According to Webster's dictionary, the word "test," used as a noun, is an examination or evaluation of something or someone. By the same authority, a "contest" is a competition or a challenge. When two cars race down a dragstrip, it's a competition. If the same two vehicles are subjected to examination of individual performance categories, such as fuel mileage, idle quality, power, and handling, it is then a test.
What separates this test of a Demon carburetor and Mass-Flo's EFI system from others is that the results are derived with the same fuel and on the same day. Both HPP and RaceKrafters Automotive Machine in Lancaster, Pennsylvania, went to extreme lengths to execute this protocol so the results would be 100 percent valid and have meaning. If we had taken the easy way out, we would not have had to spend as many long days nor had to drive as many miles as we did, but the data would have been suspect.
Most of the time, HPP generates its own technical article subject matter, but we are always open to suggestions and embrace a good topic, no matter where it comes from. This is how this series came about. Chris Richards, Mass-Flo EFI's proprietor, contacted HPP because he was designing a fuel injection system for the traditional Pontiac engine and wanted to know if the magazine would be interested in examining a prototype. The editor liked the idea but also wanted chassis dyno testing performed on the EFI induction system and the carbureted one that would be replaced.
Happenstance modified the original plan when the SD-455 T/A test car, owned by HPP contributor Melvin Benzaquen, developed a rod knock on Bob Ida's chassis dyno. As a technical writer, the author believes this misfortune was actually responsible for a more accurate test since the same intake manifold would be used for both fuel delivery methods.
Utilizing an intake manifold...
Utilizing an intake manifold lift plate on the EFI manifold to ease installation, Ed Price and Scott Hand masterfully guide the SD into place. Note: since the engine was already dynoed with EFI, the intake fuel rails and injectors were already mounted and the welding of bungs into the headers (not shown) for the O2 sensors had already been done as well.
The original test was conceived as a comparison of the complete induction systems, including their respective intake manifolds. Since the SD engine possesses one of Pontiac's best stock induction systems with its 800 cfm Q-jet carb and factory-designed highly efficient dual-plane intake manifold, and because many who would upgrade to EFI would be coming from a similar 750 cfm Q-jet/dual-plane intake combo, the editor felt that using the rebuilt SD engine and its stock 800 cfm Q-jet against the new Mass-Flo system would result in a valid test. This comparison would have also revealed how differences in the manifold designs-Edelbrock single-plane Torker II vs. the SD's dual-plane intake-affect the power curve
Then the engine expired on the dyno during initial baseline testing. Turning lemons into lemonade, the SD-455 was rebuilt at RaceKrafters (Part I Jan. '07 HPP, Part II Feb. '07) and it was upgraded with head port work and a Comp Cams hydraulic roller cam. The stock valley pan didn't fit with roller lifters so an aftermarket valley pan was installed, which in turn didn't fit with the stock 1974 intake. As a result, the decision was made to simply use the Edelbrock Torker II intake that was part of the EFI system to test both the EFI and the carburetor. Well, the spread-bore flange Q-jet doesn't fit on the square-flange intake without an adapter, which would skew the results, so a Demon 750 square-flange carb replaced the Q-jet as our test carburetor. See how easy this stuff is? We now had an EFI vs. carburetor test that eliminated the intake as a variable.
Though many readers viewed the engine dyno test in Part III (April '07 HPP) as a competition-much like a boxing match-by definition of a test, there is no winner or loser, just hard data. We clearly and accurately stated the test results and went to great lengths to explain with sound engineering, why the carburetor performed better than the EFI. This was not done to discredit the EFI system, but to state indisputable facts.
The Mass-Flo EFI is a great system that ran very well and was within three percent of the power produced by the Demon carburetor in that test. Likewise, Barry Grant did an excellent job designing the Speed Demon carburetor and should be applauded for its performance. If you want an EFI traditional Pontiac, the Mass-Flo EFI system is an excellent candidate. However, if your desire is to have the most efficient running Pontiac with minimal cost and complexity, your ticket is the Demon carburetor. We never intended to convert an EFI fan to carburetors or vice versa, just to present the facts and data of our testing.
Mass-Flo's system is MAF based...
Mass-Flo's system is MAF based and provides sequential fuel injection tuning via a Ford EEC-IV ECU. The system is delivered from Mass-Flo with a custom tune based on your specific application so the end user need not worry about tuning. The package contains an MAF, throttle-body, ECU, 36 lb/hr injectors, a custom Mallory distributor and coil, a wiring harness and all necessary sensors. Retail price is $3,750 and it can handle up to 600 hp. Extra-cost options can push the limit to 1,000 hp. A fuel system is not included.
A chassis dyno test was always in our plan but was modified slightly, out of respect to a request by Mass-Flo. The company believed the Ford EEC-IV ECU needed to be driven a few hundred miles to produce the best results. Chris felt the engine management's adaptive learning would have enough authority to minimize the power differential between the two fuel delivery methods that was documented on the engine dyno. Thus, Melvin drove the Trans Am 500 miles before final chassis dyno testing. He told HPP, "The throttle response is great on the street with the EFI. You get on it and it goes, without any hesitation. Of course, the increased power of the engine rebuild helps a great deal, but the EFI does operate as hoped for. Hot starts are no problem. It is smooth and tractable, and fuel mileage is currently 16 mpg, which isn't bad with a Turbo 400, 3.08 gears, A/C, a 4,000+ pound curb weight, over 500 hp at the flywheel, and a heavy foot." (The Demon carb was not tested on the street.)
RaceKrafters' engine dyno cell is equipped with a high level of data collection and we were able to confirm with confidence that both fuel systems were performing at 100 percent. Though the author didn't agree with Mass-Flo's adaptive learning premise, it was decided by all that putting a few hundred miles on the SD T/A before final chassis dyno testing would not hurt. If it did help and the author was wrong, so be it. The reason for this exercise was to provide our readers with accurate and unbiased data. In engineering, there is no room for an ego. The laws of physics prevail every time.
To see what it took to install Mass-Flo's prototype EFI in the SD T/A, follow along with the photos and captions. After Classic Restorations completed the installation, it was back to RaceKrafters chassis dyno to test the SD with the EFI and carburetor in a unique back-to-back comparison. The results are presented in this final installment.
This is Mass-Flo's 1,000 cfm...
This is Mass-Flo's 1,000 cfm throttle body installed on an Edelbrock Torker II intake set up for the fuel injectors.
A GM 85mm LS6 MAF is custom-machined...
A GM 85mm LS6 MAF is custom-machined by Mass-Flo to mount on the throttle-body. The opening for the Q-Jet's airhorn in the air cleaner base had to be modified slightly to accept the MAF and adapter ring, but the factory hole for the Q-jet's vent provided an easy way to route the wires. The MAF mounting area was then sealed with silicone so no air would bypass it. With EFI, all of the air the engine breathes needs to go through the MAF sensor so the proper amount of fuel can be delivered.
This EFI system employs 36...
This EFI system employs 36 lb/hr injectors. They are simply lubed at the O-rings with light oil and pushed into place in the intake. The fuel rails are installed and then the wiring harness is plugged in.
The EFI system provides electronic...
The EFI system provides electronic spark timing through a modified Mallory Ford-style distributor. Its module is a Ford EEC-IV design from a 5.0-liter Mustang.
A Mallory ignition coil and...
A Mallory ignition coil and the barometric pressure sensor (gray) were simply mounted on the firewall with sheetmetal screws near the distributor. Also shown is the Mallory fuel pressure regulator at the rear of the fuel rail, which is set to 42 psi. Note the wiring harness for the EFI system wrapped in black corrugated loom coming through the rubber grommeted hole in the firewall.
There were a few mods required...
There were a few mods required that go beyond the basic installation-remember this is a prototype system that we had. The Pontiac throttle cable would not attach to the Mass-Flo throttle body due to the geometry and linkage, so a Lokar universal cable and fabricated bracket made it all work properly.