Opinions: 8.1 Chevy

rmkrazi · Mar 31, 2009

I work with a fella who just finished doing an 8.1 swap into an '04 burban. I've road in it several times going snowmobiling and it seems to pull a fully loaded 4 place quite well. Major gas hog however and always should keep an I on temps and oil consumption.

Vern · Apr 1, 2009

take this for what its worth but this is my experiances with the 8.1 and how it compares to the diesels i know. i'm sure some of the sensitive diesel boys will get ruffled but oh well.

ya the 8.1s tend to use some oil, some are worse than others. but its not from leaks on most of them, i've heard anything from leaky intake gaskets sucking it in and burning it, oil getting hot and evaporating, to the "its a big block so its normal" reason. mine uses about 1 to 1.5 quarts between changes depending on how its driven, the harder you drive it the more it uses. oh and mine don't get changed until atleast 5000 miles and doesn't have any external leaks.

no they dont get 20 mpgs but they do good for almost 500ci engine. i have buddys with basically all the brands of diesels and any one built after about '99 only get maybe 2 more mpgs than our 8.1s and on the highway with a fourplace on not even that much differance. around town the highest my buddys get in there diesels is maybe 13-14(hand calculated, not off the lying little gauge thing) mpgs and i've seen as hi as 12-13 mpgs in the 8.1 in the same driving conditions. my bother has seen as hi as 16-17 on the highway with 3 dirtbikes in the back and all the camping gear in his 8.1.

they will pull anything, and alot of people say stock for stock the 8.1 will out pull a diesel, except maybe in the last couple years with the big torque wars goin on in the diesel market. i have no doubt that an 8.1 will pull anything just as good if not better than even a slightly modded 7.3 p-stroke.

as for reliability, my bros 03 8.1 has over 170k on it and the only problems he's had were just last summer where he changed the water pump and fuel pump for the first time. if my 01 8.1 does that good by the time it has that many miles on it i will be more than satisfied. plus they got the best auto tranny out of all of them, i hate autos but my 8.1 has the alli and i would never own any other auto trans.

that being said i wouldn't hesitate to buy another 8.1.

jthussey · Apr 1, 2009

Hey Vern

I'm not going to dis the truck. THey do have a good big block. Every vehicle has issues. As for pulling, the diesel will lug when it hits a good hill or a good head wind were the gas will be shifting non stop. I'm sorry to say that a diesel will pull circles around that truck. For a gasser, it seems to have lots of power. I used to work for an RV dealership pulling campers. The 8.1 doesn't hold a candle to the 7.3 PS we had. Mileage was about 2 better on the highway for the diesel. For winter though the gas was oh so nice to have. It was a good truck. You just can't compare it to a diesel.

theultrarider · Apr 1, 2009

jthussey said:
I'm not going to dis the truck. THey do have a good big block. Every vehicle has issues. As for pulling, the diesel will lug when it hits a good hill or a good head wind were the gas will be shifting non stop. I'm sorry to say that a diesel will pull circles around that truck. For a gasser, it seems to have lots of power. I used to work for an RV dealership pulling campers. The 8.1 doesn't hold a candle to the 7.3 PS we had. Mileage was about 2 better on the highway for the diesel. For winter though the gas was oh so nice to have. It was a good truck. You just can't compare it to a diesel.

You are right. I have driven both and currently own the 7.3 powerstroke. I am shopping for an 8.1. After comparing them, I prefer the gasser.

jthussey · Apr 1, 2009

theultrarider said:
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You are right. I have driven both and currently own the 7.3 powerstroke. I am shopping for an 8.1. After comparing them, I prefer the gasser.

I'm not diss'n the gasser. It was a great truck and was reliable. Just from personal experience, didn't pull like the diesel. I hope you enjoy the 8.1. Up in Ak its probably not a bad move. Whats the price of diesel up there?

GlennRMK · Apr 2, 2009

The 8.1 is a good engine but it doesn't pull anything like a diesel and certainly gets worse then 2 MPG less then a diesel.

I had an 04 GMC 5.3 and have had 01 and 03 Cummins trucks. I average 4-5 MPG more then my 5.3.

I never could get much better then 14 MPG on the highway with my 5.3 and it was a gutless wonder. If I had that to do over, I would of bought an 8.1 with only 2 MPG or so less and actually have some balls.

Also, maybe a 8.1 will tow a trailer up the hill at the same speed as old diesel (at 4500 RPM as opposed to diesels 2000-2500), like stock 12 valves or 7.3s and anything could outrun the 6.5. But comparing to a newer diesel, especially with a $400 programmer is not even in the ballpark.

I've had gas and diesel and will never go back to gas. Just feels gutless after you drive a diesel, especially with mods.

Vern · Apr 2, 2009

i dont tow any real huge loads with my 8.1 as so far the biggest is probably a four place with 4 sleds on it but i have not had the usuall upshift down shift issues typical to a gasser even though mines the 01 with the first stage of the alli trans she pulls fine. i know in 03 they actually programmed alli to hold the shifts longer to get rid of the up/down shift crap and it works. i know the power band may be a bit higher than a diesel but not much. im not saying that the 8.1 will pull circles around any diesel, but it will do just as good as any early 2000s diesel i've seen, once again im talkin stock for stock. i know its real easy to get big power out of todays diesel without any know how or tinkering.

as for the mileage, theres only been two diesel i've ever seen that got mileage in the upper teens normal driving, not highway and that was a 93 cummins 5 speed and my bros old 97 stroker. as i said i know lots of people with '99 or newer diesels and none of them get more than 14 tops. i'm not saying its not possible to get more but i've never seen it and i'm kinda one of them "seeing is believing" kinda fellas.

oh well, for towing you cant go wrong either way. it just comes back to to each his own.

snowx22 · Apr 2, 2009

8.1

I really like my 8.1L, but it doesn't pull like a diesel. It also was about 5-6K cheaper at the time I bought mine, and gas was about a buck a gallon cheaper than diesel. I pull up to 4 sleds with mine in an enclosed and it gets about 8 with a narrow 4 place enclosed. Empty it gets about 10.5-11 and I wouldn't expect more than that from a daully. With the big tank on the long box it shouldn't be a problem between gas stations, mine with the short box needs an auxillary tank. With that being said, we go out west with 6 sleds behind a Duramax and it will out pull mine with more sleds, but in the end it costs about the same with more gallons used in my truck with the 8.1 and more cost with diesel and additives to the duramax, but better milage. If your worried about trannys, you will not have a problem with an allison, and the engine is pretty durable too. Just my .02

JUSTIN · Apr 2, 2009

I have 2001 8.1 in a GMC crewcab short box with 60,000 miles, It does like fuel but is also holds it own pulling a 24' enclosed. I don't have to use it as a daily driver so the fuel consumption was not as critical either I just wanted something that pulled good and was reasonably priced and would not break the bank when repairs were needed.
The price when I bought mine was closer to $7000-$8000 dollars less for a like equiped diesel. The Allison transmission is awsome to pull with.
I think some people forget that the diesels are close in cubic inches to the gas engines but the gas engine does not have to have the turbo on it to get it to perform. Remember the first Ford and Chevy diesel's they were a dog.
It is tuff to beat a diesel that has some mods done to it but I sure like the ride and how quiet my truck is.
I do not have any oil leaks but it uses about a quart every 3000 miles, A friend of mine at the local Chevy dealership said that is not uncommon with the 8.1
I have a supercharger for my 8.1 that I have yet to put on, should give it a little more get up and go!
As Vern said"to each his own"

CATillak · Apr 2, 2009

Vern said:
i dont tow any real huge loads with my 8.1 as so far the biggest is probably a four place with 4 sleds on it but i have not had the usuall upshift down shift issues typical to a gasser even though mines the 01 with the first stage of the alli trans she pulls fine. i know in 03 they actually programmed alli to hold the shifts longer to get rid of the up/down shift crap and it works. i know the power band may be a bit higher than a diesel but not much. im not saying that the 8.1 will pull circles around any diesel, but it will do just as good as any early 2000s diesel i've seen, once again im talkin stock for stock. i know its real easy to get big power out of todays diesel without any know how or tinkering.

as for the mileage, theres only been two diesel i've ever seen that got mileage in the upper teens normal driving, not highway and that was a 93 cummins 5 speed and my bros old 97 stroker. as i said i know lots of people with '99 or newer diesels and none of them get more than 14 tops. i'm not saying its not possible to get more but i've never seen it and i'm kinda one of them "seeing is believing" kinda fellas.

oh well, for towing you cant go wrong either way. it just comes back to to each his own.

Ours did the upshift downshift thing when pulling a steel 4 place (car hauler damnnear) with 5 sleds up the Eagle River hill (for the ak guys reference) and the rpms spiked to 4grand and freakin stayed there and when i let off the truck would hardly run, got over the hill and the fuel pump had gone out. Had well over a half a tank when it did this. The trucks an 02 so mayybe the shifting problem wasnt fixed.

You must drive a peppy diesel GlennRMK to make an 8.1 feel gutless after driving a diesel, considering in a drag race the 8.1 is gonna me seconds ahead against a diesel.

Haha a diesel does need a turbo to perform.. but a gas needs a supercharger to make half the torque with another reason for failure sitting atop your engine spinning at however many rpm your charger will spin at.. Now your not much better than us turbo diesel guys are you, but with less tq and more heat. Dont fear the I6

Megadeth · Apr 2, 2009

CATillak said:
Ours did the upshift downshift thing when pulling a steel 4 place (car hauler damnnear) with 5 sleds up the Eagle River hill (for the ak guys reference) and the rpms spiked to 4grand and freakin stayed there and when i let off the truck would hardly run, got over the hill and the fuel pump had gone out. Had well over a half a tank when it did this. The trucks an 02 so mayybe the shifting problem wasnt fixed.

You must drive a peppy diesel GlennRMK to make an 8.1 feel gutless after driving a diesel, considering in a drag race the 8.1 is gonna me seconds ahead against a diesel.

Haha a diesel does need a turbo to perform.. but a gas needs a supercharger to make half the torque with another reason for failure sitting atop your engine spinning at however many rpm your charger will spin at.. Now your not much better than us turbo diesel guys are you, but with less tq and more heat. Dont fear the I6

Maybe if the guy driving the diesel is too dumb to do a small boosted launch.

06MXZXRenegade800 · Apr 2, 2009

Megadeth said:
Maybe if the guy driving the diesel is too dumb to do a small boosted launch.

Yea, i would like to see the bigblock gasser that can launch in 4wd in 3rd or 4th gear....

If the truck is built half decent and the driver knows how to actually drive the diesel would blow the gassers doors off...

CATillak · Apr 2, 2009

Not in a stock truck though.. We're still comparing built diesels to stock 8.1 liters? My bad

Megadeth · Apr 2, 2009

CATillak said:
Not in a stock truck though.. We're still comparing built diesels to stock 8.1 liters? My bad

No, I was comparing any of the 3 stock diesels built around the same time as the 8.1. So from 02?(first year?) to 06 or 07 when they quit making them.

Vern · Apr 2, 2009

CATillak said:
Ours did the upshift downshift thing when pulling a steel 4 place (car hauler damnnear) with 5 sleds up the Eagle River hill (for the ak guys reference) and the rpms spiked to 4grand and freakin stayed there and when i let off the truck would hardly run, got over the hill and the fuel pump had gone out. Had well over a half a tank when it did this. The trucks an 02 so mayybe the shifting problem wasnt fixed.

You must drive a peppy diesel GlennRMK to make an 8.1 feel gutless after driving a diesel, considering in a drag race the 8.1 is gonna me seconds ahead against a diesel.

Haha a diesel does need a turbo to perform.. but a gas needs a supercharger to make half the torque with another reason for failure sitting atop your engine spinning at however many rpm your charger will spin at.. Now your not much better than us turbo diesel guys are you, but with less tq and more heat. Dont fear the I6

ya, supposedly the shifting thing was taken care of in 03. i know my bros 03 will hold the gear alot better than my 01 but i still havent ever really noticed that issue on my truck yet but haven't even had it a year yet.

as for the half the torque of a diesel comment, maybe if your comparing the 8.1 to an brand new or pretty modded diesel. the stock 8.1 is rated at 340hp and like 455lbft torque, where as the early 2000s diesel like up to about 03-04 were rated at what? depending on the year and model like 225-275 hp and 450-500 lbft. so this half the torque stuff i dont know about unless like you mentioned to the other dude, were talkin about mod diesels to stock 8.1s. but i do know that you can get over 525hp and 600+lbft of torque out of a N/A 8.1 with just head and cam swap, plus you could always through the blower on top of that and that should get the output up there.

megadeth- go find a stock 8.1 and a similar year STOCK diesel and line them up from a dead stop and see how it turns out. then come back and make your assumptions. i've seen it many times and unless you got a major pos 8.1 theres not alot of trucks that get up and moving as quick as the big block. if it a long race the diesel will probably come around the 8.1 in the top end thanks to the turbo but it has to catch up first.

CATillak · Apr 2, 2009

Wasnt aware it had 500 torque! Guess that pretty much settles it. 8.1l are fast trucks lol kinda

Dogmeat · Apr 2, 2009

Snoboner said:
Looking at an 03 Chevy Dually with 8.1 gasser, 2 wheel drive. Want to know how it would pull and handle an 11'6" Camper and tow my 4 place or Jeep in the summer. I have an 02 F-350 7.3 but I'm not secure with the tranny holding up for this application. Just replaced the tranny 2 months ago and my confidence is low. The Chevy has 60,000 miles on her. Thanks

I have a 2005 2500HD Extended Cab Short Box 8.1L/Allison combo, 3.73 gears 285/75/16 Nitto tires ...

It pulls my 16' enclosed with two sleds in it without even breaking a sweat, and I get EXACTLY the same gas miledge (9-10mpg) towing that trailer @ 65 mph as I did with my old 1/2 ton 5.3L towing the exact same trailer.

I get 9-10 mpg towing my dad's 24' enclosed trailer too ....

It pulls very well, it's quiet, you never have to worry about it not starting when it's 40 below .... BUT...

The gas miledge on them is really bad. Those things were built to tow, and that's it ... I get about 14 unloaded down the highway @ 75 mph ...
15 mph @ 65.

I have a feeling if I'd dump the 285 tires and go back to the stock 245/75/16 tires i'd get better miledge, but those tires just look lame ...

Overall I've been completley happy with the motor .... only thing I wish was different is that it came from the factory with a 44 gallon gas tank.

I am probably gonna put a 30 gallon TransferFlow tank/toolbox combo in here soon so I can get ~450 miles out of a single fillup. As of now I get ~230 or so. (towing)

GlennRMK · Apr 3, 2009

You must drive a peppy diesel GlennRMK to make an 8.1 feel gutless after driving a diesel, considering in a drag race the 8.1 is gonna me seconds ahead against a diesel.

Not really, just an 03 Cummins with a 100 hp programmer and an air intake

Whats a stock 8.1 run in the 1/4 mile? 16ish?

Probably similar to the stock diesel, but with a programmer your probably going to run high 14s depending on truck???

A 8.1 with supercharger would be a better match for a chipped diesel, but at that point your at the same cost.

I'm not saying the 8.1 doesn't run well, I'm just saying the diesel power is nice!

I definitely wish I would of bought an 8.1 instead of that 5.3. Biggest mistake I've ever made.

AKSNOWRIDER · Apr 3, 2009

Dogmeat said:
I have a 2005 2500HD Extended Cab Short Box 8.1L/Allison combo, 3.73 gears 285/75/16 Nitto tires ...

It pulls my 16' enclosed with two sleds in it without even breaking a sweat, and I get EXACTLY the same gas miledge (9-10mpg) towing that trailer @ 65 mph as I did with my old 1/2 ton 5.3L towing the exact same trailer.

I get 9-10 mpg towing my dad's 24' enclosed trailer too ....

It pulls very well, it's quiet, you never have to worry about it not starting when it's 40 below .... BUT...

The gas miledge on them is really bad. Those things were built to tow, and that's it ... I get about 14 unloaded down the highway @ 75 mph ...
15 mph @ 65.

I have a feeling if I'd dump the 285 tires and go back to the stock 245/75/16 tires i'd get better miledge, but those tires just look lame ...

Overall I've been completley happy with the motor .... only thing I wish was different is that it came from the factory with a 44 gallon gas tank.

I am probably gonna put a 30 gallon TransferFlow tank/toolbox combo in here soon so I can get ~450 miles out of a single fillup. As of now I get ~230 or so. (towing)

hey dog meat..you can do either the suburban factory dual tank setup or a medium duty dual factory tank setup..all factory parts..you will just have to have the ecm flashed to do the auto fuel transfer(I did a customers truck back in 03 with it..was very clean plug in setup(tanks,mounts,lines, emissions, wiring....the medium duty setups go as big as dual 50 gallon tanks..not positve they will fit under the pickup chassis..but they make tanks to fit...(you can also use a custom tank with all gm lines/wiring/pump/ecm flash and have it auto transfer)

AKSNOWRIDER · Apr 3, 2009

GlennRMK said:
Not really, just an 03 Cummins with a 100 hp programmer and an air intake

Whats a stock 8.1 run in the 1/4 mile? 16ish?

Probably similar to the stock diesel, but with a programmer your probably going to run high 14s depending on truck???

A 8.1 with supercharger would be a better match for a chipped diesel, but at that point your at the same cost.

I'm not saying the 8.1 doesn't run well, I'm just saying the diesel power is nice!

I definitely wish I would of bought an 8.1 instead of that 5.3. Biggest mistake I've ever made.

for what you put into hotrodding a diesel..heres the 8.1 answer.....http://www.kennebell.net/superchargers/gm/gm81/gm81.htm

Opinions: 8.1 Chevy

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