agreed with all said above.. just been told several times that it is useful.. not the most important thing in the world.
but.. it can show u whats going on with the motor just as a wideband can..
Perhaps, but it's even less accurate than a wideband. Because it is also directly influenced by small ignition changes, heatsoak, and borderline cooling issues. It's hard to log all of that and make correct sense of it. I can see an EGT being a great tool on a problem vehicle where you can't have too much information, but I can't see it as being a backbone tuning tool.
and like jose said.. if ur timing is right then your egts should be within range right?
What if your AFRs are completely wrong, although your wideband (and any other wideband) reads "correctly"? AFRs are indicated and very much not actual, and the pitcher is spitting on the ball before he curves it to you.
whose to say at 22* on X engine egt is at Y..
and on X2 engine at same timing egt is at Z..??
obviously you guys know not one engine is the same.. what im getting at is.. besides detonation doesnt excessive combustion temps kill rings?
There is no difference between detonation and excessive combustion temps on the combustion level - temps get too hot for water and hydrogen to join together and form the water vapor (steam) that generates combustion pressure, and instead they consume aluminum in a rather explosive reaction. This is what creates detonation pitting. Although the situation you are alluding to involves a lot more heatsoak of the chamber and likely result in more impressive carnage, or distributes it across the chamber until one thing decides to go.
Too much heat:
- Nukes exhaust valves, sets you up for preignition
- Heats the piston, causing it to expand until it binds across the skirt. Since aluminum's strength is directly related to it's temperature, ring lands will pop off on stock units. If this is a rich or correct mix with significantly too little timing, creating an effective lean condition in the chamber, it is possible to melt the piston which will leave an aluminum residue at the top of the bore in some cases.
- Is really an irrelevant topic in a thread about EGTs
sure watching your timing will mean no need to monitor.. but like you said JD these are performance engines.. not everyone wants to run their engine to the extreme side of the spectrum.. some people just want some power...and be SOMEWHAT reliable.(yeah yeah i know power/reliable/cheap... choose 2 etc etc..
See, this is the breakdown in your understanding. Hondas, and most all inline 4's, are not knock limited engines due to having poor headflow and their cams advanced 5-10 degrees too far to create torque off of idle aka V8s. The Honda that continues to make power under detonation is rare (I owned one), unlike the lower revving big displacement motors. With a forced induction Honda you will always have 3-5 degrees of safety between best power and detonation, until you make enough power to run out of octane. Some high CR pumpgas NA builds that are all dome with no quench and a poor cam selection will mimick a V8 in the sub-2500 rpm range so that you have to pull timing to prevent detonation while also losing power to do so.
There is no difference on a peak power tune and a safe reliable tune for a Honda, Miata, SR20/KA-T, 2JZ (not fair comparo) or 3S-GTE, and a large number of other engines. The reason why these motors come apart is poor assembly, or Honda-Tech assclowns thinking a 2.0/VTEC can make 450+ whp on pump gas. When the timing requirement to make the power starts falling off hard it's because you're running out of octane and the shit is becoming volatile and unrepeatable; one tank of bad gas at the 400 whp level will do mild damage. The same gas at 450+ causes more damage. Over a long enough time, or bad enough gas, and your shit comes completely apart. I tune on a dyno that reads somewhat high if the corrections aren't turned off, recently had a local kid making 320 on it that couldn't get better than 290 on a Dynojet and was flipping out about it. I have yet to see a pumpgas Honda I would trust past 400-410 whp - power looks fine, plugs look fine, but timing is falling off and the carbon trail on the piston (FUCK plug reading, carbon trail is a much better indicator) shows signs of high frequency detonation.
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Topic: Ignition timing vs EGT's (Read 10751 times)