Martin Motorsports did a little grinding the stock heads. They cleaned up the ports and po
"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."
Surprisingly, the Ram Jet 502 does not come with roller-tip rocker arms. Martin Motorsport
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.
Air is drawn in to the 502 through the same L98-style throttle body that comes stock on th
The 502's Ram Jet manifold was plumbed for a "wet" nitrous system-a system that introduces
To accommodate the wet-flow nitrous system, the Ram Jet manifold was drilled to accept bun
Because the engine's new FAST controller allows for wide-band tuning, oxygen sensors were
Although the Ram Jet 502's stock electronic controller probably would have handled the eng
Another item retained from the basic crate engine package was the HEI-style distributor.
|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 |
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