Drag Racing with Jim Hand

By: Jim Hand

Part 14: Reviews, Corrections, Clarifications

The sole purpose of this column had been to provide information to the readers about basic drag racing, and the preparation of street and street/ strip vehicles for higher performance on the street and at the drag strip at minimum cost. The information furnished has been based primarily upon our experiences, and our research. No manufacturer's claims or advertising has been used, and discussions about actual gains or losses in driveability and/or performance has been based on our experiences. Several comments have been in error, and our views on several subjects will be clarified.

In our discussion of "Easy Speed Secrets" in the April, '96 issue (Part #  7   ), we stated that a "hotter" ignition would not normally help performance on any street/strip engine running less than 6000 RPM. The word "performance" was incorrectly used in that statement. We have always considered performance to include easy starting, good throttle response, and smooth idle, as well as actual 1/4 mile elapsed times and MPH. Our direct and tested experiences with "hotter" ignition components is that while they may very well improve starting and low speed operation (particularly on engines with wide overlap cams), they DO NOT improve the drag strip ET or MPH, when compared to a properly operating and adjusted HEI. Some of the after market systems provide a means of RPM limiting, which can be an engine saver. In summary, improved idle, low speed throttle response, and RPM limiting may be reasons to utilize such systems, but don't expect 1/4 mile performance to improve. The so-called multi-spark systems provide an array of several short sparks (rather than one well defined longer duration spark that conventional ignitions produce), but the multi-spark capability lasts only from start-up until about 3000 RPM. At that point, the capacitance discharge types revert to a single spark that is usually shorter in duration than an HEI normal spark. The multiple spark type may allow a very unstable fuel/air mixture, caused by the severe overlap on a race type cam, to be more consistently ignited at lower speeds. Thus, improved starting and very low RPM operation may be improved. Be aware that capacitance discharge ignitions systems are not compatible with some tachometers and/or rev. limiters, so check before you buy (Reference the textbook "Internal Combustion Engine Fundamentals" by Dr. John B. Heywood, for additional detailed technical theory on various types of ignition systems).

We have discussed the use of performance exhaust systems in lieu of open exhausts for drag strip operations. It is now possible to install a complete and relatively quite exhaust system that is as efficient as open, tuned headers. It must be remembered that a complete exhaust system can weigh up to 80#, and that additional weight compared to no exhaust system will slow the car at the drag strip. The point is that a good exhaust system does not cost power, but it may cause a slight loss in drag strip performance due to the increase weight. Also note the reference to "tuned open exhaust". Just opening the headers in many cases does not allow optimum performance because the headers by themselves are usually too short for optimum tuning. Adding a good complete system in these cases may not cause a performance loss even with the additional weight.

We have advised you to review advertising for high horsepower producing parts carefully. A case in point is the "Comp Cams" ad for "Pro Magnum Lifters for "Higher Revs...More Horsepower", in the October issue of "High performance Pontiac." There is nothing wrong with this ad and it appears to be completely truthful. The power graph in this ad begins at 4000RPM and ends at 6000RPM. The advertised lifters show an increased in horsepower beginning at about 4300 RPM. However, look closely at what happens below 4300. The power is down with the advertised lifters and apparently drops as quickly below that point as it increases above that point. Accordingly, unless your average RPM is at 4300 RPM or above, you will lose power (and performance) according to the ad. Of course, if your engine never sees a load below 4300, it's normal operation is above that RPM, and the engine needs the slight additional lift and duration the lifters may provide, you might benefit with a product such as this. We do not intend to belittle or condemn after market components, and Comp Cams is a very reputable company but we again advise you to understand what such parts are intended for, and how they will affect your specific application.

This concludes our series of regular columns. If you have comments about any of our material, conclusions, statements, etc., please submit them and we will print them in special columns. Please provide documentation for claimed performance results. We will continue to serve as the Drag Racing Technical Advisor.

Thanks to the following Pontiac enthusiasts for their encouragement, help, comments, and critique for the past columns: Larry Kummer, Rick Gonser, Jim Taylor, John Andra, Fred Cailey John Johnson, John Mino, Dick Duclow and Peter Woodruff

We also thank the readers who have taken the time to express their views concerning our work. Please contact the other regular contributors to this magazine. They are doing it for your benefit, and I am sure they would appreciate hearing your opinion on their efforts to held you with your Pontiacs.

As additional information appropriate for our drag racing column becomes available, we plan to furnish it to you in the form of additional occasional columns. Meanwhile, keep racing!

The End

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