Any serious racer knows that fancy parts alone won’t get the job done. With an induction package capable of 2000-plus horsepower we were keenly aware that cutting corners on the short-block could put the entire package at risk. This meant we’d need a top-of-the-line bottom end, and that starts with a strong, high-quality block. The decision to transition from a Gen I Chevrolet block to LSX was already made. With that in mind, a call to one of the best in the business, Dart Machinery’s founder and Pro Stock legend, Dick Maskin, to give us all the insider information on this cutting edge new engine block.
HOW THE LS NEXT CAME TO BE
Maskin was happy to take our call to talk about Dart’s new LS Next block. He had been looking at leveraging GM’s LS heads and manifold for years but had set aside the task in lieu of other projects. "When I first approached the LSX platform, I knew I couldn’t fix what I saw and so I decided I wanted a Gen I bottom with Gen III heads."
He explained, "As far back as 2006, we were looking at making our rocket block work with LS heads, but we put it on the shelf until the market would be better for a home builder." As the LS market surged over the next four to five years later, Maskin decided he would take another look and get serious about building a block that would best support the platform for racers and hobbyists alike.
Maskin had concerns with the stock LS design. He wanted to address cylinder length, the oiling system and the windage. He also wanted to strengthen the block for racers but maintain 100% OEM bolt-on compliance for the hobby enthusiast. For Maskin, this required a new approach.
His main concern was the crankcase and what he perceived to be a departure from a well-tested and refined Gen I platform. The result was a complete rewrite of the LS crankcase with modifications that mimicked that of a Gen I while maintaining 100% compatibility with the LS oil pan and pump if desired. These changes resulted in several key differences between the LS Next and a traditional LS block.
When GM switched to the LS design, they also pivoted from their conventional layout to a "Y-block" design. The defining characteristic of a Y-block is the incorporation of a skirt surrounding the lower crankcase. The skirt improved strength, according to Maskin, but at a potential cost by increasing windage in the crankcase.
Dick noted that experts like Bob Glidden, Larry Morgan and David Nickens had figured this out years ago and would routinely remove the skirts on their Hemi 99 blocks. For Dick, the first step in building the LS Next was to get rid of it, as well. In removing the skirt, he also widened the pan provisions to match their Iron Eagle and added ambidextrous starter mounts. However, since the block’s release, aftermarket companies like Moroso have produced spacer kits that allow a stock LSX pan to bolt in place.
Another significant change was moving from the two and four-bolt main design to a six-bolt, "cross-bolted" main system. Traditional LS six-bolt mains have four bolts that extend into the block from the bottom, while another two penetrate the skirt and “cross” into the cap from the side.
While considered stronger, the six-bolt mains require a skirt for the cross bolts. They also have a bridge profile that runs flush with the pan rail and sections the crankcase into distinct bays.
Like the skirt addition, Maskin felt the main cap design impacted windage. Maskin said GM attempted to address the issue by adding communication windows between the cylinders. However, Maskin felt removing the material had the net effect of weakening the block in a critical area while not fully addressing the windage issue introduced by the skirt and larger main caps.
To fix the windage issues, Dart simply removed the skirt.
"I took an LS1 aluminum block, put it in the Bridgeport and cut the skirt off," Maskin explained.
However, removing the skirt meant the main caps would also have to be redesigned. Luckily, Dart already had a solution in the billet splayed mains they used in earlier designs like their Iron Eagle.
Maskin’s goal of reincorporating a Gen I bottom end was perfect for our project. As was explained to us, the small factory oil pan coupled with the side skirt design could be disadvantageous for windage and might trap oil in the area of the spinning crank. This in turn could steal oil from the pan and cause the oil pickup to suck air.
Dart explained that this initial set of changes reduced the windage problem but also netted a few added benefits.
First, Dart was able to eliminate the communication windows and reintroduce material near the main webbing and under the cam tunnel. The added material reduced cam flex by shoring up the cam bores but also reinforced a section of the block that, in stock blocks, has been known to split under high horsepower loads.
As Maskin explained to us, "In a stock LS block, the cam is not tied into anything at the bottom but a chunk of metal in the main webbing and the main webbing isn’t tied into the barrels very well, because there are big open spaces. With no metal there, it’s trying to break the main webs right out of the block."
Another advantage to the added material was the ability to extend the cylinders. The LS Next has a cylinder barrel that extends 0.375" further than a stock LS barrel. The added length allows the piston to travel a distance equivalent to a 9.615-inch deck height but in a 9.240-inch deck package and further promotes ring seal. Dick clarified, "The windows used in bay-to-bay breathing meant that they [GM] had to shorten the cylinder barrels."
He went on to explain how in a stock LS engine, it’s not uncommon to have the piston become partially exposed as "the skirt almost falls out the bottom of the bore".
Dart’s Dick Maskin took a look at everything with a fresh eye during development. One of the more noticeable changes in the LS Next is the deck. By shrinking the water passages, Maskin strengthened the deck without impacting the cooling system.
"It’s got a full deck design so you don’t see a bunch of big holes in it. The holes in the gasket are the restriction, not the holes in the deck."
Beyond closing up the deck, cooling the LS Next is unique in that it can be conventionally cooled like the Gen I or reversed cooled like the later released LT-1. As Maskin noted, "[An] impeller change in the water pump would make that easy." This added flexibility means the LS Next can accommodate an OEM water pump or the builder can modify the pump configuration to suit their needs. Ultimately, the head gasket is the largest restriction in the system and cooling remains unencumbered by the deck modification.
Another key component of the deck was the six-bolt design to accommodate high performance heads like our Mozez castings. While stock LS heads use four bolts around the cylinders, LSX head heads utilize an additional two bolts that provide more clamping pressure and prevent premature head gasket failure. Last, the block can be ordered with larger-than-stock 1/2-inch head bolt provisions. Maskin stressed that he preferred to have the block leave the factory with the proper size holes as, "it’s too easy to mess up the depth and threads" cutting them in later.
After removing the skirt, Dart set their sights on the oiling system. Leveraging his Pro Stock experience, Maskin stepped the main oil galleys to maintain pressure from front to back. As he stated, "It’s bigger in the back two thirds of the block at 0.500-inch and then steps down to 0.4375-inch for the last third, which provides pressure and volume. We’re going to call this Pro Stock technology, because that’s what it is."
Then he moved on to the main oiling, "Some guys added an extra oil galley, but we completely abandoned the LS oiling system and went with a priority main system instead." A priority main-style oil system feeds oil to the mains first, then through a separate series of passages that flows oil to the lifters. The factory block’s main oil feeds come directly from the one of the lifter oil galleries.
As Maskin goes on to explain, "There are three oiling systems in a block; oil to the mains, oil to the cam bearings and oil to the lifters. That’s it…so you’ve got to do a really good job with all three of those."
Converting the block to priority main oiling provided the advantage of being able to adjust the volume and pressure of oil delivered to the mains independent of the lifter galleys. Instead of feeding oil to the lifters and then the mains, the LS Next feeds oil to the mains and then the lifters. The stock LS configuration often resulted in excessive amounts of oil being sent to the lifter galleys to make sure there was enough pressure and volume for the mains. In the LS Next block, a builder can run oil to the mains and then restrict the flow of oil to the lifter galleys to reduce the engine’s consumption needs.
Dart then tackled the lifter bores to address premature bore wear often found in stock LS blocks. According to Maskin, when LS engineers enlarged the lifter hole and then chamfered the bore, there wasn’t enough material left to maintain lifter bore integrity.
"There’s not a lot of strength because GM removed too much material when they enlarged the bore." he points out. "So as the lifter thrusts back and forth, it wears out the lifter bore because there’s not enough metal for support."
The wear results in excessive lifter bore clearance that increases the flow of oil to the pushrods and into the top end of the engine. In some of the most extreme cases, the engine would almost drain the pan while filling the valve covers with oil. To fix this, Dart reduced the size of the oil galley feed holes from 9/16-inch to the standard 7/16 and then moved them. He commented, "In a stock LS, the answer is to bush the block and use a standard 7/16-inch hole, but that requires money and for you to know there’s a problem in the first place." Last, Dart tackled lubrication in the main and cam bearings. They drastically reduced the oiling requirement to the cam, as Maskin explained.
"In some cases we’ll restrict the cam feed down to 60 thousandths because you don’t need a quarter inch hole," he said.
Then, they addressed lubrication troubles in the mains. According to Maskin, the problem in the standard LS design was not the volume of oil sent to the crank, so putting a hole in the bearing didn’t fix anything. Instead, the problem was getting oil into the mains. His solution was to reintroduce the upper shell groove found in Gen I 350 engines. This meant the LS Next mains see oil for 180 degrees of rotation, rather than the roughly 150 degrees for a stock LS. The result was more oil where it’s needed with less oil consumption overall.
After rearranging the oiling configuration, reducing the oil feeds to the lifter and cam bores and rearranging the main to use oil in a smarter manner, Maskin claimed the LS Next can get away with as little as three GPH, which is considerably less than the standard LS. In fact, he mentioned that while LS builders are moving to higher volume pumps, LS Next builders are able to use lower pressure and lower volume oil pumps that take less power to turn.
The LS Next is a lot like what some would call a hybrid, but Maskin was quick to point out, "the LS Next is not a hybrid, the LS Next is now."
Unlike most hybrid engines, this block was designed with the goal of avoiding custom and expensive one-off parts while providing solid Pro Stock-inspired technology for racers. Propelling a 3,200 pound leaf sprung sled through the quarter mile in just over seven seconds, at almost 200 miles per hour and on a 275 radial will be tough. Luckily, Maskin and the guys at Dart have our back with a block that’s just as tough.