OK so last weekend i installed a ziertronix wb system with egt and boost. when driving at 85mph in 5th gear my egt's are 15xx and when i let off the gas the drop to 600 right away. now i used my computer and got this graph. now this isnt at 85 mph but it shows just how hot my exhaust is.
mods are 2003 evo 8
br 3" tbe with tp and bullet muffler
SS o2 housing coated
stock manifold ported and polished
272 cams
mbc set at 22psi
walbro fuel pump
forge bov
arc intake
exedy twin hd clutch
road tune by Al

later tonight i went back out for another drive. i boosted to 22psi in second gear. a/f went to 10.2 and egt hit 1620!!!

 

wow that is really weird..

 

how about the 10.2 afr rich as hell

 

1500f change your reading to c makes it easier... thats roughly 825c I think u should be fine b/ that was when u were 100% throttle right?

 

yes that is with 100% throttle. that just seems way to hot. maybe i have a bad sensor? i think i need a retune car is running rich at wot

 

Usally lean will make your EGT's high? is this the first time you are logging your EGT temps...just wanting to know if its the highest you have seen and such.

anything above 1650*f yes is high...and hell on turbines and exhaust valves after long periods. Now when you get to around 1700*f+ is when your EGT's starts destroying your engine..knock might be occuring. If you can log for knock do it.

On most engines i build i try to keep the EGT's below 1600*f because we hold full throttle for a long time (+5mins)....fun seeing a engine scream that long. But they are built for Aircraft...but the concept is the same.

 

my egt's sometimes in 4th and 5th gear at wot hits 1600 to 1700 deg's and my wide band is arounf 11.4 to 10.9 11.0 at redline

 

don't go over 900celsius which is 1655F. couple of things will fluctuate the EGT is timing. base on that log your AFR is all over the place. if you can do the 3rd pull from about 2600rpm to about 7400rpm. sent me the log. i will look over. also if your AFR is straight, screw what the EGT say. base on your log everything is fine you're safe. but the AFR need a lot of work. it's all over the place.

 

Oh sorry forgot to mention.....

if they get too high just drop the boost a bit

Common things to ck are:
-Plug heat range and gap..lower heat range plug helps a bit.
-Fuel Quality plays a big part also..having Gas that is actully the right octane rating
-Agressive tune...depends on the tuner but running to the engine to the edge just for good HP#'s will shorten life span.

....im sure others will chime in to insert other things that i forgot to mention but im sure you get the point...just drop the boost a bit if it gets any higher. Air density might have been a big factor btw in the difference in the daytime pull VS the night one.

I myself was looking into getting the PLX devices R-500 or the Zeitronics ZT-2.

Cheers

 

Actually .. you forgot to mention where you placed the EGT .. is it before or after the turbo .. that will have an impact on the readings and what it means ..

If your probe is located at the exhaust manifold .. the numbers actually reference a nice tune ..

If your probe is after the turbo, either at the elbow or the downpipe (bad position) .. a rough compensation of approx 100C as the turbo does its job puts you way overheated ..

 

1550 is the highest I ever want to see on a piston engine. Above that is way too hot to me. 1650 is the max I'd like to see in a rotary.

 

jeff, so the EGT's at idle are back down to normal now? when we first started it up, idle EGTs were showing 1100+ deg F with normal idle AFR of 14.7:1.

after seeing the idle temps i was certain the probe itself was the problem because the car was idling normal and idle temps are not that high.

but if you are idling at 600 now, then it shows the probe is doing what it needs to be doing. i would suspect the tune is causing the rather hot EGT, but it is a very rich tune which would make one think otherwise...

 

Also excessivley rich will cause egt to be high, the unburnt fuel will combust in the manifold instead of the chamber where it is supposed to.

 

egt probe is in the exhast manifold on the far right tube on the passanger side. yes the egt's are still very high on start up. they only do below 950 deg when i get off the gas and i use the motor to slow the car. i will go do a few logs tonight of 3rd gear pulls and show you guys. i need to lean the car out i think becuase as soon as i floor it i go rich

 

jeff, can you check and see what the EGT shows when the car is on but not running. prefferably before you start it in the morning.


i want to see what the EGT reads when it is cold. it should read near ambient...