Acceptable EGTs?

[Avendit]

Hi All,

Quick question - what would you say 'safe' EGTs are? I cruise at around 600*C (1100*F), but quite often see 700*C (1300*F) in closed loop acceleration. WOT is fine as extra fuel is dumped in, bringing temps back down to ~600*C.

How high is too high?

Thanks in advance,
Avendit

[Gtsjeg04]

Thats a good question. I dont think many people tune by EGT anymore though.

[Avendit]

Its not really for tuning - its monitoring when I'm actually using the car. I'm still boosting quite high while in closed loop until I get time to get and fit the o2 thing from URD, and can't find any basic info about EGT temps to know if I'm doing damage or not.

It can get pretty high temps when going up a steep hill at cruise speed, or accelerating out of a corner (again just traveling, not racing), just need to know where to set my worry point.

cheers,
Avendit

[blinding-gts]

^ I would say when the pipe starts glowing red you have a problem. I used to a have a diagram of stock EGTs. I suppose you can go from there.. I'll see if I can find it and post it.

[jlitman]

Its not really for tuning - its monitoring when I'm actually using the car. I'm still boosting quite high while in closed loop until I get time to get and fit the o2 thing from URD, and can't find any basic info about EGT temps to know if I'm doing damage or not.

It can get pretty high temps when going up a steep hill at cruise speed, or accelerating out of a corner (again just traveling, not racing), just need to know where to set my worry point.

cheers,
Avendit
How much boost and under how much load? If both are relatively minimal, hovering around stoich is probably okay for short periods of time. Leaner might get scary, but in closed loop it shouldn't go lean for more than a tenth of a second, assuming everything is working properly.

The bigger question is whether you are seeing any knock, and if not, I wouldn't be overly concerned.

I highly doubt you're going to warp the head at whatever EGT's you are seeing, so the only issue that matters is knock.

Anyway, to quell both high EGTs and potential knock, one solution if you are stuck in closed loop is water injection, activated by boost.

Let me know if that URD gadget works as advertised... very curious.

I used to a have a diagram of stock EGTs.
Neat. I'd like to see that :D

[Avendit]

How much boost and under how much load? If both are relatively minimal, hovering around stoich is probably okay for short periods of time. Leaner might get scary, but in closed loop it shouldn't go lean for more than a tenth of a second, assuming everything is working properly.


2 different scenarios really. Cruising, motorway, lets imagine ~80-85mph on a theoretical private road. Sitting around 600*c on the flat boost reading ~-5psi. But as I start up a longer incline, reasonably steep boost climbs to the low negs -2 to -1, and stays there for say 5 minutes. At the end of this the EGT is reading more like 700*C. If that speed were increased to 90mph or I try to accelerate up the hill to 90(in 6th, a lower gear with more torque is different) I see EGTs heading upwards and I tend to chicken out at 750*C.

This is all at stoich as I'm in closed loop with nothing overriding it (yet)

Similarly at stoich, the other place I see problems are hard, but not WOT accelerations, eg on single carriage way interesting roads. These aren't even that fast, but moving from 40-60mph in 4th quickly but not racingly so not WOT. I can see 8PSI boost at 3500rpm with 60% throttle. EGT gets upto 750*C again


The bigger question is whether you are seeing any knock, and if not, I wouldn't be overly concerned.
I highly doubt you're going to warp the head at whatever EGT's you are seeing, so the only issue that matters is knock.

I have a knock sensor light setup, and it isn't reporting anything, but I can feel the power varying as the AFR flexes between 14:1 and 14.7:1 (just random variation and non perfect LTFT tuning I think)


Anyway, to quell both high EGTs and potential knock, one solution if you are stuck in closed loop is water injection, activated by boost.

Let me know if that URD gadget works as advertised... very curious.


I was previously tempted by the WI - wire it into the extra injector channel of the emanage blue, but it doesn't feel like the right solution. At 250bhp (crank) on a 140 I'm at my self imposed limit for power, but the rest of the system isn't really, and I see the WI as a solution to give you that last 15%. I think the right way to go is either PFC or the URD thing (or an F manage you pointed out).

I will be doing something better in the longer term, I'm just trying to work out how dangerous the current situation is to the car in the mean time, and found that I couldn't find any decent info on how I should be interpreting the EGT guague which is embedded in my dash. If its useless I should replace it with something more useful, like oil temp/pressure, if it is useful I should learn at least at what point I should become worried about what its telling me!

Mozso seems to have had some success with the URD, so will add to that thread once mine is in (TBH, knowing me it will be 3 months +, so don't hold your breath)

cheers,
Avendit

[the ronin]

Hi All,

Quick question - what would you say 'safe' EGTs are? I cruise at around 600*C (1100*F), but quite often see 700*C (1300*F) in closed loop acceleration. WOT is fine as extra fuel is dumped in, bringing temps back down to ~600*C.

How high is too high?

Thanks in advance,
Avendit This brings back old memories......cruise temps 1,200., light load 1,400, full tilt 1,600*f.........

If you're seein 600*c under full load you're pig rich and need serious tunin and losin power...

[jlitman]

2 different scenarios really. Cruising, motorway, lets imagine ~80-85mph on a theoretical private road. Sitting around 600*c on the flat boost reading ~-5psi. But as I start up a longer incline, reasonably steep boost climbs to the low negs -2 to -1, and stays there for say 5 minutes. At the end of this the EGT is reading more like 700*C. If that speed were increased to 90mph or I try to accelerate up the hill to 90(in 6th, a lower gear with more torque is different) I see EGTs heading upwards and I tend to chicken out at 750*C.

This is all at stoich as I'm in closed loop with nothing overriding it (yet)

Similarly at stoich, the other place I see problems are hard, but not WOT accelerations, eg on single carriage way interesting roads. These aren't even that fast, but moving from 40-60mph in 4th quickly but not racingly so not WOT. I can see 8PSI boost at 3500rpm with 60% throttle. EGT gets upto 750*C again



I have a knock sensor light setup, and it isn't reporting anything, but I can feel the power varying as the AFR flexes between 14:1 and 14.7:1 (just random variation and non perfect LTFT tuning I think)



I was previously tempted by the WI - wire it into the extra injector channel of the emanage blue, but it doesn't feel like the right solution. At 250bhp (crank) on a 140 I'm at my self imposed limit for power, but the rest of the system isn't really, and I see the WI as a solution to give you that last 15%. I think the right way to go is either PFC or the URD thing (or an F manage you pointed out).

I will be doing something better in the longer term, I'm just trying to work out how dangerous the current situation is to the car in the mean time, and found that I couldn't find any decent info on how I should be interpreting the EGT guague which is embedded in my dash. If its useless I should replace it with something more useful, like oil temp/pressure, if it is useful I should learn at least at what point I should become worried about what its telling me!

Mozso seems to have had some success with the URD, so will add to that thread once mine is in (TBH, knowing me it will be 3 months +, so don't hold your breath)

cheers,
Avendit
750* C is a bit high, but again, are you getting any knock?

EGT's were mainly referenced before affordable widebands were available -- as it turns out, EGT's can soar from running either too rich or too lean. Actually, poor VVT tuning will probably affect that too, as would a crappy turbo manifold, etc. etc.

Like I said, if you are stuck in closed loop, and are worried about EGT's (though I'm not 100% sure you need to be...) you have really three options:

(1) Play with your tune (e.g., advancing the timing if you can will cool off the combustion chamber, very retarded timing tends to build heat, experiment with valve overlap if you can tune that).

(2) Try WI, tuned to come on at a given boost level (ideally progressive spray -- don't get a cheap-o kit)

(3) Get out of closed loop via the URD thing, F-manage, or a stand alone :shrugs:

[mozso]

One important thing, where do you monitor your EGT?

My figures:
- pre turbo EGT, right in the middle of my exhaust manifold around 9cm away from engine
- maximum EGT I ever recorded 890 degrees C after close loop highway speeding at 150km/h for 30 minutes and then 3 minutes WOT uphill with constant 9psi boost.

Typical EGTs:
- highway cruising at 140-150km/h, close loop boost max 2psi, ~14.7-14:1 AFR: 720 degrees C
- usually after 30 minutes my EGT goes up 50 C due to heat in the cast iron exhaust manifold

- uphill climb, light-medium racing, 130-170km/h, close + open loop, max 6psi, ~13.2-12.5:1 AFR: 800 degrees C
- in this mode the URD O2 sensor calibrator already kicks in, before using it I had 850-870 EGT, thus did not really push the car in this region...

- cruising on normal road, max 110km/h, close loop, mainly vacuum or 0psi, ~ 14.7:1 AFR, 600 degrees C

- closed circuit racing, WOT everywhere it is possible, mainly 2nd and 3rd gear, many corners, 9psi boost, ~ 11-10.8 AFR: 780 degrees C max.

I have now 25k miles with F/I. No problems so far, except rattling at idle @ 630 RPM (no clues why and I cannot raise my idle, at artifical 750RPM idle or above that no noise at all).

[jlitman]

I have now 25k miles with F/I. No problems so far, except rattling at idle @ 630 RPM (no clues why and I cannot raise my idle, at artifical 750RPM idle or above that no noise at all).
Probably just that idle speed causes a harmonic that vibrates something a bit. Other than making sure everything is secure, it's probably no big deal.

What engine management? If a piggyback with factory ECU, you can also bump up the idle slightly by adjusting the throttle set screw. Just tweak it a tiny bit until the idle comes up about 100 RPM. Best measured on a datalog rathe than using tach. Also note TPS, you don't want it going up more than about 2%.

[Avendit]

He's on a Blue as well - I'm guessing an old C2 kit from the location?

I think my EGT is also pre-turbo. Thanks for posting the info - significantly re-assures me :). Guess that will be another pint! I may yet make a dash for sziget/red bull air race - if I go we should meet up!

Avendit

[mozso]

I cannot adjust the screw, I have DBW unfortunately. Emanage Blue + URD O2 calibrator. I tried to advance timing at idle (1-3 degrees), but not really helps. My injector duty cycle is 0% at warm idle maybe that's giving a bit of headache to factory ECU?

Initially it's made by C2Gas yes, but it's quite a custom as my ride is a 2006 Corolla 3ZZ-FE so lot's of custom work and trial and error.

Air Race is august 19-20. On August 20 we will have HUGE fireworks over the city, you should see it. I will be there for sure at least for the Air Race on August 20.

[jlitman]

I cannot adjust the screw, I have DBW unfortunately. Emanage Blue + URD O2 calibrator. I tried to advance timing at idle (1-3 degrees), but not really helps. My injector duty cycle is 0% at warm idle maybe that's giving a bit of headache to factory ECU?

Initially it's made by C2Gas yes, but it's quite a custom as my ride is a 2006 Corolla 3ZZ-FE so lot's of custom work and trial and error.
Hmm. I don't think the ECU likes timing adjustment at idle -- it adjusts itself quite a lot. I always got some off idle bogging if I added timing there.

If it's DBW, the only thing that comes to mind is to tweak TPS by about 2% at idle with the emanage (might need to use one of the auxiliary connections for that). That should be within the ECU's acceptable limit and should bump up idle speed a few 100 RPM.

Another trick that might work is to pull fuel at idle and let the ECU create a moderate positive long term fuel trim there (may run a bit boggy until the long term trim stabilizes), which should also bump up duty cycle and stabilize the idle. Might run a tad rich on decel tho', as the idle and decel long term fuel trim tend to be the same.

After that, you'd have to get creative... you could try drilling a very small hole in the throttle plate to allow a little more air in... I wouldn't try that unless you have a spare tho' :p:

[turbophil]

On the DBW, you can create a vacuum leak to help like Jordan said, but another way is to use a vacuum line and just plumb it back to the intake path. Vary the size of the leak using an orifice in the vaccum line until you get the idle you desire. Easy to undo and make changes that way... When you don't have control of the DBW, creativity is your friend;) 1/8" leak with the DBW otherwise shut is about 11-1200 RPM... 1/16" leak is about 900-1,000 RPM... Think of it like a fixed IAC. It actually works VERY well...

Good luck,

Phil

[mozso]

hmmm interesting ideas.

Idle timing advance doesnt work, tried today again 1-3 degrees and nothing, dial in 10 and boggy idle + missfires.

Jordan, what do you declare as moderate positive FT? 5-8%? The TPS needs more work and I'm currently on vacation so it's bit more difficult.

Phil, from where should I get vacuum to re route back to intake? I assume it should be after the turbo, and before the MAF, right?

I have many vacuum lines:
1. intake manifold->greddy pressure sensor->URD O2 calibrator (this was an extra connection previously used for manifold gas recyrculation, but disabled for turbo)
2. BOV ->Defi pressure sensor (T-tap)->wastegate (I'm not sure about this)
3. other source?

[mozso]

Toyota meet 2009 07 25
http://www.youtube.com/watch?v=I3d3IAskDRQ

My car is from 2:41 till 3:00. On track I went almost identical time with 4wd 290HP Subaru WRX. I had two runs and had to take care of my tires due to vacation. He had 4 runs and only beat me in 4th.

[turbophil]

Mozso- You want to tap a vacuum line post throttle body. I'm not as familiar with the Celica vacuum diagram, but on the Lotus (which is going to be similar, but simplified), there are 3 vacuum ports just after the TB. 1 large and 2 smaller ones. Either of those two smaller ports would be fine. I'd recommend not tapping the line that goes to the brake booster or your DEFI pressure sensor. FWIW- You should really try to have dedicated vacuum line runs to MAP sensors like your URD 02 cal, and defi pressure sensor for instance... Nevertheless, the vacuum "leak" is simply a controlled path for air to bypass the throttle body and sourced after the MAF (if you have one with your EMS). However you want to accomplish that will work just fine and probably solve your low idle issue with the DBW assembly. The primary item to play with is the size of the orifice. On the Lotus ECU, a 1/8" orifice is perfect for those cars that do not have separate DBW TB controllers to fine tune the throttle plate...

Out of town for the next week. Have fun!

Phil

[jlitman]

On the DBW, you can create a vacuum leak to help like Jordan said, but another way is to use a vacuum line and just plumb it back to the intake path.
That's a really good idea.

Yeah, try that if the tuning options I suggested don't work.

Idle timing advance doesnt work, tried today again 1-3 degrees and nothing, dial in 10 and boggy idle + missfires.
Yep, that's what I figured -- although adding 10 degrees is waaaaay too much. Anyway, even 1-3 degrees will piss off the ECU. It constantly tweaks ign timing at idle.

Jordan, what do you declare as moderate positive FT? 5-8%? The TPS needs more work and I'm currently on vacation so it's bit more difficult.
Really, anything below 10% is fine, and no worse than many cars see coming offf the assembly line. If you need to go higher, I'd try to keep it below 20%, but I don't think it will need that much correction to right itself.

The idle trim doesn't really affect anything else except the decel trim (throttle off, dashpot to idle), at least to the best of my knowledge. Over 10% LTFT there and it might skew rich on decel, but not enough to hurt anything.

It might slightly throw off the trim in surrounding cells, but you should be able to fix that if it causes any driveabiliuty quirks.

[mozso]

Well I'm still a bit confused about this vacuum stuff, can any of you guys make a diagram or give me a link when I can read about this re routing of air?

[mozso]

Some update if I engage the clutch in neutral the idle rattle is way less prominent. If I disengage the clutch then it's more audible. Why is this?

Engine load? Clutch was replaced by Exedy Stage 1 organic. My flywheel was intact and nice although not measured by any device just eye inspection. I don't really have any clutch vibration. Some slight when RPM is low, but nothing serious.

For the last 6 days I was travelling in high mountains 500-1700m altitude above see level. Car behaves like stock, not a single glitch in all performance modes.