[mgarblik]

Originally Posted by pont406

Question? are these Proline 481X and hemi motors close to replicating a factory GM or Mopar design as far as head chambers, valve layout, bore spacing, and other parts location parameters? or are they clean slate redesigned setups, (kind of like the LS was for the SBC V8 GM lineup)?

The 481X and Hemi don't look anything like a modern hemi, an old school hemi, or BBC IMO. I am sure some of the best features of many different engines finds it's way into the design, but they look like unique, purpose built, billet drag racing engines to me. A long, long way from any production engine. When we raced the Boss Bird, most of the well funded teams we ran against had billet blocks and heads, Alan Johnson, Brad Anderson Hemi's, mostly. Their biggest advantage against our production based Pontiac engine was ease of at the track parts replacement. The deep block offered easy access to all the main bearings for replacement. The Pontiac valley cover with it's two fasteners was always a concern to seal. These billet engines are designed for service. We could run right with them though, including our #1 qualifying spot at the NHRA Hot Rod Reunion. Here is a link to some information on the hemi and 481X from Proline. Looks like a used hemi is about 75K and a used 481X around 60K. Bring your checkbook.

https://www.prolineracing.net/produc...stage-4-engine


To try and answer your parameter questions a little better, the 481X uses a BBC bore center, not sure about the hemi. Here is a little more info from another source on the 481X .




" Running a high horsepower mill on an engine dyno is an abusive task for any dynamometer, and every dyno has a limit to how much torque and horsepower it is capable of keeping loaded. So as a means to preserve their high dollar investment, when most engine builders connect a freshly assembled 3,000 horsepower mill to the engine dyno — prior to shipping it out to the customer — the engine is generally tested at a fairly conservative power output which is often nowhere close to its peak potential, or even near the same level that the customer will be pushing it to in many cases.

To better stress-test their engines at a higher horsepower, to be fair to the customer, Steve Morris resorted to designing and building his shop’s engine dynamometer himself. While Steve states that this specific 525ci 481X engine is capable of holding itself together at 90 psi, not even the SME dyno would survive a max power pull with this engine. So this 481X was instead tested to between 40 and 50 psi of boost, which is still much higher than most dyno cell operators would dare to go.

The Build
481X Billet Block Pistons

AJPE’s billet 481X engine block and SME’s custom spec Diamond pistons.

As stated earlier, AJPE’s 481X engine platform is a hybrid between the big-block Chevy and Hemi architecture. It retains the big-block’s 4.84-inch bore spacing, but utilizes mostly Hemi patterned auxiliary components. And AJPE teasingly calls this combination the “Anti-Hemi.”

Additionally, many of the parts used in this all-billet build are designed in-house by the team at Steve Morris Engines. Including the custom SME designed billet intake manifold, 90mm twin throttle body setup with a tight radius “Ram’s Horn” intake elbow (for better clearance), SME valve covers, front motor plate, balancer, crank trigger pickup, and cam sync design!

The top end includes AJPE’s lightest “stage four” 6061-T651 billet cylinder heads, weighing just 36.6 pounds each! The heads also feature 73cc combustion chambers, 50 degree valve seat angles, Trend 1/2-inch intake and 9/16-inch exhaust pushrods, 0.937-inch Jesel lifters, and a custom grind SME camshaft to time the 2.450-inch intake and 1.920-inch exhaust valve events.
Steve Morris Engines - 481X Billet Block

AJPE’s billet 481X engine and “stage 4” cylinder heads, with a custom SME billet intake manifold.

Internal lubrication is handled by a five-stage Peterson dry sump oiling system, and fueling is accomplished using an Aeromotive front mount fuel pump feeding a set of Atomizer injectors — which are both powered through a single SME belt drive assembly.

Boost pressure is forced through the 481X using two Pro Mod-spec 102mm Precision turbochargers, while boost control is managed through a pair of Turbosmart wastegates and blowoff valves. But Steve says they will most likely be downsizing the turbos to better suit Tuttle’s needs before sending it out to him.

Holding all of that boost within the cylinders is achieved through the use of SME’s custom spec Diamond pistons, while a set of MGP connecting rods handle the torsional and tensile forces, and a 4.150-inch billet Bryant crankshaft keeps it all in rotation. And engine management for this project is controlled through a FuelTech FT600 EFI system, and Steve was just recently trained by FuelTech’s own Luis De Leon when he paid the SME shop a visit.
Steve Morris (left) and Luis De Leon (right)"