With a small increase from 6% to 9% nitro, in preparation we dropped the AFR to from 3.7 to 3.4. As a result, we picked up a tenth of a second and about 4 MPH over 6% nitro. (more…)

Just a note about our test engine for this year. We put our blown alcohol engine back together for nitro testing this year.
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Question: Different racers get different boost readings (more…)

In our drag racing, we did use air to fuel ratio as a controlled value to get the engine into a linear range. That task is an extensive explanation through out writings. The linear range is where the engine is completely predictable. We achieved that very well in our racing. (more…)

Congrats to Scott Williamson for great result reported as follows:

“… I raced last weekend at the Jegs Cajun Sports Nationals (more…)

A blown nitro ford combo was reviewed that was run for a year with no breakage, no burned pistons, and no other problems associated with nitro. An extensive analysis tech info may follow if there is interest. Let us know.

Message: in your fuel injection book, you show a vacuum gauge with a telltale,
do you know where to obtain one of these gauges? KS

It is not a vacuum gage but a pressure gage. You probably
want a 0-200 psi, liquid filled, tattle tale gage. (more…)

Question: Effect of lowering blower overdrive?? More or less power?
Bob?s answer: A trend now is gearing the blower to the racetrack. That is done with rear end gearing, tire size, shift point, and blower overdrive. Adjustment of any of those will change the speed attained by the blower at the end of the drag race or the straightaway.
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Question: Fuel injection adjustment with launch controls for a torque converter racecar

Answer: When a mechanical fuel injection throttle is part open, such as in preparation for launching from the starting line using throttle control setups, the air to fuel ratio is dependent on that throttle position at the time just before the launch. (more…)

Question: Can we put an 8-71 blower on a high output, normally aspirated Big Block V-8 with very high compression ratio (15 to 1)?
Answer: The detonation can be controlled with enrichment and air to fuel ratio control, theoretically regardless of the compression ratio. However, I am not sure about the mechanical strength of the components.? With that real high compression using a blower and a wedge head, the power stroke starts on one side of the dome. If you are using short skirt pistons or pistons that are not full circumference at or below the wrist pin (typical of normally aspirated high output engines), you may have a problem with skirt deflection, breaking a piston, or galling it. An 8-71 Roots blower, at 10% overdrive, theoretically pumps the same amount of air as an engine approaching 900 cubic inches. The math for that is in Fuel Injection Racing Secrets. Stuffing that amount of air into your BB engine gets a lot of boost and loading. FYI; Our book 5000 Horsepower on Methanol provides information about actual compression ratio with supercharging including simple math on how to determine it.