NASCAR Sprint Cup Engine - Ford's Sprint Car Resurgence - Open Wheel

ASCS rules say that the first portion of the port up to the "ASCS" stamp in the runner can be worked, so Roush Yates developed a CNC program specifically for these heads to maximize airflow.

Here's an interesting problem just for Fords. Sprint Cars spin the external oil pump off the nose of the camshaft using a hex adaptor. But the timing gear bolt on a Ford goes through the center of the cam. To fix this, Roush Yates drills and taps all the camshafts with three bolt holes (Chevy style) along the perimeter so that a hex adaptor can be installed as you can see here on the custom camshaft from Comp Cams.

Most Sprint Car motors use a gear drive timing setup, but Anderson says their tests have proven that gear drives can transmit power-robbing harmonics. Anderson uses a timing chain setup for the Fords using Roush's Hy-Vo timing chain. It is hard to see here, but it is much heavier duty than the standard double roller timing sets most of us are used to. It needs to be because it not only spins the camshaft, but also the five-stage oil pump, the power steering pump, and the fuel pump.

This is the inside of the timing cover which is cut from billet in the Roush Yates shops. It utilizes a tensioner (the white "finger") which takes the whipping motion out of the timing chain that can happen when the driver stands on the throttle. This should help stabilize the valvetrain even further.

The billet crank is right out of the Cup program. The short 3.400-inch stroke slows piston speed at TDC, which helps build cylinder pressure during combustion and, in turn, makes power.

Roush Yates went with a Jesel aluminum shaft-mounted rocker system which should provide maximum stability. Lash adjusters are included (unlike Cup rockers) to ease maintenance. The pushrods are 3/8-inch one-piece units with 0.080 wall thickness.

The lifter bores are opened up from NASCAR-mandated 0.875 inches to 0.905 to accept solid roller lifters. Notice the aluminum tops which help keep the weight down on these trick lifters while still giving them enough height to clear the lifter bores.

Most Sprint Cup motors don't use a damper, but Roush Yates uses one after finding it didn't hurt power and helped smooth things out. It also provides a place to etch timing marks which makes accurately setting the ignition timing much easier. The damper, by the way, is the same one that Roush Yates has used in its Nationwide Series plate program.

Anderson installs the magnesium intake and fuel injection system from Engler.

One difference Anderson mandated for the fuel injection system is to move the injectors from the outside of the runners (which you can see are plugged in this photo) to the inside. This requires welding on new bungs, but it points the injectors directly at the back of the intake valves and helps keep the fuel atomized as it enters the combustion chambers.

Anderson said one of the goals was to make the engine system a complete unit to make life easier for racers. For example, the oil tank is attached to the engine as you can see here, so everything can be removed as one unit.

The five-stage external oil pump is driven off the camshaft. For simplicity, all stages scavenge from the oil pan, unlike the Cup engines which dedicate a stage to scavenge oil directly from the lifter valley.

Here's a shot of the water pump, which attaches to a cage off the timing cover and is driven by the spinning damper.

The plumbing you see here is a pressure line that feeds cool oil to the valvespring oil squirters.

The Dyno Sheet-Engine builder Jeremy Anderson was admittedly a little hesitant to hand over the dyno sheet for Roush Yates' new Sprint Car racing engine. "I've spent a lot of time building Cup engines, and it's hard to get used to sharing this information we used to consider top secret," he says. Still, we have the numbers in our grubby little hands, and now we're sharing them with you. The averages were 607 horsepower and 504 lb-ft of torque.