GM 8.1 Vortec: Everything You Want to Know

The GM 8.1 Vortec (also known as the Vortec 8100) was the last engine in the big-block lineup. Old truck guys are very familiar with the good old Chevy big block. The Chevy C20 my father owns has a 454ci big block, and man, can that thing pull. If towing is your main concern, then a diesel is probably your best option. But, what if you want a gas truck? That’s where you’d turn to something with a big-block gas motor.

Unfortunately, big-block engines are becoming a relic of the past. With emissions standards tightening and the need for more efficient engines, GM phased out the big-block engine family entirely. The last big-block to go to the grave was 8.1 Vortec, and it has an interesting place in history.

8.1 Vortec: Engine Basics

The Vortec 8100 is rather obviously an 8.1L V8, that’s where the “8100” in the name after all. GM designed the 8.1 Vortec as a diesel alternative for its GM pickup truck line-up. You might be wondering, why offer an alternative to diesel, if diesel is objectively better in all performance-related categories? Well, there are a few reasons: price, availability, and convenience.

While diesel is generally available at any given gas station in the US, there are remote parts of the US where diesel isn’t at every gas station. There are also locations such as Alaska, where diesel trucks are less convenient, as they need more time to get started in cold mornings. Diesel trucks are also generally much more expensive to buy new or used compared to gas trucks.

The 8.1 Vortec borrowed much of its design from the 454ci big-block we all know and love. The main difference between the 8100 and big blocks of old is the increased stroke, which increased the displacement to an impressive 8.1 liters!

You might be wondering, why isn’t this massive engine used in a performance application? The Chevy LS is super popular, so why isn’t this engine? Well, quite a few things are holding the 8.1 Vortec back from ever becoming popular:

  1. Iron block and heads, total engine weight is over 750 lbs.
  2. Older big block parts don’t fit on the 8.1 Vortec.
  3. Chevy LS parts don’t fit on the 8.1 Vortec.
  4. Limited production makes them more challenging to find than an LS.

In terms of basic specs, the 8.1 Vortec is very similar to the big-block engines before it. It uses an all-iron construction for cheaper manufacturing and superior strength, a single cam-in-block with pushrods and two valves per cylinder, a 4.250in bore and 4.370in stroke, a 9.1:1 compression ratio, and it only features one variant throughout the years of production.

  • Cylinder Block: 90-degree, cast-iron construction
  • Cylinder Head: Cast-iron construction
  • Valvetrain: Cam-in-block with pushrod, 2v/cylinder
  • Bore: 4.250in
  • Stroke: 4.370in
  • Horsepower: 320hp – 340hp
  • Torque: 440lb-ft – 455lb-ft
  • Compression Ratio: 9.1:1

8.1 Vortec: Applications

The 8.1 Vortec was used in GM pickup trucks as a diesel alternative, as I mentioned above. But, GM also used it in a few other applications:

  • Chevrolet Silverado
  • GMC Sierra 2500HD & 3500HD
  • Chevrolet Suburban
  • GMC Yukon XL 2500
  • Chevrolet Express 2500 & 3500
  • Chevrolet Avalanche 2500
  • Chevrolet/GMC Kodiak
  • Workhorse Class A motorhomes
  • T-98 Kombat armored vehicles
  • Malibu Boats
  • MasterCraft Boats

As you can see, the 8.1 Vortec was used in a host of different vehicles. Chevrolet offered it in all of their heavy-duty applications. The coolest application would have to be the T-98 Kombat armored vehicle. Most importantly, these are all applications that could also use a diesel engine. For many of these applications, the 8.1 Vortec was offered as an optional replacement for the standard diesel engine.

For applications such as the Suburban and Yukon XL, GM never offered a diesel engine platform. Instead, the 8.1 Vortec was offered as an upgrade to the GM 6.0L LQ engine.

RELATED: 4BT Cummins: Everything you Need to Know

T-98 Kombat armored vehicle

8.1 Vortec: Performance Data

This part gets a little interesting. If the 8.1 Vortec is supposed to be an alternative to the Duramax engine, then it must create lots of torque. Torque at low RPM is one of the single most important factors of a heavy-duty engine. So, how does the 8.1 Vortec do? For this, we’ll look at the performance data for the GM truck applications.

Vortec 8.1:
330 horsepower @ 4,200 RPM
450 lb-ft @ 3,200 RPM

LB7 Duramax:
300 horsepower @ 3,100 RPM
520 lb-ft @ 1,800 RPM

I know what you might be thinking. “Why does an 8.1L only make 330 horsepower?” That would be abysmal if this was a performance application; however, this is a heavy-duty application. It makes an impressive 450 lb-ft way down low in the RPM range. Other versions of the 8.1 Vortec make as much as 550 horsepower and 690 lb-ft.

8.1 Vortec: Tuning Potential

The 8.1 Vortec isn’t super impressive in stock trim, but it’s designed for heavy-duty work. Like I said earlier, standard big block parts won’t fit on the 8.1 Vortec, so the performance parts available for it are close to none.

However, this company offers some very interesting 8.1 Vortec parts. Raylar Engineering is pretty much the only company interested in the 8.1 Vortec. They have developed multiple stroker kits to take it from 496ci to 511ci or up to 540ci.

They also offer everything from camshafts to blowers. Their stage 3 package 540ci engine will make an insane 685 horsepower and 680 lb-ft of torque. Unfortunately, the stock Vortec internal components are fairly weak, so any heavy modifications will require a forged bottom end.

RELATED: 6BT Cummins: Everything you Need to Know

So, Raylar Engineering makes a bunch of really cool parts to wake your 8.1 Vortec up, but is it worth it? If you’re just towing their towing camshaft and the 511 stroker kit will be a killer combo for you.

If you want to go fast, their bigger camshaft and 540 strokers will make big power for you.

8.1 Vortec vs Duramax

Most of the trucks that are equipped with the Vortec 8.1 could’ve been equipped with a Duramax instead. Why would someone take a gas engine over diesel in a heavy-duty truck?

Although the Vortec 8.1 was designed to be an alternative to the Duramax, why would you want the gas engine? The main reason for this is diesel availability. Diesel isn’t available at every single fuel station, unlike gasoline.

As far as tuning potential, it’s pretty obvious the diesel can and will make way more torque. You can easily get 800 lb-ft or more from a Duramax; good luck achieving that with a Vortec engine.

Not only that, but the Duramax will also outlast the Vortec 8.1 engine. I’m not saying the Vortec engine isn’t a bad choice, but given the opportunity, I would always pick the diesel first.

8.1 Vortec vs LS 6.0

Although we love LS engines, they aren’t exactly built for the same purpose as the Vortec 8.1. A 6.0 LS would make an excellent engine for a high horsepower street car, but not a truck that tows stuff a lot.

The Vortec 8.1 was designed for maximum torque at a very low RPM, that’s what allows it to tow so much better. On the other hand, GM designed the 6.0L engine for general use, so it’s not as specialized for towing and hauling.

You could always supercharge or turbocharge a 6.0L to achieve the same torque as a Vortec 8.1. The only problem is the factory reliability won’t be there anymore. When you introduce power adders to your engine, such as superchargers or turbochargers, the engine’s longevity will ultimately decrease.

I know people claim to have excellent reliability with modified engines, but there’s a reason why manufacturers don’t push engines that hard from the factory.

The manufacturers thoroughly test their engines for longevity and reliability. If you increased power, you also decrease long-term reliability. Hence why the Vortec 8.1 can reliably achieve a much higher torque number than a 6.0 LS.


So, the Vortec is an excellent heavy-duty engine. It nearly matches its diesel brother in torque and beats it in horsepower. But, due to its heavyweight, enthusiasts rarely chose it as their ideal engine swap candidate. It is slowly becoming more popular thanks to companies like Raylar Engineering who can turn it into an absolute monster. Let me know what you think of the 8.1 Vortec in the comments below!

70 thoughts on “GM 8.1 Vortec: Everything You Want to Know”

  1. I just discovered this monster exists! The problem is engine management. MSD doesn’t make a box like they do for the LS cousins. Anyone who has information on something like that please let me know!!

    • the 8.1 is a 24x reluctor crank trigger and a phase cam sensor just as an ls1 they use the same computers and ls ignitions can and do run 8100

      • You can use a msd box meant for the other ls engines and it should work. When I was doing a setup with this engine I was looking at using the msd 6014.

    • I just saw this article and thought I could offer a different perspective. I had a 8.1 in both my Avalanche and my 23.’ Essex boat. The Mercruiser 8.1 was factory rated at 425 horsepower in the version I owned. In both cases the 8.1 s were among the best engines I have ever owned. I towed many thousand miles in Duramax 2500 Silverado over the same route as I did with the 8.1. The 8.1 did get lower fuel mileage than the Duramax : 8 vs 10 mpg with a 24’ enclosed trailer being towed. I had made the same trip over 20 times with both engines. The Duramax really performed better above 5,000 feet due to the turbocharger. On flat ground there was little perceived difference in power. In the boat the 8.1 has lasted over 15 years and 750 hours without anything other than normal yearly oil changes. The increased maintenance costs of the Duramax negated the better mileage . The 8.1 is a great engine.

      • With a special intake manifold. My V10 Ford engine that is in my F250/350 SD
        is from Fords medium duty line up. The special fuel system increases the horsepower and torque by at least 20% when it is required and needed. It works better than most
        pickup truck diesels on 9% grades above 7,000 feet elv. With the need for an turbo. I never had any problems towing an 9,000 pound trailer with an 17,000 pound load over 10,600 Ft ELV pass’s at 40 mph over the top. Diesels seem to have an problem from the same year. My truck has the Allison 5 plus one gear tranny. Less maintaining cost of gas over the high cost of diesel repairs. My gas V10 medium duty engine is rated to do 500,000 miles before rebuilding.

  2. Nice article to read but I will have to disagree on the longevity of the Duramax vs.the 8.1 I’ve worked on multiple Duramax and 8.1s and have talked to many who agree that the 8.1 out last the 6.6 Duramax almost every time in respect of dollar signs and total break downs. Many of whom I’ve talked with that have 8.1s myself included having 3 the 8.1 asking as it’s maintained some what well will last 300,000 plus with very little problems where you can garrenty with a lb7 you’ll be dumping thousands into it. Yes a select few have had great luck with the lb7 and haven’t had to put much money into their Duramax but me personally being a mechanic and mainly focused on gm over all I can say hands down a 8.1 will last just as long if not longer than a lb7. I personally never thought the 8.1 would amaze me pulling but wow was I wrong. Call me stupid I don’t mind but when pulling our dozer my 2002 stock 8.1 will tow just as well as my bosses 6.4 powerstroke. Long story short I like your article I love the 8.1 and wish they were still on the market today from gm

    • Yeah, I chose the 8.1L to have the towing power without the high dollar maintenance of the diesel. I’ve had cummins and powerstroke and I have 3 cousins with the duramax but the repairs are so costly with a diesel.

  3. I agree, the 8.1 is a workhorse and as reliable or more than reliable than a Duromax. I have seen more folks interested in the 8100 for drag applications. One thing Rayler offers is aluminum uppers to reduce the weight, but there’s something to be said about a cast iron block – without it, you’d be on two wheels. I’ve towed as much with my 8.1L as I have in our 01′ F350 with the 7.3L, and also our 2013 6.6L Duramax. Yes, in the low end the diesels may have an easier initial roll, but at 283,000 miles, the 8.1L still has no problem rolling a 30′, 10-ton tandem axle gooseneck loaded with seven bundles of crossties. I actually prefer the 8.1L with the Allison over the 7.3L – a much smoother pull. Way over the legal limit, but it hauled it just fine on the interstate. Stock motor with normal maintenance – the only things replaced attached to the motor have been a crank sensor, pully tensioner, and alternator. I’m beginning to look for an engine shop for an overhaul at the 300,000 mark. The 8.1L is a big motor, big fuel consumption, and big sound – seems like a perfect combination for a hot rod. Bigger is better, right?

    • I have one in a “kodisk” body (old schwans) that runs on LP gas, which is also 2$ or more a gallon cheeper than diesel.

  4. Overhauled a 97 1500 suburban 4×4 with the #vortec8100. She eats everything alive on the highway and tows 10 like a snap. Please call Jeff @ Harris Used Truck Parts. They have engines galore and will put any #Duraburb to shame. I am so happy my wife is jealous!

  5. I own a 2001 chevy surburban 3/4ton with the 8.1 Litre engineI tow my camping trailer that weighs 7300lbs dry.This vehicle tows it with ease.

    • I got the LPgas version, and have aboht the same size camper and I forget the camper is back there sometimes. Electric brakes are a must, cause you get trucking 80 mph hauling 7000 lbs on the interstate and you better have stabilizer bars on your hitch, I wouldn’t have ever ran that fast (though legal) I had just forgot I was towing the camper for a second. The truck basically doesn’t care.

  6. I had a F350 7.3 and it could hardly pull it’s self around so I replaced it with my 2003 HD 2500 GMC. The GMC has been great and now has about 145K on it so was looking into a replacement engine. After reading about these engines running up to 300K maybe I still have some life in the old mill. The 8.1 has only had mobil 1 oil in it, has 4.10 gears and the allison 5 speed trans. I mainly pull a 10K horse trailer and you really know it is back there. Someone said they were getting 16 mpg but didn’t say if that was an improvement or what they got before? My 8.1 seems locked into 10 mpg at best. I would like some more get up and go and if better mileage were possible that would be great. maybe do the intake and put a performance tune on it?

    • Go to youtube and watch Hptuners 101, beginners guide – GM ECM tuning overview. It’ll give you an idea of what GM left on the table

    • Hi Ken I might be late with an answer for you but here’s what I did. I got it tuned with HP tuners, the ecu on most new GM vehicles are tuneable through HPtuners and EFI live, that means if you find a good tuner in your area they can definitely improve the performance of your 8.1. I did my own tweaking along with my transmission through HPtuners. The best economy I’ve gotten was 14mpg unloaded I don’t know if that helps. I’m still modifying my Suburban but next for me is a rebuilt trans and shift kit along with a Hughes towing Torque convertor I’m hoping that it’ll hold gear longer and lower

    • I have a very similar setup as you describe. However, I bought my 2001 3500 HD as a backup for my main tow vehicle (F550). I pull a 10K horse trailer quite a bit – it is a square nose front and pulls hard. I’ve only used the 3500 a handful of times with the horse trailer and have gotten 7 – 8 miles per gallon on flat terrain. It does pull hard – I pulled a friend’s trailer with a tapered nose and that sat a little lower than my trailer – it pulled noticeably easier.

  7. I’m Looking To Tow A 30′ 3 Axle Toyhauler. Has Anyone Looked Into Using Propano Gas ? Would This Be Cost Effective?

  8. I can’t say enough about the 8.1. I’ve owned dually’s that my 2000 2500hd has put to shame. Actually all the other trucks I broke with a 20′ flatbed trailer and the weight put on it. I’ve had the 2500 for about 4 years now and I love it. Only thing is torque management. Can’t I just pull a wire and add a required voltage to remain constant? Too easy,I know. But theirs got to be an easy way around it.

    • You can get HPTUNERS or EFI live and tune or adjust the trans and engine to what you need. You can also fine a tuner in your area to make the adjustments for you. The factory GM ecu on almost everything after 97 are able to be accessed and reprogramed

  9. Go to a salvage yard and get a complete donner engine combination from a 2001 to 2006 2500. pick up every nut and bolt you take of. every thing, hoses , cooler lines, computer is interchangeable. I prefer the 4l80 trans as it requires less HP to turn it. Also all the programming is in the computer. Very easy.

  10. I drive a 2001 suburban with the 8.1 in it. Love the engine to death even being a deisel freak. I’m a welder so towing all the equipment and machines can get heavy, I do own 2 duramaxs but I drive suburban daily. The 8.1 will tow absolutely anything I put behind it no problem. I was towing 12,000 up a mountain and I forgot I had a trailer that’s how amazing the truck tows. Now gas on the 8.1 is a little crazy. I get 6 MPG and it’s a 40 gallon tank so it’s not cheap to fill up. I’m a die hard Chevy fan and always will be. I’m going to keep that 8.1 forever. Not the biggest gas heavy duty fan as I own 2 duramaxs with one of them being a dually, but by far the 8.1 is THE BEST engine I have ever had in my trucks. Highly recommend

  11. I have a 8.1 in my 04 Silverado single cab I use it for everything 2 wd when people c it they want to buy it I use it for everything but she not Towing anything I use it as a regular car on hwy 12 not bad runs great

  12. I have owned a 2001 2500HD Crew Cab 4X4 with the 8.1/Allison combination since early 2010. The only work to the engine other than spark plugs and wires that I’ve done is replace the fuel pressure regulator, which is a cinch to get to on this engine. They put it in such an easy place that I was sure the engineers knew that it would need replaced one day and wanted to make it easy to do.

    The biggest problem with the truck has not been the engine. Mine has about 150,000 miles on it. All it’s ever done is pull trailers. It doesn’t use oil. It doesn’t rattle. It doesn’t knock. It’s perfect. The biggest problem with this truck has been all the damned rust! The body will rust away before the engine dies. Other than that, the transmission range selector switch on the side of the Allison has given me a couple of fits, but it’s a simple enough change, even if the price has more than doubled for the part in the time since I bought the truck.

    I get 10 to 12 miles per gallon empty or loaded. I just cannot eke anything more out of it. This truck isn’t meant to be a daily driver. It’s a truck meant to work. My daily driver is a half-ton that gets 18MPG.

    The 8.1 pulls like no other big block that I’ve ever owned. Only the Ford 460 has come close, but even then, my 8.1 is stronger than the stock 460 that I once drove. My 8.1 is the most reliable engine that I’ve ever owned. It’s too bad that I cannot say the same about the rest of the rusty truck.

  13. well I just got a 2001 8.1L and all the goodies to drop it into my 1978 chevy mud truck. 6″ lift, 40″ hawgs, detroits, snorkel and many more… cant wait to see how it performs vs my 1991 caprice police motor (96 Tahoe heads, comp cams xtreme 4×4 cam, holley truck avenger)

  14. I have a 2000GMC8.1 not to long ago i let my grilfrend drive it she put desil in the tank took off then it blowed the oil plug out.I cleaned the desial out put gas in it then she fired up took off not 1 mile later she started knocking i shut it down got to the house with her fount the problem new oil plug new oil but still has a knock what do i do

  15. I am on my third 8.1 and they have all been rock solid. I had a 2003 Suburban 2500 that I bought brand new (never should have sold that truck), a 2001 2500HD and my current truck is a 2006 2500HD with the 6-spd Allison and 4.10 gears. It is a beast and will roast the rear tires off the line. The fuel economy sucks, about 10 mpg, but I didn’t buy this truck for the economy. I need it to pull my 26′ boat and 24′ camper. I had a 6.0 in a 2006 2500HD with the 4.10 gears and there isn’t a comparison. The fuel economy with the 6.0 was about 12 mpg, not much better.

  16. I acquired a avalanche 2500 earlier in the summer and my only complaint is fuel consumption. Had 175000 miles and drives like a dream has 3.73 gears with 35″ tired that I thought might be a little higher than acceptable. But with the programmer providing ability to re-tune the tranny I’m pleased to say with this setup I have only a couple times averaged 15 mpg, 12-14 hwy. Although city and towing has more reduced economy 8-10 city and 8-11 hwy towing, don’t tow much, have a 87 one ton to do most that with. With all the aftermarket wheels lift and chrome added I’m more than pleased with a 8,000+-lb truck that feels as nimble as a 5,500 lb car.

    • What year? I have a 04 with 190k now. A good friend was going through a hard time and was going to let the truck go shortly after he got it. I asked him if he would accept me making payments for him. Well after around 8 months of me paying on it kind of looked at each other and we both knew that the truck was mine now. I paid off the remaining balance for a truck I did not want. Let me tell you something I’m singing a different tune nowadays. I absolutely love this truck. 8.1 is a true monster when it comes to pulling. Just recently had to put a new fuel pump in so I decided to do both pumps at the same time. Just replace most of the steering components, new shocks all around, tires, brakes, and even all the lines. I’m in need of a fuel rail now which is discontinued and I’m also in a pickle because the part information and everything I’ve read on is conflicting. Supposedly in 04 they went to a non return fuel system which is in my truck which is an 04, look up the part and number and it’s for a return style system…. Either someone swap the motor out before I owned it with a newer one or the internet is wrong….

  17. Love the power just having a low fuel pulse #6 cylinder replacing everything need fresh views on this

  18. I love my 8.1L! I have a 2002 Chevy Silverado 2500HD with the 8.1L and an Allison transmission. It is the most powerful and fastest truck I’ve ever driven (aside from those that were not stock). I am very interested in Raylar and what they can do for my beast. The only problem I have with it is that it was burning oil until I switched to a heavier weight. It recommends 5W-30 but I switched to a Dello 15W-40 and it’s sooo much better in that regard. The other issue I’ve had is breaking tires loose and loosing traction very easily. With that much power, it’s easy to understand. Pulling a trailer this truck runs and performs better as it’s too light in the rear for that much power. I bought it as a farm truck and back up but now it’s my every day driver just because I enjoy driving it so much!

  19. hay guys, i save gas with my 2003 gmc 2500hd 8.1L and drive about 87 miles to a lake pickup my rv trailer set it at the lake enjoy come home and drive my 2003 dodge 4.7l thanks

  20. I forgot to get back to the site and this is a great site. Thanks for your suggestions on the tuner it sounds excellent. My 8.1 is a 2003 GMC 2500 HD with the 5 speed allison that I bought new. I feel the allison trans is perfect due to its gear spacing for the 8.1 Other trucks I have had get caught between gears (spacing) as the drop in RPM causes the engine to slow to much etc. Two things I didn’t like with my diesel trucks were the oil gets real nasty and if it leaks on your driveway if is not coming of for awhile and black stuff (like particulates) gets all the engine compartment. If you work on the engine you come out covered with black stuff. With the electronics washing the engine off was a bad idea for me. I pull horse trailers and somehow they have extra drag to them. I cannot explain why they put more drag on the trucks. Maybe they are built extra strong/heavy to protect the horses but even small empty ones have a lot of drag. I pull race car trailers and never a problem. My trans will throw a code now and they when I take off fast trying to merge into traffic with a heavy trailer. A transmission shop that does a lot work on modified diesel truck said they could improve the fluid pressure which would fix the problem (for 2,000$). Some the the tuner kits talk about transmission pressure?

  21. Came across a 8.1 and plan to swap into my 66 Impala. Having trouble trying to find a kit that will bolt up the engine to the stock mounts. Anyone have any idea where such kit exists? I’ve called Raylar and they flat out said, “nope, no kit that we know of”. Also picked up a 4L80 trans to match. Any help is appreciated.

  22. Very interesting article. I have found an engine in the crate with the following numbers: 122556105; 10XJB; W982435453.
    Would this engine be the Vortec 8100? I’m trying to figure out what to do with this baby. It’s strange looking to me.

  23. I have a 2007 GMC c5500 with a 8.1 with a big hole in the block. I have been trying to find a replacement in central Maine with not much luck.

  24. I have a 2004 Chevy 2500 with a 8.1, it has a bad knock and mechanic said over $3000 to fix it, my son found a 2001 8.1 our of a Chevy truck are they interchangeable, he thinks the electronics are totally different

  25. Ordered my 2500HD Crew Cab 4×4 with 8.1/Allison in 2004. This truck was my daily driver until 2010. It is now used to tow, hunting/fishing trips, & hauling things. Mine has cold start knock, but quiets down after about 30 seconds. Doesn’t burn any oil and gets consistent 10-12.5 MPG.

    Read an article about the 8.1’s development by a GM engineer. He said this engine was designed for extreme-duty use — medium duty trucks, generators, etc. They even use the 8.1 as a pony-motor to start huge diesel marine motors used in ships. He felt the 8.1 in a light-duty truck was overkill.

    I repaired rusty rockers, cab corners, and rear wheel wells (come on GM, fix the rust problems!!). Mine has only 134k miles…I plan on keeping it for a very, very long time.

  26. Just bought a 2004 2500HD with an 8.1L / Allison transmission combo. The truck has 22K miles on it, has almost every option on it, and looks like it did when it was purchased 15 years ago. I wasn’t sure whether I should buy it or not but after reading some of these posts I probably will be glad I did.

  27. Have an 05 Suburban with 99,900 miles. Owned it for over 6 years and only put 7500 miles on it. Been garaged since I’ve owned it. It was a Covert Operations Vehicle for supposely the FBI. Has always been a Texas Vehicle. 8.1 with 4:10 gears 4×4. Several years ago I installed a Magnaflow true dual exhaust system and K&N cold air system for better mileage. Didn’t help any on MPG but had a power increase. Was fixing to list it since its not driven much but after reading this post, might be changeing my mind. Its stock but a beast. Ive heard these Suburbans are real rare. I like driving it but that gas station needs to be in tow. Worst mileage was 6.75 and best is 11.0. Only problem is the air bag on the steering wheel black cover is rubbing off. Now to figure out how to solve that issue.

  28. i have a 2001 2500hd with the 8.1 love the truck it’s jacked up way high sittin on 37’s I’m getting an average of 9 to the gallon i have the 11.5″ rear end and I’m wondering if a re-gearing to bigger gears would help with the bigger tires this truck really isn’t used much for pulling unless my buddies get their 4×4’s buried in the mud so I’d just like to know would it be worth it especially if down the road I’m looking into putting beefed up performance stuff on it

  29. I own a 2001 Silverado 3500 extended cab dually. 8.1L bone stock. I pull a Featherlite 4-horse slant load trailer with forward dressing room. Truck now has 170,000 miles and, while it has had a transfer case issue, the engine has never been touched other than scheduled service. It runs strong and is an absolute pleasure to drive. I would buy a new Silverado if they still offered an 8.1L!

  30. I have owned an 2004 Chevy Silverado 2500HD 8.1L 60,000 original miles for two years now.Bought it to pull a 31 foot camper. I have owned a lot of 3/4 ton trucks of every brand. But this has to be the cheapest weakest pile of junk i have ever driven. Weak springs really has a hard time handling any kind of load.Have had 1/2 tons that fared much better. The 8.1L engine is grossly over rated in HP and Torque. Any grade at all and and your down to 40mph when hauling any kind of load. Thats with the pedal to the floor.No engine problems. running like it should.Just a weak poor design..ive had a lot better luck with just plain old 350 motors..stay away from the 8.1L. A real Junker.

    • You must be a ford employee, because all of these posts are positive except yours. I also own a 2500HD with the 8.1 and I pass diesel trucks (chevy, ford, dodge) every trip with a camper on the back pulling a 20′ enclosed and loaded car trailer. I’m talking every hill between WA and southern CA. Ignore this post…. This truck/engine, is best tow rig ever built. yes, gas mileage is not best, but I have a bumper sticker for that: “there is more to life than gas mileage”

  31. I have a New 8.1 just sitting in the crate ready to drop in a “boat” or truck. It has dyno time on it only. I was told it is an Ilmor engine. I think it is an indmar engine. I was going to put it in my boat a few years back, sold the boat. I’m told it was 500+ HP. It needs a good home. Can anyone tell me what it is worth? It is a shame to just let it sit when someone could be using it.

  32. I swapped an 8.1 into a 69 Chevelle with 4l80e. Raylar reworked my intake and added 90mm throttle body. It makes 550 rwhp and 585 ft lbs torque.

  33. I have an 01 Suburban 2500 2wd, 8.1, 195000 miles in Illinois, had it for several years now, finally sold my 96 2500 suburban 4wd with a 502 in it, I was keeping it because I never thought I would ever find a suburban I liked better ( Love the 96 body style ) neither of them has any rust ( keep them clean top and bottom ) The 01 has never needed anything in 195000 miles, except oil and filters, plugs, and a serpentine belt. No smoke, no knocks, no rattles. Admittedly, the 502 sounds impressive leaving a stoplight, deep impressive bellow, slight lumpy cam…etc., but the 8100 has been amazing. I have a 91 SS454 pickup that is tired, I think it is going to get 8.1, crank triggered with a carburated intake lumpy cam and headers….It will probably destroy the 700r4, but it should be fun finding out.

  34. Own an 01 2500hd (61K), an 05 Yukon XL 2500 (121K), and had an 01 Suburban 2500 (125K) all w/ 8.1. Have made 4 roundtrips CO-VA, one one-way with at least 10K-lb 20′ enclosed trailer (9mpg). Been up a mountain in snow with chains & w/o chains, slept in the Yukon several nights. Towed up to 10K’ in elevation. Yukon/Sub unloaded average 11mpg. Pickup unloaded avg 12. Biggest issues on these trucks are not drivetrain. Try keeping window regulators and power seat switches working, but the engines just run and run and run. At sea level the 8.1 is a blast to drive. At 7K’ elevation where I live, the 8.1 is not nearly as much fun, but continues to be a workhorse, towing and driving well. It feels underwhelming unloaded at elevation, but then just pulls a trailer up a mountain w/o drama. Love these engines. The 6.0 is a fine engine but at 75mph or towing it will get the same fuel economy, so whats the point, unless you are hotrodding something that won’t be towing anyway? I do find that all of them burn a little oil when running hwy @ 80mph, but you do not notice until you check the oil (in other words, no smoke or smell) Maybe 1/2 or 3/4-qt on a 3500-mi roundtrip. I use factory recommended weight synthetic (mobil1 or amsoil). Little heavier weight would probably stop that but then maybe I wouldn’t get 11-12 mpg. Also owned an 05 Duramax (65K), loved it very much, just as dependable and just as much fun to drive (maybe with the added fun of watching black smoke pour out when the hammer drops), but for the additional purchase price of a duramax and the expensive oil changes and the higher cost of diesel I just can’t bring myself to justify another. Do the math, and you can put a LOT of gas into your 8.1 and still be money ahead with performance in the same ballpark. FYI, my 05 duramax towing a 6×12 enclosed trailer w/ maybe 1K-lbs gear CO-VA @ 80mph only could manage 11 mpg. (Yes an ’06-07 6-spd could do a little better)

  35. Own ’02 Silvarado 2500 HD with the 8.1, Allison 5 speed extended cab LT since new. Other than regular maintenance, fuel pump, runs like a champ at 80k miles. Pulls a 8k pound boat like it’s not there. In Alaska we have steep grades in places, haven’t had a problem keeping up on the steep grades pulling. This truck is a keeper. Kept outside for all these years, no rust, none. Look at today’s pullers. Sure Diesel has the torque and longevity, but at a high cost. This truck has and will continue to serve me well.

  36. I have a 2001 Silverado 3500 with the 8.1 and Allison 5 speed and recently installed 4:56 gears. Current mileage is around 90,000 miles. I tow an enclosed race trailer that weighs roughly 8,500 lbs. and a 5th wheel that’s close to 15,000 lbs. Towing fuel mileage varies from 8.5 to 6.5 MPG depending on load and terrain. Last year we towed the 5th wheel up over a Colorado mountain pass that exceeded 11,000 feet in elevation and I can safely say we almost didn’t make it due to overheating and reduced speeds down to 20 MPH. In my experiance if you keep your loads below 10,000 lbs. and elevation under 8,500 feet then the 8.1 Vortec will work for you.
    This year I am currently in the middle of installing a high torque cam, modified intake, and shorty headers, with the hope of adding a little more reserve power when I hit the hills towing the heavy 5th wheel.

  37. I have a 8.1 in my 2001 Winnebago class A motor home. I tow a 7,000 pound trailer with it. The only engine problem I have had with it was spark plug wires because of the under hood heat. Stock wires are not up to the task neither are Taylor wires. Wires from a RV parts supplier for $150.00 worked miracles. I love this motor, it is better than the 454 big block that I had in a previous motor home.

  38. If your are thinking of buying a truck or RV with a Vortec 8.1l, but are on the fence, think about this. If a crank sensor, cam sensor or fuel pump take a dive while on a road trip, you could probably fix it yourself with parts from the local parts store. Try that with an injection pump or injectors in a diesel. Also, while Raylar is the real deal, his stuff is quite expensive; mainly suited to guys with expensive power boats. Don’t let anybody fool you, there are parts available from other sources. Comp and Crane both make cams for this engine. Comps Tri-power line is a drop in. Dart makes cylinder heads which are significantly less expensive than Raylar’s. Gibson and Hedman make headers for this engine. Flowmaster makes a muffler. Raylar makes rocker arms and will port your intake. Nelson and Blackbear do custom programs. All these mods are a good start, most are smog legal too.

  39. I have the opportunity to purchase a safari trek motorhome with the 8.1L…I’m encouraged by what I’m reading here because the motorhome only has 7500 miles and from what I’ve read here, that’s not even broke in yet! Looking forward to many miles being put on it and hoping it’s the last motorhome I’ll need. Does anyone else have or know of motorhomes having the same power and reputation as the truck owners on here? Thanks for the great comments.

  40. I’ve been wanting to do a swap in my 86 chevy 4×4 back and forth between a 454 and a ls but by reading all these comments sounds like the 8.1 vortex might b what I’m looking for and the Allison trans over my Manuel trans I usually only pull car trailer so should b good

  41. I’m the happy and proud owner of an 01 8.1 Chevy C3500, 4×4, extended cab, flat bed dually.
    Totally lucked into this excellent work truck combo.
    Didn’t know much about the 8.1 & Allison trans, but I was looking for, and WANTED a gas engine truck so I could wrench on it myself.
    …but I haven’t had to!!
    Hearing about the repair tabs on diesels scared me!
    Bought it 4 years ago with 152K, and it has just ticked over 241K, with nothing more than regular oil changes with Lucas Synthetic Oil Additive, 2 spark plug & wire changes, and a new fuel pump.
    Truck has been a delight, with lots of towing grunt, and is surprisingly quick for a 9,000# (empty) vehicle.
    Regularly and easily tow 6-8K# trailer with equipment or materials.
    I’m an unapologetic FAN!!

  42. Help I can’t find my Engine Family Number anywhere on vehicle.
    GM 8100 Vortec engine 2004 Winnebago sightseer. Need it for CARB to find approved replacement Catalytic Converters

  43. Love the article and the comments. 92 GMC K2500 454/4L80E couldn’t handle our 24ft enclosed trailer (probably weighing 10-11,000lbs) without overheating (even with aftermarket radiator added). So I’m in the market for something better. Diesel maintenance and repair costs worry the heck outta me. The info here has convinced me to focus on a 2001-2006 GMC/Chevy 8100/Allison combo. Hope I can find a good one!


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