This project is clearly getting some traction. While initial reader responses have largely been in support of CT's "green racing initiative," there has not been sufficient, hard data to support the project's viability . . . until now. In the following paragraphs, you'll have an opportunity to review the unwashed results for our first engine dynamometer session at Mast Motorsports. Fortunately, several of the players from whom you heard comments a month or so ago were present for and participated in the tests. You'll recall previous observations from Rob Fisher (CT's Editor), Forrest Jehlik (key project engineer from Argonne Laboratories), Dave Kalen (Account Executive and motorsports enthusiast from Semtech, the PEMS company), and Horace Mast (mechanical engineer and owner of Mast Motorsports). A follow up story with their comments relative to this test begins on page 40 immediately after this feature. You will likely be interested in what they reveal.
In order to help you derive the most benefit from the dyno results, we've chosen to focus our discussion on the graphical representations the data provides. The computer skills of Forrest Jehlik produced the graphs shown. Our belief is that by looking at the "visuals" and correlating them with the practical and theoretical perspectives they reveal, you'll come away with the majority of your questions answered, for now. At least that is our intent. We'll also tack on a few concluding remarks at the end of the story as we head into the project's next phases.
Although 93-octane gasoline was included to compare it with 100-octane racing gasoline (actually blended with 10 percent ethanol to raise the octane rating) and E85, a lack of performance resulted in its removal for the continued analyses. As a result, the 100-octane "Street Blaze" gasoline and E85 (both from VP Fuels) became the fuels used for subsequent tests.
As you will note, data from the "fuels comparison" tests show a torque and power degradation from about 4,000 rpm to peak rpm at 6,750 where the output from all three fuels converged to approximately the same value. Largely attributable to the engine's overall diminishing volumetric efficiency relative to net airflow at higher rpm, other factors played into this convergence. However, from 4,000 rpm to around 6,250, E85 tested marginally better than the 100-octane Street Blaze. (Note: At this point, it's important to know all tests were conducted using the same ECU calibration. For multiple reasons, parts-specific spark and fuel maps were not sought to optimization. Future tests will address that issue.) The data shown indicates only slight differences (w.o.t. throttle, full load) between the torque output comparing 100-octane racing gasoline to E85. As a result, power output differences you will see comparing data from various parts combinations (EFI, carburetion, catalysts, and so on) will be true to the differences such parts represent, not owing to variations in fuel performance.
Carburetion vs. EFI
VP's Street Blaze 100 gets...
VP's Street Blaze 100 gets poured into the tank for a round of dyno pulls.
At the moment, there seems to have been two areas of particular interest among racers and engine builders regarding a shift away from the conventional use of carburetors and racing gasoline. One pertains to how much power might be lost, switching to EFI, and the other the extent to which catalytic converters would reduce on-track performance.
If you subscribe to the notion that torque is a major factor in race car acceleration, you may find the torque curves displayed in the attending graph of interest. In particular, aside from the approximate 7 percent gain in torque (at the rpm of greatest torque difference or roughly 4,500 rpm), note the general broadening and flattening of the overall torque curve produced by the EFI and 100-octane package. Part of this can be traced to improved fuel atomization (a topic discussed in previous "Enginology" columns) and in part to a basic intake manifold design that favors low- and mid-range torque.
This latter condition can also have influence on peak power (compared to a single-plane manifold with inlet runners shorter than the EFI manifold), and you can see the effect of this factor at peak rpm. However, there is evidence of where in the engine speed range an improvement in torque can build a case for better on-track performance potential using the EFI system. Also note that neither of these tests was conducted with catalytic converters in place. More on this a bit later in the story.
Catalyst vs. No Catalyst
Interesting stuff here. If you'll refer to the previous graph (Carburetor vs. Fuel Injection), you'll note that peak torque for the EFI and 100-octane Street Blaze gasoline was a corrected 496 lb-ft. Compare this with the configuration (catalyst vs. no catalyst) of EFI, 100-octane street blend and the 100 cpi (cells per inch) catalysts and you'll see only 5 lb-ft of torque were lost at peak torque. Plus the previously broadened and flattened torque curve (from around 3,250 to 5,500 rpm) was retained as a function of the EFI manifold design.
So for those who might believe the addition of catalysts would have a materially negative effect on overall torque output, here's some data to consider. The fact peak horsepower and torque output (with and without the catalysts) was virtually the same again points to other factors, including maximum volumetric efficiency obtainable (at higher rpm) with this parts package. Once again as a reminder, at this stage in the project, no attempt was made to optimize either functional integration of parts or best ECU calibration.
with 100 street blaze
catalysts vs. EFI
with E85 and 100 CPI
catalytic converters You may want to spend a little time studying these results. The baseline data was recorded using a carburetor, 100-octane Street Blaze racing gasoline, and no catalytic converters. Note peak horsepower was a corrected 552 hp, compared to a corrected 539 peak horsepower for the EFI, E85, 100 cpi catalytic converters package. Admittedly, given the current parts configuration, peak power decreased 13 hp. But before you condemn this outcome, pay attention to the way the EFI parts combination affected corrected torque from about 3,500 to 5,500 rpm (plus-22 lb-ft). Given how a particular circle track car might be geared and the track layout, this span of rpm could fall within a very desirable range of on-track engine speed.
In addition, if you will refer to the Carburetor vs. EFI data graph, you'll discover peak torque (EFI, E85, and no catalysts) produced a corrected peak torque value of 498 lb-ft. Compare this value with peak torque (carbureted baseline with 100 street blend gasoline without catalysts vs. EFI with E85 and 100 cpi catalysts) for the EFI, E85, and catalysts package at 499. Maybe this comparison sheds light on some conventional thinking that suggests catalysts will materially decrease power.
Catalyst Substrate Density Comparison While these data get into the minutia of how pumping losses can affect power and the effects of catalyst density on such losses, you can see that increasing substrate density by a factor of three (from 100 to 300 cpi) still allows the higher density, EFI, E85 catalytic converters combination to produce superior torque when compared to the carbureted, 100-octane Street Blaze, no catalysts package (by a higher peak torque value of 12 lb-ft).
Cycle Weighted Emissions
Here you can see a comparison among four parts combinations; carbureted with 100-octane Street Blaze gasoline and no catalytic converters, EFI with 100-octane Street Blaze and no cats, EFI with 100-octane Street Blaze and 100 cpi converters, and EFI with E85 and 100 cpi cats. Keep in mind that no ECU recalibrations were attempted to optimize each of these combinations. Still, note that although there were slight reductions in HC and CO emissions, NOx decreases were on the order of 50 percent compared to non-catalysts versions. Future chassis dyno and on-track adjustments (as pointed out elsewhere in the story) are projected for further improvements in power and emissions reductions.
Based on Engine Dyno Tests to
Date Although additional conclusions are forthcoming, based on practical and theoretical analysis of the dyno results, following are summary points from discussions among the project's team members.
The configuration of EFI and E85 resulted in a significant horsepower and torque increase across the entire rpm span, excluding a small reduction near maximum rpm. A consistent 5-7 percent increase was produced at peak improvement rpm. This slight reduction in peak power can be compensated for by ECU recalibration, nozzle design change, or both.
Catalytic converters are defined...
Catalytic converters are defined by the number of cells inside the unit called the substrate. This honeycomb-looking interior has 100 separate cells per inch of surface hence it's designation as a 100 CPI converter. The higher the number, the more cells and, more efficiency in converting harmful exhaust to inert gases.
The 100 cpi catalysts had only small impact on overall power. In fact, using EFI, E85, and catalysts, more power was produced throughout the rpm span compared to the combination of carburetor and 100-octane Street Blaze racing gasoline.
Use of the catalysts did a good job reducing NOx (on the order of 50-60 percent) but not as well for CO and HC. A lack of O2 for peak power and durability calibrations was the cause. This deficiency will be addressed during the on-track testing portion of the project. Expectations are CO and HC will be reduced significantly during this phase of testing.
Even though the E85 fuel generated more HC emissions than the Street Blaze, a solution proposed to enable increased O2 should reduce these emissions significantly. Future, on-track emissions testing will be the proof of this solution.
The benefits derived from use of the EFI system (manifold design and greatly improved fuel atomization) that led to increased torque and horsepower suggest this combination to be very worthy for circle track applications, particularly regarding where in the engine speed range these improvements occurred.
Next Steps in Project
One of the immediate conclusions...
One of the immediate conclusions is that additional engineering is going to need to be done on the catalytic converters as they began to show signs of collapse after three days of intensive dyno testing.
As initially planned, the 2010 "Body in Yellow" Camaro is being built out as a "putting stock back into stock car racing" vehicle. In so doing, it will feature suspension components of design iterations functionally similar to the OEM components replaced. Based on these critical parts, the Camaro will be transformed into a bona fide race car capable of helping us evaluate major aspects required to span the gap between a conventional circle track package and one that addresses specific objectives of a more "green" approach to racing.
As the Camaro is being built, we will utilize a special experimental chassis that will allow easy access to the testing equipment for the initial on-track evaluations. These evaluations will include the use of an on-board ECU (controller), dual catalytic converters (as initially evaluated during the engine dyno tests at Mast Motorsports), a repeat comparison of the induction systems and fuel choices already discussed in this story, and a Sensors, Inc. PEMS to enable measurement of exhaust emissions during laps comparable to actual race conditions.
Present at the on-track sessions upcoming will be the same team already involved in this project, along with motorsports-oriented staff from the Federal Environmental Protection Agency. It's vitally important that CT readers understand that the efforts of this project are directed toward, and aligned with, assuring the future of circle track racing by providing a thought-provoking approach to advancing the sport while addressing a variety of environmental concerns. The use of sustainable fuels in motorsports is an objective CT has deliberately included in the format of this project. Over time, the blending of this approach into the core of circle track racing is a particular goal, and the project's steps thus far completed reflect that objective.