Thread: Let's talk Gauges.... (Now with EGT theory)

WOAH WOAHWOIHEOPIU TPezoighsrlghdriuthqodjsrfh;AWKD

What the shit is going on with this EGT talk?

EGTs let you know how well your ignition is timed. Yes, it can be used for other things but that's only if you know and can trust your ignition timing absolutely. There's no way you're going to tune air/fuel ratios with EGTs and no wideband. EGTs are for tuning timing. It can help to let you know many other things, but leave that to the professionals please.

Exhaust gas tempertaure...has to do with timing? please explain

Personally, I like to tune with as much information as I can get. If that means gauges, then so be it. Once I'm finished tuning, I don't need any extra gauges at all. The tachometer and fuel gauge are all I require.

Good things to have while tuning in order of importance:
Air/Fuel ratio gauge connected to wideband sensor.
Air flow gauge connected to MAF or MAP sensor.
Intake air temperature gauge with open element (fast) sensor close to throttle body.
Coolant temp gauge with sensor in non-radiator section of coolant flow.
Oil pressure gauge.
Fuel pressure gauge with sensor on post-injector side.
Exhaust Gas Temperature gauge with sensor on known hottest cylinder.

Fun things to have:
Air/Fuel ratio gauges connected to wideband sensor on every cylinder.
Intake air temperature gauges with open element (fast) sensors directly after turbo and intercooler.
Coolant temp gauge with sensor in radiator section of coolant flow.
Fuel pressure gauge with sensor on pre-injector side.
Exhaust Gas Temperature gauges with sensors on all cylinders.


Even more fun stuff:
Idle control DC % value gauge.
Injector pulse width gauge.
Injector duty cycle gauge.
Ignition advance gauge.
Exhaust Gas Oxygen Correction gauge.


If you don't know what a gauge is, or what it measures, or how to make use of that information, you don't need it. =D

I gotta agree. Please please don't tune fuel ratios with EGT. You can be completely lean and see low EGT's. It's not the right way to go about it. Tuning for fuel should be done with wideband, tuning timing should be with EGT. We determined hottest cylinder with a high range IR pyrometer on the dyno, and we decided on #4 I think, but haven't looked at it for a while. Also, when using an EGT gauge, you need to remember that most gauges use a huge and slow element, which gives you delayed information. I like the Zeitronix gauge for EGT because it is so fast. My last probe lasted me 4 years, which is the one downfall to a faster smaller probe, it's going to wear out sooner, but hey, 4 years isn't so bad IMHO.

It's pretty simple really. If you ignite the mixture early you get a complete combustion and lots of time left over before the exhaust valves open. During this time the exhaust gas losses energy (temperature) to the cylinder walls, ceiling and piston heating the engine and cooling the exhaust gas. By the time the exhaust leaves the combustion chamber is is significantly cooled and readings are low.

If you ignite the mixture at the opportune time you get a complete combustion and a little time left over before the exhaust valves open. During this time the exhaust gas losses energy again but not nearly as much as before. By the time the exhaust leaves the combustion chamber it is partially cooled and readings are typical.

If you ignite the mixture late you get an incomplete combustion and no time left over before the exhaust valves open. There is no time for energy to be lost from the exhaust gas and usually the mixture is still burning as it exits the exhaust valves. When exhaust leaves the combustion chamber it is very hot and readings are very high. Also there's high risk of melting the exhaust valves as the gas exits.


EGTs are more dependent on ignition timing than anything else, and this is why it is used to tune timing.

A good point to make note of. Most EGT probes are labeled for use by N/A engines or forced induction, and the mass of the probe is the deciding factor. There is no reason to buy the thick/big probe. Get the probe with the least mass every time. Same goes for intake temp sensing, etc.

Personally, I'm really sold on my zeitronix as far as monitoring goes. It gives me boost, super fast egt's, wideband, tps, rpm, and then the capability is there to monitor any other sensor I want voltage wise. Their datalogging software is simple and fast, with something like 60 reads per second. As far as in-cabin gauges go, I'm going simple: STRI water and oil temps, oil press, wideband and boost via zietronix's new 52mm gauge, and STRI fuel pressure (post injector, of course). I've had others before, but these are the ones that I find I like to watch during daily driving. Of course, for tuning I'll be running my Calumsult ECU so i'll be watching a whole lot more than those. I find the laptop is a very nice gauge to learn to use!

There's a gauge a customer's car had that I really liked. It had inputs for AFR, Boost, Oil pressure and water temp. Might have had inputs for others. It's an OLED display that can display all four things at once, or any one thing in a bunch of different ways (analog gauge, giant digital display, and my favorite, a 10 second history graph trace). After a while I could tune a bunch of stuff by looking at the gauge instead of logging with the laptop. Was very nice.

I still don't want any info during daily driving, but it was decent to tune with.

I forget the name of it. I guess I'll ask the customer.

I have the greddy e-manage, zeitronix wideband which all data logs and what not on the laptop Then oil pressure, boost and water temp on the pillar. Thats all definitely worked out fine for me with tuning. I may want to try using an EGT now to do timing.

I have really liked tuning with EGT. When you're on the dyno it tells you a lot. Also, there are guys who tune to MBT, mean best torque. Meaning that you shoot for the EGT (and thereby timing) that gives the best torque. It requires a lot of dyno time, but I've seen some guys with 4 cylinders get some really nice flat torque curves by tuning to EGT.