Which is more important to get it you had to pick between the two. I want the least ammount of gauges i need. Preferably two but just help me out on this one
EGT versus AIR FUEL gauges
- Thread starter edhgreatone
- Start date
def. turbo
EGT is much more accurate than an A/F gauge. The A/F gauge is basically just a light show. If you've got the money, a wideband 02 sensor would be the best way to go about it, though.
The EGT probe should be placed a couple inches away from the head on the port most likely to go lean. I really have no idea what that would be, ask someone more knowledgeable about hondas than me, but on my mustang that would be cylinder 7 or 8.
The EGT probe should be placed a couple inches away from the head on the port most likely to go lean. I really have no idea what that would be, ask someone more knowledgeable about hondas than me, but on my mustang that would be cylinder 7 or 8.
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alright thanks just double checking because i'm ordering it very soon don't want to waste money its a greddy gauge so thats $150
That's a negative. The EGT tells you how close you are running to lambda since peak temperatures occur at that air/fuel ratio--richer or leaner the temperature drops off (provided all other factors are unchanged). The trick to tuning with the EGT is to know what side of stoichiometric you are on (rich or lean). An A/F gauge can hint you if you're running lean or rich, but really it's only good for a light show and at WOT. I do not recommend testing a boosted car at WOT to see if you're rich or lean. If you were to get only one gauge, get EGT.SeanMc300 said:
so lets say your temp is really high does that mean your running lean or what?
Usually a higher temp means you're running lean, but extremely high temps can also be caused by running really rich. If you're running really rich some of the unburnt fuel can combust in the header (right at the egt probe) and show a higher temp that what is really happening in the combustion chamber.
When you're temps are really hi, a number of factors can determine why. Sometimes, it's just the engine design. Combustion chamber design, compression ratio, cam design all affect the final word on how an engine operates. Some engines will run hotter than others, don't you think? If the ignition timing is retarded too much, exhaust gas temperatures will also rise because a lot of the fuel is still burning late in the combustion cycle (sometimes, as exhaust gas is leaving the cylinder). And like TurboZinc pointed out, running really rich can affect EGT as the gas will still be burning as it leaves the cylinder.
A cheap trick (and lost art) to determine if you're running rich or lean is to do a full power, full load pull and then shut of the engine immediately. Take out the spark plugs and check them. If the plugs are black and sooty, smelling of gasoline, you're running rich. If the plugs are light and "powdery" looking, you may be running lean. If there are traces of metal on the plugs, the engine may be experiencing knock.
Running lean is all relative. Lean of stoichiometry is different from lean of, say, Rich Best Torque (RBT). For a turbocharged engine under full load, stoichiometry is far too lean, much less you might not be able to run the engine without problems at that A/F ratio. However, running just lean of RBT might (or might not) yield a few lb/ft of torque (it's all about tuning and "trial and error"). But like I said, EGT will usually be hottest at an A/F ratio right around 14.7:1. Lean or rich of that, temps usually drop.
A cheap trick (and lost art) to determine if you're running rich or lean is to do a full power, full load pull and then shut of the engine immediately. Take out the spark plugs and check them. If the plugs are black and sooty, smelling of gasoline, you're running rich. If the plugs are light and "powdery" looking, you may be running lean. If there are traces of metal on the plugs, the engine may be experiencing knock.
Running lean is all relative. Lean of stoichiometry is different from lean of, say, Rich Best Torque (RBT). For a turbocharged engine under full load, stoichiometry is far too lean, much less you might not be able to run the engine without problems at that A/F ratio. However, running just lean of RBT might (or might not) yield a few lb/ft of torque (it's all about tuning and "trial and error"). But like I said, EGT will usually be hottest at an A/F ratio right around 14.7:1. Lean or rich of that, temps usually drop.
The best way to do it if you're going to run an EGT gauge is to have the car tuned on a dyno w/ a wideband o2. Make sure to check your temps during the pull. This way, you know your a/f is where you want it, and at about what temp your EGT is showing. This way, while on the street or at the track, you can keep track of your EGT's and see what the car is doing. It is basically a helpful tool, not an end-all solution (wideband o2). There are way too many factors that determine EGT's to just tune straight off the temps.
Freeflyin also makes a great point. Checking your plugs can give you a great idea of what the engine is doing. The only problem, especially on a turbo car, is shutting the car down immediately after a hard pull. The oil is still extremely hot, and will coke up on the bearings and shaft.
Freeflyin also makes a great point. Checking your plugs can give you a great idea of what the engine is doing. The only problem, especially on a turbo car, is shutting the car down immediately after a hard pull. The oil is still extremely hot, and will coke up on the bearings and shaft.
Yep yep. And the impeller shaft will be spinning at tens of thousands (sometimes 100's) of RPM's, cutting off oil flow to the shaft and bearings would lead to short turbo life. Don't recommend it without proper continuing oil circulation after a hard pull on a turbo vehicle.TurboZinc said: