There's nothing more disappointing than seeing a kick-ass classic or late-model Ford or Chevrolet street truck at a show, only to discover a wimpy-looking engine occupying its gargantuan-sized engine compartment. As a matter of fact, the engine compartments in most fullsize, pre-emissions-era street trucks produced from the early-'50s to late-'70s were fairly huge. They can swallow up a small-block Chevrolet or Ford engine with ease. These engine bays just beg for a big-block, a blower, or multiple carburetor systems. They look great, run great, and get great gas mileage. Just ask anybody at a Popular Vote truck show. They always go for the truck with the killer engine compartment.
By now, we've more than made our point. However, it's kind of hard to be original these days. If you want something unique and exotic, consider Weber carburetors. The Italian-manufactured Weber 48 IDA downdraft carburetor and street truck engines are a natural catalyst for stunning oohs and aahs.When bolted onto an individual runner (IR) intake manifold, these sexy little Italian downdraft carburetors look absolutely great. The 48 IDA Weber carburetor provides peak torque and instant horsepower (as opposed to a conventional plenum-type four-valve carburetor and intake manifold, which progressively ramps torque and horsepower), while maintaining those performance characteristics over a much broader powerband. Simply put, the 48 IDA Weber downdraft induction system performs similar to a mechanical fuel-injection system yet gives you the driveability and performance of a conventional four-valve carburetor.
But here's the dilemma: These carburetors went out of production sometime in the '80s and are in extremely short supply. While it is true that N.O.S. (new old stock) Webers can still be purchased through a very limited supplier network, their relative scarcity dictates a lofty selling price. On the other hand, used sets or rebuildable cores also fetch a veritable king's ransom. In November 1999, Bob Ream and partner Wes Henderson founded Imagine Fuel Injection. "The Weber 48 IDA carburetor was quickly disappearing from the performance aftermarket, and there were enough people out there who still wanted the performance, economy, and looks offered by the Weber 48 IDA without all the eccentricities like fuel vaporization or standoff and its notorious tuning characteristics," said Ream. The two of them reasoned that if they could offer an IR-based, electronically managed Weber-type throttle-body fuel-injection setup at a competitive price, they could effectively recapture, as well as revive, a waning market segment of the performance induction systems industry. "Today everybody drives an electronically managed, fuel-injected truck. They drive them to work, to the store, and to the racetrack. One thing which the EFI cars and trucks from the '90s have taught motorists is they can perform at peak operational levels with this type of system. So, why not install a setup similar to this on the truck you drive for pleasure?"
Using readily available cast-aluminum Weber IR intake manifolds as the foundation (ie: Inglese Induction Systems, Moon, Blue Thunder, and Ultra for small-block applications and Inglese, Blue Thunder, or Moon for big-block applications), the guys from Imagine Fuel Injection designed a pair of billet-aluminum downdraft throttle bodies, which essentially use all of the outer dimensions of the Weber 48 IDA. "By producing it this way, we can use the Weber intake manifolds, their gaskets, their induction stacks, and a tall-stack throttle-body setup looks great under the hood of a vintage street truck, and even their air cleaners," said Bob Ream.
Imagine offers two IR throttle bodies: a low-profile unit with a 2-inch upper throttle-body half and a similar 3-inch unit. Both are manufactured from CNC-machined T-6, 6061 heat-treated billet aluminum and feature a 2-inch, 50.8mm standard throttle bore size with stamped aluminum throttle plates. On turnkey induction systems, these throttle bodies are port-matched to the IR intake to achieve maximum air/fuel flow and performance. Imagine Fuel Injection's billet bodies can also be had in either a clear, bright, anodized finish, or an optional polished-aluminum show finish.
"When it came to the throttle linkage, we found that due to the proximity of the electronic fuel injectors, we had to relocate the system's throttle linkage 1 inch higher on the throttle body for clearance. This modification was also necessary to maintain fuel-injector intake-valve alignment, which is so critical with throttle-body, multi-point, fuel-injection systems on the Ford and Chevrolet small-block engines."
What type of fuel injector does Imagine use with these systems? "A lot has to do with the compression ratio of the engine, the rpm powerband which you intend to operate the engine at, and the cam profile which you're using," says Bob Ream, "Traditionally, you would use either a Lucas or Bosch constant-pulse, electronic fuel injector with these applications. For example, we would use a 43-lb/hr fuel injector for a 427/454 Chevrolet engine application, while we would choose perhaps a 30-lb/hr electronic fuel injector for a small-block application such as the Chevrolet 350/400-motors.
Imagine Fuel Injection manufactures CNC-machined, billet-aluminum fuel rails from raw bar stock. They work in conjunction with a standard Bosch 200-pound electronic fuel pump along with an Aer-O-Motive billet aluminum high-pressure fuel regulator and filter. So much for the mechanical aspects. Now for the Star Wars technology. "We like using either the HalTech F9A, or Electro-Motive distributorless engine management systems," said Ream. "The F9A is a well-known unit with a 15-year track record for precision and reliability. This system is primarily used on applications featuring conventional electronic-type distributors. "It is very trouble-free, and in any type of motorsports, that is the name of the game." On the other hand, Imagine recommends the Electro Motive distributorless engine management system for more high-tech applications such as a late-model Chevy or Ford truck application.
Another integral component in the Imagine IR throttle-body system is the use of an RS-232 driver cable, which can be setup to interface with either Ford or GM-type electronic engine management sensors. Ream went on to relate that rather than employing the more commonly used Microsoft Windows engine-management systems software program, the company has elected to use the older DOS version. "The reason we did this is because the DOS computers are inexpensive and plentiful. As such, they become practical to take with you on the road where adjusting fuel distribution and airflow is critical. You can beat these old laptops around. You can get dirt on them, and should one of them ever fail, you can go back to the local swap shop and pick up another one for around $150."
Imagine Fuel Injection also builds a number of use-specific wiring looms that interface with their electronic throttle-body fuel-injection systems. "We offer and manufacture wire looms for both small-block and big-block Fords and Chevys. We even manufacture a wiring loom for Volkswagen throttle-body applications. Basically, the sky is the limit."
Of course, you can talk all day about how great a product is, but how well does it hold up in real-world situations? We have two examples: Dyno man Terry Kell at Kell's Automotive in Las Vegas claims this system is the best thing he has ever laid his hands on. Last winter, Kell & Co. tested one of Shelby American's aluminum alloy 427 FEs built by Shelby American's resident engine expert Mike LeFevers in conjunction with the folks at Las Vegas' Finish Line Motorsports, builders of the Shelby CSX4000 Cobras.
"We pitted our intake manifold against a Holley 850-cfm-equipped Edlebrock Victor dual-plane intake. We recorded torque, horsepower, and exhaust gas temperatures. At 4,500 rpm, the Holley/Edelbrock setup produced its most significant amount of torque, 406.24 lb-ft. On the other hand, the Imagine Fuel Injection throttle-body setup produced 427.19 lb-ft of torque at 4,500 rpm. On the horsepower side, the Holley setup came in at 5,500 rpm, registering 399.98 hp, while the Imagine IR system recorded its best horsepower figures at 5,000 rpm, registering a solid 418.96 horsepower." When it came to Bow Tie power, the guys at Imagine recently hooked up with the folks at So Cal Speed Shop and tested a 350 Chevrolet small-block installed into a '32 Ford Highboy roadster on their new Mustang Chassis dynamometer. However, the numbers are indicative of those if the motor were installed into a classic truck. Once again, the group used an Edelbrock intake with both Holley and Carter APB four-barrel carburetors to see which performed the best against the Imagine throttle-body system. Out of the two, the Carter AFB turned in the best performance numbers for a conventional carburetor, registering 187.6 hp at 87.5 mph and 393.6 lb-ft of torque at 70 mph. With the Imagine IR Throttle Body system, the results were considerably better. The little Deuce registered 234.6 hp at 82.5 mph and 521.6 lb-ft of torque at 70 mph.
Naturally with any IR type intake setup, the exhaust gas temperatures (EGT) also straightened out between cylinders. The Imagine Injection IR system showed as much as a 400-degree ambient temperature drop between engine cylinders. That's a lot. "This is really the intake system to have for any street rod, classic '60s musclecar, or street truck," says Henderson. "It runs as smooth as a Mercedes, yet exhibits absolutely crisp throttle response while exhibiting a slight lope, which will give you an indication of the performance potential which lies beneath the huge hood."
How do you lay your hands on one of these killer IR setups? Should you already own a Weber setup, or already have the intake manifold, any or all of these components can be purchased separately. Or, you can purchase the whole nine yards for about the 1qsame money as you would spend a fully decked-out 48 IDA setup. For dealer information, just contact Imagine Fuel Injection. Or, truck on down to Phoenix, and tell them Truckin' magazine sent you.