Also just for reference, here is an IAT chart.

 

And the only thing you can spin at a high rpm like that is a distributor.......

 

lol wtf

 

alright somtimes I say things and i expect people to "look into the mirror" or whatever but it comes off wrong because nobody thinks I am being subtle.

I was being subtle/ironic when I say "afford $80 egt gauge" or "afford anything ____" . I am not actually suggesting anybody is poor like me (if you can afford a car... you can afford a ____) to afford an EGT, it just means that if we put together a high performance engine and then all stand around in a big circle scratching our heads asking about something that looks like it is melting the first question I would ask is "how hot did it get?". You can't just come on the internet forum and figure that out with a giant jerk off internet circle. Thats where the irony is boiling over- someone put $15,000 or $25,000 into a build and neglected an $80-$250 critical data-collection tool then came on the internet looking for opinions about what caused the melting (was it high temperature???)

I don't know if you caught this. But you can drill a 1/8" NPt hole in a wideband bung plug and install an EGT probe into that temporarily. at least this will give you a downstream read. If I saw 1550*F in the downpipe at this location I would know there is a problem upstream, probably with fuel.
I don't blame you for not having an EGT. I am not saying it is even necessary- I would not have installed one prior either, especially using that good of a fuel, and truly we do not need an EGT if everything is "looking good" for a mild build (2x output is mild) I am ONLY saying that as a diagnostic tool it is VALUABLE for people with the exact problem you are having, thus making it go from not-required to absolutely-necessary (ironically of course).


The iaT is so low, if we rule out the engine being assembled/configured wrong (no hot spots, no pressure leaks, no preignition due to temp, no funky flame propagation due to poor port work, no poor quench or combustion interference property, etc...) then that only leaves the fuel. what are the chances the fuel you are getting is old, bad, or watered down? I would try a different fuel/supplier if you've been depending on the same one all this time.

 

No problems here or offense taken by me personally from anyone. I posted this here because I figured someone, somewhere at sometime has had this happen or at least has seen this happen and would have at least an idea of what it "might" be. I completely understand the sensor idea and where you are coming from. I always planned on installing one just hadn't gotten to it just yet. I do understand how it would help though an these things are why I like to log everything possible.

As for the fuel, I get my barrels straight from VP in San Antonio. It inst old or diluted in anyway. They are the main supplier for most on the country. I dont like to buy fuels from tracks or small suppliers as you just never know. I've had dirty fuel before.

 

FWIW,, I've sold VP/Sunoco/and a couple others, they all use recycled drums and I've gotten grunge from all of them at one time or another, I always use a 4 micron pump filter and a water trap to monitor.. YMMV>. Literally

 

Not a bad idea.

 

Be careful putting too much faith in those EGT sensors... Installing them at a different distance, angle or orientation can drastically skew the results.

 

If everything else is setup right, EGT sensors are irrelevant on a spark ignition motor. While they CAN be used to tune individual cylinders, the quote above shows why the potential variance can render them useless. Unless you can control the test situation in a manner that is unlikely in most garages, you get data that tells you nothing more than what you already saw on your wideband.

 

EGT is more powerful than wideband

wideband doesn't tell you when something is too hot

It can't help you save the engine if the a/f ratio is correct but **** is melting down

this may not be a problem for low output configurations (what you must be referring to) but is absolutely necessary on high output racing scenario where it is allowed.

 

That’s kinda BS IMO for several reasons. More data is better, no argument there. But an EGT system alone is not a better tuning tool. Installing 1 EGT probe is also pointless IMO. You need them on every cylinder for good data. One hot and one cold cylinder will average out to a “good” EGT reading. Sprak plugs are the cheap easy heat monitors.

If you know how to tune, the plugs will tell you when it’s too hot. There is no need for 8 cylinder EGT logging on mild builds. Sure it’d be nice. You can tune much more quickly and successfully with a WB02 reading spark plugs than you could with only an EGT monitoring system.

Depending on the EGT probe placement the EGT readings will also vary a ton. So knowing the limit or “happy place” EGT wise per cylinder varies a ton with every setup. The only way to find the “limit” with an EGT system is to push it to failure. Then Steer clear of that failure temperature point for that specific setup. Which won’t apply to other setups/engines.

Also an overly rich/lean mixture may indicate a much cooler/hotter EGT. Without knowing the actual air/fuel ratio you could be leaving a lot on the table.

 

All valid I completely agree and maybe I spoke out a little hastily and harshly against what I saw as an unfortunate disregard for the power of knowing the temperature in such a difficult place to measure for such little cost. But if you read my message carefully you will notice that I never mention using as a tuning tool, only as a safety device which it is one of many possible ways to evaluate an engine as you put it, "more info is better". I never suggested individual cylinder monitoring (2x to 3x output does not quite qualify), only that the op was having what appeared to be a temperature related malfunction and that EGT is a direct measure of at least something coming off the engine (its better than touching it with your finger to see how hot it is anyways)

I think you are slightly underestimating the value of the EGT probe in combustion tuning for max economy, and low timing threshold. When measuring those two things, you are not concerned with the number on the EGT gauge, only the difference between numbers. In other words, 1200*F is arbitrary, but the difference between 1250*F and 1120*F is what we are looking at, compared with other changes. I am going to take a stab and say that These things probably do not interest you because saving fuel is probably not your main concern (where it is for me usually).

For example if I Put an EGT in after the turbine in a random engine I might see during cruise:
20* of timing: 1440*F
25* of timing: 1350*F
30* of timing: 1290*F
35* of timing: 1270*F
40* of timing: 1268*F

I can see clear as day that I am throwing fire into the exhaust around 25* and that this engine would be safe in the 32-36* range where it's at for a cruise given the existing load/weight it was tested with. The exact arbitrary meaningless number on the gauge didn't tell me that though, and a wideband couldn't tell me either.

 

The same applies to a wideband o2 as well, correct? and the same about checking plugs would apply

 

Do some pulls with new plugs and learn which are your hottest cylinders. #5 for me and tune based off your leanest cylinder. This is a safe and effective way if you do not have individual cylinder fuel control.

 

Its true they may average out to an ok reading, but they are not as sensitive to placement like an egt. Keep them at least 1ft from a downpipe and away from any couplers and open air and it's going to read very close to the same AFR unlike egt probes that can vary quite a bit based on placement.

 

Based on past experience with other drag cars with 1500+ hp ratings, the EGT's are always placed withing the first couple of inches of the header tube leaving the head. If all of the egt sensors are placed in the same location, then the placement, orientation ect should be irrelevant.

On using the egt sensors. It doesn't hurt to have backup data for the data. So using the egt's to verify what the plugs are telling us is a good thing.

Also I am running the MS3 box so everything is tune-able. Each cylinder can be controlled by spark and fuel individually.

Right now I am learning tuning with the MS3. I want to get as good as I can, or at least to a certain comfort level before I pull this engine for a full forged setup and make much more power. I want to learn on a stock bottom end before blowing up a high dollar piece. Popping this one would suck already, but it wouldn't hurt my pocket as bad.

 

Nothing I’m discussing is related to economy. This here’s racin… I will say in light load cruise/idle conditions it’s pretty darn hard to hurt an engine. I can cruise with little to no timing rich or lean and it’s not going to hurt a thing. I also believe I could tune a car better/faster fuel mileage wise with a wbo2 vs a single EGT.

I did say all data was good data. But the point was the EGT failure points vary engine to engine. Unless you are running the same engine down to the “T” parts and tune wise (compression, fuel, timing, AFR etc) then even with the probe in approx. the same position, you can see large differences in reported temps. Something as simple as a differently shaped head port/CC or valve size will make a big diff in the reported egt temps.

EGT is more for extreme racing engines IMO. As you almost have to melt an engine to get the most valuable data form them. Salt flat dudes are a good example. With a 7-10 second window on mild LS turbo deals the plugs and WB02 are going to give you pretty darn good data by themselves.

Might not mean anything, but I noticed many of the Engine Master guys are running a wb02 in every cylinder now to squeeze the last out of their EFI setups… not EGT’s. It’s not like they couldn’t run both... If the A/F ratio was spot on in every cylinder… wouldn’t the EGT be somewhat irrelevant?

 

i've often wondered what would be the best way to detect whether an individual cylinder issue is occurring in real time or at least after a pull. reading plugs after a run is great but who honestly wants to do that after every pull (some are easy to get to some aren't) and its not like plugs are free either.

setting pulling plugs aside for now, i'm thinking of a scenario after the majority of dialing in/tuning a combo (fuel and spark) has been done and an engine is being run hard frequently...parts fail, possibly an injector flow rate degrades, coil becomes erratic, valve springs, piston rings, combustion chamber hot spot, etc.

would be great to have a way to look at a datalog with individual cylinder egt or wideband data and just be able to see one deviate to clue you in that something is going to go wrong... while 8 data inputs cost money, compared to a full motor failure seems like it would be worth it. wonder why this hasn't caught on more outside the world above junkyard engines and below engine masters.

 

might as well add the two obvious reasons that an 8 channel wideband setup isn't used...cost and the fact that they won't live long in an fi application

so if an 8 channel egt setup would be considered cost effective for a particular application, would it be sensitive enough to pick up one of these potential problems before a failure occurs? assume that the temperature/location relation is not an issue i.e. all are placed the same distance from the exhaust port etc.

 

From my perspective its more of an issue with diagnostics after the fact. In other words- we maybe don't run an EGT (even I just use a wideband, like the majority of others would (even the OP)). However, once a problem occurs that the wideband isn't helping with anymore, this opens up options. First thing I think when I see melted metal is temperature thus the EGT pops into existence.

Tuning is what many think appears on the wideband(s). Individual wideband for example "tuned" to the safe a/f ratios... still may not give even flat EGT. Timing changes EGT, where timing per individual cylinder is never perfect and changing conditions manifests as varying EGT. What is more important, identical EGT or identical WBO2 readings? $1000's can go into this aspect in search of $0.0001's of power , whereas for us diagnostically all we need is $80 china gauge EGT just to make sure the temperature isn't ridiculous for the following experiments where a problem occurs.


I might take this approach
1x, 2x, 3x, 4x, 5x... represents power levels over OEM
1x = 1x oem power, 2x = 2x oem power etc...
Lets define 1x as 300 horsepower
so 2x = 600 horsepower, etc... 5x being (5*300 = 1500 horsepower)

So now we have an easy way to "look" at joules/minute (thermodynamics) per engine output. 1x output is 300 horsepower converted to joules/min = 13 422 597.69 joules per minute (J/min) [http://convert-to.com/conversion/pow...-per-min.html]

so lets say 13 million J/min @ 1x
take a linear approach: 26million J/min @ 2x, etc...

for around 13 million Joules/min peak power lets say the EGT (wherever it is installed) records 1300*F during a single "pass" (one blast on a dynometer) in a car, remember it only touches that spot for an instant (the engine starts off making much fewer J/m and rises to peak power)

whereas, pretend it was a reliable stock boat engine, and If we hold the engine close to there (like a boat at wide open throttle sitting on peak horsepower) EGT continues to climb past 1300*F all the way to 1550*F after 10 minutes.

So we can gather this data either way, however the vehicle is being used (car, truck, boat, i.e. actual EGT operating data from stock engine at 1x)

The a/f ratio for both the single blast, and the continuous steady state, is the same. Since the engine is stock (or was run stock @ 1x) our data tells us that this is probably "safe operating range" (because its a just a regular stock engine). Even though the EGT is meaningless, we still have the factory's intended use coupled to that number (we used a plain stock engine so whatever it does EGT wise must be "safe") So lets take these EGT numbers, call them "safe" for now, put out 10-13million J/m gives us some EGT data.


If we take all of that equipment and double the output to the 2x, what will happen to EGT? It must rise. If everything else is the same, Our meaningless arbitrary EGT number will rise, even with A/F ratio WBO2 output stays the same. Like everyone is saying, the number is useless because unless we demolish an engine at WOT and repeat the experiment to find some "lethal" EGT it doesn't really help us as much.

However, if I take my 2x engine and FORCE the EGT down to the level of the 1x engine, I have just more or less guaranteed that at least for the sake of the metal components in the engine, I am "safe as I was when it was stock". It doesn't mean the fuel isn't exploding violently due to compression ratio excess (30psi of boost at 350*F will still probably blow things apart when 87 octane is used) it just means that whatever is coming out of the combustion chamber is probably not going to warp or melt any of my engine's parts, (anymore than the 1x engine did). How do we control the EGT down to 1x from 4x or 5x? = water injection (or similar).