|Fuel Injector Design Issues, New Driver Relaxation Technique, Numerical Control, Weather Corrections, HP Corrections
Newsletter No. 6 - Fall 2012
Links to perfect holiday and birthday gifts are provided in this issue. In the technical department, information is featured about fuel injector nozzle design & function. For new drivers who may be apprehensive about getting behind the racer's seat for the first time, very powerful relaxation techniques are provided. There is more on numerical tuning control. I also added weather corrections for tuning that are compared to weather corrections for horsepower output. The next newsletter after this will be sent out Spring 2013. Forward this newsletter to a friend by clicking the link at the bottom on this email. To unsubscribe, use the other link at the bottom.
It is that time of year for the perfect holiday or birthday gift for the racer. How about a racing technical book or fuel injection jetting calculator. Here are links to our various gift ideas:
Buy any two or more items, and shipping is free to most locations.
Links to free info:
IHRA Articles air scoop size, nitro, alcohol, working the starting line, weather corrections, eighth mile vs quarter mile conversions, race pavement preparation, and others.
Racecarbook.com Blog on racing technical subjects
Newsletter Archive air scoop size & other racing subjects; also info on USA taxes & racing as well
Air Density Online - Track Weather free weather info for tuning for many racetracks & courses in the USA & Canada, and the only source for air density forecasting
Air Density Online - Free Calcs free calculator to determine air density, density altitude, water grains, dew point, vapor pressure, & uncorrected barometer from a corrected barometer value.
Fuel Injector Design
Regarding Fuel Injector Improvements for Normally Aspirated Stacker Engines
We were recently asked about fuel injection nozzle design. It got me thinking about several responses throughout our technical manuals and other racing experiences.
In one respect while a fuel spray into the intake port may interfere with air flow, it is fuel vapor that burns, not liquid. There is not enough time for the fuel droplets entering into the cylinder to fully vaporize and burn in the brief combustion event. Changing the fuel delivery to another location or fuel flow method may increase air but at the expense of vapor formation. I saw several cases where a reduction of fuel vaporization dropped power. Read the rest of this article
Racing With A New Driver
All race cars & boats at some point in their lives start out with a new driver or someone who is the first driver. The following are a couple items to help that unknown Read the rest of this article
Our Motorsports Weather Corrections manual (revised
) was changed to include new information about horsepower correction technology. Both the previous and the new editions cover the differences in weather corrections needed for fuel injection jetting changes (as well as carburetor jetting changes). For example, assume a baseline fuel injection setup is based on 100% air density. If the combination of temperature, humidity, and barometer make up an air density of 92% for the next outing, then the fuel flow is adjusted with nozzles and jetting for that same 92% of the previous amount of fuel to the engine used for the baseline. In the reference, three different race track locations with the same air density are analyzed with different combinations of altitude, temperature, humidity, and barometer. In the example, all three are at the same 92% air density. The same fuel injection nozzle & jetting correction at all three locations occurs. Our Fuel Injection Racing Secrets book
, jetting for NA small blocks
, jetting for NA big blocks
, and Pro-Calc
provide math to do the nozzle & jetting determination for that air density as well.
Horsepower Corrections Are Different
Corrections to horsepower from temperature, humidity, and the barometer are different however. Examples in the reference are provided that again show the three different locations with 92% air density. However, horsepower corrections range from 91.3% to 93.8% at the different locations for a normally aspirated gasoline fueled racing engine. Horsepower corrections for methanol fuel are different. And for nitro, different also. The math is based on equations that are similar to those used for the weather corrections. However, exponents are added to the equation that affect the amount of horsepower correction. Exponents are different for different fuels. They are different for normally aspirated vs blown engines. Different exponents from different fuels and induction method effectively de-rate the weather effects on horsepower. Those results are illustrated by drag racecars in different classes running at high altitude racetracks. Some classes slow down a lot. Others do not.
Revisions to the Weather Corrections Manual -- Blown Engine Inlet Vaporization Effect
The new additions to the revised weather corrections manual are specific to blown engines. Those additions consider the change in horsepower from blower inlet fuel vaporization. The type of fuel at the inlet affects the amount of vaporization and horsepower correction from the weather. Methanol is shown to be the best for power improvements from vaporization.
Revisions to the Weather Corrections Manual -- Fuel Temperature Effect
New additions to the revised weather corrections manual also consider the change in horsepower from the temperature of the fuel in the tank. Cooling of the fuel increases the amount of condensation at the inlet. That increases the amount of air at the inlet. That increases the amount of boost and power as a result. Those effects are illustrated.
Numerical Control to Avoid the High Cost of Breakage
When we ran our drag racecar in the beginning, I had the experience common to most of a "guestimated" tune-up. That included jetting, spark advance, blower overdrive, and clutch settings. Some of the settings were in the parts that I bought, from phone calls to suppliers, and local racing tips. The combination as it was put together was not the same as any that I ever ran before. I recall running at a high altitude racetrack for the first time. We started the engine with the sea level jetting, and it was 'drunk rich'. A friend with a lot of experience said to put the largest main bypass jet from my tool box into my engine to attempt to lean it down. I recall wondering, "lets see what happens". We dumb lucked out on that one and made a full pass, although it did not set any records. On another occasion, I recall setting up a blower overdrive higher than I ever ran. Then on the next pass, shredding the blower belt. I recall many experiences with unknowns that dominated the outing. I recall the expense and time for those numerous outings. It took a long time to sort out the combination. The cost for all of the previous trial-and-error test runs without numerical knowledge or planning was the cost of a new racing engine. That is what I spent through the years working it all out. From that experience, I started the development of numerical control. When the combination was sorted out, measured by numbers, and numerically controlled, the outings became predictable. In those subsequent outings, the settings were done ahead of time with an adjustment plan. I did little unknown tuning on race day.
Expense of Trial-And-Error vs Numerical Control
Many of us like to go to the races to unwind. We go there wanting to relax and concentrate on racing. I recall times when I did not want to think. I just wanted to start that big engine and hear all the noise. I wanted to see it on the racetrack running fast. Unfortunately, as the power went up, the opportunity for mistake increased, and the mistakes cost a lot more. I found that numerical controlled tuning, while it was cumbersome at times, reduced the frequency of mistakes. Racing was again fun. Since that time, I had mostly successful experiences running well right out of the trailer. That was a trip.
Numerical Control & Record Keeping
I soon realized that record keeping was a major task in running this racer. If I had it to do over, I would set up a crew person or relative to take charge of record keeping. With the math in our books, a high school student taking algebra can really get into numerical control. Finally a practical application for all of the theory. I found that math exercises in racing that produced good runs were a lot more fun than math in accounting, tax computations, or school homework.
We are busy working on a new publication about running low percentages of nitro with a blower for the most horsepower per dollar. In essence, it is a book about taking a blown methanol engine and upping the power with nitro with good practices that reduce the risk of damage. That book will be out shortly. At this point, tt looks like it will be over 150 pages with very meaty setup & tuning information about nitro. Volume mixing, weight mixing with specific gravity, air density corrections, and horsepower corrections will be included. Also there is a very revealing section on nitro mixtures and lambda. More information about the availability will be on our website. If you are interested, send us a message on our contact page.