EGT's
 

Surely there must be a few guys monitoring this now ? either on n/a, Supercharged ( same as n/a ) or turbo motors.


If so, anyone care to share their temps ? and what might be deemed safe, or unsafe ??


I only ask, as Ive been logging cylinder 5 over recent weeks, probe about 4-5" down the header tube from the cylinder head flange.

At the end of a run, temperatures appear to be in and around 800degC/1500degF

AFR's usually mid 11's, give or take.

i used to, and saw them deep in the 1600's, but afr's were good, no engine harm, so i quit looking at them, just look at afr's and read plugs-your timing can affect the egt's some i think

Further question. How fast is the response of a typical 1/16" probe ?

Fast enough to be reliable ? What sort of lag time is there ( from my own logs, going from WOT, to closed throttle, I would think they are pretty quick. Not sure if I'd like to quantify it though )

Do a search for CJ peddy's sn/ He posts as GueSS Who

I know in tennesse for the LSX shootout, i believe he was seeing 1100 to 1200 in temps for the EGTS.

Fahrenheit or Celsius ? If degC, thats incredibly hot. If DegF, its incredibly cold, depending on sensor location too.

I was doing it just to check cylinder to cylinder variation, 1400-1500*F Is where I was usually at with the probe about 2" from the port. Response was fairly quick it seemed, but since I wasnt using it for tuning all I was concerned about was having one line on top of the other in the logs.

Did you log all 8 at once ?

Only four at once, was mainly looking for the supposed #7 and 8 leanout with an LS6 intake.

On the same subject....

What causes EGT to change ?

I run normal pump fuel when on the road. When racing, I inject water/meth ( but will be moving towards straight meth again I think )

Should this cause any change in EGT ? ( I havent really noticed any myself )

What temperature would be considered dangerous ?

At present, above 1500degF, I have my ecu set to increase fuelling automatically. At 1650degF, I have it set to increase fuelling by 8% ( linear percentage increase between 1500-1650degF, and 8% is nothing more than a figure plucked from thin air ) based on the input seen by probe in header tube 5.

Purely as a safety measure.

If I had enough logging channels, and some patience, I'd do all 8....At present, Id have to use a separate logger to do it though, which would make it awkward for boost/rpm etc.

Honestly I dont pay much attention to the actual EGT, back in the old turbo buick days before widebands were available all you had was EGT and I could have told you more of the nuances of EGT tuning 20 years ago. I remember water alone would drop EGTs but meth didnt make much of a difference, as far as whats safe or not I cant say, IMO wideband is a better indication of whats going on.

Unfortunately 8 widebands could get a little pricey so for individual cylinder you are stuck with EGTs. Sorry I cant be more help, I can see if I can find the logs and software on a CD and take some screenshots but I'm pretty sure that was all on my old laptop that is long gone. I'm not real good at backing up car related stuff and I sold off the EGT box long ago.

No worries....

8 widebands is OTT, and I dont have any ability to trim individual cylinders. So Im better off not knowing that information. And welding 8 bungs for sensors into the headers would be a PITA too....

Still only logging wideband on the left hand bank......must sort out one for the other side too, just for curiosity's sake.

back in the day i had two sensors wired to a switch and would flip between them

based on past experience i should get an aluminum sensor put in my headers to know when things are too hot ;)

having a port on each tube helped me isolate and fix a potential problem.
since I only use pump gas, there is less margain for error.

mine are usually 1450-1500. it will go higher if the A/F gets richer than 11:1 or so. it seems like the sweet spot for my engine is 12:1.
I tune it to 11.5 past 10psi to be safe.

again to be on the safe side, I start with low timing, keep the A/F a tad rich, and start adding timing till the EGT comes down to an acceptable level.
the plugs are the only way to go from there. then the gauges are just a reference.

I personally believe EGTs are damn near useless without a comprehensive understanding of plug readings. They can go high because of being rich OR lean. I do, however see them as a great alternative to multiple widebands for individual cylinder tuning. Unfortunately on gas engines, timing plays such a role in EGT as to dramatically skew their frame of reference to AFR.