Let's discuss GM's new RUMORED Big Block reintroduction!

[JoePorting]

Seems like the general trend with GM over the past 10 years has been to offer smaller motors with turbo's. I'd be surprised if they offered a big motor again. They seem to be in PC hell, so I assume all the PC people will be screaming bloody murder. Then again, they tend to compete with Ford. So if Ford is offering a bigger traditional pushrod motor, I guess GM will follow.

[GARY C]

I think so far DI is overrated, a little more power for a lot of dollars in costs and complexity.

As far as waiting 3 years before buying one, why do that with almost all pretty much proven and existing technology and sophistication. How sad it would have been for the market if all the LS buyers had waited to buy one of those successful engines?

Deep skirted crankcase strengths and larger crankcase for windage control and main line strength makes just good sense to me. Especially with better designed crankshaft counterweights.

Yes, definitely use the good old chevy bellhousing and flywheel dimensions and patterns. Keeps down cost and keeps it simple.

You notice we all kind of have that "We wanna performance use lean for that big boy!" Just another parts horse for the aftermarket and keeps the guys at GMHP busy with more product and crate engine sales!

Come on GM Let's Do This !!

The first year or 2 both the LS and Duramax had issues, even the 01 6.0 gas engine, it had lifter and lifter bore issues as well as the LS famed oil consumption issues.

Fortunately for them there are enough people that will rush out to be the proud owners of anything new on the market.

[GARY C]

Seems like the general trend with GM over the past 10 years has been to offer smaller motors with turbo's. I'd be surprised if they offered a big motor again. They seem to be in PC hell, so I assume all the PC people will be screaming bloody murder. Then again, they tend to compete with Ford. So if Ford is offering a bigger traditional pushrod motor, I guess GM will follow.

After the bail out they are under more pressure to be Americas Green auto maker so they will have to sell it as the Greenest Big Block on the market, with the push to get rid of Diesel all together I am sure they can convince their masters that this is the way to go... They can even paint the block green to show how green it is.

[Alan Roehrich]

Entirely pointless and not cost effective to reinvent the wheel. An update to the old 8.1L Vortec is all that is necessary. If you can take a stock long block 8.1L to well over 400HP and 500 lb/ft of torque, with no durability issues, and decent fuel economy in a 10,700 pound GVW or larger truck, everything needed is already there. And actually, while it is not likely that they'll build a big bore engine, there are no real cooling issues with the siamese cylinder big block blocks. Proper block and head drilling will make it work fine. But odds are they'd never go past 4.375" bore, as they don't need the displacement, and emissions could be a problem. An easy 4.375" bore and 4.25" stroke in a 10.2" block packages extremely well, and offers more than enough displacement and power. If you wanted, a 4.375" stroke fits easily. I actually own an 8.1L, I know what it will do. You could bring it to modern spec, cheap, make 450-500HP and 550 lb/ft with ease.

Adding the expense of a "clean piece of paper" design, and the attending teething difficulties, makes it a money LOSER. The old 8.1L only needs an improved intake manifold with a larger throttle body, and a new PCV system to reduce oil consumption. A better cylinder head would be nice, asthe original head is sort of limited, but it will make good power as is. No need for a raised cam, extra tall block, huge bores, or anything trick. This is an engine for a Silverado or Sierra 3500 or medium duty truck, it ain't your next bracket engine.

The only way I'd consider replacing my 3500 8.1L is if GM came out with a new version, with the old rock solid reliability of the original big block pattern. I wouldn't even consider some over sized LS/LT engine. I'm towing a race car, not racing my tow vehicle.

In any event, considering the short sighted myopic mindset at GM, I wouldn't hold my breath on a new 7.0 to 8.2 liter gasoline pushrod engine.

[Bazman]

Why the need for a gas powered big block trucks today when modern diesels make north of 400hp and 1000lb/ft while getting much more mpg?

[Schurkey]

Why the need for a gas powered big block trucks today when modern diesels make north of 400hp and 1000lb/ft while getting much more mpg?

VW, Mercedes, and a host of others prove that it's not possible to meet customer expectations AND environmental regulations with a diesel.




"I" would roll-back diesel emissions requirements to 2006 levels. But nobody in Government asks my permission for anything.

[Nikolas Ojala]

VW, Mercedes, and a host of others prove that it's not possible to meet customer expectations AND environmental regulations with a diesel.

Bosch claims they have a solution.

• Breakthrough: new Bosch diesel technology provides solution to NOx problem Bosch, 2018-04-25.
• Rauwald, Christoph: Bosch claims a 'breakthrough' that could save diesel engines Autonews, 2018-04-25.
• Van Roy, Joris: Bosch claims breakthrough in clean diesel technology New Mobility News, 2018-04-25.
• Bosch says it has solved diesel NOx problem; as low as 13 mg NOx/km even under RDE; refining existing technologies Green Car Congress, 2018-04-26.

[JoePorting]

The cheapest and easiest solution would be to throw a turbo on an LS motor.

[COMP461]

This is the truck engine plane and simple. You have only look at the Ecoboost motors to know where they’re going the only reason for a bigger displacement is to replace the turbos on the 2.8 and 3.2 ecoboost motors. Imagine taking a 4.1 L combustion chamber now give it the sweptvolume of an 8.1 L engine. This Emulates that 4.1 at 14.7 intake boost assuming 100% VE. No expensive turbos no intercooler just more air. This effectively makes for a cheap truck engine. People are sick of the $12,000 price tag of a diesel opition. This coupled with almost a dollar more per gallon. This is the future of the 3/4 and 1 ton truck.

[Newold1]

I think the reason and Ford are both going to be releasing their respective gasoline N/A larger cubic inch engines is probably for some of these reasons.

1. They are understanding that the cost of the current and the next generation of truck and medium duty diesels are getting to EXPENSIVE AND COMPLICATED in meeting the ever tightening emissions standards and the cost of light and medium duty truck diesels is raising the cost for buyers with the recent rapid escalation in those trucks even with just current available gas N/A engines.
2. The current gas N/A engines like Fords V-10 and GM's 6.2L DI V-8 engine need enhancements for low rpm torque increases and simplicity in design and service for simple maintenance and lower costs for fleet and commercial users.
3. Meeting the ever increasing emissions, cost and NOX emissions on the diesel engines is getting more difficult and somewhat to expensive.
4. Ford has already released their new big block N/A contestant and I think for marketing and bragging rights, GM wants to do the same. GM has plenty more recent experience with big block N/A engines and already can use possibly some re-engineered big block offerings that have been use in the industrial powertrain system to date.
5. Don't think if they are going to do something better and more efficient they will resurrect the 8.1L. The reason being that engine was a heavy beast and all auto manufacturers today FINALLY realize how important weight is to improve fuel economy and customer wished economy improvements. The 2000 vintage 8.1L also had a lot of problems with not so great fuel mileage, oil consumption and meeting cold start emissions requirements, that's one of the reasons it was dropped in 2009, So much manufacturing technology and easier aluminum casting and manufacturing methods is now at GM that applying that to casting and manufacturing large volumes of all aluminum heads and blocks is the standard now and as far as strength, I think the successes with the 6.2L LS truck engines has proved that lighter aluminum based engines have a dominance in truck engines. I also think that even the industrial powertrain market wants a lighter more efficient big block N/A engine.
6. Think if GM does put a new N/A V-8 big block in the HUNT, I hope they use a clean sheet of paper and introduce a better preforming and operating big block design and if were are lucky it will have some nice performance and aftermarket potential! The LS engine sure didn't hurt DID IT!

[Alan Roehrich]

The 8.1 is not that heavy. I suppose if you want to knock 60 pounds off you can put aluminum heads on it. Any cast iron block of similar displacement and durability, in a truck, is going to weight what the block weighs. That displacement requires a given bore and stroke, and a given deck height to get there. And it requires a given amount of meat to contain the displacement and power and still be reliable. There won't be any "tricks", tricks are unreliable and cost extra.

The oil consumption is strictly a matter of piss poor PCV system design. It draws an oil mist out of the lifter valley. Stop that and oil consumption is practically non existent. I simply switched mine to 20W50, same power, same fuel economy, better oil pressure, and nearly zero oil consumption. I've fixed several. As far as pistons and rings go, the 8.1L as it was will accept any improved design there.

Fuel consumption is mostly due to horrific OE programming, it has no timing, and a poor enrichment strategy. Common to see them go from 9MPG to 14MPG with a reprogram. It takes X amount of fuel to make Y amount of HP, especially when you have a given displacement, a given RPM range, and normal aspiration. Especially with a two valve per cylinder pushrod/cam in the block design. There are only so many BTU's in a gallon of gasoline.

Anything between 7.0L and 8.5L is going to have a relatively similar bore, stroke, and rod length, regardless of engine family. Displacement in a truck engine is displacement in a truck engine. You want 8.1L? You're going to have around 4.25" bore and 4.375" stroke. Because that's what fits. You don't want or need a much bigger bore, it's going to hurt emissions and raise the power band. Much smaller bore and you need too much stroke to make displacement, friction is up, and actually, power is down because the bore is too small to unshroud the valves.

Start from a clean sheet of paper, and you have an expensive route to production, the engine is too expensive you have to amortize the development cost quick enough to suit bean counters) and has teething problems. Expensive and teething problems alienates the people who want a truck instantly. Trucks like that do two things. They either make money, or they haul fun stuff. Neither customer wants to spend a lot (that's another reason they don't want a diesel) and neither customer will tolerate down time. People in the market for those engines want to pay as little as possible over your basic 6.0-6.5L "small block". They're going to pay maybe $1500, not $4000. If the new ones give much trouble in the first year or two, you'll never be able to give them away after that. And those people will expect mid teens in lightly laden fuel economy. They know that there's no magic engine that pulls that kind of weight and gets 20+ MPG.

[68post]

Alan R. - I couldn't agree more. I'd think they'd lean towards slightly revised AL heads on their proven 8.1 platform, and the above mentioned improvements.

[Keith Morganstein]

The stop gap for the 2020HD is a 6.6L gen 5 LS.

6.6L Gas V8

The engine feature iron block and Chevy’s venerable small block proportions. The displacement is bumped up to 6.6-liters, and compression is increased to 10.8-to-1. This engine uses direct injection to produce 401 horsepower @ 5,200 rpm and 464 lb-ft of torque @ 4,000 rpm on regular octane. The engine will be mated to an updated version of GM’s 6L90 6-speed automatic transmission.

[Keith Morganstein]

The Diesel torque and fuel mileage won’t be matched by the gas job, BUT as said before in this and other threads, commercial truck consumers are getting very weary of tow jobs, downtime, repairs, high initial cost and fuel cost and DEF.

[GARY C]

The cheapest and easiest solution would be to throw a turbo on an LS motor.

That was my thought, my 09 6.0, 6 speed with just under 400 lb ft already has a 13,000 lb towing capacity. A mild turbo on the newer 6.2 that already makes 420 horsepower at 5,600 rpm and 460 lb-ft of torque at 4,100 rpm and one of the newer 8 or 10 speeds would be more than enough and wouldn't require much to do it.