Whos running GM8100 Vortecs? How do they pull? What kind of mileage do they get towing and empty? How about bitter cold weather starting,(like our -25 minnesota winter mornings. I',m thinking of replacing my 92 dodge 3/4 ton cummins,(body is getting rough). I love the diesel but I put less than 5000 miles a year on it. I'm looking at the price difference, and the amount I actually use it and leaning towards a big v8 or possibly v10. The other issue is that around here, diesel has been about 75 cents higher than gas which to my thinking makes fuel costs pretty similar when you facter the economy differences. I tow 10,000-16,000 lbs.
anyone running GM 8.1 v8's?
- Thread starter MOE
- Start date
Help Support Arborist Forum:
Stihl051master
ArboristSite Operative
I have 2 friends that have 2500HD's with the 8.1 and both have been disappointed with the power, towing, or mileage. Seem to get about 12 on average, although towing they don't get a lot less. I have driven one and expected it to have a lot more get up than it did. It seemed like the older vortec series (like the 5.7's and 7.4's) had much more torque. I don't own one myself though so maybe their expectations an mine were just a little high 
. I do, however, have a 92' Cummins and think if you tow 10-16k trailers you will be downgrading quite a bit with an 8.1 with regards to towing and mileage. Trailers that heavy over any distance are in diesel territory.
. I do, however, have a 92' Cummins and think if you tow 10-16k trailers you will be downgrading quite a bit with an 8.1 with regards to towing and mileage. Trailers that heavy over any distance are in diesel territory.Ultimus_ab
ArboristSite Lurker
'02 Chevy with a 6.0
I have a '02 chevy with a 6.0 and it pulls damn near anything. Of course I have tweeked it out a bit. (intake, exhaust, programmer, ignition, wires, headers) Thing pulls like a bull and flys on the high way (unladen) Never drove an 8.1 but the 6.0 is nice if you open them up a bit. Also getting nearly 16 mpg and that is with BF Goodrich 285/17/75 tires. Hope this helps.
I have a '02 chevy with a 6.0 and it pulls damn near anything. Of course I have tweeked it out a bit. (intake, exhaust, programmer, ignition, wires, headers) Thing pulls like a bull and flys on the high way (unladen) Never drove an 8.1 but the 6.0 is nice if you open them up a bit. Also getting nearly 16 mpg and that is with BF Goodrich 285/17/75 tires. Hope this helps.
William Balaska
Addicted to ArboristSite
I have an 01 25ooHD GMC with the 8100 and allison 5speed auto trans. I have some minor upgrades (air intake spacer and dynomax exhaust) It gets 10 to 12 mpg, 8 towing. It pulls quite respectablly I tow a 30 foot cigarette boat. The older 5.7's and 7.4's don't have anywhere near similar torque. Please remember all the new powerboats utilize the 8.1 as the powerplant of choice so they are indeed a good motor.
Stihl051master
ArboristSite Operative
No doubt that they are good reliable engines. Have you ever had one apart or seen a cutaway of the construction of the bottom end? Very beefy indeed! What I was getting at was that yes, the 8.1 has more peak torque - what I was getting at is that it occurs at a much higher rpm that the previous generation vortecs. The more torque available at low rpms the better for towing IMO. These new motors are superb for boats because they make more power at higher r's, and reliability shouldn't be an issue as they are very well constructed.
I'm just thinking that if the original poster has a Cummins diesel now and pulls a 16,000lb. trailer, he's going to be disappointed in the performance towing that same trailer with a gas engine truck. The gas truck will do the job, but it isn't going to do it as well as the diesel.
I'd say if the ol' Dodge is getting rusted out, I'd be looking for a newer Dodge... or a Duramax, or Powerstroke. Prices are getting pretty reasonable on the used ones now.
I'm not trying to ruffle anyone's feathers here, just offer my opinion for what it's worth.
I'm just thinking that if the original poster has a Cummins diesel now and pulls a 16,000lb. trailer, he's going to be disappointed in the performance towing that same trailer with a gas engine truck. The gas truck will do the job, but it isn't going to do it as well as the diesel.
I'd say if the ol' Dodge is getting rusted out, I'd be looking for a newer Dodge... or a Duramax, or Powerstroke. Prices are getting pretty reasonable on the used ones now.
I'm not trying to ruffle anyone's feathers here, just offer my opinion for what it's worth.
Octane
ArboristSite Operative
They dont get very good gas milage (8 mpg on a good day, downhill in neutral) and the lowend torque cant match a Ford V10.
William Balaska
Addicted to ArboristSite
The Ford V10 is a turd I owned one, The cam profile for the 8100 marine versus the gas is very different as with the heads, marine motors utilize stainless valves and larger valves and make 425 for the high output model of the mercury 496ho. The truck motor makes peak torque under 3000 rpm. I was very unhappy with the ford v10 that's all I have to say about it, and of course the diesel makes more torque the cummins has the least headaches except for the injector pumps
thejdman04
Addicted to ArboristSite
They are pretty gutless. 10 mpg empty 8 loaded heavy. The ford and dodge v10s are the same imo. Seat of the pants, the 5.4 fords had near the same as the v10's. If you need that much horse go witha diesel
No doubt that they are good reliable engines. Have you ever had one apart or seen a cutaway of the construction of the bottom end? Very beefy indeed! What I was getting at was that yes, the 8.1 has more peak torque - what I was getting at is that it occurs at a much higher rpm that the previous generation vortecs. The more torque available at low rpms the better for towing IMO. These new motors are superb for boats because they make more power at higher r's, and reliability shouldn't be an issue as they are very well constructed.
I'm just thinking that if the original poster has a Cummins diesel now and pulls a 16,000lb. trailer, he's going to be disappointed in the performance towing that same trailer with a gas engine truck. The gas truck will do the job, but it isn't going to do it as well as the diesel.
I'd say if the ol' Dodge is getting rusted out, I'd be looking for a newer Dodge... or a Duramax, or Powerstroke. Prices are getting pretty reasonable on the used ones now.
I'm not trying to ruffle anyone's feathers here, just offer my opinion for what it's worth.
I totally agree that a diesel will pull better. I guess what I'm factoring in is the low miles I put on in a year on it and that there is about a $7500 price difference for compareable used trucks. The reason I have been looking at GM 8.1's more than v10's is the Allison transmission that is mated to a lot of them.
Thought about that but it would cost more than it's worth and the big complaint I have about the 92 is the terrible brakes,(and I do keep the rears adjusted). I'll keep it for a snow plowing, wood hauling beater truck........and I'm pretty sure chicks still dig it.
Octane
ArboristSite Operative
The 5.4L isnt in the same league as the 8.1L or the V10s. The 5.4L is a good, reliable engine that has all the power youd ever need in a 1/2 ton truck, but its a tad bit underpowered for a 3/4 ton.
Octane
ArboristSite Operative
Clearly you havent owned one...
Stihl051master
ArboristSite Operative
That is a good call on the Allison if you are getting an automatic, they're the most durable as far as the autos go. How many miles do you have on your old Dodge? Make sure you check out craigslist.com in your truck search. I did a quick search on the Minnesota ones and there were a bunch of 99-newer 4x4 diesels for under $12,000.
Tree Trimmer
ArboristSite Member
I don't really know anything about the 8.1's. They seem to last well, but I've never heard anyone that was excited about owning one.
I like the Ford V-10. I have owned two (one now) and it seems to be fine for the 10,000 lb mark (auto with 3.73 gears). If you want to tow more than that you will need a lower rear end. The biggest complaint I have is the auto tranny, they do not last like you would need it to. A straight drive would probably pull more, but you won't win any races. I occasionally have to pull a 7% grade with my 24,000 lb combo if I use the F-350. I drop it all the way down to 1st gear and tach it up at 4k rpm, puts me at about 35 mph. As long as I leave it there, the coolant needle doesn't move and the tranny temp guage doesn't go up by more than 10 degrees. However if I am in a steep neighborhood I usually leave the front hubs unlocked and putt around in 4wd-low.
With an auto tranny the V-10 mileage will range between 7 and 14 mpg with a 3.73 rear end and 6 to 12 with a 4.10. Considering my last F-550 with 4.88's and the 6.0 powerstroke never got above 9 mpg unloaded on the highway I think those numbers are respectable; especially when you factor in the extra 1$/gal for diesel around here. Again you'd never win a race between the two, but the savings I've experienced seem to outweigh the 3 minute difference in arrival time to the job site.
If you go V-10 and work it you will have to change the oil regularly at 3k miles to prevent damage to the bottom end. The first V-10 I had still ran like new at 158k miles before I sold it. The current one has 168k miles and is still as smooth as a sewing machine.
TT
I like the Ford V-10. I have owned two (one now) and it seems to be fine for the 10,000 lb mark (auto with 3.73 gears). If you want to tow more than that you will need a lower rear end. The biggest complaint I have is the auto tranny, they do not last like you would need it to. A straight drive would probably pull more, but you won't win any races. I occasionally have to pull a 7% grade with my 24,000 lb combo if I use the F-350. I drop it all the way down to 1st gear and tach it up at 4k rpm, puts me at about 35 mph. As long as I leave it there, the coolant needle doesn't move and the tranny temp guage doesn't go up by more than 10 degrees. However if I am in a steep neighborhood I usually leave the front hubs unlocked and putt around in 4wd-low.
With an auto tranny the V-10 mileage will range between 7 and 14 mpg with a 3.73 rear end and 6 to 12 with a 4.10. Considering my last F-550 with 4.88's and the 6.0 powerstroke never got above 9 mpg unloaded on the highway I think those numbers are respectable; especially when you factor in the extra 1$/gal for diesel around here. Again you'd never win a race between the two, but the savings I've experienced seem to outweigh the 3 minute difference in arrival time to the job site.
If you go V-10 and work it you will have to change the oil regularly at 3k miles to prevent damage to the bottom end. The first V-10 I had still ran like new at 158k miles before I sold it. The current one has 168k miles and is still as smooth as a sewing machine.
TT
John D
Addicted to ArboristSite
I own a 2001 GMC K2500HD with an 8.1 and allison. It is a strong powertrain combination.IMO,its the toughest gas powetrain you can get in any truck.You will never kill the Allison,and the 8.1s were designed for a 200K life cycle,meaning most run a lot longer than that. In stock form the truck empty isnt any quicker than a 6.0 gasser up to about 60mph.After 60 mph,the 8.1 walks away.If you tow a lot,the 8.1 gets better towing mpg than the 6.0 gasser,and are the same price on the used market.My friend has a 6.0 gasser,and it cant hold OD towing a snowmobile trailer on hills at 65 mph with 4.10,my 8.1 can hold OD on grades with a much larger trailer,and 3.73 gearing.There is a big torque difference between the 6.0 and 8.1.
The thing is the 8.1 has a lot of torque management in stock form,you need to do 2 things to wake one up,a simple tune,and close he spark plug gap up to .045.Believe it or not,these 2 steps increase RWHp about 40-50hp.Dont waste money on an intake or exhaust,until you do the tune and splug gap. I also own a 2000 Dodge Cummins which is highly modified to produce around 600RWHP,and 1100ft lb torque,and there isn o comparison to a diesels torque.But Im very happy with my 8.1 towing between 8K and 15K.Id buy another one in a second.The only thing id do different is get 4.10 gearing if you plan to add larger tires or tow over 10K a lot.
The thing is the 8.1 has a lot of torque management in stock form,you need to do 2 things to wake one up,a simple tune,and close he spark plug gap up to .045.Believe it or not,these 2 steps increase RWHp about 40-50hp.Dont waste money on an intake or exhaust,until you do the tune and splug gap. I also own a 2000 Dodge Cummins which is highly modified to produce around 600RWHP,and 1100ft lb torque,and there isn o comparison to a diesels torque.But Im very happy with my 8.1 towing between 8K and 15K.Id buy another one in a second.The only thing id do different is get 4.10 gearing if you plan to add larger tires or tow over 10K a lot.
The dodge has 199,000 on it. It runs and pulls great but as I said the rest of the truck is getting rough. I certainly haven't ruled out another diesel. I guess the thing I've noticed with a lot of the $12000 diesels is that they have pretty high miles,(people with diesels seem to put a ton of miles on them) I guess I'm still leaning towards something with an allison tranny.
clearance
Addicted to ArboristSite
Banshee
Addicted to ArboristSite
Even if it's sitting in front of an Allison, it still will never be the motor your Cummins is.
I get over 20 mpg with my Cummins/6spd. When I had a 454 I got 8 mpg. That sure does make up for the 75 cent gallon differance. IMO
I get over 20 mpg with my Cummins/6spd. When I had a 454 I got 8 mpg. That sure does make up for the 75 cent gallon differance. IMO
John D
Addicted to ArboristSite
The older cummins mechanical motors got great MPG. 89-93s were the best,as the truck is the lightest,and the pump robs the least amount of hp.The 24Vs never got the MPG of the 12Vs although when released they claimed a 5% increase in MPG,which was BS.My 2000 Cummins even when stock got 16 mpg empty highway,and the same in town. Its a 4x4 with 4.10 gearing.At 75 mph it gets 15 mpg.Towing my 10K sunnybrook at 68 mph it gets 10-11 mpg.My 2001 GMC 8.1 gets 14 highway at 75-80 mph 10 in town,and 8-9 towing my 10K sunnybrook. Right now diesel is .80 more a gallon than gasoline.So if Im running highway,the gas motor costs me less than the Cummins as long as both are empty.I realize if i had 3.55 gearing in my Dodge it would get much better highway mpg,but I plow,and tow a lot,and i bought it used,and its what it had.
