| Basic Budget Dyno - Just Tested
When analyzing the function of our favorite test tool, the Dynojet dynamometer, horsepower is measured by the rate of time a vehicle takes to spin the Dynojet roller, based on the roller's weight.
A Dynojet is equipped with a magnetic pick up that mounts to the roller's shaft, which provides the needed data. Using this same concept, Blitz allows the user to plug in a vehicle's weight (with driver) to represent a dyno's roller weight. The Power Meter also replaces the Dynojet's roller magnetic pick up with the vehicle's vehicle speed sensor.
The result is an on-board dyno that can calculate horsepower and if the unit is run through the proper set-up procedure, horsepower will be calculated at the flywheel, rather than at the drive wheels. Horsepower can be viewed in three different modes: graphical power, digital power and power vs. speed. While in digital mode, not only can the readout be viewed in bar graph form, it is also shown numerically, including a max net horsepower peak/hold feature. By using the "Up" and "Down" arrows, the horsepower bar graph can also be displayed in outputs as high as 1,200 hp. Power can be viewed in five different readout modes: 0-200, 0-300, 0-400, 0-800 and 0-1200. (Since the Power Meter screen is so small, the 1-200 screen will have better resolution than the 0-1200 screen.)
If graphical mode is preferred, a line graph will appear when the vehicle is in motion. For instance, let's say you started the graph at a steady speed. The line graph will show your horsepower in real time throughout each gear change and as well as the throttle percentage as you accelerate.
If the vehicle comes to a complete halt, the graph will stop until the vehicle is in motion once again. Think of this mode as an EKG scan that monitors horsepower fluctuation. Graphical mode will also allow the user to view power in numerical form in real time, including a peak/hold feature that displays the vehicle's highest horsepower reading.
The last mode that can view horsepower is the chassis dyno mode. This mode allows the user to view power vs. mph. This screen is also viewed in real time and can be used to analyze horsepower in different gears. (This information can be used to dial-in the scramble boost mode of the Dual SBC controller) Selecting through the "Enter" button will also allow the user to view peak/hold horsepower readings.
Dash ModeAn added bonus to the Power Meter is its ability to record various time trials. By entering "Dash" mode, the user can record various types of runs from 1/8, 1/4, 5/8 mile and 0-60 mph. Not only does the unit display the time in seconds for the selected application, it will also show the vehicle's mph.
For 0-60 time trials, the unit starts the clock and is able to record the moment the speed sensor is activated. However, the unit is not able to compensate for wheelspin, so all recorded times must be performed with minimal or no wheelspin. Scrolling down one screen from "Dash" mode allows the user to review the last six runs recorded, whether it be mph or e.t selections.
TestingAs a quick accuracy test, we decided to install the Power Meter on a '91 Toyota MR2 Turbo. Installation consisted of locating a visible mounting point and connecting the following three wires: ignition power, ground and speed sensor signal. We decided to consult the factory service manual to access the factory ECU wiring for all three wires. Since our test vehicle is an MR2, the ECU is located in the trunk, which meant we had to run our wires from the driver's seat through the engine bay and into the trunk. In other words, we had some long-ass wires. Once we had the meter installed, it was time to program the weight.
When establishing the weight, a few things must be taken into consideration. The best way to establish the correct weight is to locate a public scale. Many times, you can find scale at truck stops along the highway or at moving truck companies.
Fortunately for us, we found a moving truck company two blocks from our dyno facility. Before weighing the vehicle, we removed stuff not normally found in the car, like a camera bag, skateboard and technical service manuals. Believe it or not, this type of weight can add up, ultimately affecting horsepower accuracy. Gas level is also a weight factor that needs to be taken in consideration. Since gas weighs 6.2 lbs per gallon, you want to make sure you remember the weight prior to weighing the vehicle. In our case, the MR2 was holding a quarter tank of gas. We could guess-timate a little about the weight; since the MR2's gas tank carries 14.6 gallons and we were at a quarter tank, we came up with a rough estimate of 23 lbs added by the quarter tank of fuel. At the weigh station, the car weighed 3,037 lbs with driver. Once the weight is calculated, we input the vehicle weight into the Power Meter with the correct power loss listed in the installation manual for the specific vehicle application.
With weight and power loss entered into the equation, all that was left is to calibrate the vehicle's speed with the Meter. Since our vehicle was equipped with Kosei RT Penta 17x7.5 wheels and 205/40-17 Falken tires, our speedometer was too far off to tune. Since we were doing a horsepower comparison with the Dynojet, we decided to use the speedometer on the dyno to calibrate. Our other option was to run along side a vehicle equipped with stock wheels to use their speedometer as a tuning device. Not practical.
With the meter programmed correctly, we did a quick third gear pass starting at 2000 rpm in "Power Graph" mode to simulate what would be a dyno sheet. After our recorded run, we strapped the car to a Dynojet to get a comparison. Since Dynojet rates the car's power at the wheels and the Blitz Power Meter does the same, we ran the power meter on the street immediately after making the run on the dyno. Dynojet horsepower equaled 184.7 hp and the Blitz Meter read exactly 184 ponies to the flywheel, giving us an almost accurate reading.
What is handy with the meter is the ability to make weight changes to compensate for added passengers or loss of fuel. By simply adding the additional weight to original vehicle weight, the meter was able to calculate the horsepower for a loss and an addition in weight.
ConclusionIf you have ever been curious to see what small changes could do to pump up the horsepower level of your vehicle, the Blitz Power Meter can be the best, most affordable on-board dyno system to measure the results of performance upgrades done to your car. Not only will this system read horsepower, it is also equipped with a peak hold for the highest horsepower registered. It also reviews a complete power run while shifting through the gears. As an added feature, it comes with datalogging capabilities. Let the tuning begin.