427 LT5 Stroker Engine - Engine Builder Magazine

427 LT5 Stroker Engine

Looking to add horsepower and displacement to his Corvette ZR-1, Phil Wasinger's engine build started when he came across a used LT5 engine on Craigslist in 2014. See what went into this six-year project.

Engine of the Week is presented by

Due to its unique design and limited production for the 1990-1995 ZR-1 Corvettes, the naturally aspirated LT5 engine did not receive much love or attention from the performance aftermarket like it has shown to the other mass produced engines from Chevy, Chrysler and Ford. However, that hasn’t stopped Phil Wasinger from rebuilding his LT5 engine in his 1994 ZR-1 Corvette.

1994 ZR-1 Corvette

The main thing the LT5 engine had going for it is when Lotus Engineering (owned by GM at the time) designed the LT5, GM insisted they use the same cylinder bore spacing, block deck height and crankshaft main bearing bore diameter as the SB Chevy, even though otherwise it is a completely different engine design with no common parts between them, except for the crankshaft rear oil seal. From the factory the LT5 block is an open deck design with the lower block bored to receive 4.173˝ OD stepped aluminum liners.

Wasinger’s engine rebuild started in 2014 when he came across a used LT5 engine for sale on Craigslist.

“I purchased my 1994 Corvette ZR-1 in 2007 and in the meantime had upgraded the engine with the usual bolt-on mods available for these unique engines,” Wasinger says. “This included long tube headers, performance cat back exhaust, ported intake, performance tune chip. For a 350 cid, the mostly stock engine ran quite well putting out around 485 hp and easily turning to 7,200 rpm. However, I really wanted to see what the DOHC LT5 engine design could do with an increase in displacement, worked over cylinder heads and custom performance cams. Thus began my epic six-year 427 cid LT5 journey.” 

Phil isn’t your average DIYer when it comes to engine building. He spent a major part of his professional life working for large German diesel engine manufacturers MTU Friedrichshafen and MAN Augsburg heading up their U.S. operations. The U.S. Navy, U.S. Coast Guard and U.S. flag commercial shipping companies were among his principal customers.

This LT5 got machined for closed deck liners from Darton.

However, unlike the work his did during his career, this LT5 build was a personal hobby project that was mostly done in Phil’s home garage. Machine work and balancing were performed by a local engine machine shop near his hometown of Fairfax, VA in Northern Virginia. To kick things off, Phil knew he wanted more horsepower and more displacement.

“The goal was a smooth and reliable 650 hp for street and cruising,” Wasinger says. “Because of the LT5’s unique design, the stroker crankshaft had to be machined starting with a billet blank. The crankshaft has extensive internal drillings that act as the sole oil distribution channel to the main and connecting rod bearings. Fortunately, I was able to acquire an unused billet steel 4.00˝ crankshaft from a gentleman in Texas who had originally purchased it for an LT5 build that failed to materialize.

“In order to reach the target 427 cid with a 4.000˝ stroke crankshaft, the cylinder bores had to be increased from the original 3.900˝ to 4.125˝, which required the block cylinder receiver bores to be enlarged. For this, I turned to LT5 engine specialist Pete Polatsidis of Chicago, who has developed a closed deck ductile iron liner conversion in conjunction with Darton Sleeves for the LT5 engine.”

The LT5 block is designed to use a 99mm aluminum liner and pistons produced by Mahle. The liner inner surface is Nikasil plated, which provides a very durable wear surface. The configuration is an open deck design with the lower part of the liners slip fitting into receiver bores machined into the base of the block.

To achieve the 4.125˝ bore that Phil wanted, it was necessary to switch to a closed deck design using a specially modified ductile iron liner originally produced by Darton Sleeves and modified by Pete Polatsidis.

“With this closed deck liner the cylinder bore could be safely increased to 4.125˝ with the added benefit of being much more stable in the block,” he says.

With the crankshaft and the engine displacement figured out, Phil turned his sights to other internal components such as the 6˝ billet steel connecting rods that weigh 605 grams each, and are paired with custom Diamond forged aluminum pistons with skirt coating and offset pins.

“The pistons are 12:1 compression and the offset pins and skirt coating were specified to reduced cold start piston noise,” Wasinger says. “I also used Total Seal piston rings – a 1.5mm ductile barrel faced moly top ring, 1.5 mm ductile taper face twisted second ring, and a 3mm oil control ring.”

The LT5 is a DOHC

The LT5 build also received Calico-coated bearings – OEMs on the mains and 2.1˝ coated Clevite 77 bearings on the rods. Both rod and main bearings were installed with 0.0025˝ journal clearance.

Moving to the cylinder heads and the valvetrain for the build, Phil noted that the LT5 four-valve cylinder head combustion chamber design is very resistant to detonation allowing higher compression ratios to be used while running pump gas. To maximize his set up, the cylinder heads were fully ported and flow tested. The intake ports were opened up to 37mm and intake bowls were also enlarged.

“The original 39mm intake valves were replaced by 42mm stainless steel valves from Ferrea with 8mm stems,” he says. “Intake valve seats were also enlarged to take full advantage of the larger intake valves, and I also used Ferrea springs and retainers.”

To make the valvetrain operate properly, Wasinger chose custom, billet steel camshafts from Jones Cam Design. Aside from the work he did himself, Phil says the rotating assembly balancing and custom cylinder head valve work was done locally by Lloyd Lovelace of Custom Automotive Machine in Lorton, VA. And the final in the car dyno tuning was performed by Haibeck Automotive Technology in Addison, IL.

Once the LT5 was fully assembled and tuned, Wasinger says he got the 650 horsepower he was hoping for. Now this 1994 ZR-1 Corvette is back cruising the streets.

Engine of the Week is sponsored by PennGrade Motor OilElring – Das Original and Scat Crankshafts. If you have an engine you’d like to highlight in this series, please email Engine Builder Editor, Greg Jones at [email protected].

You May Also Like

ProCharged 540 cid Big Block Chevy Engine

Prior to Sick Week 2024, we saw photos of Big 3 Racing co-owner Chuck Stefanski’s wagon, a 1981 Chevy Malibu rebodied as with LeMans parts, getting finishing touches, including an awesome ProCharged 540 cid big block Chevy engine. Check it out!

Big 3 Racing wagon big block Chevy engine

There’s just something about wagons that hit different. And, if that wagon is anything like the one Chuck Stefanski of Big 3 Racing competes in drag-and-drive events with, it’s certified badass. Prior to Sick Week 2024, we saw photos of Stefanski’s wagon, a 1981 Chevy Malibu, getting the finishing touches before making the trek from Big 3 Racing’s HQ in Hinckley, OH, just outside of Cleveland, all the way down to Florida for Sick Week. Since photos don’t always do a car justice, we knew Chuck was someone we wanted to catch up with – not only because his Malibu wagon was badass, but because it features a ProCharged 540 cid big block Chevy engine!

2,662cc Air-Cooled and Turbocharged VW Engine

This 1969 Volkswagen Beetle was just $600 when Steve Dalton bought it in high school. Having tweaked the performance of the car every year, he’s gone way past that mark and several iterations of the VW engine. Today, it’s a 2,662cc air-cooled and turbo’d VW with a bunch of aftermarket goodies.

Volkswagen Beetle’s Air-Cooled and Turbocharged Engine

This Volkswagen Beetle cost owner Steve Dalton $600 when he bought it back in high school for use as a daily driver. Every year since he’s owned the car, the Beetle and its engine have gotten some sort of performance upgrade to the point that it is at now. Steve is a regular on the

ProCharged 572 cid Big Block Chevy Engine

Inspired to build a hot rod with all its systems exposed, Leroy Edwards used his 50 years of mechanic experience to build this cool-looking car himself. Powering this hot rod is a ProCharged 572 cid big block Chevy engine with nitrous adding an extra kick. Check it out!

big block Chevy engine
Twin-Turbo 6.4L Gen III Hemi Engine

After rebuilding his ‘Lil Red Express truck for the past two years following a collision during the Midwest Drags, Rick Russell got back to drag-and-drive competition at Sick Week 2024. This time, ‘Lil Red Express featured a twin-turbo 6.4L Gen III Hemi engine!

Lil Red Express
Other Posts
Turbocharged Nissan SR20 DET Engine

For a number of years now, Derek and Rita Cho-Sam of DRZA Auto in Tavares, FL have been among our top Nissan engine shops. When we realized that Sick Week would be rolling through their part of Florida, we made arrangements to stop by and see DRZA in person. Derek and Rita gave us a

Nissan SR20 DET engine
Kevin Smith’s Turbocharged 388 cid LS Engine

Kevin Smith, owner of KSR Performance & Fabrication, has been a big part of the drag and drive community for a while now. His shop, in addition to all the performance and fab work it regularly does, stays open during events like Sick Week, so competitors can utilize the lifts and tools to get back

KSR LS engine
Kolby Bouck’s Twin-Turbo Gen II Coyote Engine

Kolby Bouck’s twin-turbo Gen II Coyote-powered Mustang was hard to miss at Sick Week 2024. Competing in the 1/8th-mile class, he was knocking out very low 5-second passes. Hear what’s inside his high-horsepower Coyote engine in this episode of Engine of the Week! Related Articles – There’s More Than Meets the Eye to Connecting Rods

Gen II Coyote engine
Scat Red Label Series Rotating Assembly for Gen III Hemi Engines

Scat’s new Red Label Series rotating assemblies for Gen III Hemis feature a 4.050″ stroke crank, 4340 steel 6.125″ connecting rods, and 2618 RaceTec pistons.

Scat Hemi engine rotating assembly