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8.1 Vortec Engine Swap Questions

Curious to hear your experience with this guy doing the swap. Im always thinking what will be the next motor in my burb, and have considered having a shop do it, depending on the time frame it needs to be done in.

Good luck!

I say leave you doubler, and make it work.

4l80e for sure for teh trans, unless you get a good deal on an allison. Besides taht, go with whatever motor you feel is best. I think the 6.0l would be a beast with the right tune.
 
I am pretty much a sucker for big engines so given a choice I would do the 8.1. Leave it dead bone stock with a tune on the computer. I have driven one before and after a tune and holy crap the difference is quite impressive.

I would also do the 4l80 and keep the doubler, I really like the doublers gearing options
 
I think unless you feel you just have to have a big block that the 6.0 would be a no brainer. The 8.1 wasn't for made for very long for a reason and technology is continuing to develop for the ls series of engines. I had an '02 8.1/Allison 4x silverado for 60k miles. Truck weighed about 6200lbs and usually got 9-10 mpg. The Allison may be a very durable transmission, but it's huge and felt like a power robbing pig to me. I've spent years with a vortec small block and 4l80e and thought the 4l80 was great. It doesn't have the wow factor of Allison name, but gets it done well and seemed like it robbed less power. I think comparable to better power, 25-35% better fuel economy, and cheaper parts plus easier install/swap would be with 6.0 and 4l80e.
 
How bout just installing a healthy rebuilt 454, possibly aftermarket injection and leave your drive train alone...:dunno:

sometimes simple is best. sounds like you have your whole rig diled but you just want some more power. my 454 with a mild cam has lots of torque and motors my pig of a burb up the passes with no problems. just a thought...
 
Im far from an expert . but tossing in my half cent ( dont rank the full 2 cents yet)lol

I have a 06 2500 Hd with the 8.1 and the allison 6 spd . It is truely a beast . I have a cold air intake a hypertech programmer and a throttle body spacer. I have also found hotter coil packs and some headers , but thats about it for street mods . there are some for the marine applications, but that probably wont get you thru smog. Here in kansas we dont inspect at all unless newly registering it from out of state .

I think the 8.1 is 375 hp /455 tq ish stock , and mine is running 420/500 ish. I get about 9.5-10.3 in the city . and about 14 tops on a 55 mph country highway . about 12 75-80 mph .. unloaded but it will scoot the 7000 lb truck easily. the allison is very smooth and stout and has a pto take off ( if you have an app for that ). but they are both very heavy.

I think i a wheeler the 6.0 /4l80 might be a better choice for the reasons above and the lighter weight. I have not driven them to know the difference from a personal stand point .
 
I have considered going with the older style 383 stroker or a 454. However, from a performance standpoint, you just can't beat the newer LS engines. My original plan was to simply swap out my 350 block for a crate HT383 and put all my parts back on. The challenge I face is that after adding my D60, doubler, Corp14ff, a full roll cage, the larger tires, my 45 gallon gas tank, the very heavy front and rear bumpers, and all the other goodies, then loading up the interior with camping gear, I am really a very heavy rig. Most everyone I have talked to agrees that the 383 just isn't going to give me the power I need.

So, I looked at the 454. A new crate 454 is going to run over $6k and used ones are not easy to find. On the other hand, picking up a used LS engine is quite easy, albeit more complicated to install. The performance of the 6.0 is head and shoulders above the older engines especially with frequent altittude changes when I am heading over the passes to Nevada. Gas mileage should be a bit better and fine tuning is easier as well. I compared the cost of a 454 with all the parts I would need and it meets or exceeds the costs of picking up a used 6.0 with 4L80E attached including all the wiring and extra parts.

I agree on the Allison being big and it could force some floor mods that I don't want to mess with. John has discussed moving the engine forward a bit to place the 4L80E in close to the same spot as my existing setup. With an electric fan setup in the front instead of the belt driven deal, I should have some space to work with. I'd like to keep my doubler but I would consider just going with a 3:8:1 Atlas. This would keep my drive line angles reasonable.

If it turns out that the 6.0 could be moved forward and my TC's stay in the same spot, that would be ideal and most cost efficient.
 
I've owned my truck with the 8.1 since new and have driven my dads 2500 and my friends 2500 both with 6.0 enough to know what they are like.

I love the 8.1/Allison. Even in stock form it has plenty of power to haul around the many, many cars, trucks, scrap metal and whatever else I have dragged behind my truck. Gets OK mileage for what it is. It's great for it's intended purpose, in a heavy truck, towing or hauling whatever. Would I put it into a K5? No, I would not. K10? No. K20 or Burb tow rig? Yup, without a doubt.

I think the 6.0 makes plenty of torque in stock form for the average built K5 and can be improved with little investment. Unless you want the wow factor for having the 8.1 under the hood and don't care about gas prices, your choice is clear. The 6.0 should be easier on the wallet for install and gas mileage.
 
I am wondering though about just how much power the 6.0 makes. A stock Blazer or a slightly modified one would probably find ample power in the 6.0. I have probably added several hundred pounds with the one ton running gear, very heavy bumpers, doubler, cage, and other items which changes the situation. My dilemma is, will I really have the power I want with the 6.0? I am hearing that comparing the LS 6.0 to a slightly modified 350 such as mine is apples and oranges. Is that really true? And, I am just starting to look at mods for the 6.0 if I go that route to gain power. Flashing the PCM? Headers? CAI intake?
 
Desert Rat said:
I am wondering though about just how much power the 6.0 makes. A stock Blazer or a slightly modified one would probably find ample power in the 6.0. I have probably added several hundred pounds with the one ton running gear, very heavy bumpers, doubler, cage, and other items which changes the situation. My dilemma is, will I really have the power I want with the 6.0? I am hearing that comparing the LS 6.0 to a slightly modified 350 such as mine is apples and oranges. Is that really true? And, I am just starting to look at mods for the 6.0 if I go that route to gain power. Flashing the PCM? Headers? CAI intake?
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All your worries about the 6.0L not having enough power are making me worry about my theoretical future swap into my burb. As a tow rig.

:(
 
A good exhaust and intake and tune will get you started. If you want to go further, then look into the L92 heads and a LS7 cam. I was talking to a friend about this the other day and he said that would be the way to go for the goals I want.

Scott
 
What goals are those? My purpose is to have low end grunt and torque. I don't drive my Blazer very fast and the most I will hit on a freeway is 85 mph, maybe. I want to be able to haul my rig full of gear all over the desert, up and down hills and passes, and slow climb up steep grades without any issues. Some other Blazer owners who mud might want to able to crank up the RPM's. A rig that doesn't see slow crawling and is more for street or flat dirt roads is going to have different needs as well.
 
After seeing what Ryans rig can do i would not hesitate to install a 6.0 in your rig. I will ask him to check out this thread when he gets a chance. I still think you would be better off talking to him over the phone though as he has a TON of info on this swap.
 
Desert Rat said:
What goals are those? My purpose is to have low end grunt and torque. I don't drive my Blazer very fast and the most I will hit on a freeway is 85 mph, maybe. I want to be able to haul my rig full of gear all over the desert, up and down hills and passes, and slow climb up steep grades without any issues. Some other Blazer owners who mud might want to able to crank up the RPM's. A rig that doesn't see slow crawling and is more for street or flat dirt roads is going to have different needs as well.
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The rig will be a street driver, wheeler on trails like the Rubicon, sometimes taken in the mud and snow, and on the rare occasions I take it to the Hammers I want to be able to have some high speed fun on the lakebed. So I want to build a Vortec 6.0L that has low end grunt along with some power up top to fully optimize it for what it will be used for.

Scott
 
4X4HIGH said:
After seeing what Ryans rig can do i would not hesitate to install a 6.0 in your rig. I will ask him to check out this thread when he gets a chance. I still think you would be better off talking to him over the phone though as he has a TON of info on this swap.
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Maybe I can speak to him in person? He is in the south bay isn't he?
 
Desert Rat said:
Maybe I can speak to him in person? He is in the south bay isn't he?
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Ok, i just got off the phone with Ryan and he said right after work today he is heading up to a friends cabin through the weekend and will reply here when he gets back. He did say for me to PM you his phone number and he can spend 10 minutes or so with you on the phone and give you some insight into this swap. He did say though that you would be better off doing the 6.0 swap UNLESS this was a dedicated tow rig.

PM coming your way now.
 
No replies from somebody who has actually done the swap with an LS 6.0 or 8.1 yet. Somebody must've done the swap and are driving a Blazer with either engine and the new tranny.
 
I may have to step back from this project as the costs are starting to spiral out of control. I think I am going to drop in a set of 4.88 gears and pull my 4.56's first to see how the RPM's go. When heading up a steep grade, or even on the freeway, I always seem to be in the 1600-1800 RPM range. This is not optimum for making power. If I could bump those RPM's up into the 2000 - 2400 range, I think I would make better power. I am going to try this first before taking the engine swap lunge as I am starting to look at over $10k for everything at this point.
 
Desert Rat said:
I may have to step back from this project as the costs are starting to spiral out of control. I think I am going to drop in a set of 4.88 gears and pull my 4.56's first to see how the RPM's go. When heading up a steep grade, or even on the freeway, I always seem to be in the 1600-1800 RPM range. This is not optimum for making power. If I could bump those RPM's up into the 2000 - 2400 range, I think I would make better power. I am going to try this first before taking the engine swap lunge as I am starting to look at over $10k for everything at this point.
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How much is the guy going to charge you to install the engine/trans combo? You can pick up a complete package engine/trans/ECM/harness for around 2K and then it's just a matter on installation. Maybe you should ask Ryan what he would charge you to do the install. He has done quite a few of them already.

What size tire are you running? If you already have 4.56's i would suggest jumping to 5.13's. With a 700R4 having 5.13's would be like driving with the trans in Drive with 4.56's all the time as far as RPM's are concerned.
 
I've debated the 5.13's as well. The engine/tranny combo would be coming from Santa Clara Truck Wreckers. The prices have ranged from $2500 to $4000 depending on the mileage, year, size, and tranny. This includes though all the wiring, PCM, and everything needed to do the swap. The problem is, I am going to either have to fab up some different motor mounts to try and move the whole shebang forward to accomodate the existing TC setup, or replace my doubler with an Atlas to keep my drive shafts a reasonable length. Then I am looking at new exhaust as things will change there. I also would probably have to go with a different radiator and wanted to go electric fans instead of the belt driven fan. I also would need to swap out the gas pedal for a drive by wire one as well. There are a lot of other little things that add up too. I have 35's now and with 4.56's, it should be the ideal setup. But, I always seem to be down under 2k RPM's unless I am really getting my foot into it going up the passes. I think if I bump up the RPM's I will be running much better.

John Deetz isn't cheap, but his work is top notch and I trust him.
 
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