i'd like to see a dmax review

[THE BIGPUNN]

i'd like to hear it from previous 8.1L owners on how much you like or dislike the dmax after trading up for one. in your opinions, was there much a difference to really make it worth it?

[jelisfc]

Try this.

 

http://dieselplace.com/forum/forum_posts.a...W=Steve+Cornell

 

You need to read his reply about half way down for the comparision.

[bigdogs]

I'll just add my $.02 with my Duramax. Most of my driving is city and my average MPG is 18.7. I have never had a truck (even with a small block 350) get that kind of mileage.

[Steve Cornell]

Since I've owned and towed (heavy) with all the combos I feel I can give an "unbiased" opinion.

 

I was very happy with the Duramax but since I sold my car hauler I really no longer had a need for it, I probably would have kept it but this was a $47,000 truck that I purchased for $39K less the $1500 rebate at the time and after a year and a half sold for $37,000( with the rebates I could have bought the same truck for less, so why not let it go

 

The diesel had better takeoff and held overdrive much better than the 8.1 however it did not "out pull" the 8.1, yes it got better mileage and pulled at a lower rpm but the 8.1 would go "faster" up a long grade, yes the 8.1 was "screaming" and sucking gas but it would run........ note: both trucks were stock with 3.73 gears with the exception of a UPD (NSV) intake with stock filter on the 8.1.

 

The diesel was a great running truck both loaded and empty and I've never "complained" about the mileage on any truck I've owner (it's a HD truck, if I wanted economy I would have bought an import) but ........ it never got "twice" the mileage as the gasser as you see posted so many times on these forums, I got 16-18 running around empty and 8-9 towing (grossing 22,000 lbs) the 8.1 got 11-13 normal driving and 6-8 towing the same trailer.

These numbers are from actual mileage calculations at each fillup, I can't find the spreadsheet from my 99 ext cab with the 6.0 but I recall the empty mileage was 13-15 and towing 10,000lbs was 7-9, I'm on my 4 tank of gas with the new GMC and the first three were 14.9mpg, 14.7 mpg, and 15.1 mpg.

 

I have a company truck (04 Ford Power Stroke Crew)puke.gif that I can use for many things but we are planning on building a new home and the wife will need a 4WD this winter so we decided to purchase another truck, the crew cab was great but my oldest is now off to college and the shorter truck is easier for the wife to get around so we decided on the ext. cab this time.

 

It is hard to justify (cost wise) the diesel unless you are towing a lot or just "want one", many people with diesels will never pull anything but this is America so if you want one and can afford it I say "Go For It", the 6.0 is a very good running engine and I think I'll be very satisfied with it for my current needs.

 

Steve

[8100HD]

Thank you, Steve for alway giving a truthful, un-biased opinion on this "touchy" subject.

 

Just to add some insight from a blown 8.1 owner who tows with both...prior to putting the Whipple on my 8.1 I would go for the Dmax everytime I was going to tow...now its a toss up...long trips the nod goes to the diesel just for the mpg's...around town and shorter tows...gasser all the way.

[Daubs]

Steve Cornell: Good points on gas vs. diesel. I seriously considered a D-max when ordering my 2500HD CC this winter.

 

I did spreadsheet and calculated my average miles per year (around 12k), then looked at MPG I would be getting from 8.1 vs. the D-max. Took in to consideration the extra cost of the D-max and found that the 8.1 was a better fit for me. Calculated lower MPG and found I could drive the 8.1 for six to seven years before cost savings would off set price of diesel engine.

 

Other factors: I don't pull any large trailers, just my small 14' fishing boat. Don't care for the smell of the diesel fuel or exhaust (although I like the sound!). Finding diesel is sometimes difficult in rural Missouri.

 

That said, I'm very pleased with my 8.1 / Allison. Getting close to 10 around town while averaging 22-25 MPH for the tank of gas. Getting 13 on the highway. I can't complain a bit with those numbers. Sure they aren't D-max numbers, but I can't complain.

[Shawn T]

Steve Cornell:  Good points on gas vs. diesel.  I seriously considered a D-max when ordering my 2500HD CC this winter. 

 

I did spreadsheet and calculated my average miles per year (around 12k), then looked at MPG I would be getting from 8.1 vs. the D-max.  Took in to consideration the extra cost of the D-max and found that the 8.1 was a better fit for me.  Calculated lower MPG and found I could drive the 8.1 for six to seven years before cost savings would off set price of diesel engine. 

 

Other factors:  I don't pull any large trailers, just my small 14' fishing boat.  Don't care for the smell of the diesel fuel or exhaust (although I like the sound!).  Finding diesel is sometimes difficult in rural Missouri. 

 

That said, I'm very pleased with my 8.1 / Allison.  Getting close to 10 around town while averaging 22-25 MPH for the tank of gas.  Getting 13 on the highway.  I can't complain a bit with those numbers.  Sure they aren't D-max numbers, but I can't complain.

 

<{POST_SNAPBACK}>

 

 

 

Daubs,

This is funny because we are comparing apples to oranges. It is all a matter of personal preference. I currently have a D-Max. I put about 24000 miles per year on my trucks. I also did a spreadsheet on the fuel cost savings. I will be saving money on the diesel after only three years. I live in rural Utah and diesel is on every corner. A D-Max is in the most demand around here, by far. The 8.1's just sit on the lots while it is hard to even find a used D-Max at an auction. I am not knocking the BBL though, it is a tuff motor. It is also demographics too. When I trade after four years it is an abvoius advantage to have a diesel around here. I will sell it in a heartbeat, for whatever I want. Just my 2 cents

[whitesnake01]

I own a 93 K2500 Suburban with a supercharged 454. Its fuel consumption is almost identical to the 8.1L; I get 9.5mpg towing and 14mpg solo on hi-way.

 

I recently got a 2005 2500HD witha DMAX/AT. Costs more, some of which improves resale value. I do not think I've ever had to worry as much about fuel issues with diesel as with gas. With the 454 I just filll it up with super and off I go. With diesel you got to worry about things like water, fungus or if you'll have any skin left in your palms after you run it dry.

 

Noise. DMAX is quiet when compared to a blown 454 with headers, etc. Fuel economy: big plus for the DMAX. About 50% better in my case. This not only means less dollars for fuel, but also longer range on a tank. No harder to find decent diesel than 93 Octane for a blower. Smell. Diesel is not nice, be it fumes or getting it on your hands or clothes. Don't forget all the icky additives you end up spilling and that diesel is typically sold in the dirty part of the gas station. Punch. Blower has a bit more punch and responds faster, but the DMAX comes around when it spools up. Another big plus for the DMAX is a lot of power out of the box. It also climbs hills, trailer behind, in 5th of OD locked at 1,500rpm. The 454 has all sorts of add-ons. Can be a real issue when you get stuck along the highway. You are more likely to find a DMAX tech than someone who can do good job on a modified engine. Ablity to take a beating. I have no complaints about the 454, although the blower exposes it under load and when it is hot outside. I have not yet towed with the DMAX in hot weather in serious hills.

 

Another item that should not be overlooked. The DMAX and many truck diesel engines do not have stable designs. That is, truck makers are making sweeping changes every few years. This has gotten worse in recent years. This means you might effectively end up with a low volume engine, in the grand scheme of things. With the gas BB, not much has changed in the past 10 years. And I doubt GM has a big staff working on making it better. The design is proven. It works well. But it is also a pig when it comes to fuel consumption. They have effectively not done squat about that since the early 90s except releasing a few more HP by adding a mile of pipes and wires.

 

With my 454 it is hard to justify driving it to work. I just use it for towing and family outings. With the DMAX, it does almost as well as my old Crown Vic. Switching over to diesel for my tow truck appears to be the right thing. Given the stream of investment that diesel technology is receiving, it would appear as if we'll see more innovation there than in the gas space. The question is: when to cross over as an individual. For me, the new LLY appeared to be the right time.

[4-By-4]

I now own both, amost identical trucks..both 4x4 ext cab long beds. The 03 is an 8.1 LS loaded with everything but leather, and the 04 is a Duramax LT. The only reason I have both is I was far enough upside down on the 03 that I decided to drive it a couple years before I sell it.

 

I think both are excellent vehicles, but my 8.1 just didn't like my 10,000lb+ toybox. Last winter, I had an approx 8,000lb trailer, and had to upgrade this spring. The 8.1 towed the smaller trailer very well, and got about 8 mpg fully loaded. Soon as I hooked up the bigger one, mileage dropped to 5, and the truck became a white knuckle ride for me. It pulled the trailer, but, I could feel it struggling with it. Plus, the 5mpg reduced the range enough that there is one leg of my normal trips that would require some additional gas capacity issues.

 

I've towed the new trailer with the Dmax..I find it significantly improved. Perhaps it's psycological, but I am able to relax, and don't feel the truck is at it's "edge" with the trailer as the 8.1 does. That feeling alone is worth the extra price for me, as I go camping to relax, and the last thing I want to do is be stressed on the way to and from. Also, the diesel looks to be in the 9-10 mpg range, which keeps my trips normal, and eliminates worry about running out of gas..fuel..whatever.. I do like the lower rpms while towing. I feel there is more "accelleration" available while towing with the diesel than the gasser.

 

Around town, I don't see much difference between the two. I can get a grin on my face from either, and it's fun when a little riceboy finds out his fartmobile isn't faster than a big old truck..either one takes care of that problem. The 8.1 loses the gas mileage contest here too....10 versus 15 with the dmax. On the highway, unloaded, both are fine, with the 8.1 returning about 13 and the dmax currently 19-20.

 

I haven't had any issues with diesel, yet. But I only have about 2200 miles on it. The diesel does have a little bit more routine maintence, but I tend to overmaintain my vehicles anyway..just some more stuff to do. I'm concerned with the long term injector issues, but I'll just have to deal with that when the time comes. I had one problem when the turbo charged inlet hose blew two weeks ago, but the dealer fixed it and said it had a TSB out on it. The 8.1 had the auto a/c go out in the first 500 miles too, so neither is a clear winner in initial quality in my book either..

 

Now having had both, I really don't understand the big arguments between diesel and gas proponents that happen all to frequently. They are both great trucks, and do what they were designed to do. I think in my case anyway, I am just too close to the edge of the limitations of the gasser for the way I drive, with what I drive, and where I drive. If I hadn't of upgraded the toybox, I would have been completely happy with my 8.1. Time will tell with the duramax, but I feel right now, this is the right truck for me and my situation. I don't think you can go wrong with either, depending on your circumstances.

[8100 Power]

This is funny because we are comparing apples to oranges. It is all a matter of personal preference. I currently have a D-Max. I put about 24000 miles per year on my trucks. I also did a spreadsheet on the fuel cost savings. I will be saving money on the diesel after only three years. I live in rural Utah and diesel is on every corner. A D-Max is in the most demand around here, by far. The 8.1's just sit on the lots while it is hard to even find a used D-Max at an auction. I am not knocking the BBL though, it is a tuff motor. It is also demographics too. When I trade after four years it is an abvoius advantage to have a diesel around here. I will sell it in a heartbeat, for whatever I want. Just my 2 cents

 

Hey sstimothy, i went to the Nashiville Auto Auction and there was 1 Duramax out of all them truck and it was 2wd. Im going to try the sale again next week and see what i can come up with.

[MCourson]

With the gas BB, not much has changed in the past 10 years. And I doubt GM has a big staff working on making it better.

 

<{POST_SNAPBACK}>

 

 

 

Not much change other than a complete redesign with the 8.1.

[whitesnake01]

Not much change other than a complete redesign with the 8.1.

 

<{POST_SNAPBACK}>

 

 

Out of curiosity, what new technology did they incorporate that the Vortec 7400 did not have of late?

 

Thanks,

[MCourson]

Im not an engine technician so I dont know. But I do know that the 8.1 and 7.4 are COMPLETELY different engines.

[Chev8.1]

SFI fuel injection not CPI(central port)

 

Replicated ports (aka LS1 like)

 

LS1 style engine controls

 

Different block

 

Different coolant flow

 

Are few things that changed. Just a general redesign, nothing ground break like the LS1 was.

 

Just waiting until the V10 comes out in 2007

[Haulin' 8.1]

Here's some info I found on a SAE web page about the inovations incorporated into the 8100:

 

"GM Powertrain engineers used the Vortec 7400 as a basis for creating the Vortec 8100 and focused on only those improvements that the company believed would provide real customer benefits. As an example, while the Vortec 7400's same general envelope size was maintained, engineers were still able to increase power and performance. The larger displacement comes from the longer stroke of 11 cm (4.37 in) used in the 8.1-L. The same bore size was maintained. A 50% increase in ignition energy, a reduction of emissions, and an improved idle quality are advantages obtained from the coil-near-plug ignition system.

 

Internally balancing the crankshaft led to a reduction in its stress by removing the counterweight from the flywheel. There's a new firing order that provides an additional 7% decrease in crankshaft stress. The cylinder heads have been redesigned to create replicated ports for the combustion chamber. This common-style porting and porting length minimizes the variation in torque from one cylinder to the next, producing a much smoother operating and cleaner engine.

 

Even-length runners in the intake manifold are used for each cylinder to create a more even combustion and greater efficiency in the combustion process. The fuel-rail system is part of the manifold itself, creating an integrated air/fuel module. The throttle body now sits front and center on the intake manifold, where it can distribute the air more efficiently and can also enhance engine package ergonomics. The technological envelope of the engine's piston and ring design was expanded to provide improved power, performance, reliability, and durability, as well as package-efficient size. The new pistons have a much shorter combustion height and a tighter ring pack than those in many other engines.

 

The engine uses cast stainless steel exhaust manifolds, a first for GM 3/4-ton and 1-ton truck engines. This material withstands higher temperatures better than cast iron exhaust manifolds and is more durable. Cooling system enhancements include quick connections that replace compression fittings throughout the engine/transmission oil cooling system, for enhanced durability and easier assembly. Radiator hose ends are specially formed and provide tighter, more reliable and durable fits. Special beads on the hose inlets and outlets also ensure tight fits.

 

GM engines are designed from the beginning to meet both the vehicle and marine customer's requirements. Some of the specially designed marine features for the Vortec 8100 include the water pump, camshaft, cast-aluminum oil pan with baffle, marine external water crossover (no water in intake manifold), and a coating of the cast-aluminum oil pan to accept marine paint."

 

 

It is a completely different engine and a major step forward for big block gas engines.

 

Vernon