If you haven't noticed yet, I'm a big fan of the nitrous bottle. I can clearly recall being 17 years old and reading about Jim Salonisen's '67 GTX in The Complete Do-It-Yourself Guide To: Nitrous-Oxide Injection and how author David Vizard claimed to light the tires at a 50-mph roll with a 440 and a big hit of spray. The fun was backed with a photo of a huge smoky burn for distance. That got me behind the wheel of my '74 Dodge Dart Sport to attempt some burnouts of my own. The Slant Six was never in the mood.
Today I still dream of sneaky Petes or pro foggers wired on the bottom side of an intake manifold for a hidden 350 shot. Nitrous bottles hidden in toolboxes, hoodscoop spray systems, and feeds running inside of rollcages or plumbed into phony PCV vacuum tubes are all seared into my memory as tricks and tips that I've read voraciously since the first time I heard about the WWII Allied fighter bombers using the gas to gain altitude, and advantage, in the sky. The first hands-on tech story I wrote for then Petersen Publishing was a story about ... you guessed it, a nitrous install. I didn't hide the system very well but still it netted me $20 and magazine glory when the gambler didn't bother to check under my hood. I had installed it secretly the night before.
So it's good stuff. Recently you might have seen the Formula Firebird that we rescued from commuter hell for some drag tuning and speed. Another benefit to nitrous that I haven't pointed out yet is the fact that it can be installed on any car of any year for the track then disconnected for the street or removed entirely for any kind of state vehicle inspection. So we were intent on using the stuff for the final kill shot at the track. After a string of frustrating mid-14-second runs, the nitrous was a refreshing whack at the timers. With a roller-coaster drop for the stomach, the 'Bird launched hard and posted an uncorrected 13.10, which at that track should correct to 12.70. And that is the problem.
Should we correct for nitrous? That's a tough question that I asked myself and about as many guys as I could find to get a general consensus. Here's how it played out.
Smith: "It would be the same correction factor for normally aspirated and nitrous cars."
McGean: " You can't just throw correction factors at nitrous runs because nitrous provides its own air. But I see Glad's point [below]."
Freiburger: "Dragstrip correction factors are bogus in general. They correct altitude, not temp and humidity, so they are not totally predictive even though the NHRA-published corrections are generally very close. They can tell you how the car would run at a different altitude on a day with the same temp and humidity of the day you ran the car. However, corrections are for naturally aspirated engines, and you generate a greater range of inaccuracy with nitrous and blower cars. The more nitrous you use, the less accurate correction factors are, since the oxygen in the nitrous becomes a greater percentage of the engine's overall air consumption. The less natural atmosphere the engine is using, the less accurate the correction. Small nitrous shots can probably be corrected and not be totally bogus. But it's all just bench racing anyway. It would be best if we could only use observed numbers and print the weather conditions. We've gotten away from doing that since we invariably look stupid compared to the fantastic numbers other magazines generate at tracks the likes of Englishtown."
Mike Flynn (Former head of the Tech department at NOS.): "The engine is still naturally aspirated, so there is going to be an (altitude) effect. The atmosphere is still what's pushing the air into the engine, and the nitrous system is still going to put in the same amount of nitrous and fuel. So you really can't get away from correcting for altitude."
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
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