BBF 528 Pump Gas Engine: 737HP & 672lb-ft Torque

[Paul Kane]

528 Ford Specifications

• Bore: 4.42"
• Stroke: 4.30"
• Rotating Assy: SCAT cast crankshaft, H-beam rods, 36cc "D" shape dish Diamond pistons, King bearings, balanced
• Heads: Blue Thunder 74cc, ported, +.100" Ford Racing valves, 3-angle valve job, 10* locks & retainers, 1.625" dia. springs, 230 lbs seat
• Compression ratio: 9.8:1
• Rockers: Miller 7075-T7 aircraft aluminum, 1.7 ratio
• Camshaft: Billet steel roller, custom ground for this engine combo. Lobe = 0.4550" / .4170", LSA = 109* Dur@.050" = .266 / .278, Lift at valve = .757" / .709"
• Roller Lifters: Morel
• Block: D0VE-A with Boss 429 bulkheads, thermocleaned and mag checked, High Flow Dynamics Stage 1 oiling mods
• Bearing clearances: mains = .0035"; rods = .0030"
• Timing Chain: Ford Racing double-roller with billet gears and 9-position keyway
• Carburetor: Holley 4500 Series Dominator, 1150 cfm
• Distributor: MSD breakerless
• Oil Pump: High Flow Dynamics Stage 1 prepped Melling M84DHV
• Oil Pan: Armando's 10-qt jet boat pan and pickup
• Intake: Edelbrock Victor 460 with Dominator carb flange, ported to Blue Thunder intake port size

This engine was dynoed at Westech, which is the same facility where the recent Engine Masters Big Block Shootout had their engine finalists tested. Results were 737HP @ 6300 rpm and 672 lbs-ft of torque @ 4600 rpm, and 95% of peak torque was sustained all the way up to 5900 rpm. A torque curve that flat obviously extends well below the 4600 rpm mark but I don't have the data because the facility focused on pulls from 4600 rpm & up due the customer's applicaton of the engine (jet boat). I was not in attendance of this session and could not make several requests and changes on the motor during the pulls.

Also, I'm pretty sure there's still more HP in it. Due to some top end oiling debugging from the start of the day, some valve train parts were changed out by the dyno operator for the sake of getting to the pulls, and the replacement parts installed by the facility--I feel certain--cost the top end about 11-14 HP. Additionally due to the time constraints, trials of carb spacers were never evaluated and I think we might have found another 9-12 HP there (the posted results are without a plenum-increasing carb spacer!). In other words, this engine could have conceivably generated as much as 760 peak horsepower on pump gas.

Bottom line is, when the day was over and the customer had his requested 700+HP, he felt we that delivered and so there was no need to search for any more.

Also, I want to emphasize the fact(s) that this engine recorded 737HP with a very conservative 9.8:1 compression ratio and one carburetor.

Honorable mentions go out to:

• Chris Straub (Straub Technologies) for camshaft consultation. Our customer wanted 700HP / Pump Gas / Reliable, which is a tall order and we wanted to be sure we met his needs. I turned to Chris for this build because he profiles camshafts for a lot of big name professional competition engines and he obviously calculated a profile that works excellently with this particular engine combination.
• Charlie Evans (Evans Racing Engines), because I must have called Charlie 4-5 times to discuss the approach I wanted to take porting these Blue Thunder 74cc heads and also discussed with him several valve train hardware options (BT heads ship bare). Charlie provided a lot of insight.
• Van Heskett, my engine building partner, for his never ending patience over this motor build. Of all the engines that we build together, I vehemently insisted this engine have special attention and it was mocked up countless times, while we tried different valve train setups, different valves in the heads, different crankshaft and connecting rod bearings, etc.

528Insalled_2.jpg

528Insalled_1.jpg

Paul