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New Chevy 6.0 & 8.1


Well-Known Member
I need some opinions on these motors and how they are performing in the HD2500 either excab or crewcab. I'm about this close (I---I) to getting a new truck and can't decide which motor to go with. I'm towing a 20' flatbed car hauler and a 24' piece of driftwood some call a boat. The retro-raft (boat) is pretty heavy(not sure the exact weight) and the flat hauls no more than 3500lb vehicles. Both motors are really nice, plenty of power, but I kinda would like to get a little mileage(do I really need the 8.1??) since I don't tow that often. If anybody has a truck with these motors I would appreciate your opinions on performance, mileage, and anything else(trans).
6.0 gets ? mpg
8.1 gets ? mpg

BTW the truck will be a 4wd crewcab HD2500

Thanks for the help!


Well-Known Member
From what I've heard from customers and friends, you can expect about the same mileage out of both engines. 11-13 around town, and 14-16 on the highway...unless of course you have a really light foot? Unless you're planning on towing something bigger, I'd stick to the 6.0L simply for weight.

Matt Nelson
Team Kwik Racing


Well-Known Member
GET A FORD!!!!!! You cant go wrong with a Powerstroke or V10 superduty!

"We've done so much with so little for so long, we can do anything with nothing!"


Get the Diesel!

You'll be amazed at the driveability and will be very happy with the much better, MPG.

If not, get the 8.1.

Either gas motor will yield MPG between 8 and 11 around town. The Diesel can get as high as 14 around town with a conservative right foot.

As in the Ford Powerstroke, your resale value will be considerably higher.

The only thing that bothers me about the Duramax diesel are the aluminum cylinder heads. Regardless, this is easily a 150k motor. The Navistar diesels can go 250k between overhauls.

Get the Diesel .....



Well-Known Member
You'll have a hard time beating the proven reliability and performance of the 7.3 Navistar. As for engine life, 250k is very conservative. I have a friend with over 300k and the only problem was the water pump after 150k and a new clutch / flywheel at 250k. I am just getting mine broke in with just over 50k. Best truck I have ever owned. I get at least 15 now matter how I drive and if I keep it under 70 on the hwy I can get 18+ loaded or empty doesn't effect the mileage on mine.

Step up to the blue oval.

"The only source of knowledge is experience." - Albert Einstein


Well-Known Member
You're on the right track with a Chevy. My best friend JUST bought a new 3/4 ton HD with the 8.1. He hauls a 38' travel trailer, so he needs the big motor. His first tank of gas was 13.5 mpg around town. I've heard about the same figures for the 6.0 as the 8.1. His old vehicle was a 3/4 Surburban with the 7.4 L 454 ci. That thing sucked the gas down. The 8.1 is great on gas considering it's size and power. If you decide to go with a diesel, as much as I love Chevy's....steer clear for a little bit. I've heard some horror stories with the Duramax heads. However, since you're looking for a gas, I'd definetly recommend the 8.1 Chevy HD. Great truck, gobs of torque (compared to other gas engines), and conservative on fuel. Good luck with your shopping!

Joe B.


Well-Known Member
If you buy a Ford, make sure to get the extended warranty and keep my shop in mind for your repairs. after all, broken Fords keep me in business ;-)

Matt Nelson
Team Kwik Racing
Matt, what is the name of the repair shop and where is it? I have an '98 F-150 and opted NOT to buy an extended warranty. Just wanted to keep my fellow dez dude in mind. Thanks.



Well-Known Member
Thanks for the info so far. I've considered the Ford SD's because I wanted Kregs lift but my blood flows to much Bowtie. I also forgot to mention I'm actually going to drag this behind my motorhome to the local races so I am concerned about curb weight. I haven't checked the SuperDuty curb weight yet but the HD2500 weighs in at about 5500lbs ( i think). They make a towbar(roadmaster) that hooks to Suburbans and Yukons that will work and the Subs & Yuks have the same curb wt as the HD2500. If I was towing more often then I probable would get a diesel. Has anybody put headers on theirs yet? If so what brand?

Thanks again for the input. Keep it coming.


Well-Known Member
We have the 6.0 Diesel, and it is killer. It gets about 17 mpg around town, and we have an alfa trailer that we take down to glamis, and we get between 10 and 12 taking it out there, driving it pretty hard. The trailer weighs about 10,000 lbs, and we can do 65 the whole way up the grades no problem. With the turbo it is incredible. the throttle response is not as instant as the gas engine (from a stop), but it will out pull many trucks out there. Let me know if you have any questions. I have the 4x4 LT just extended cab short box

Check out Banks Performance. I think they are pretty up-to-speed with diesel performance.



Well-Known Member
You have got to go with the Ford Powerstroke Superduty and one of Kreg's systems. As far as bowtie blood....................bowties are for little boys!

EJR Racing #244


Well-Known Member
Whats that fine looking patriotic truck in the photo under your name?!?!? Thats a funny looking Ford!! I will look at the Ford SD before I buy something but I doubt I'll change my mind.
I know Banks has a kit for those. So does Gibson and I think Edelbrock but I'm not certain.


Well-Known Member
if you are going to tow anything the diesel is the way to go. but if you are a gas guy the biggest thing to consider between the 6.0 and the 8.1 is the transmission. the allison transmission is the best transmission on the market, the ford automatic transmission is a p.o.s. and so is the dodge, and who wants to drive a stick shift in a big tow vehicle??? the allison and the 8.1 is NO DOUBT the hot set up, next to the duramax and the allison. the 8.1 will get better mileage towing than the 6.0 because you won't have to have your foot into it as much. but then again the diesel will get better mileage than both of them!!!

once again if you are a gas guy: ALLISON & 8.1!!!!!

i drive a bad ass bowtie and i am damm proud!!!
My friend works over at Banks he said that a new SD diesel with all their upgrades will smoke even a duallys rear tires....BUT they are working on stuff for the duramax and he said that its going to out perform the powerstroke without a doubt, I rode in his truck it boost 23lbs but it doesnt like to drive faster that 70-75, he said the new duramax will cruise at 80-85 with no problems. If everything goes well he will be trading in his 2001 SD for the new HD next year....


Well-Known Member

I have friends with all 3. The Ford Superduty is a good truck. We like the solid front axle, and the diesel. However...we have raced a 99 Superduty Crewcab 7.3, 4.10's....with a Chevy HD Cewcab, Duramax, also with 4.10's....the superduty got smoked. Not bad, but it got beat. The Chevy can Tow more as well. I believe the max for towing is about 12k lbs. That's alot of weight!! transmission wise, Allison is the hot setup. They last forever, and they know their stuff. For the aftermarket goodies, stick with Banks...all they do is diesel. They can get a 7.3 Ford to smoke the tires and powerslide through turns...and the truck was on 35's. I can't imagine what a chevy will do. That's gonna be nuts, considering you have 520 ft lbs from the factory. Isuzu builds the engines, and they run aluminum heads to run more boost. Less detonation, more boost=more power.

The only dowfall I see to the Chevy is the Ford's solid front 4X4 axle. I believe they run a Dana 60 or Dana 70 up front in the F350's. Chevy has the IFS, which rides nice, but has a tendency to eat up ball joints and tie rod ends. I am a chevy guy, John Bitting will confirm this. I have a 94 Z71, and a 98 1 ton Crewcab, 454 right now. I would love an HD, but can't afford it.


Build it like a Rhino, and Leave it be.


Well-Known Member
a friend of mine has the hd with the 8.1. its got pretty good power, but hook up a heavy trailer, and it has awesome power. he was getting around 11 mpg, then added a spintech muffler and a k&n filter. it picked up a ton of power, and he gets 13-14 mpg now.

i am and always will be a ford guy, but the v10 sucks balls (and gas), and diesel isnt for everyone.

i have to admit , the hd is probably the way to go.