If you’ve been around this hobby long enough, you’ve probably come to realize that engine building is, to a certain extent, just engine building. The block gets machined, the rotating assembly balanced, and then stuff gets torqued. You spend as much as you can on the good stuff, you cheap out in one place that inevitably comes back to haunt you, and at the end of the day you hope you end up with a stout new powerplant that can keep you happy for as long as it takes you to save up enough cash to do it all over again. At Vette magazine, we’ve covered hundreds of engine builds throughout the years, diving into the tech that really matters, all while trying to help build combinations that work well for the real enthusiast.
With the advent of the fifth-generation LT1 small-block engine, this tried-and-true formula remains pretty much the same. The camshaft goes in the same hole, the crank still gets held in place by the main caps, and the heads still need to be torqued in what seems like 500 different steps. However, not everything about the Gen 5 small-block is business as usual, and before you go ahead and pull those 6.2 liters of technology out of your C7, we suggest you do a little more research into the intricacies of direct injection, variable valve timing, and GM’s new take on many old ideas.
That’s not to say this can’t be done—quite the opposite really—but it is worth spending some time with guys on the cutting edge of the field before you end up wondering how quickly you can get a new high-pressure mechanical fuel pump from your local dealer. That said, when Howard Tanner of Redline Motorsports told us he was ready to tear into a new LT1, we were all eyes and ears. Redline, as you may know, has been on the forefront of C7 technology, and took the time early on to partner with other key shops, tuners, and parts suppliers to get a step ahead of the Gen 5 curve before it came barreling down the track.
This work up front allowed piston manufacturers like Wiseco early access to Gen 5 cylinder heads and pistons, while shops like Redline and Vengeance Racing were already working on new camshaft designs and supercharger combinations. Callies was quick to work up new crankshafts and connecting rods, while bearing manufacturers worked up solutions to the new three-piece thrusts. All of this came together thanks to an industry willing to push the boundaries while working with one another, and that hard work has culminated in the smashing of barriers (10- and 9-second C7s, 1,000+ horsepower street driven Stingrays, etc) in record time. A 416 cubic-inch stroker motor build for a C7 already equipped with a supercharger, long-tube headers, and more before the first six months of new car deliveries is even over? That’s progress, people! And now you can do it all yourself at home without having to learn as you go. Want to find out what’s new and what’s business as usual? Hang with us and Redline as we dig into a 416 cubic-inch Gen 5 LT1 build.
1. The foundation of the Stingray’s direct injection 6.2-liter engine is the all-new aluminum block, which features cast-over cylinder liners, deep skirts, and nodular iron six-bolt main caps, along with improved windage and larger M12 cylinder head bolt provisions.
2. The Gen 5 block is precision cast from 319-T7 aluminum and features new cast-in-place liners, which are encased below the aluminum deck surface. This smoother surface, combined with the larger M12 cylinder head bolts, allows for improved cylinder head sealing.
3. From the underside, the Gen 5 block looks very similar to its Gen 4 brothers, although every Gen 5 LT1 ships from the factory with polymer coated bi-metal crankshaft and connecting rod bearings.
4. Of note, the thrust washer has also been upgraded to a three-piece, 180-degree washer design that is laser welded during assembly for maximum strength and longevity.
5. The factory crankshaft is no doubt a stout piece, although Redline Motorsports had no use for its stock 3.622-inch throw. The new Callies Magnum crankshaft sports 4.000 inches of sling, which is enough to punch this little LT1 out to 416 cubic inches, while supporting big power down the road.
6. Note the difference in thrust bearing area of each crank. The Callies unit has a much softer filet for maximum strength, although that does require running a slightly thinner thrust bearing.
7. Not a deal breaker, but it’s certainly something to remember before you dig in to your own build at home.
8. Tried-and-true 6.125-inch connecting rods still work in the LT1, and these Ultra units from Callies have been withstanding big power in Redline builds for years. The ARP bolts, H-beam construction, and Timken steel forging make these a favorite of engine builders across the country (and if you’ve built an LS1 in the past, you’re already ahead of the game here).
9. Of course, the real magic of the LT1 is in the direct injection (DI) design, and as you can see from these gorgeous slugs from Wiseco Pistons, that magic is about as complex as it gets. GM is said to have spent more than 6 million hours on computational analysis to design the direct injection combustion system, and Wiseco’s job was to add strength, reliability, and performance without compromising the mixture motion and combustion characteristics of the DI system.
10. That combustion system also relies heavily on the cylinder heads and camshaft designs, which must all work together perfectly to create maximum efficiency and power. It’s worth noting that the LT1 features reversed intake and exhaust valve locations, along with large, straight rectangular ports to really take advantage of every bit of airflow possible.
11. And, like every Vette engine, the camshaft design remains critical. Vengeance Racing supplied this boost-specific camshaft to Redline, which was cut to maximize performance while optimizing valve timing. We’re not at liberty to divulge much more than that … sorry!
12. With all of the main pieces in place, it was time to start assembling the Redline 416 LT1. With the polymer coated main bearings installed and properly lubricated, the Callies 4.000-inch stroker crankshaft can be dropped into place, which is held to the block by five upgraded nodular iron six-bolt main caps.
13. Next, the 6.125-inch connecting rods and 4.070-inch pistons can be assembled and dropped into place. You’ll find that this is easiest to do with the connecting rod caps removed, which you should do prior to installing the piston and pin into the small end of the connecting rod.
14. The 4.070-inch direct injection specific Wiseco piston is a beautiful piece of machining, but the real beauty lies in the design. Engineered for the LT1 engine, the Wiseco piston features a unique injection “fuel bowl,” a thick 0.420-inch deck, a -18.5cc dome volume, and angled 2.230- and 1.750-inch valve pockets.
15. The underside of each Wiseco piston has been notched to make room for the included oil piston squirters, which come standard on the new LT1 engine. These oil squirters cool the piston under normal and extreme driving conditions, which helps decrease the likelihood of pre-detonation, knock, and excessive heat.
16. With the pistons, rods, and crankshaft in place, Howard turned his attention to the camshaft, which slides in place just like in any traditional small-block build. Note the new triangular lobe found on the back of the camshaft, which drives the mechanical fuel pump that feeds the high-pressure injectors. This is one area where the aftermarket is already experimenting by designing different fuel pump lobes to help increase fuel supply.
17. A close-up of the rear fuel pump lobe, along with a look at the high-pressure pump itself, reveals how the system works. A hydraulic roller lifter rides along the lobe, which in turn powers the mechanical fuel pump.
18. Fuel, which is delivered by a traditional electric fuel pump, is then pressurized to upwards of 2,175 psi before being sent to the high-pressure injectors.
19. The front end of the camshaft also contains some high-end technology thanks to the oil pressure controlled variable valve timing (VVT) camshaft-phasing mechanism. This mechanical phaser allows up to 62 degrees of camshaft phasing throughout the rpm range, although Redline restricts phasing control to just 20 degrees with larger camshafts like the one featured in this build.
20. Speaking of oil (kind of…), check out the massive crank driven, variable-displacement, dual-pressure oil pump, which continuously adjusts oil flow to maintain proper oil pressure at the bearings. Don’t mess with it, just put it back in place.
21. Oh, and bad news for you “cam only” warriors out there. You can’t simply drop a new camshaft in the LT1 without removing the oil pump, which now means you also have to drop the oil pan. That’s lame, since that requires dropping the subframe in the C7, practically doubling the installation time of a new bumpstick.
22. And once you’ve got the oil pan and front cover off, there is no longer a nice metal-impregnated gasket to slide between them and the block. It’s old-school Ultra Grey sealent time, as the Gen 5 LT1 features no oil pan or front/rear cover gaskets. Yeah, go figure.
23. That said, the cylinder head gaskets are still just as nice as ever, and they feature the same multi-layer steal (MLS) design that’s been used on the Gen 4 engines for years. These new LT1 units are ready to accept 12mm head bolts right out of the box, which is another nice touch for builders looking to add some boost to a build.
24. Topping off the 416 is a fresh set of LT1 cylinder heads, which Howard and the crew at Redline didn’t upgrade much, except for a new set of dual valvesprings to match the upgraded camshaft. The intake drops on next, and you’ve practically built a new engine. The only thing left to do is to drop it in the car and make some noise!
25. Back in the car, and with a centrifugal supercharger attached, the C7 Stingray hit the chassis dyno at Redline Motorsports. Given that a stock C7 baselines at just a tick over 400 hp (and torque) to the wheels, these numbers of 870 horsepower and 794 lb-ft of twist (on 13 psi of boost) shows that displacement and boost are like the peanut butter and jelly of the performance world.