Twin Street Demons and Lamar Walden’s New 409

Written by Moore Good Ink In the dyno room, Lamar Walden’s first production road-going 409 fitted with twin 625 Street Demon carburetors revved with enthusiasm to 6,293rpm and generated 602.4 peak horsepower and 602lbs-ft torque at 4,600rpm. For some, the emergence of the new Street Demon and the re-emergence of a new 409 have been the biggest hot rodding news of 2012. Earlier in a comparison test, twin Edelbrock AVS carburetors had generated a commendable 553hp @ 5,800rpm and 575lbs-ft torque @ 4,470rpm. Why had the Street Demons triumphed by 49hp and 27lbs-ft of torque? “I imagine,” said Lamar, “its supremacy lies in the size of its secondary throttles.” Unlike any conventional 4-barrel layout, the Street Demon is a three-barrel carburetor inhibited by few restrictions—the secondary throttle bore is one big opening. Read the full story compliments of Drag Racer...

Lamar Walden unveils new serpentine belt systems for Chevrolet 409:

Written by Moore Good Ink What is it that would persuade Lamar Walden to enter the serpentine drive business? He succeeded in building an image so favorable—the definitive authority on the Chevrolet 409—that his engine shop has been a dynamo of energy for over forty years. “Well, our local specialists, Concept One, don’t make a serpentine kit for the 409, so I looked at a couple of others brands. After installing one kit my customer barely made it out of our driveway before the serpentine system destroyed the water pump—it was turning way too fast. And on the second occasion a freeze plug was blown out of the block! But it was belt squeal under acceleration and the lack of options that finally put us in the serpentine belt business.” Here is news of Lamar Walden’s new belt systems for the desirable W engine—the 409. Doraville GA: Lamar Walden has taken the initiative and unveiled a new series of serpentine belt systems to suit Chevrolet 409 high-performance engines. Importantly, it is the first serpentine system available for aluminum 409s. Though all the kits have an effective spring-loaded idler to avert belt squealing, it is the options available that are, perhaps, the most appealing. The full kit includes the A/C compressor, power steering pump, alternator, and high-flow water pump. In addition it contains all necessary pulleys, brackets, Gatorback belt and accessories. “However, most of our performance guys,” says Lamar, “particularly those that run at the track, don’t use the A/C compressor or power assist on the steering.” In addition to the wide range of options, attention has been paid to...
Rod stretch and rod bolt fatigue: Beerhorst talks boosted engines

Rod stretch and rod bolt fatigue: Beerhorst talks boosted engines

Written by Moore Good Ink: When the crankshaft pulls the connecting rod downward on the induction stroke of a naturally aspirated engine, a stretching load is exerted on the con rod because the piston area is so much greater than the column of air being drawn into the cylinder. In contrast, when the inlet valve is open on a boosted engine, the rod is always under pressure, not a stretching load. Therefore the life of all rotating parts in the boosted engine is significantly prolonged. Of course, there is also a stretch on the rods when the throttles are closed and the engine is decelerating. It’s under these conditions where most con rods fail on oval track cars: when the throttles are closed as the car approaches the corner. Consider that situation for a moment: the piston is sealed to the bore by the rings and the crankshaft is pulling it down against huge resistance. Remember, the throttle plates are closed so there’s not much air pressure in the combustion chamber to assist.  A streetable naturally aspirated engine producing 2,000hp doesn’t exist. But if it did you’d be lucky if the engine’s rotating parts survived for more than a few quarter-mile passes. There are, however, large displacement maximum-effort engines operating near this power range, but they are not streetable and only the most durable could complete 50 quarter-mile passes without a rebuild. In contrast, when you boost the engine, it will make this vast amount of power and you could run it on the street. Using lower engine speeds and with less radical valve train it will run for...
Overcoming suffocation when dragster headers switched from Weed-burners to Zoomies

Overcoming suffocation when dragster headers switched from Weed-burners to Zoomies

By Sam Logan: During early July 2015, the Snake & Mongoose movie began airing on the Starz television channel. The film, first released in September 2013, recorded the events leading up to “Mongoose’s” famous victory over “Snake” Prudomme during the 1978 NHRA Funny Car US Nationals and depicted the lives and times of the two drag racing rivals as well as revealing several ground-breaking achievements of the time. According to Tom McEwen, universally known as the Mongoose, safety equipment began in California in the late nineteen-fifties with Bill Simpson in his single garage with one sewing machine. He was just starting out and his priority was to create a parachute to retard drag racing cars beyond the quarter-mile. He also energetically pursued the development of race suits and other apparel to protect the racer against burns. One often wonders about the depiction of Simpson’s own life on film. His achievements certainly would assure his position as a great contributor to the world of racing; it could also be a shocking and brilliantly amusing account of a life that only Bill Simpson could have lived.  In engine development, conventions changed rapidly much like today. McEwen recalls an engineering friend of Chrisman & Cannon, the famed Hustler drag racers, informing them they were not taking advantage of the thrust issued from the headers. The engineer, then employed at Rocketdyne to study World War II German V-2 missiles, estimated they might be squandering around 50lbs of thrust per pipe. To gain downforce on the rear tires as well as some forward momentum, try curling them upward and angling them backward, he suggested, terminating...
Evil twins: first twin 625 Street Demon carbies on the first new 409 hotrod engine

Evil twins: first twin 625 Street Demon carbies on the first new 409 hotrod engine

Text by Sam Logan. Photography by Moore Good Ink. Download text and Hi-res images. In the dyno room, Lamar Walden’s first production road-going 409 fitted with twin 625 Street Demon carburetors revved with enthusiasm to 6,293rpm and generated 602.4 peak horsepower and 602lbs-ft torque at 4,600rpm. For some, the emergence of the new Street Demon and the re-emergence of a new 409 have been the biggest hot rodding news of 2012. Earlier in a comparison test, twin Edelbrock AVS carburetors had generated a commendable 553hp @ 5,800rpm and 575lbs-ft torque @ 4,470rpm. Why had the Street Demons triumphed by 49hp and 27lbs-ft of torque? “I imagine,” said Lamar, “its supremacy lies in the size of its secondary throttles.” Unlike any conventional 4-barrel layout, the Street Demon is a three-barrel carburetor inhibited by few restrictions—the secondary throttle bore is one big opening. It’s taken Demon a while to compose a convincing answer to the Edelbrock AVS. But once Larry Tipton, Demon’s distinguished senior designer, focused his creative energy on the new design in 2010, we suspected a beacon of carburettor ingenuity could be in the works. And when it appeared on May 25, 2012, it not only looked the part in a market where appearance is of primary concern but also it proved to be a very strong performer. Based entirely on a brand-new concept this innovative three-barrel 625 Street Demon has noticeably smooth contours especially around the air entries, unlike its Edelbrock counterpart. Though both carburetors have dual mounting points, accommodating square-bore or spread-bore manifold mounting without adapters, Tipton is particularly pleased with the effectiveness of his triple-stack boost...