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502 Big Block Addition - Crate Addition

A Tweak Here, A Shot Of Nitrous There And This Ram Jet 502 Is Crowding 900 Hp!

By Barry Kluczyk

"Its limit is simply less than the engine's capability," explained Martin. "The engine would definitely make more power with a bigger throttle body."

Nevertheless, the breathed-on 502 comes alive with the wet-flow nitrous system, plumbed into the intake runners on the Ram Jet's tunnel-ram-style intake manifold. The wet-flow design is more complex than a simple dry-flow system, but it allows for increased tuning flexibility at the racetrack.

Controlling the nitrous system, and the related fuel and timing deliveries falls to the FAST controller. It's a speed-density-type system that is more programmable than the Ram Jet 502's stock controller.

"We could have left the stock controller in place if we used a dry-flow nitrous system," says Martin. "But the Fast controller gives more tuning flexibility with trimming fuel and timing."

It also allows for wide-band tuning, so oxygen sensors were screwed into the headers. The additional tuning capability of the FAST ECU gives the engine an incalculable edge in long-term performance-and Martin says longevity was definitely a priority.

"This is a street/strip engine that has to last the customer a long time," he says. "It's not something that's going to be torn apart after every run, let alone after every season."

Indeed, Martin Motorsports' tuning and dyno testing delivered some impressive numbers with admittedly conservative parameters. The non-nitrous dyno pulls were made with 92-octane pump gas and 36 degrees of timing. When sprayed, timing was dialed down to 12 degrees and 110-octane gasoline was used.

"It makes great numbers and should last a long time," says Martin.

The nitrous system and blueprinting-type rebuild of the engine were the biggest chunks of the cost of this engine project, which added roughly 50 percent on to the cost of the Ram Jet 502's over-the-counter price.

As always, value is in the eye of the beholder, but we think this modified 502 represents a comparative bargain when judged against custom-built racing engines.

The modification of crate engines might just take steer the hobby in a slightly new direction.

Dyno sessions with the revamped Ram Jet 502 saw a 78hp normally aspirated jump over stock, from 502 to 580. Torque increased to from 565 to 583 ft-lb These numbers were made on 92-octane fuel and 36 degrees of total advance. Tests with nitrous were performed with 110-octane racing fuel and a very conservative 12 degrees of timing, resulting in 861 hp and 898 ft-lb of torque. This performance can at roughly a 50-percent premium over the cost of the base Ram Jet 502 engine package.

Martin Motorsports Ram Jet 502
Engine type OHV V-8 with iroblock; four-bolt main bearing caps
Bore x stroke (inches) 4.446 x 4.000
Displacement (ci/liters) 502/8.2
Crankshaft Forged steel
Connecting rods Forged aluminum I-beam
Pistons Forged aluminum
Compression ratio 9.6:1
Camshaft Hydraulic roller; .566/.566 lift; 296/302 duration; 110-degree centerline
Cylinder heads Aluminum; oval-port design; 110cc chamber volume
Valves (inches) 2.25 intake, 1.88 exhaust
Valve springs Comp Cams #924
Rocker arms 1.7-ratio roller-type
Fuel delivery Electronically controlled port fuel injection
Ignition HEI-type
Electronic controller Speed density with wide-band (closed loop) capability
Power adder Nitrous oxide "wet" system
Horsepower without
power adder 580
Torque without power adder 583 ft-lb
Horsepower with power adder 861
Torque with power adder 898 ft-lb
SOURCES
GM Performance Parts
www.gmperformanceparts.com
Martin Motorsports
55390 Lyon Industrial Dr.
New Hudson
Mi  48165
By Barry Kluczyk
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