Take the RY45 engine to the next level with Wilkins racing engines


There’s no denying that when it comes to the most advanced engine technology, big (and big-priced) racing series are often at the forefront of design and development, as their competitiveness within the rules. often dictates their funding. Several months ago, we introduced you to Chevrolet’s state-of-the-art NASCAR engine which has been repurposed as a badass street / strip engine. Now we bring you its avant-garde counterpart of the Blue Oval, repurposed for a top off-road racing truck team.

Based on Ford’s NASCAR Cup-specific FR9 engine design, Jeff Huneycutt takes us on a tour of what could very well be the most exotic block cam engine on the planet – the RY45 modified by Wilkins Motorsports. The RY45 was an engine assembly that took Roush-Yates’ knowledge of the FR9 engine in Cup competition and applied the parts to other forms of motorsport in the RY45.

Obviously, the “RY” in the name stands for “Roush-Yates” while the “45” denotes the engine bore spacing of 4,500 inches. This is 0.120 inch more than the standard 4.380 inch bore space of the Windsor family. Designed to be more economical than the FR9 program for people who don’t work with huge support, the FR45 has found its biggest market in late super model racing. However, Sandy Wilkins of Wilkins Motorsports put his twist on the RY45 for other forms of racing. Which makes sense, since Wilkins was part of the original design and development team for the RY45.

RY45s for dirt

In order for the Carlson Motorsports team to be competitive in the Pro-4 class of the Amsoil Championship Off-Road Tour, they required between 890 and 900 horsepower to be competitive. For the 2020 season, Wilkins was able to supply the team with 925 horsepower and hopes to win a few more ponies in this rebuild. As such, Huneycutt points out that some engine detail is kept near the vest.

The RY45 block is made of cast aluminum and has been designed so that there is no excess material. The 16 cylinder head studs in three different sizes have been computer designed to provide optimum cylinder head sealing with minimum weight.

The RY45 engine block is very similar to the FR9 block, in that the casting has undergone a thorough design based on finite element analysis to be able to remove every possible ounce of the final part without requiring additional machining hours. The 4,500-inch bore spacing allows for a maximum bore of 4.250 inches and the cylinder and main strap design and 9.200-inch bridge height allow for up to 4.00 inches of stroke. In addition, the RY45 block has provisions for bolt-on piston sprinklers to keep everything cool.

The actual bore and stroke of this particular engine has not been disclosed, simply because it is not the normal arrangement. However, the total displacement was shared, reaching 438 cubic inches. The crankshaft is a fully polished piece of machined steel from Bryant. The work of art is found in a set of 2.750-inch coated Clevite H-series main bearings while a set of billet steel four-bolt main caps hold the crankshaft in place.

The RY45 block also has machined pads for the billet piston oil jets. They are adjustable via the jets at the end of the nozzle.

The rods use the same Clevite coated bearings, but because the crankshaft has an enlarged fillet radius at the journal, the bearings are narrowed on the lathe before installing into the Carrillo H-forged rods. Their center-to-center length is another of Wilkins’ undisclosed specifications, but the rod bolts receive a whopping 100 lb-ft of torque to achieve the desired fastening stretch of 0.0065 inch.

The pistons are from Mahle, with a lightweight and cutting edge boxed design. There isn’t an excess gram of weight on these pistons, from shrunken skirts to a shrunken pin boss and shorter wrist pin. The flat top crowns have large intake valve relief and small exhaust valve relief, and sport a top and second ring thickness of 0.043 inch / 0.043 inch.

Engine lubrication at 8,500 rpm is provided by a Dailey Engineering dry sump system. Its four-stage recovery system draws from individual compartments sealed within the oil pan and uses no external pressure lines, as all fluid is moved through internal passages in the billet oil pan system. ‘aluminum. The external pump assembly bolts directly to the pan serving not only as a direct connection for pumps, but also as a convenient mounting system.

In a very unique configuration, the ATI Super Damper harmonic balancer is placed behind the timing set and is secured to the crankshaft not by a traditional interference fit and central crank hub, but rather by being sandwiched between the pinion. bottom and hub face of the crank muzzle.

In a very unique arrangement, the balancer is behind the timing gear in order to shift the center of gravity rearward.

8,500 rpm Valvetrain and high-end

In order to properly seal the cylinder heads to the block, sixteen cylinder head studs of different sizes are used to generate the required clamping force on the cylinder heads. Cometic MLS gaskets, which were custom designed with assistance from Wilkins, provide the true seal between head and block.

The RY45 cylinder heads are an uncompromising aluminum cylinder head design. The 37cc chambers combine with the flat-topped pistons to create a compression ratio close to 15.0: 1. The tiny chambers house large 2.170-inch titanium intake valves and 1.650-inch titanium exhaust valves, both with a lightweight 7mm valve stem. The volumes of the intake and exhaust ports are confidential, but are quite large and identical to the ports of the FR9 Cup engine.

In order not only to survive at such high engine speeds, but also to thrive there, the components used must be extremely well matched. As such, some of the specifications, like all cam lobe specifications, are retained as proprietary information. However, what has been shared is that the camshaft is a solid billet roller design, with a base circle of 60mm. As part of the RY45 block design, the cam tunnel is completely closed, only the tappet bores and a single oil supply port have access to it, meaning the cam and tappets are constantly drenched in water. oil.

Like the block, the cylinder head profile is designed to support an absolute minimum weight. The 37cc chambers allow for nearly 15: 1 compression with the flat-topped pistons.

The tappet is 0.937 inch in diameter with keyway rings installed. Jesel keyway roller lifters are used to reduce the mass of the valve actuator and provide additional push rod clearance, without tie bars. The tappets are coated with a Diamond-Like Carbon coating to increase wear resistance in the tappet bore.

The valve springs are a double interlocking arrangement, with titanium latches and retainers with an installed intake height of 2.165 inches and an installed height of 2.85 inches on the exhaust. Additionally, the cylinder heads have integrated valve spring grease towers, which soak the spring in engine oil to help keep them cool and dampen harmonics.

A Jesel shaft rocker arm system with a massive 2.15: 1 rocker arm ratio translates movement from the camshaft to the valves. While the rocker system is available with and without an adjustment mechanism (to save weight), since the team will be performing track maintenance, the team has gone with the adjusters.

Integrated, adjustable valve spring grease nipples and both keep springs cool while dampening harmonics. The Jesel steel rocker arms have a whopping 2.15: 1 ratio and the team went for the adjustable versions, even with a slight weight penalty.

Since the RY45 was originally intended to work with a carburetor and distributor, and this will use port fuel injection, the distributor hole is blocked and a crank trigger and position sensor cam switches had to be installed to supply the Motec M140 ECU with the data it needs. A billet monoplane intake manifold is fitted with standard specified fuel injectors in the channels, while the Braswell series 1000 cfm throttle body sits on a four-hole tapered spacer.

The results of all this work and effort are quite impressive. 958.4 horsepower at 8,500 rpm and 657.8 lb-ft of torque at 6,600 rpm, which gives a solid 2.19 horsepower per cubic and a solid 1.50 lb-ft of torque per cubic . Plus, that’s 33 more horsepower than last season’s engine, which the team were already incredibly happy with.

Visually, this is a pretty boring dynamometer graph. But once you read the numbers – 958 horsepower at 8,500 rpm and 657 lb-ft of torque at 6,600 rpm – the awesome really begins to kick in.


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