbers galore in multiple threads on this site. My build thread has what I used when a ran a 5.3 in mine, but it's a very common swap now. Search is your friend here.

Now having said that if you are used to the low end torque your 454 put out you are gonna be disappointed with the 6.0 and the same gearing. They are great engines don't get me wrong, but they don't put torque down at low rpm. They do it a 2000 rpm and up. The fuel injection is worth doing it for sure, but just keep the low end torque in mind when you are thinking about the swap.
 

rileymurph41

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It's been done quite often around here. The basics needed are adapter mounts, harness (reworked original or new aftermarket stand alone) stock truck manifolds work for the exhaust. The fuel pump needs to change for a unit capable of delivering 55-65 psi. Delco ep381 is a common pump used that replaces a stock tbi pump. Speaking fuel, you'll need a tbi tank and sender.

There are part numbers galore in multiple threads on this site. My build thread has what I used when a ran a 5.3 in mine, but it's a very common swap now. Search is your friend here.

Now having said that if you are used to the low end torque your 454 put out you are gonna be disappointed with the 6.0 and the same gearing. They are great engines don't get me wrong, but they don't put torque down at low rpm. They do it a 2000 rpm and up. The fuel injection is worth doing it for sure, but just keep the low end torque in mind when you are thinking about the swap.
My 454 was built. But I just dynod it and got 230hp and 300 torque to the rear wheels. Something is going on with it and I think the 6.0 will do just fine. Thanks though! I’ll go check out your build thread! Did you have to relocate that front crossmember?
 

ZooMad75

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My 454 was built. But I just dynod it and got 230hp and 300 torque to the rear wheels. Something is going on with it and I think the 6.0 will do just fine. Thanks though! I’ll go check out your build thread! Did you have to relocate that front crossmember?
To answer your question, no the front cross member stayed put on mine. We left my 5.3 in the stock location for the original small-block so there were no issues with the cross member other than one cast nub on the front of the driver side that needed a little filing to clear. That allowed the trans to stay in its normal spot and left the driveshaft lengths stock.

As far as the 454 vs 6.0 goes, the difference is where the torque is made. The 6.0 is better than the 5.3 I had, but not by a huge amount (stock vs stock). But the issue at least was for me was magnified by the heavyweight of my truck, the less than optimal gearing (4.10's with 35's) for the tires I have, and finally the addition of the camper for aero drag. When my K5 was first finished with the 5.3 it was peppy, quick, and fun to drive. But loaded down with gear for two big dudes for a week of travel/off-road fun the load killed the pep and climbing mountain grades had me whipping it hard to maintain speed. The camper made the issues more noticeable because it gained weight and drag. I ran it for 5 years, 3 with the camper. I had to retrain my brain how to drive it. Mostly it was not to be afraid to rev the snot out of it when the need came up. Climbing mountain passes required a heavy right foot and gear down to keep the rev's up above 2500 and higher to keep the little 5.3 in its torque curve. It handled the beating without issue, but it's still unsettling for an old school guy like me to let the engine wind out at 3000-5000 rpms for extended stretches.

In the end, I had planned on going to a big block at some point. The camper kind of requires it for me. That and my location has me climbing into the Rockies for a lot of my exploring. So the 5.3 got pulled for an 8.1 and I'm not looking back. But everybody's needs are different for sure. If you have more optimized gearing for your tire size the effect of the lack of the low-end torque isn't as much. Even going deeper on the gearing wouldn't hurt with the LS as it would keep the engine higher in the meat of the torque curve.

Here's the other dirty secret. Fuel economy. Because the LS is getting spun to higher RPM to deliver the torque you are using more fuel. Everybody thinks the LS engines are going to net much higher fuel economy, but unless you are running close to stock size tires and fairly light you won't see crazy high fuel economy. I had seen as high as 16 mpg average without the camper, normal running around dropped to 14 mpg. The camper dropped it more between 11-12mpg. The 8.1 in the same type of driving gets the same kind of mileage. Plus it's doing it without getting wound up over 5,500 rpm to get up to speed or pass.
 

rileymurph41

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To answer your question, no the front cross member stayed put on mine. We left my 5.3 in the stock location for the original small-block so there were no issues with the cross member other than one cast nub on the front of the driver side that needed a little filing to clear. That allowed the trans to stay in its normal spot and left the driveshaft lengths stock.

As far as the 454 vs 6.0 goes, the difference is where the torque is made. The 6.0 is better than the 5.3 I had, but not by a huge amount (stock vs stock). But the issue at least was for me was magnified by the heavyweight of my truck, the less than optimal gearing (4.10's with 35's) for the tires I have, and finally the addition of the camper for aero drag. When my K5 was first finished with the 5.3 it was peppy, quick, and fun to drive. But loaded down with gear for two big dudes for a week of travel/off-road fun the load killed the pep and climbing mountain grades had me whipping it hard to maintain speed. The camper made the issues more noticeable because it gained weight and drag. I ran it for 5 years, 3 with the camper. I had to retrain my brain how to drive it. Mostly it was not to be afraid to rev the snot out of it when the need came up. Climbing mountain passes required a heavy right foot and gear down to keep the rev's up above 2500 and higher to keep the little 5.3 in its torque curve. It handled the beating without issue, but it's still unsettling for an old school guy like me to let the engine wind out at 3000-5000 rpms for extended stretches.

In the end, I had planned on going to a big block at some point. The camper kind of requires it for me. That and my location has me climbing into the Rockies for a lot of my exploring. So the 5.3 got pulled for an 8.1 and I'm not looking back. But everybody's needs are different for sure. If you have more optimized gearing for your tire size the effect of the lack of the low-end torque isn't as much. Even going deeper on the gearing wouldn't hurt with the LS as it would keep the engine higher in the meat of the torque curve.

Here's the other dirty secret. Fuel economy. Because the LS is getting spun to higher RPM to deliver the torque you are using more fuel. Everybody thinks the LS engines are going to net much higher fuel economy, but unless you are running close to stock size tires and fairly light you won't see crazy high fuel economy. I had seen as high as 16 mpg average without the camper, normal running around dropped to 14 mpg. The camper dropped it more between 11-12mpg. The 8.1 in the same type of driving gets the same kind of mileage. Plus it's doing it without getting wound up over 5,500 rpm to get up to speed or pass.
I would love the do an 8.1. That’s a beast! I have 3 other vehicles with 6.0 in them right now as well as my wakeboard boat. I’ve been super happy with em. I may even swap the beads to 6.2 heads and throw a cam in this motor as well. We will see. Good to know the crossmember didn’t need to be moved. I don’t think this swap will be that big of an issue. Did you power steering lines adapt to the old rack and pinion? What did you do with your fuel system? I have a return system now that can be gauged down or up to 90 psi
 

ZooMad75

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The stock power steering lines bolt right up to the pump since they use the same metric fittings.

I used the stock tbi fuel lines up to the filter. From the filter forward I used lines from a workhorse rv that are no longer available. The 6.0 runs at 55-65 psi so you'll want to regulate it down to that level.
 

rileymurph41

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The stock power steering lines bolt right up to the pump since they use the same metric fittings.

I used the stock tbi fuel lines up to the filter. From the filter forward I used lines from a workhorse rv that are no longer available. The 6.0 runs at 55-65 psi so you'll want to regulate it down to that level.
That’s great to know! I’m actually regulated down to 65 psi for the big block right now. It’s a return system though so I don’t know what the 6.0 needs. Thanks for the info! It’s actually looking like it’s not a terrible project.
 

ZooMad75

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That’s great to know! I’m actually regulated down to 65 psi for the big block right now. It’s a return system though so I don’t know what the 6.0 needs. Thanks for the info! It’s actually looking like it’s not a terrible project.
You are in the right zone at 65psi. However, if it's a return-style system or not depends on your LQ4. GM moved to a returnless system on the trucks in the mid to later 2000's. Pretty easy to tell by looking at the fuel rail. The return system will have two fuel line connections with a pressure regulator on the rail, where the returnless will only have one fuel line connection at the rail.
 

rileymurph41

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You are in the right zone at 65psi. However, if it's a return-style system or not depends on your LQ4. GM moved to a returnless system on the trucks in the mid to later 2000's. Pretty easy to tell by looking at the fuel rail. The return system will have two fuel line connections with a pressure regulator on the rail, where the returnless will only have one fuel line connection at the rail.
It’s an 04 LQ4 so I would have to modify the fuel delivery system I guess. Bummer I just dropped the tank and put in a new pump/sending unit and tig welded the vent in
 

82OilBurnr

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Hey Riley, I'm Brian. I'm currently in the home stretch of a LQ4/4L80e swap into my 82 Jimmy which came with a 6.2 diesel. This has been a marathon, no sprint. It's been difficult to find an easy way to do everything because I'm just a weekend mechanic and have no fab tools nor fab skills. I wished that I could find a detailed writeup with part numbers like @Larry did for an 8.1L swap. Here is my good deed of the day:

A lot of my experience has been trial & error and I have made a fair amount of returns for parts I bought that I later realized would not work for my setup. Summit Racing has been great. My goal with the build has been to use as many off the shelf parts as possible as I intend to keep this truck for a long time and want to be able to buy replacement parts should the need ever arise.

Please keep in mind that my build is not a budget build. While I am conscious of the price of all this stuff, I want a badass rig that I'm proud to say I built myself and can maybe pass down to my kids someday. Plenty of guys on here have done this for less money and with more creativity.

Engine Mounts:
With the right mounts, the engine bolts right in with no clearance issues with the firewall, or the engine crossmember. I used ICT Billet 4wd Squarebody LS swap mounts (Mfr. #: 5510-KIT003EM) which come with new clamshells, rubber inserts and all hardware. I had already cleaned & repainted the factory clamshells so I went with an Energy Suspension poly insert. Once I fire this baby up, I'll be able to tell if the clearance for the trans dipstick and the clearance between the driver side cylinder head and firewall are enough or if some trimming of the firewall is necessary. As it sits, there appears to be decent clearance.

Exhaust:
The whole reason I bought a 6.2 truck was for the smog exempt title so I can beef this thing up eventually (I'm in CA). Because of the lack of smog, I went with Schoenfeld squarebody "4x4" LS swap headers (Mfr. #: 1302LS1-C). They fit nice and bolt right in. The O2 bung on the driver's side is too close to the rear leaf shackle so I'll need to have it plugged and have bung welded into the top of the collector. My 4L80e also has the long shaft for the shift linkage so I'll have to swap that out for the shorter shaft in order to clear the header collector.

Electrical:
Wiring seems basic enough (and I know nothing about wiring other than + & - ). The guy I got my engine & trans from hooked me up with a re-worked harness and a base tune on the ECM. Not at all neceassary but may provide peace of mind would be a new chassis harness which you can find from multiple vendors. Maybe I'll do this someday if I strip the truck for a re-paint.

Fuel System:
Fuel was quite a research project as everyone on these forums seems to have some mechanical expertise and/or experience working on GM trucks. I found this really cool thread where the author used a late-model GM fuel pump and a Vaporworx fuel ring to apply factory reliable fueling to our old-school trucks. (http://67-72chevytrucks.com/vboard/showthread.php?t=693077) Again, I wanted a bolt-in solution so I ordered a new 31-gallon tank from RockAuto with new straps, vent & fill hoses. You can re-use your stock tank if it's in good shape. When I pulled my 6.2, the fuel in the lines & filter was opaque/orange so I can only assume the tank is full of rust & 40-years-worth of other crap. Better to just start new. Brothers Trucks and Holley offer a complete tank/pump/sending unit combo but only in a 25 gallon capacity. Like @ZooMad75 said above, I am not expecting much above 10mpg so the extra 6 gallons the 31 gallon tank offers means another chunk of miles before you need to refuel. Thankfully, Holley has a solution. I went with their 350lph Fuel Pump Module (p/n 12-333, just got delivered today) which comes with the sending unit, wiring, lock ring and O-ring. My engine is a returnless setup so I'm going to use a Corvette regulator/filter and will plumb with AN line & fittings from hotrodfuelhose.com.

Power Steering:
My truck has hydroboost and the stock fittings bolted right up to the LQ4 PS pump. I'm just guessing the other 2 lines are return lines and not pressurized so I plugged them into the 2 empty provisions on the PS reservoir. I'll figure out if this works once the engine is running.

Cooling:
For over a year I had my eye on a Griffin radiator setup with shroud & 2 fans. Bling bling. You read mixed reviews on aluminum radiators but a year ago, the cost seemed like it could make sense. Now that setup is going for almost $1,000 which is bonkers to me, thanks COVID. The 6.2 radiator is massive, has 4 cores, has an integrated oil cooler & trans cooler so I'm hoping a local shop can restore that baby because I'm waiting on delivery of a Derale shroud & fan setup that on paper, seems like it should fit the 6.2 radiator almost perfectly.

Wish List:
  • I'm just guessing I need a shorter rear driveshaft and a longer front driveshaft. Can't figure that out until I get a 32-spline input into my 208c. The guy I bought my truck from had swapped in a th400 and welded a 27 spline output shaft into the th400 :what: so I can't bolt up the transfer case without a 32-spline input.
  • I really want electronic exhaust cutouts so I can feel like Dale Earnhardt driving a 4x4. Summit has a pair that is reasonably priced. I'm hoping to re-use the huge Magnaflow mufflers I was running with the 6.2 so it sounds unassuming until the press of a button, however the inlet & outlet may be too small. We'll see.
  • Dakota Digital RTX Gauges are the bees knees and if you're running a LS swap, having all that diagnostic info (and a tach) would be huge.
  • You do need to figure out how to link your shifter (sounds like that's already handled for you since you already have a 4L80). I'm assuming I need a cable setup to make the column shift work. The 6.2 came factory with a 700r4 so the shifter should have gates for all 4 forward gears.
  • Vintage Air - this is obvious.

Here is a question for you my amigo:
  • What's your trans crossmember setup for the 4L80? I don't know anything about pinion angles or anything so I'm thinking I'll just jimmy rig it to have it towed to a trans shop where they can maybe fab up a nice crossmember to help clear the dual exhaust. Best I can find on here is "jack up the trans until the crossmember hits the frame. Drill & bolt" but I have no idea if my pinion angle makes sense (I have a small lift) and don't know how to be sure the trans is centered between the framerail - does it need to be offset to one side due to the pumpkin on the 10-bolt? I have no idea. This is the crap that keeps me awake at night.
Appreciate any advice and if not, good luck with your build!
 

6872xtc

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It’s an 04 LQ4 so I would have to modify the fuel delivery system I guess. Bummer I just dropped the tank and put in a new pump/sending unit and tig welded the vent in
As far as I know, you can just swap the fuel lines, and I believe the rails, from an '01 to '03 to get a return line. I almost did this myself, and then didn't because of the PCV connections on my '01 worked better with the cable throttle body.
 

Blue85

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Now having said that if you are used to the low end torque your 454 put out you are gonna be disappointed with the 6.0 and the same gearing. They are great engines don't get me wrong, but they don't put torque down at low rpm. They do it a 2000 rpm and up. The fuel injection is worth doing it for sure, but just keep the low end torque in mind when you are thinking about the swap.
Going from 7.4L to 6.0, it makes sense to drop the differential gears. The 4L80-E has a steep 1st gear and the converters that come with them are fairly high stall. It's about expectations. You can gear it to run 1900RPM on the freeway and get good fuel economy or you have it perform well. 6.0 can do plenty of work, but it needs to rev.
 

Chuy84k5

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One thing that I do want to add to this is that even though it's not necessary, but very overlooked is a baffed fuel tank.I used one out of a 87-88. When I did my first swap on my 82 c10 I used the stock tank.If I had less the half a tank and turned a corner too hard my in tank pump would starve for fuel. So when it came time to swap my k5. I went with a new baffled tank (also bc my truck had been swapped from a 305 to a 6.2 diesel).
 

Blue85

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I went with a new baffled tank (also bc my truck had been swapped from a 305 to a 6.2 diesel).
What kind of tank did you use? A K5 tank is different than truck tanks. I'm only aware of the original TBI tanks with effective (but eventually doomed) plastic baffles and aftermarket stuff like Spectra with the small steel pan in the middle of the tank. I run the Spectra and have no problems until I get into the last few gallons of fuel...but I haven't been brave/dumb enough yet to attack steep angles without 1/4 tank or more.
 

Chuy84k5

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I was young and had more ponies then my 305 had given me for the couple of years I kept it stock. As far as the tank goes I got a 31 gallon tank from a 88 k5.
 
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