Since the March newsletter I have experimented with a number of ways to increase my engine coolant temperature. A friend and fellow experimenter suggested blocking the air to the radiator with a piece of cardboard and that has been inconsistent in keeping a set temperature. I have purchased a ball valve that I still plan to install in the radiator hose but I have not done that yet. I will get to it eventually but for now have little time for experiments and modifications.
I n the process of testing cardboard in front of the radiator I theorized that I could block the radiator better by tapping the ventilation openings in the front of the car, like Nascar teams do for aerodynamics. While I was at it I thought a full air dam in front of the vehicle all the way down to the ground would decrease drag caused by turbulence under the vehicle caused by all the air tumbling around down through the engine compartment and all the uneven surfaces under the car. While deciding how to build a clean air dam to cover the whole front of the car I decided to first add a piece of plastic to the short hinging air dam that is already under the front bumper. An 8 inch extension would come close to the ground and would hinge if it hit the ground so I installed a piece of sheet PVC used for trim stock with vinyl siding by contractors.
I trusted the Scangauge to be fairly accurate and decided to do 16 mile round trips on the interstate highway at 70 mph and at 55 mph with the air dam and card board in front of the radiator, with the air dam removed but still with cadrboard in front of the radiator, and finally with no air dam and no cardboard installed. The following chart lists the mpg of each southbound leg and each northbound leg of each configuration and speed:
Air Dam and cardboard
Speed Coolant temperature MPG Speed Coolant temperature MPG
70 207 38.1 70 216 39.9
55 206 50.0 55 209 49.8
70 218 39.4 70 218 41.3
55 211 51.7 55 216 51.7
No Air Dam or Cardboard
70 206 39.0 70 211 42.6
55 208 50.2 55 211 51.4
Or in a more useable form the data could be arranged as follows:
AD & C 70 207 38.1 70 216 39.9
C only 70 218 39.4 70 218 41.3
None 70 206 39.0 70 211 42.6
AD & C 55 206 50.0 55 209 49.8
C only 55 211 51.7 55 216 51.7
None 55 208 50.2 55 211 51.4
Now since we really have two variables (wind resistance and engine coolant temperature) we will have to study the data an draw conclusions that may not be accurate. I would have preferred to have just one variable at a time but with the temperature bobbing all over the place we’ll have to do what we can to interpret the data.
I think it is quite easy to draw a conclusion about the air dam at both speeds. The air dam did not cause less drag and higher mileage. It indeed did quite the opposite. The air dam caused a lower mileage in all cases. This could be explained by the fact that it was causing quite a bit more wind resistance because of the increase frontal area of the vehicle with the air dam attached.
If we made the same conclusion about the cardboard in front of the radiator, we would expect the mileage to increase when removing the cardboard. This however was not always the case. However if we examine the mileage versus the coolant temperature we find that at 55 mph the mileage was always higher when the coolant temperature was higher. In fact this was also the case at 70 mph with only one exception. This could be accounted for by the fact that the wind resistance was decrease with the removal of the cardboard.
Air Dam caused more wind resistance and lower mileage.
Cardboard in front of the radiator caused more wind resistance and lower mileage.
Increase coolant temperature caused higher mileage.
All of these findings are logical because more frontal area causes more wind resistance. The reason for higher coolant temperature causing better mileage can be explained as follows: Higher coolant temperature means higher engine temperature, which causes more of the injected fuel to vaporize before combustion, causing more complete combustion and better efficiency. The obvious thing to test next is the installation of the ball vale to control coolant temperature while keeping the air flow around and through the vehicle uninhibited. After that we could always go back to the theory of turbulence under the vehicle and see what we can do to reduce that. My suggestion is to install a pan across the bottom of the car from the front bumper to the rear bumper. Of course this may cause a problem with cooling air not having a way to escape after going through the radiator and into the engine compartment. I think this will be a minor problem because we will not likely be able to seal off the engine compartment. Air will likely find its way out. Whether it will be enough to keep the engine cool is unknown. Who knows, after installing the ball valve in the radiator hose we might find out that at 55 mph the valve is closed anyway and the radiator is not doing any cooling. I bet at 70 mph that will not be the case. I predict that a good clean bottom pan instillation will cause an increase in mileage at 55 mph but may cause overheating at 70 mph.
So why do Nascar teams put an air dam on the front of their cars? I suspect that it is to prevent air from ramming under the car at 200 mph and lifting the car up into the air and flipping it over, like it does when a car starts to slide sideways at high speed. Its not to lower wind resistance, it is to keep the car on the ground. Safety.
Tour de Sol is a competition for alternative fuel and hybrid vehicles. Tour de Sol began about 15 years ago as a solar powered vehicle competition. This year the Tour de Sol has expanded its competition to include a “Monte Carlo Style Rally” that is a self paced and self routed mileage competition. Competitors can start their mileage competition at a number of spots across the country and finish in Saratoga Springs, New York on May 13th or 14th. Since I live near Saratoga Springs I figured it was another opportunity for independent verification of the mileage achieved by a Hydrogen Boost equipped vehicle. I rearranged my schedule on May 13th and plan to enter the Monte Carlo Style Rally with the hopes of achieving better mileage than at least one Hybrid, hopefully a Toyota Prius. My goal is to use my worn out (152,000 miles) 1996 Saturn SL1 equipped with Hydrogen Boost components, and pick a route where I can use most of the driving techniques in the Hydrogen Boost Manual. My goal is to achieve 72 miles per gallon on rural roads at modest speed. Anyone who thinks it can’t be done can check back next month and see how we did.
Larry Trowbridge has been a Hydrogen Boost customer for over two years. At first he installed on a Dodge Durango and later I convinced him to get a Saturn. This past week Larry got serious about mileage and used Hydrogen Boost driving tips and equipment to achieve 81.22 mpg. He traveled 102.5 miles with 1.262 gallons of fuel. I verified with Larry that he did indeed go to the exact same station and fill his tank to overflowing and waited to insure the fuel did not settle into the tank. Here are pictures of his rebate offer form and gas receipts: The receipt on the right is the one from his fill-up at the beginning of the test run.
Larry did use three fuel additives that I will be testing in the future if I can get some. One of the additives is straight Acetone at 2 fluid ounces per ten gallons of fuel. The other two I will test before disclosing them. Larry would love to compete in the Tour de Sol this week but is too busy and too far away to make it. I will be using Acetone as well as Ethos Fuel Reformer for this week’s competition. Congratulations Larry on your excellent mileage achievement. Here is a picture of our 1996 Saturn SL1 with 154,000 miles, ready for the Tour de Sol:
Mileage update on Saturn SL1
During preparation for the Tour de Sol I wanted to take control of the excess fuel vapors coming from the fuel tank during operation with the fuel heater and 208 degree engine coolant. I have been having trouble keeping the fuel ratio at the normal 14.7 to one target of closed loop operation of the ECU (engine control unit). When the fuel heater is engaged and the engine coolant temperature is so high vapors will build up in the tank whenever I am driving with the throttle at close to full throttle or close to no throttle settings. Then when I go to mid range throttle settings the vapors are sucked into the intake and this overwhelms the ECU, which doesn’t make fuel injection corrections fast enough to handle the extra vapors. The ECU will begin to make short term fuel trim adjustments until it reaches –50%, then it makes adjustment to the long term trim but usually not fast enough. During the 5-10 seconds it takes to purge the tank of the accumulated vapors the ECU makes changes in the fuel trim and just about the time the trim catches up with the vapor output of the tank the vapors run out or the throttle setting is changed and now the trim is too lean without the vapors. Now the engine hesitates and bucks. This is unacceptable.
While working on controlling the fuel ratio for the Tour de Sol driving techniques I reinstalled our electronic circuit #2 and adjusted the ratio for the hottest full throttle burn, using my exhaust gas temperature gauge as a guide. Even without the vapors from the tank the ratio at full throttle is too rich. For the Tour de Sol competition I didn’t want to waste any fuel.
A byproduct of this adjustment was that the cruise mileage went up surprisingly. Since I was traveling a couple hundred miles to look at a VW Rabbit Diesel that I have commission to convert to hydrogen fuel, I tested the new adjustment on the road. Using the Scangauge, which I have now calibrated, I monitored the trip mileage at 70 mile per hour cruise. To my surprise the mileage was higher than I had ever achieved without driving tips. The Scangauge reported 52 mpg during that segment of the trip that was normal highway driving conditions. The whole trip, including some long steep uphills and some stop and go city driving worked out to achieve 43.7 mpg by calculation of miles versus gallons pumped. This verified the Scangauge’s mileage for the trip of 43.7 mpg. Having verified the Scangauge for accuracy I can rely upon it for segments of a tankful test. 52 mpg was a 30% increase over the stock 40 mpg highway mileage. This even impressed me because this test included NO driving techniques. Both baseline and this test were done at 70 mph cruise on the highway. I am so encouraged that I now think that it is possible to achieve 80-100 mpg on the Tour de Sol Rally. I will keep you all updated.
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