[iqraceworks]

I've had my 05' F250 for around 8 years, and I've been running the same IDP towing tune for that last 5 years. According to IDP, with their 75hp+ towing tune there should be no limits on the amount of weight I can tow (like some of their higher HP performace tunes). My camper that I've had for years weights in at around 6Klbs...fully loaded. The truck makes awesome power, and I've never had any problems towing my camper.

That being said....I recently installed an EGT gauge to monitor my EGT temps. I put the sensor in the passenger side exhaust manifold.

So, the first day driving my truck with the new EGT gauge...I'm getting around 350f at idle, 8-900f at cruise on the highway, but if I hold wide open throttle for a long time (getting up to 90+mph), I'm able to hit 1300f and it's still climbing pretty fast so I let out of it. Is that normal?? I'm sure if I held my foot down it would hit 1400+ if I let it.

I'm stock turbo, and stock injectors.......I wouldn't think the EGT's would get that high. When I'm towing the camper, according to my TorquePRO app, I never usually use over 70% thorottle...so maybe that's why I haven't had any issues?

Just trying to make sense out of the high EGT readings. The turbo has been cleaned recently, the EBP sensor and tube and new...the truck truck runs great. Would a bad/sticky injector cause those high EGT's?

Any info would be helpful. Thanks!!

 

[John in OkieLand]

at 1200*F, the pistons are almost ready to melt down.
I never exceed 1150*F

I would think you have been lucky at staying at 70% power.

 

[bugman]

There is no problem running at 1200 degrees. Even with the melting point of aluminum what our pistons are made of at 1250 or so, the melting point is raised just because of the influx of cool air and piston cooling jets that shoot motor oil at the bottom of the pistons.

You also have to remember that a piston is not at that constant temperature, your reading is on the exhaust side of 4 other pistons.

 

[bobofthenorth]

1200+ is bad news. You bought the gauge for a reason. Trust it. All the smart fellers here telling you its no problem will be long gone when it comes time to replace a collapsed piston.

 

[iqraceworks]

So I guess my next question is....why would a 75hp towing tune have such high EGT's? I'm hitting 27psi booth, I'm running stock injectors, stock turbo, and a 4" straight pipe exhaust...no cat.

 

[bobofthenorth]

You're way above my pay grade now but my WAG would be either too much fuel or restricted exhaust. I've seen melted pistons on a 466 that we pushed way too much fuel through. They're ugly.

 

[bugman]

1200 degrees is fine for pre turbo temperatures.

Those that don't believe me need to do some research on the subject. And while aluminum melts at a slightly higher temperature, that temperature is a constant temperature and not like it is in a vehicles combustion chamber. Now 1300+ should not be maintained for very long but the conscientious is for a very short time it is fine, just don't hold it there.

As for why with a 75 hp tune is quite simple. More fuel equals more temperatures. Most tuners try and keep their tunes in the safe level but there are those who could care less. This is why one of the first mods a person should do when thinking about a tune is a set of gauges. Exhaust and transmission temperature ones are a must have along with the knowledge of what is too hot and what you can do to keep them withing limits.

 

[JGK]

None of these pickup engines are “continuous duty rated” installations... with maybe a circa 200 hp 7.3 being close. Strap any of them on a dyno, put your foot to the floor, and virtually every one will self destruct in less time than you’d likely think.

As a general rule, more horsepower means more temperature. Also, as a general rule, exceeding 1/2 hp per cubic inch usually begins to push the limits of a continuous duty industrial diesel engine. (yes, I know that modern technology has increased the envelope, but the 6.0 is not that engine.). Not trying to badmouth the 6.0, and I am certain that lots of users are able to get substantially more than 200 continuous horsepower out of the 6.0 without harm, but these are usually guys that monitor carefully and know what they can get and how hard they can push it.

that extra horsepower is for passing, hillclimbing, and fun… But it doesn’t mean you can use it all the time without harm. Wisdom is key.

 

[Stanleyp]

Read your replies and questions, let me have a new understanding

 

[Bob7.3]

So guys, this thread is a good opportunity to check my real-world EGT acumen. Please help me out as needed.

• Higher EGTs are caused by unburned fuel going out the exhaust valve;
  Fuel finishes burning in the exhaust manifold or up pipe, not in the cylinder.
  
  
• With same air intake, after fuel ignites, the degree to which combustion can be completed is dependent on two variables:
  • Amount of fuel present, which is dependent on TPS ("how much foot in it")
  • Time in cylinder, which is directly proportional to engine rpm
    
    
• So under the same load conditions, EGTs will increase with engine speeds.
  Higher engine speeds accompany higher vehicle speeds (lockup or high gear) so it's impossible to go faster without higher EGTs.
  
  
• At constant engine speeds, EGTs will rise under increasing loads.
  A worthy side note is that at more reasonable engine speeds, say 2000 rpm or less, EGTs will rise proportionally less than at higher ("less reasonable" haha) engine speeds.

 

[JGK]

Bob,

I would not agree with all of your statements. In a properly functioning engine without slobbering injectors, you will get higher EGT‘s from what is occurring within the cylinders as the load increases.

Doing the same amount of work at a higher RPM will usually result in lower EGT‘s than doing that amount of work in a higher gear and lower RPM. This is because as the RPM builds, less work must be done per each power stroke because there are more of them , and with that higher rpm typically higher boost is achieved scouring the gases and introducing more cool air into the cylinders. I can see my EGT‘s go up when I’m in that in between speed and shift to a higher gear and drop my RPMs.

 

[JGK]

And just another add… EGTs that are too high can melt pistons. When this happens, it certainly is not from fuel being burned in the exhaust manifold or up pipes. It is from what is occurring in the cylinders. The entire purpose of the EGT gauge is to tell you what’s happening inside your cylinders.

 

[klhansen]

Doing the same amount of work at a higher RPM will usually result in lower EGT‘s than doing that amount of work in a higher gear and lower RPM.

Exactly. Go load up your truck and and run up a hill at a constant speed in top gear. Then make the same run at the same speed, but one gear lower. Your EGT's will be higher on the first run than the second.

 

[69mach1377]

I concur with bugman. I used to run up to 1250 no problem, at 1300 I would get nervous after a few seconds, so that was my limit. Preturbo of course.

 

[Bob7.3]

Thanks, guys.

Pretty sure we're on the same page with the first part;

...In a properly functioning engine...you will get higher EGT‘s from what is occurring within the cylinders as the load increases...

Same as "At constant engine speeds, EGTs will rise under increasing loads."


But the second part I found eye-opening. Where I wrote "(U)nder the same load conditions, EGTs will increase with engine speeds," the opposite appears to be true;

...Doing the same amount of work at a higher RPM will usually result in lower EGT‘s than doing that amount of work in a higher gear and lower RPM...

and

Exactly. Go load up your truck and and run up a hill at a constant speed in top gear. Then make the same run at the same speed, but one gear lower. Your EGT's will be higher on the first run than the second.

and

I concur with bugman. I used to run up to 1250 no problem, at 1300 I would get nervous after a few seconds, so that was my limit. Preturbo of course.

So the general conclusion is that loading has more of an impact than engine speed on EGTs. Or, "Under the same load conditions, EGTs will decrease with engine speeds.'

That is just counterintuitive and I will lose sleep over this lol. (At least some bonus material for OP.)

 

[klhansen]

So the general conclusion is that loading has more of an impact than engine speed on EGTs. Or, "Under the same load conditions, EGTs will decrease with engine speeds.'

While the total load on the truck might be the same (payload, grade, and speed), the load on the engine is lower, because of the gearing.

 

[Bob7.3]

While the total load on the truck might be the same (payload, grade, and speed), the load on the engine is lower, because of the gearing.

No doubt your and the others' observations are correct. But the analysis shows that:

1. All energy going into the system comes from fuel. (Like with a bullet; the only energy source is the propellant.)
2. Under comparison conditions, the overall fuel consumption must therefore be the same.
3. So proportionally less fuel is injected on each stroke at higher engine speeds.
4. With power delivery equal in either case, the shorter duration power stroke would be expected to yield more uncombusted fuel.
5. The marginally higher cooling due to faster coolant pump speed would be expected to have negligible effect on EGTs.

Hmm...the quantity of fuel in the cylinder also impacts the amount exiting unburned (boosting EGTs); more fuel >> more unburned. So it must be that observation 4. needs clarifying:

​

Concerning higher EGTs, while the shorter duration power stroke at higher engine speeds does provide less time for combustion to complete, in-cylinder fuel-quantity-per-stroke has a proportionally higher negative effect on combustion completion. So even at higher engine speeds, there's ample time for smaller amounts of fuel-per-stroke to finish combusting.​

This is making sense now. Getting an education here, thanks.

 

[klhansen]

The fuel quantity may be the same (your observation that the energy comes from the fuel is correct), but there's more air running thru the cylinders that provides a cooling effect at higher RPMs.

 

[shoguy89]

Diesel engines are different than gas engines. A gas engine routinely runs with 1500-1600* EGT. On a light cruise, the air fuel ratio can be 15:1. As you put more fuel in, the EGTs go down. The leaner the mixture the hotter the EGTs. A diesel is backwards. It'll run anywhere from 8:1 to 80:1. It simply burns what you put into it. In a diesel, as you add fuel, the EGTs go up. These are electronic control, so as you add fuel, you MUST increase the timing. To add fuel we hold the injector open longer. This moves the Off Point. The entire injection and combustion cycle must happen before TDC. If the fuel is burning after TDC and on the way down, it simply makes heat and smoke. Timing is super critical in a diesel. Timing is power. In a gas engine, tuning is pretty straight forward. Get the air fuel ratio correct and throw as much timing at it as it will take. In a diesel, timing is also power. You've got to get the fuel in it as quickly as possible. When you're doing it right and hit the throttle from a stop, there should be a truck sized puff of black smoke, that should turn into a solid column of grey. If you can't see thru the grey, it needs more timing. With respect to EGT, when you shove a bunch of fuel, the temps go up. When you increase the timing, the temps go down. So for example, when you add 100hp worth of fuel, you've gotta add some timing. How much depends on your combination, but as an example, stock, stock, stock, on a full pull from zero to 90mph, the EGTs might top out at 1200*. If you just add 100hp of fuel, it smokes like hell and the EGTs go to 1500*. As you add timing, those temps come down while the power goes up. Once you're done, the engine might want 6-10* of timing and you're back down to 1250* and grey smoke on the pull.

The real question from OP is about how much EGT this engine can take. The turbo has to handle all that heat. At 1250* the tips of the turbine blades start to glow. If they get too hot, they straighten out and bad things happen, BUT, it'll live all day at 1300*. Another thing to cover. Where you measure the temps make a difference too. TIT is Turbine Inlet Temp and TOT is Turbine Outlet Temp. The turbo USES heat and pressure to do it's job. That means that what's going into the turbo is hotter and under a lot more pressure than what's coming out. The delta from TIT to TOT is how hard the turbo is loaded. At idle with no load, there might be a 50* delta, but on a hard pull, there can be 300-350* delta. So when measuring EGT after the turbo, you might see 1000* but 1300* inlet temps.