GMPP Gen VI 502 Engine Build - Plan B
NHRA Pro Stock Racer Jason Line Builds an 812 Big-Block With Help From Summit Racing
From the April, 2011 issue of Chevy High Performance
By Steven Lindle
Jason’s Biscayne wagon weighs...
Jason’s Biscayne wagon weighs approximately 4,500 pounds—about twice as much as the Pro Stocker he drives in the NHRA Full Throttle Drag Racing Series—so he needed some big cubes. Here’s the GMPP Gen VI 502 block he used as the foundation for the Biscayne’s engine. It was bored to 4.500 inches, align-honed, and jet-washed before the build.
It all started innocently enough. Following a race last year, Summit Racing Equipment NHRA Pro Stock driver Jason Line bought a ’68 Biscayne station wagon as a side project and laid out a quick, simple plan: Take an old 427 engine from a donor car, refresh it, and drop it harmlessly between the framerails of the wagonthen came Plan B.
Almost from the start, the guys at the shop were hacking on me about putting a relatively stock engine into the wagon, says Jason, who also builds and tunes the engines for the Summit Racingsponsored KB Racing Pro Stock team. That started me thinking. One thing led to another, and before I knew it, I was starting to assemble the pieces for a completely new custom motor.
Jason’s Plan B was to build an all-new mild 9.6:1 compression 557ci mill with the goal of topping 750 hp on pump swill. A lot of people build 540s, 565s, or 572s, but I wanted something a little different, Jason says. Basically, I wanted a race engine with low compression so I could drive it on the street.
Jason started with a GM Performance Parts Gen VI 502 block with four-bolt mains to handle the considerable power he had planned. He had it bored out to 4.500 inches and clearanced for a 4.375-inch stroke crankshaft, producing 557 ci. He then contacted Summit Racing to help piece together the remainder of the components for the build.
The rotating assembly includes an Eagle Specialties forged crank with H-beam connecting rods and Diamond coated pistons. The top end is anchored by a set of Trick Flow PowerPort 360 cylinder heads, which got a little special attention from Jason; using his NASCAR and NHRA engine building experience, he altered the intake runners to increase airflow from 365 to over 400 cfm. A port-matched Trick Flow single-plane intake and a Willy’s carburetor complete the top end.
The valvetrain centers around a COMP Cams solid roller camshaft, which Jason says is mild and durable enough for the street without sacrificing the power numbers he was shooting for. In fact, the 557 exceeded Jason’s goals, delivering 812 hp on the dyno.
Anyone can duplicate this build using parts right out of the Summit Racing catalog, bolt it all together without the extra port work, and get close to the horsepower we made, Jason says. That would certainly be enough for most people, but our team motto is: Anything that can be done can be overdone. Jason’s 557 is proof of that.
The main bearings were prefitted...
The main bearings were prefitted with clearances between 0.0025 and 0.0030 inch; the typical range the team shoots for with its Pro Stock engines. Jason chose an Eagle Specialties forged crankshaft to handle the 812 hp at 7,000-plus rpm.
Gen VI blocks are designed...
Gen VI blocks are designed to work with one-piece rear main seals, but the Eagle Specialties crankshaft required a two-piece rear main seal. To make the block and crank work together, Jason used a special B&B adapter to give the rear main seal a place to sit. End clearance was set at 0.005 inch before the main caps were torqued to 105 ft-lb.
Jason chose Diamond pistons,...
Jason chose Diamond pistons, which are used on the team’s Pro Stock engines. The team has its competition pistons vertically gas ported, but for this street-oriented 557, Jason went with a lateral gas porting option. The gas porting allows cylinder pressure to get behind the top ring and push the ring against the cylinder wall for better sealing.
For the piston ring package,...
For the piston ring package, Jason went with Total Seal. An oil ring spacer was installed because the compression height of the piston caused the wristpin bore to break into the ring lands. Using fish scale, he set the oil ring tension to 11 pounds of drag to prevent the big-block from oiling or smoking.
The pistons were installed...
The pistons were installed on a set of Eagle Specialties 6.385-inch length H-beam connecting rods. Diamond recommends a 0.0065-inch piston-to-wall clearance, but Jason elected to go with a tighter 0.0060-inch clearance to keep the engine running quieter.
At the heart of the engine...
At the heart of the engine is a custom-ground COMP camshaft with 254/270 degrees of duration at 0.050-inch lift that was installed and set into place with a Jesel front cover. The custom ground, solid roller cam and lifters were used to avoid the high rpm “valve float” sometimes associated with hydraulic valvetrain setups. Cam endplay was set to 0.005 inch using a set of shims, which was supplied with the cam seal.
Forgoing a conventional timing...
Forgoing a conventional timing chain, Jason opted for a Jesel beltdrive system. With numerous dyno runs in store for the 557, he wanted something that was user friendly and easy to adjust on the fly.
The oiling system features...
The oiling system features a Stef’s standard volume oil pump and Stef’s aluminum oil pan. The lightweight pan uses a baffle and trapdoor setup to keep the 557’s oil under control.
Jason turned to Trick Flow...
Jason turned to Trick Flow Specialties for a set of PowerPort 360 cylinder heads. While the heads flow well right out of the box, he couldn’t resist putting his own stamp on the castings. In their off-the-shelf form, the heads have 360cc intake runners and deliver an impressive 365 cfm of airflow.
|By the Numbers |
|RPM ||LB-FT ||HP |
|4,300 ||701 ||575 |
|4,400 ||711 ||596 |
|4,500 ||718 ||616 |
|4,600 ||722 ||633 |
|4,700 ||725 ||649 |
|4,800 ||726 ||663 |
|4,900 ||726 ||677 |
|5,000 ||725 ||690 |
|5,100 ||724 ||702 |
|5,200 ||723 ||715 |
|5,300 ||721 ||728 |
|5,400 ||719 ||740 |
|5,500 ||717 ||751 |
|5,600 ||714 ||761 |
|5,700 ||710 ||770 |
|5,800 ||705 ||778 |
|5,900 ||698 ||784 |
|6,000 ||692 ||790 |
|6,100 ||686 ||797 |
|6,200 ||681 ||804 |
|6,300 ||674 ||808 |
|6,400 ||666 ||811 |
|6,500 ||656 ||812 |
|6,600 ||645 ||810 |
|6,700 ||634 ||809 |
|Max Torque ||726 at 4,800 |
|Max Power ||812 at 6,500 |
|Avg. Torque ||700 |
|Avg. Power ||730 |
Using a bridge dial indicator,...
Using a bridge dial indicator, Jason found that the pistons protruded from the bore by 0.005 inch, effectively lowering the deck clearance and increasing compression. Since he was shooting for 0.046 inch of deck clearance, Jason ordered a set of 0.051-inch-thick Cometic MLS gaskets to increase the deck clearance to his liking; the result is a 9.6:1 compression ratio.
Using his years of experience...
Using his years of experience with top-end engine components, Jason did his own port work on the heads. He started by welding material on the intake runner floors, essentially raising the runners by 0.150 inch. He left the cross-sectional areas alone, but changed the intake valve angle from 45 to 50 degrees. Once he was finished, the intake runners were still 360 cc, but airflow was increased from 365 to over 400 cfm. The good news is you can expect Trick Flow to carry Jason’s version of the PowerPort 360 heads in the near future.
For increased valvetrain stability,...
For increased valvetrain stability, the rocker arms were welded together—a trick the team uses on its Pro Stock engines.
|Parts List || || |
|MFG ||PN ||Item |
|COMP Cams ||CCA-01-000-9 ||Camshaft |
|CCA-883-16 ||Roller rockers |
|Clevite ||CLE-MS829HX ||Bearings |
|Cloyes ||CLO-9-3149A ||Timing set |
|CLO-P9005 ||Timing chain bushing |
|Diamond Pistons ||*Call || |
|Eagle Specialty Products ||ESP-445443756385 ||Crankshaft |
|ESP-CRS63853D ||Rods |
|GM Performance Parts ||NAL-19170540 ||502 block |
|Holley ||HLY-12-454-20 ||Fuel pump |
|Summit Racing ||SUM-G6316 ||Timing cover |
|SUM-850510 ||Ignition |
|SUM-850051 ||Distributor |
| Trick Flow Specialties ||TFS-41410007 ||Heads |
|TFS-41400111 ||Intake |
|TFS-41400804 ||Valve covers |
| *Custom order from Diamond Pistons |
Trick Flow’s R-Series intake...
Trick Flow’s R-Series intake features a single-plane design for 500-plus cubic-inch engines, making it perfect for the 557. Jason sent the manifold to Wilson Manifolds, where it was massaged and port-matched to the custom runners he created for the Trick Flow heads.
The Trick Flow intake works...
The Trick Flow intake works with Holley Dominator–style carburetors. Jason’s carb was outfitted with a set of Willy’s Carburetor and Dyno Shop metering blocks and bolted onto a Wilson Manifolds spacer to enhance airflow and air velocity.
Thanks to this 812hp Pro Stock–inspired...
Thanks to this 812hp Pro Stock–inspired 557, Jason’s 4,500-pound Biscayne wagon will have no trouble getting the Line family to the grocery store in a hurry! CHP