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Holley Stealth Ram EFI Kit - Grand Slam Stealth RamFrom Carb To Caviar From the February, 2009 issue of 4Wheel & Off-Road By Jerrod Jones Photography by Courtesy Of Holley, Jerrod Jones
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The Holley Stealth Ram kit... The Holley Stealth Ram kit for a Chevy small-block comes with everything you see here. Depending on what horsepower rating your engine is putting out, Holley will include different pound per hour (PPH) injectors. The manifold, plenum, throttle body, wiring harness and connectors, sensors, fuel pump and filter, and ECU all come together as a package. You'll also need to pick up new throttle cable linkage and tranny-kickdown linkage yourself. Plus you'll need a distributor designed for a factory TBI Chevy small-block, as an HEI unit will not work since the cap diameter is too large. Electronic Fuel Injection (EFI) has clearly come out as the fuel-delivery system of choice in every type of motorsport. The advantages are clear, and it's no secret that you'll feel better throttle response driveability, and you'll likely see an increase in fuel economy and engine power. Our editor, Rick Pw, pointed out that, in a perfect world, an EFI kit should make no more power or improve fuel economy over a carbureted system. But the chances of finding a carb that is perfectly tuned for the absolute best mix of fuel economy and power are slim. And if you factor in elevation and climate changes during driving, it is nearly impossible for a carb to keep up with a wideband EFI system. The control module of the EFI takes multiple parameters into account and makes adjustments based on data delivery from the O2 sensors, MAP sensors, intake air temperature sensors, and coolant sensors. There are two main types of EFI systems: throttle-body injection (TBI) and multipoint fuel injection (MPI). TBI fuel-injection retrofits are nice because they're easy, they're cheap, and they require minimum modifications as a TBI system bolts to the existing manifold. If you're looking for a kit with better throttle response, you'll need to step up to an MPI kit, complete with a replacement manifold and a fuel injector for each cylinder. The cream of the MPI crop is tuned port injection (TPI) kits, and this Holley Commander 950 Stealth Ram MPI system that can supply a small-block Chevy engine enough fuel for 300-670 hp. We teamed up with DC Performance in Los Angeles, to install and tune Holley's Stealth Ram kit on a bone-stock '75 Chevy 350 engine. Unless you are very experienced with tuning EFI systems, we suggest letting professionals like the guys at DC to do your engine tuning for you. The installation of the kit itself can be done at your house if you have enough time, but the tuning is best left to the pros. The Stealth Ram kit is also not 50-state legal, so you'll have to have a '75-or-earlier vehicle to use it in California. DC Performance highly recommends checking out the engine before putting on an expensive system like this. It's always exciting to see an untouched (since 1975 when it was built) engine get ripped into. Before this, the biggest mod it'd seen was the Thorley headers on the sides of the block. That being said, it was ugly under the hood. The red and blue lines running over the manifold are discharging the air-conditioning system. Since the line from the A/C compressor to the condenser had to be removed to get the Stealth Ram's plenum on, we had no choice. We'll have to pick up a custom A/C line to run it past our new Stealth Ram system.  The manifold comes partially...  The manifold comes partially assembled with the rails on it, but you'll have to pull them off to stick whatever PPH fuel injector you're using. Since we were dealing with a bone-stock 350, we used the smallest injectors Holley offers with the kit-24PPH injectors.  DC Performance dropped the...  DC Performance dropped the fuel tank in order to hook up the new high-pressure fuel lines and to check the filter sock in the tank. Holley provides new SAE 30R9 180-psi fuel hose to plumb the new fuel system.  Once the tank was checked...  Once the tank was checked and prepped, Ramiro Macarieus mounted the supplied electric fuel pump and fuel filter on the inside of the C-channel frame for protection. Eventually we will place a heatshield guard on the frame to protect the pump from exhaust heat.  One of the things not included...  One of the things not included in the kit is a TBI distributor. We already had an MSD HEI unit in our engine, and we were disappointed we had to throw it out because it's too big. Since we were having to buy the complete unit anyway and the price difference was negligible, we decided to go with MSD's Pro Billet drop-in replacement distributor for '87-'95 TBI engines (PN 8366).  One of the most tedious tasks...  One of the most tedious tasks when installing this kit is the wiring. Dan Cragin of DC Performance spent lots of time constructing the wire network, and even went as far as to rewire our ignition system since he didn't think it was quite up to snuff. (Ha! We'll have you know we wired that very professionally at 2 a.m. after we got home from the bars....)  This is the wideband controller...  This is the wideband controller used in the closed-loop EFI system. A narrow band (open-loop) EFI system is set at stoich (14.7), and does not compensate for climate change. A closed-loop system like the Holley Stealth Ram kit uses a wideband and Bosch O2 sensor capable of readings from 10:1 to 16:1 to try to maintain the target air/fuel ratio of 14.7:1. It can account for altitude, pressure, and temperature.
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