This year I've been out on the road quite a bit tuning and R and D-ing for some NHRA Pro-Stock teams. We've got some new concepts we're working on and these cars are great test beds.
NHRA Pro-Stock cars are equipped with all kinds of great data gathering pieces of equipment. They have EGT’s and wide band O2 sensors, Accelerometers and every type of pressure gauge imaginable. But all this equipment is only as useful as the person reading/interpreting it. I may spend the better part of an hour looking at the data on the computer after a run. But when all is said and done, the plugs come out, the headers come off and they’re the boss.
As intricate as modern technology and data acquisition is, it still lacks the ability to read the heat on the plugs or interpret header burn patterns or detect detonation or possible timing change requirements down track or distillation curve needs or staging temperature wants.
A couple years ago a detonation/knock sensor was designed by a company for offshore boat racing. The idea was to use it to adjust timing when knock was sensed by the system. But modern day performance engines with their huge camshafts and massive valve trains make so much racket when they operate that detecting detonation is nearly impossible. That particular system burned up or slowed down a lot of engines.
So basically, its up to you to go back to basics every time the car comes back to the pits. You can look at the data, but the bottom line is, you could probably shut the computer completely off and any tuner worth his salt can make that car a frontrunner. Obviously, if you have a professionally built set of carburetors that offer a good fuel curve for your application the hard part is already done. Now you just need to adjust the important but simple stuff.
Lets talk about the basics of air.
Humidity: Did you know that at any given moment all across the world there is approximately 40,000,000,000,000 gallons of water in the air.
Oxygen: We all know from reading our O2 meters that typically 20-21% of the available air is oxygen. That’s the stuff we need to go fast. The rest of it is useless Nitrogen, Water and a few other components. Obviously nitrogen is required as an inert, because as you know if your O2 content is high enough then your pistons can be used as a fuel. I remember seeing a video of a guy who used liquid oxygen as a fuel to burn a gas grill to the ground. (Remember liquid oxygen has to be super-cooled to stay in a liquid form so you can’t buy it and pour it in your tank.) He simply got his grill going on charcoal briquettes and then poured on the liquid oxygen and burned the grill to absolutely nothing, wheels and all. Pure oxygen can use almost anything as a fuel. Now you see the importance of inert materials for ease of control.
So you can see that our atmosphere can be a volatile place. A 5% change in the oxygen percentage either way and we’ll have rampant fires or lack the ability to even start a fire.
Pressure: Well your engine builds its own sensitive atmosphere. It compresses the available mixture (that’s constantly being altered by the barometer and hood scoop pressure) so its very close to auto-ignition. Now its up to you to start the fire, at the right time, under the proper load and at the right ratio. Good luck. Sad but true, a modern day racing engine is currently more sensitive than the electronics that monitor it. So if you’re lost on your program, put the electronics away and get educated on reading plugs and pipes and listening to the car run.
I get phone calls everyday of people asking me what their EGT’s should be or what O2 number am I after. Well, you don’t know until you’re done tuning the engine. After you’ve tuned it for the best power for that pressure, temperature and humidity you have a baseline. But guess what, when the pressure, humidity and temperature change, so will those EGT and O2
requirements. It changes every moment of everyday. So get tuning, the scope is in your tool box and the PRO-SYSTEMS tuning video is in your VCR. Pull those sparkplugs out of your engine, plant yourself on the
couch and get educated.
Next time around we’ll talk about super heated air and the effects of flame-front speed.
Stop in again.