From what I read 1500+ EG temps are pretty normal highway cruising. At 60 going uphill mine slowly creep up past 1500 but I back off before it gets too high. I'd imagine it would top off or lower after a I gain momentum, but I still feel insecure with this new motor. 8.8:1's and Eagle rods. When I give it throttle and the turbo spools, the EGT's climb quickly so I don't let it go too far before letting off. My question is... Is it safe to run at 1500+ while cruising and should I be backing off? Are rapidly rising EGT's while boosting common? Would I notice detonation? Would I be safe to let the EGTs rise until they either top off or lower, or should I ask how long can the engine withstand those temperatures and to which temperature should I be backing off? Any info would be apreciated. BTW 120 mile trip to ocean city maryland tommorow. I have 100 miles on the new motor and I will be doing an oil change before we leave.

whoa dude. cruising at 80-85 my egts are 1400

Originally posted by soulcontroller
whoa dude. cruising at 80-85 my egts are 1400

Yep same here. I just got back from a long road trip right after installing my turbo and at 80mph running at 3,000rpm my egt's are no higher than 1400 degrees.

What size exhaust are you running?


best time so far 14.3 @ 101.1mph(no traction)
www.cnnmotorsports.com

im not turbo so i dont have a lot of experience in this area, but doesnt high EGT's mean you are running lean? Cant you just adjust your FPR to run a little richer?


Im still learning here so if im wrong please correct me.

I run about 1300 at 80mph but my egt probe is tapped where all 4 pipes joing not right outside #4. So 1400 sounds right if you have it probed right outside #4.

ya, 1500 is like crazy.

Sorry, I didnt mean crusing, but lightly accelerating to get up to 60-70mph the egts would slowly rise up to 1500+. Does this make things any better? I'm running SFMU with 2.72 disc, and I think the longer spring with 19psi idle pressure on 335ccm injectors. Fuel should be near correct. I no longer have a datalogger because someone stole my laptop, but I havent chagned the fuel system and prior to this rebuild I had good fuel trims between -5 and +5.

BTW: 2.25" downpipe to 2.5" cat back. I don't think this would make a difference in egt tho. Also the probe is in the middle where all 4 runners collect to the turbo.

got mine tapped on the top corner of cyl#4 and at light accel 60-70 it gets to about 1450 but at normal cruise at 75mph its 1350deg. my probe is also kinda close to the cyl head.

I'd imagine temps would be slightly higher in the runners as compaired to the collector area, but not much. I'm not taking the eclipse on vacation this weekend unfortunately. Part of my shock broke and busted up into my hood, left me with a decent size dent in the hood, but it should be repairable. I've been hit by a freight train carrying bad luck this week. First my subs/amp/laptop were stolen and now this. At least the motor is running strong. I'm redoing the entire front suspension. The new motor + new suspension/steering(tie rods, control arms, etc) should get me on track to getting this car into tip top shape and show worthy. After I get a new downpipe(+cat removed) made and the new suspension parts on, I can start working on the body repairs. I am curious if anyones EGT's ever hit 1500+ though. I've read quite a few past posts of people saying that 1500+ temps under light acceleration is not uncommon, but from what you guys have said in this thread I don't understand. Many of the posts say that even N/A cars commonly reach 1500+ EGTemps.

On a hard 4th gear pull going over 100 my old motor's egt's would hit 1600* then again that is probably why my Je pistons melted.

best time so far 14.3 @ 101.1mph(no traction)
www.cnnmotorsports.com

While cruising at 80 I'd be at about 1350. While lightly accelerating...I'd see around 1400~1450.

Good fucking god. EGT is useless.

If you are running lean, it will be hot. If you lean it out a bit, it will cool down. Why? Because there won't be enough fuel to burn to get hot. Your engine will still knock and self-destruct, though.

If you are running rich, it will be cool. If you richen it up a bit, it will warm up even more. Why? Because you will be burning fuel well after the turbo. Is that fun?

That isn't the worst of it, though. If your engine hears knock, it will reduce timing advance (<cough> Also known as "retarding timing," if your a fuckass). What happens when you reduce timing advance? The EGTs go up. You could be running richer than do you want to be, and lean it out a bit more. BOOM! :D

EGTs are most strongly affected by timing. Timing has vastly more influence on an engine than does AFR. Think of it this way; a combustion chamber, during ignition, is at 2500* or so, with some (not much) variance due to compression ratio, fuel temp, intake air temp, and AFR. What happens between the spark plug firing and that cylinder's contents passing by the EGT probe determine the lion's share of what the temperature is going to look like. Ignition timing determines how much time the combustion chamber gets to dissipate heat before it hits the exhaust. Therefore, more advance will cool the exhaust temperatures.

What I would do would be to tune the AFR with a wideband, and then add timing until it starts getting pulled.

Trusting your tuning to an EGT gauge is akin to trusting your tuning to a narrowband O2 sensor. Who does that?

LASTLY, engine internals do not melt at 1600*F. Pistons would melt a lot earlier, but they use the rings (and the cylinder wall), oil being splashed up, and the connecting rod/bearing/crank to dissipate heat.

I think EGT's are a pretty good way to keep an eye on your cars status...lot better than trusting some blinky-light AF gauge. i have the EGT, along with a digital AF gauge....if im lightly accelerating up a hill, my EGT's will reach 1500 or so...then, i can watch the AF meter stick to something around .93 or so, then watch the EGT's fall to 1350 or so. You arent gonna hurt your engine by cruising/accelerating out of boost....unless the engine wasnt built right to begin with, in which case, no matter of pussy-footing it will keep it together anyways... :) like the guy above stated, if you REALLY wanna monitor your engine, and youre that worried about it...get a wideband. but if the engine is built right, and your fuel system isnt all outta wack, you arent gonna hurt the thing just cruising.


1997 Silver RS
Built
T3/T4 BB Turbo
20psi
Most current 1/8th mile time: 8.1@93mph 2.015 60'
1996 Black Supra TT
2004 Silver Snake

I would be willing to bet that your EGT change from 1500* to 1350* are more of a result of a decrease in timing advance than would it be to be an AFR change.

Sure, the blinky gauge is horrible. It will change voltage based on O2 content in the exhaust, the exhaust temperature, and if you look at it funny (try it sometime). I wouldn't trust an expensive motor to EGT readings. It just isn't the best way to keep your engine safe.

I went for another ride today, and I believe for some reason I was reading 1400+ as 1500+. I guess I smoked a few too many hits. Anyway... todays cruise my egts were between 1300-1475 regular cruising. The only time they went over 1500 was up hills, and they would get up near 1600 very slowly on large hills under acceleration. I don't know how safe it would be to continue at that throttle posistion so I let off and let the egt drop back down. That is not boosting. I can hear the turbo spooling but not giving enough accel to boost, and as you said... in vac it shouldn't be a threat, but I'd like some confirmation on this. As you said Ducking_Fumbass, egt's could be effect by other things other than a/f conditions, but are they directly related to the heat the cylinders are taking and the possibilty of melting or breaking something? And BTW, the engine now has 150miles on it. I haven't given it 100% throttle yet and I haven't really driven it any harder than normal driving. I fixed the strut today, and after reading a post in the handling section about steering wheel shudder, I decided to clean the surfaces between the rotors and hub, and the wheel to rotor surfaces, and the major shuddering I was experiencing is now very minor. WOOHOO. Can't wait to up the boost and go WOT. And also the guy from ground control is sending me replacement parts for the damaged stuff for free.

I think those injectors might be a little small for the disk you're running, I use that disk with 446cc injectors. try the largest disk maybe.

my egts have never been above 1450 @ WOT.
i dont understand why your egt's are soo high going up hills. mine are like 1350 going up hills.

That's not at WOT, that is at about 10-15% throttle.