My opinion: Yes, correct it if you are adding more than one speed part. Here's why. When we test parts on a car, we usually run it at Los Angeles County Raceway, a track with a hideous 2,700-foot elevation. The NHRA altitude correction factor is 0.9679 for e.t. and 1.0339 for mph. That usually equates about 0.40 off the e.t. and an additional 4 mph for 12-second stuff. So without the correction on the baseline run, the Firebird would look a lot slower than it really is (resulting in hate mail). With the correction factor, a realistic number is produced that should represent what would happen if we ran the car at a sea-level track on a 70-degree-F day. So we used it. Each mod we performed was based on the original corrected number, so for instance, when the exhaust work netted us 0.050 gain in e.t., we used the corrected number. We did that for every part we installed. When we got to the nitrous run some people loudly objected, saying you can't correct for nitrous. Since our corrected number was around 14.12 before the nitrous run, a non-corrected nitrous run would be 13.10, therefore telling you that a 150 shot of nitrous was only worth 1.0 second when that much nitrous is usually worth 1.5 seconds or more; it's the difference between a 12 and 13 second pass. So I think if you correct one number, you correct them all for this reason.
So what do you think? Are we crazy to correct for the gas? Is it an accurate enough depiction of the real speed numbers that you can evaluate how much these parts are worth on the track? Let us know at CarCraft@primedia.com. We're still arguing about it.-Douglas R. Glad
Car Craft Mag
6420 Wilshire Blvd
Los Angeles, CA 90048