The LS engine platform has proven its worth over the years with the capability for outstanding performance on the dragstrip, when prepared properly. But as power levels reach the stratosphere, reliability suffers due to a number of factors, and that’s where the guys at Dart Machinery enter the picture.
In 2012, they released their LS Next platform, which offered significant changes to the standard LS architecture and solved a number of problems identified by Dart’s engineering team, led by company owner and longtime engine fanatic Richard Maskin.
Through research and development, they’ve continued the evolution of the LS Next platform into the focus of this article – the all-new LS Next2, which is seen here in completed form for the very first time. Follow along as we detail the specifics of the new design along with a preview of a future engine build, which you’ll be able to see in an upcoming article. The LS Next2 will be available in three different forms of construction; cast iron, aluminum, and billet CNC versions.
Why The Changes?
“There are things that go on in a drag race engine that don’t happen in a road-race, circle-track, or street engine,” says Maskin. “The main thing is the rate of acceleration. For example, a Pro Stock car is in second gear for three tenths of a second – that means the car is accelerating from 8,500 to 11,000 rpm or higher in three tenths of a second. The only other form of motorsports where an engine is called on to do that would be Formula 1 or IndyCar, unless it’s disconnected from the drivetrain.”
A radial-tire-equipped car won’t be as quick as a Pro Stocker, but they still impart extreme loads to the engine and all of its internals. As a result of these extreme duty requirements, drag race engines specifically offer the greatest opportunity for the Dart team to learn what works and what doesn’t from customers that are pushing their equipment to the point of failure and beyond.
“One of our customers that runs twin turbochargers brought his original LS Next block in because he was struggling to keep it together trying to make 2,500 horsepower. I had him bring in all the pieces with it, and after we analyzed the block and other parts, it was pretty obvious to us what was going on – the caps were dancing around quite a bit on the block,” says Maskin.
The main problem in that particular case was the crankshaft, which was flexing enough to cause the block to flex – and prompted Maskin to make changes in the block’s design to better handle the abuse that top-shelf LS programs are capable of inflicting. The result is the block you see here, the LS Next2, which Maskin feels is going to be the prevalent platform of the present and the future for Chevrolet enthusiasts – especially since moving forward, there most likely will not be any new pushrod small- or big-block engines forthcoming from Detroit.
Thicker Main Webbing
One of the major changes to the LS Next2 is the use of a larger main bearing diameter of 2.750-inch, or the same as a Ford Cleveland dimension. This is done for a number of reasons, chief among them the tendency for many racers to treat the LS platform like a small big-block engine, which necessitates the use of stroker crankshafts with ever-increasing arm length.
“When the stroke goes from the stock 3.500-inch to 4.000-inch and even 4.500-inch, the instability gets worse because the crank is twisting further away from its centerline. As the strokes get longer and the rod pin gets farther away from the center of the crank, it causes the crankshaft to be weaker. By going to the larger 2.750-inch main diameter, we can get the strength back into the crankshaft,” says Maskin.
“Even though it’s not a huge amount, it’s still bigger, and that’s what we need here, is bigger.”
The main webbing in a factory LS block is not very strong by design. The side rails tie the main caps into the block, but are hollowed out to allow for the longer crankshaft stroke, removing material from one of the places where it’s most important. The windows that exist in the factory block for oil control also hinder block strength; these issues are gone in the LS Next2.
“There are six main cap bolts in a factory block, but four of them aren’t doing anything,” says Maskin. “By taking the material out from the main webbing to accommodate the bolt holes, you weaken the block by removing material from what’s theoretically supposed to be the strongest part of the block.”
After close inspection of the original LS Next’s dimensions along with the factory LS dimensions, Maskin realized that there was enough room in the crankcase to allow for the larger webbing dimensions.
“From the time we decided to do this, we had Ford main caps on an LS block with a Ford main bearing housing bore in short order. We already had the caps from our Ford blocks and used the same main studs we use in the Ford by drilling the fastener holes to the same depth as we use in the aluminum Ford. Now you have a 2.750-inch main bearing, which is the same as a big-block Chevy, a Top Fuel Hemi, and a Cleveland Ford. Parts availability is much more common,” Maskin says. “The bulkhead width in the block is now .960-inch, which is the Ford width, rather than the .920-inch size of the LS.”
As an important side note – the LS Next2 is also available with LS-style mains in both cast and billet-block options; the thicker mains are still in place, which serves to provide the added strength regardless of which option a user chooses. In fact, the block in the engine down below uses the stock LS main dimension (2.559-inch) as we were under a time crunch to get it constructed and couldn’t procure a crankshaft with the larger dimensions in time to meet our construction deadline.
“We didn’t invent this; what we did was take what was possible and incorporate it into our design. All of the blocks are the same, but the part is made out of different material,” Maskin says.
Billet Versus Cast
Maskin says that Dart’s also working on a solid-cast LS Next2 block with no water jackets, for the racer who is planning to run the engine water-free but doesn’t have the coin to work with the substantially more-expensive billet block.
“I can put in stronger sleeves if there are no water jackets, and if I can pour the material without any shrinkage we’ll have a good piece. There are some challenges, but none that we’re not aware of,” says Maskin.
There are a number of different ways to keep the material shrinkage down as the casting is made, and this is why it’s not so simple – it’s trial and error to get a good block. Dart currently uses some of these techniques and is working to deploy them successfully during solid-block construction.
The above image shows the solid deck surface in our billet block.
The billet blocks are cut from 6061-T6 aluminum that has been heat-treated to 115 Brinnell specs.
According to Maskin, the compacted-graphite cast iron blocks are stronger than both the cast aluminum and billet pieces, but that strength comes with two caveats – heavier weight, and less elongation strength – which leads them to be more prone to cracking in the event of a tuning error.
“The big problem with the LS engine – whether it’s aftermarket or GM parts – is that there is no strength within the crankcase itself. They often break from the bottom up. As the block houses the framerails of the engine, it has to be super-strong. If you do everything right, you can take a not-great crankshaft and make it OK, but it’s still causing the problem,” he says.
The above is the reason that’s driven Dart’s creation of the original LS Next and LS Next2 designs.
In addition to the strength provided by the upgraded main dimensions, Dart also engineered other changes into the LS Next2 to make it more user-friendly, especially for drag racers.
In conjunction with the beefed-up main webbing, the ability to use a stronger 1/2-inch fastener becomes possible. Wider, stronger, taller, main caps are also part of the equation, which permit the fasteners to be torqued to 105 foot-pounds, which is designed to stop the caps from walking around. The machining process also accounts for the use of a center-counterweight crankshaft.
The LS Next2 is also available in a raised-deck configuration to allow for maximum stroke combinations. The iron LS Next2 is available in deck heights from 9.240-inch up to 9.450-inch with a standard cam position. The iron block can handle up to 4.200-inch bore dimensions.
The aluminum LS Next2 block is available in three configurations; from 9.240-inch up to 9.450-inch with a standard cam position, 9.240-inch up to 9.450-inch with a raised cam position, or a raised-deck, raised cam design with 9.750-inch to 9.950-inch deck height as used in our project engine shown here. 4.000-inch and 4.125-inch bore sleeve dimensions are available regardless of the aluminum block configuration. The largest recommended bore size in these is 4.165-inch, which nets .0675-inch minimum sleeve thickness at that dimension. Deck thickness is .625-inch minimum to provide a stable base for those high-horsepower combinations.
Dart has also worked with Darton on their MID sleeve system with the LS Next2 and offers this configuration in 9.240-inch and 9.750-inch deck heights for the aluminum blocks.
The 441ci Cast Aluminum Engine In Practice
The engine shown here uses the LS Next2 aluminum block featuring a 9.75-inch deck height – stock deck height is 9.240-inch – and 4.125-inch bores, working in conjunction with the rotating assembly to provide a total of 441 cubic inches. The block has been modified to run water-free by Late Model Engines, similar to this engine we covered recently. It’s also been filled with Moroso‘s Hardblok concrete to help provide additional strength in the crankcase.
Other features in the block include the .388-inch raised camshaft location that allows for long stroke crankshafts to work without the worry of running the rotating assembly into the camshaft. Additionally, there’s a 55mm camshaft bore, .937-inch lifter bores, and 1/2-inch ARP head studs with 3/8-inch outer studs.
A Callies billet 4.125-inch-stroke crankshaft uses the stock 2.559-inch main bearing dimension in this iteration. The crankshaft, built from Timken 4330VM alloy steel, has been balanced with heavy metal and machined with Callies’ Ultra-Shed counterweight profiling. Their Aero-Shed super finishing process has also been performed to help the crankshaft’s counterweights shed the oil in the crankcase.
The rest of the rotating assembly consists of GRP 1200 Pro Series billet-aluminum connecting rods measuring 6.300-inch long, with a 2.100-inch journal dimension and .927-inch pin bore. ARP’s L-19 connecting rod bolts measure 7/16-inch. Clevite rod and main bearings that have been coated for friction reduction by Calico Coatings are used.
Diamond Racing pistons offer lateral gas ports and double pin oilers to go with the hard-anodized tops and anti-friction skirt treatment. They ride on Trend Performance DLC-coated wristpins, with Total Seal rings in place. Custom .080-inch thick SCE Pro Copper head gaskets – with no provisions for water – have bores measuring 4.140-inch.
We didn’t invent this; what we did was take what was possible and incorporate it into our design. – Richard Maskin, Dart Machinery
We’ll cover complete engine buildups – using both this cast aluminum block and the forthcoming billet block – in a future article, but keep in mind that this engine will be capable of high 6-second elapsed times when equipped with the ProCharger F-1X-12 supercharger running from a Component Drive Systems gear-drive unit.
Dart’s new LS Next2 continues a long line of innovative products from the company; Richard Maskin has a history of identifying problem areas and then applying solid engineering principles to build products to solve those problems. The cast-aluminum engine above is installed into one of our project vehicles, and despite not having any time to test it prior to its maiden voyage, went out and won its very first race under very challenging track conditions. As we have more time to work with the product – and install the next version of the engine, based around one of the billet blocks, we expect performance to improve yet again.