How many 8.1L/496's out there?
 

Ordered my 2004 2500HD CC 4x4 from factory loaded with the 8.1L/Allison combo. Been a great truck for me and now is no longer my daily driver. The 65 mile round trip commute warranted a 30MPG Accord.

Aside from the piston slap at cold start, my truck has been very solid, requiring very little maintenance. Allison leaked a little, and they replaced the torque converter (both covered under warranty). Did brakes and shocks a while back. Just over 100k miles so far.

Who has the Big Block? Challenges? What do you like / dislike?

Re: How many 8.1L/496's out there?
 

VERY good engines.I dont get to many calls on them at the salvage yard.

Re: How many 8.1L/496's out there?
 

Enjoyed mine in the Burb - loaded down with family/stuff/fuel it'll pull out and pass with no problem. Just don't care for a heavy suburban with the 5.3, cause I use my truck as it was built for - to haul lots of people and stuff. I did have Blackbear tune the computer. Also switched the plugs out (google the 8.1 and plugs - I think it's one range colder but can't remember the AC part numbers. Helps with the oil burn that is common. Also upgraded to Taylor wires.

But I will agree, it's like any other BB and likes to drink. Would be hard pressed to DD it with gas prices, but thankfully I have a work vehicle.

Re: How many 8.1L/496's out there?
 

I had 1500 Ext Cab Silverado prior to my Big Block. When i was looking to get the 2500HD Crew, buddy of mine (who is service manager at GM dealer), said might as well get the Big Block. The 6.0's in HD Crew Cabs were getting about same MPG.

I've been averaging about 10.5 MPG city and 12 highway. I did put 285's on, re-program the CPU and install Volant intake.

My dad had a 1976 K-20HD with 350 v8 and 4 speed...and it got...wait for it...6 miles per gallon. That was city/highway, uphill/downhill, wind-at-back/in-face, full moon/new moon... S I X M I L E S P E R G A L L O N. Dad thought i was crazy to get the Big Block. But it turned out okay in my book.

Wife's Mazda Cx-9 gets 14 mpg, which ain't much better. And that's her daily driver. At least I still have the Accord rocking 30MPG.

Re: How many 8.1L/496's out there?
 

yeah I agree, I doubt it's much if any worse than the 6.0's. I also have 285's, 4.10's - I think my mileage is pretty similar to yours. that is, if I don't feel the need to teach the kid in a BMW a lesson about torque when he tries to speed up to keep me from changing lanes. :)

Re: How many 8.1L/496's out there?
 

496bb: Mine has 3.73's in the rear -- i was hoping I could squeeze a little more MPG out of my truck.

Neighbor has a BMW, and I beat him off the line. He did catch and pass me shortly thereafter, but it was fun seeing the look on his face when my seven thousand pound truck jumped out in front of his pricey sports sedan :)

Re: How many 8.1L/496's out there?
 

Re: How many 8.1L/496's out there?
 

I would have to agree with you on 6.0 getting bad MPG. I drive an 07 chevy 1500hd classic with 6.0. My comute to work is almost all city miles and i have not gotten better then 10.8 mpg. I have not had this truck for very long, so far I like it, but the mpg is terrible.:waah:

Re: How many 8.1L/496's out there?
 

I have owned the 8.1 for over ten years. 120,000 miles and still strong. Goes by everything except a gas station. Wish there was some more of these motors, maybe there would be some more things to do to it to wake that monster up, as anything worth doing costs upwards of $6,000.
:chevy:

Re: How many 8.1L/496's out there?
 

I just traded my '96 for a '02 2500HD ECSB 8.1L the other day, loving it!

Re: How many 8.1L/496's out there?
 

Had to order my 2006 1 ton 8.1 with the 6 speed allison , used to pull my toy hauler 8k loaded . stick in cruse at 75 MPH and enjoy the ride . Everybody waiting for me to sell it , its not for sale and won't be!

Re: How many 8.1L/496's out there?
 

03 Crew cab 2500HD 8.1 with Allison & 4.10's here. 68K miles - best tank so far 11 mpg.
Anybody done any performance mod/s to theirs?

Re: How many 8.1L/496's out there?
 

Re: How many 8.1L/496's out there?
 

Cut the stock muff of mine also, has a pair of Flowmaster super 44's now.
Thinkin' 'bout a set of headers after I get the SAS done.

Re: How many 8.1L/496's out there?
 

The 8.1L was a great alternative to a Duramax. I bought mine brand new on September 21, 2001 during the “Keep America Rolling” campaign after 9-11. It is somewhat rare with a 6 speed manual and bucket seats (& 4:10 gears). Almost 13 years later and I’ve only racked up 61,000 miles on it. The truck is like brand new and bone stock inside and out, right down to the airbag decal hanging from the glove box. I love the engine but I absolutely hate the truck and the ZF 6 speed as it has the most awkward shift pattern and shift gates of any manual I’ve ever driven, hence the reason it has low miles (I drove an ’89 Suburban and ’92 4Runner everywhere else). It is also the worst riding truck I’ve ever owned. I’ve been very seriously considering selling it as I am beyond tired of the 6 speed manual and have a major man crush on the new 2014 Silverado 1500’s but we have fresh baby at home so it will be a while before a new truck will happen.
http://farm6.staticflickr.com/5009/5...2b4f3cd6_z.jpg

http://farm6.staticflickr.com/5166/5...50f9558e_z.jpg


I also installed an 8.1L in my K10 in 2008. Works great and still better on fuel than any old carbureted engine ever could be with twice the power. It is like having diesel power without the BS of owing a diesel. This one is running Torque Management delete, EGR delete, drive-by-wire delete, a hot tune added and a bump in fuel pressure. The tuner claims to have dyno’d this combination at 425HP/555 lb. ft. of torque. It doesn’t take much to wake up one of these beasts. A larger cam would even do more wonders for it. I have one more 8.1L hanging on an engine stand to go in to my Burb as well.
http://farm9.staticflickr.com/8057/8...b74bc1d5_c.jpg

The only reason GM discontinued the 8.1L is because they had to invest close to 100 million dollars into the Duramax to meet 2007 and 2010 diesel emissions. The 8.1L cannibalized sales from the Duramax in the medium duty and HD trucks and with the 8.1L needing another round of emissions certifications in 2010 as well (with a cost of around 6 million), GM chose to kill it off in hopes of forcing what would be 8.1L sales to a Duramax. Plus they had "bigger" plans for the Tonowanda, NY engine plant where the L18 was built. That is a fact that can be researched with googling.

BTW, the 8.1L is not dead. GM sold the production rights to an independent engine manufacturer where they still build it today for heavy truck manufacturers like Freightliner, stationary well pumps/generators, and the marine industry (Mercruiser, VolvoPenta, etc.). In fact, they have even hogged out a version of it to an 8.8L running on gasoline, propane and natural gas.

Here is a thread I created regarding all things L18 8.1L related. BTW, the L18 was never part of the “Piston slap” frenzy like the early Gen III small blocks. The piston design isn’t even remotely the same, although a very high mileage 8.1L can develop piston slap like any other old high mileage engine can. The L18 pistons are more common with the older L29 7.4L and all older big blocks, not the Gen III small blocks.

I snapped a few pictures of the last L18's to roll though the assembly plant for one of the vehicles my company built. This was in late 2010. :whine:
http://farm5.staticflickr.com/4064/4...554c4ca6_z.jpg

Re: How many 8.1L/496's out there?
 

Cool
Thanks for the info.

Re: How many 8.1L/496's out there?
 

DirtyLarry, if you really are interested in selling your truck, I'd be interested.

Re: How many 8.1L/496's out there?
 

I’ll keep you posted. With a new baby, a wife in grad school and one new car on the payroll already, a new truck for me probably won’t happen this year. Maybe next summer.

Re: How many 8.1L/496's out there?
 

Sounds good. I've always wanted a truck like yours.

Congrats on the new baby!

Re: How many 8.1L/496's out there?
 

When was the last 8.1 put into a production truck ? I got a 2006 and was told that was the last year you could order the 8.1 from chevy.

Re: How many 8.1L/496's out there?
 

I had a 2005 2500hd ECSB 6.0 with the snowplow prep package (stiff tbars) and hated the way it rode. I now have a 2002 2500hd CCSB and think it rides pretty nice, even compared to regular 3/4 tons, let alone hd's. Nice truck, really like the dynamics of the truck. would prefer it was an 8.1 though.

My bro has a 2014 1500 crew and isn't too crazy about the trans shift feel, mileage, or the rock hard head rests. Its pretty sharp besides that though.

Re: How many 8.1L/496's out there?
 

2001 & 2002 where the only years for an 8.1L in the G-van
2006 was the last year in pickup trucks, Avalanches & Suburbans
2009 was the last year in GM Medium Duty
2010 was the last year of the 8.1L in the Workhorse RV chassis.

But, the 8.1L is still used in production today for stationary well pumps, etc. as well as some specially natural gas and propane powered trucks built by Freightliner and International. Powertrain Solutions International now manufacturers the 8.1L and sells it to any manufacturer that wants to use it. They even have an 8.8L version. GM Powertrain sold the production rights to them around the time of the GM bankruptcy.

Re: How many 8.1L/496's out there?
 

Thanks for the infoe dirty larry , I guess I do have one of the last 8.1 alison 6 speed auto in my 3500 P/U took delivery in Nov of 2006

Re: How many 8.1L/496's out there?
 

Cool to see some 8.1L guys on here! I picked my '03 up about 6 months ago. Really like the power of the big block and the feel of the Allison. Just have a leaky oil cooler line to take care of soon. I'll try to get a decent pic of the truck for the thread. Has about 145k on the clock.

Chris

Re: How many 8.1L/496's out there?
 

I have an 01 Suburban with an 8.1. Love the truck. It has a drop in K&N the cats removed and a Black Bear Tune. Love the 8.1's Thinkin about putting an 8.1 in my 1972 C/50 Rollback.



Scott

Re: How many 8.1L/496's out there?
 

I dug around a little and I swear I've read most of DirtyLarry's 8.1 posts, have yet to find the answers I am seeking.

My DD, Vortec 7400 powered, love it, am looking into some upgrades for it. I get that heads/intake/block all have different bolt hole locations, bolt patterns, etc, nothing interchangeable there with other engines(excluding classic bellhousing pattern). One of the upgrades I'm researching is coil-over-plug ignition, another is headers...they are slim pickings for GMT-400 7.4 powered trucks.

- Will 8.1 exhaust manifolds/aftermarket headers bolt to a Gen VI? If so, recommended brand/model, or is there a nice high flowing factory manifold?
- Do 8.1 valve covers bolt to Gen VI heads?
- Does the 8.1 timing cover bolt to my Gen VI?

Re: How many 8.1L/496's out there?
 

Re: How many 8.1L/496's out there?
 

DirtyLarry, you are the man! Thank you very much for the information. Yes, I first came across the L21s in the GM Electronic Parts Catalog (that is where I started thinking it might be possible for me to get C-O-P on my L29), my research shows them to be C-O-P in 1999 & 2000, carrying the RPOs L21 & LP4. In 1998 the EPC shows, 366 (LS0) & 427 (LR0) V8s with distributors...I would presume them to be the fuelie versions of the classic tall deck BBCs.

From what I can tell I need one of the L21 cam sensors, crank sensor, and reluctor wheel. Don't remember, might need L21 timing cover. I am bundling this with an 0411 PCM swap, btw.

Looks like I'm on the hunt for some 2-year only valve covers, sweet, I love rare parts.

Re: How many 8.1L/496's out there?
 

I just picked up a 2002 2500HD crew cab with the 8.1L/Allison. So far, I'm very impressed with the combo.

Re: How many 8.1L/496's out there?
 

I just bought a 2002 GMC Dually with the 8.1L/Allison. Needs a little work (crank sensor broken off in the block) but I got a screaming deal and it only has 59k miles. I bought it for the engine to put in my C10 but the truck is too good to trash, I'm going to fix it and re-sell it. I have my eye on a Yukon XL with an 8.1 that I may buy for a tow rig.

Re: How many 8.1L/496's out there?
 

Now how on earth did I miss THIS thread?? :)
Here's my 2001 2500HD 8.1/Allison. A little over 13k mi. I gotta dump those steps. Wish Kodiak still made there retractable steps. Thinking of the shortened AMP steps that some members have show pictures of, but I'm kinda cheap...

Re: How many 8.1L/496's out there?
 

Attachment 1910183
Love my truck 60,000 miles very clean!

Re: How many 8.1L/496's out there?
 

Hey Guys,

Just picked up one of these 8.1 Trucks!

I have a question. Does this engine have factory roller lifters?

Thanks