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EGT temp??

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Vgt on 5.9's

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I was researching "safe egt temp" last night. Just wanted to ask the question again. The 325 engine can run at 1450 for 30 minutes safely, in one post. I also read a post about a bombed 3rd gen that was running 1750 with no apparent problems. This seems hot but at what point do you need to worry. I can hit 1500 pretty easy and back off at that point, not WOT. sw 4 TNT rp2 timing2 tq3
 
the 325 can run 1500* continuous but i would never exceed 1600* and only for short durations then. we modify our engines to run at lower egt than stock. ours never get above 1250*. your truck is set up to play with and for short burst of power. if you tow with it you will have to drive it by the pyrometer. changing your camshaft to a pdr cam will help some and see if you can find the equelivent sr. setting as the default economy setting as the jr. your nozzles are 40 hp to big for good results towing. i can not stand automatics but i think by changing to the economy setting it will help with the low end torque and keep the egt down
 
I have been thinking about a cam swap, seems like a good upgrade. I do tow but I go back to stock. I'll be bringing a 35ft sail boat from SF down to San Diego over the grape vine. Towing the 25ft box support trailer goes just fine except for the tow/haul mode. The engine will pull in OD but gets hot pretty quick. If I force a downshift she cools down but then I am flying into the rear bumper in front of me. Then I lift then she up shifts and gets hot, repeat cycle. The BD OD lock out is next on the list. So 1500 is safe?
 
No kidding? The 325 can run 1500 with no probs? If this is true, then my worries are over. I panic every time my pyro gets to 1400. I back out of the throtle, slow down, and catch back up on the downhill side of the hill.



Why/how does the 325 horse 5. 9 live under such temps? I was always told that "aluminum melts at 1300, so you'll melt your pistons at temps beyond 1300. "



Please explain. If this is true, it's great news to me. I can roll up up the hills without worrying, and use all that power left in my right foot.
 
Why/how does the 325 horse 5. 9 live under such temps? I was always told that "aluminum melts at 1300, so you'll melt your pistons at temps beyond 1300. "



Exhaust gas temps are just the residual heat that hasn't been used. Cylinder temps can exceed 4000 degrees under a hard pull, in the combustion stream. However, the cooling system will draw a lot of heat off as will the oil cooling on the pistons.



The aluminum alloy actually melts a bit higher than 1300 but that is from direct heat source on the unit with no heat removal.
 
OK, then I'm not going to drop 5K on a set of towing twins, if I can live with 1400 degrees on a long uphill pull with no adverse effects to the engine. I've been fretting over my high temps for a while now... Hammer down!
 
OK, then I'm not going to drop 5K on a set of towing twins, if I can live with 1400 degrees on a long uphill pull with no adverse effects to the engine. I've been fretting over my high temps for a while now... Hammer down!



Before you get too comfortable, these engines will run 1500 on STOCK tunes and Cummins will tell you they will be fine.



However, do not assume 1500 degrees on a stock tune is the same as 1500 on a Smarty tune. You will shoot yourself in the foot quickly with that assumption. Even 1400 degrees is not recommended if you are running power tunes, 1200-1250 is all you want to see if your running timing or anything more than SW3.
 
I presume when you ask about EGT, the concern is not melting a piston or harming the engine. As a result, high EGT is not the real concern; rather, it is heat soak of the pistons/head/valves/etc. An engine running stock retarded timing may be fine at 1500° F for hours on end, whereas an engine running advanced timing, increased duration, and higher rail pressure may melt a piston or drop a valve running at 1350° for a short time.

In cylinder temperatures are much higher than the melting point of aluminum. The piston oil squirters combined with low in-cylinder residence time of the exhaust gas allow for 1500° + temperatures to be run for extended periods of time on stock trucks.

This all changes on modified trucks. As you advance timing, much more heat is being absorbed into the piston. If you have an oil temperature gauge, you can see this effect.

--Eric
 
I understand that advancing timing, fueling, and thus increasing cylinder pressures can change the entire dynamic of EGTs. One thing I don't understand is all the discussion about 1500 degrees "for long periods of time" in a stock truck. Stock trucks never see these temps. The fueling/timing parameters just won't get you there, or at least that's my experience. I've never been able to to 1350 in the hardest of pulls, loaded at nearly 30,000 gross. I think 1500 degrees in a stock truck is a bit of a red herring.
 
Stock trucks never see these temps. The fueling/timing parameters just won't get you there, or at least that's my experience.



Oh, they will. Run it out the back door with a load on a grade and you will see just how high the stock tune will push the temps. At 3000 rpms with 10k on a 6% grade mine was bumping 1500 easily.



Once I fixed the crappy OE converter and added a little power 1200-1250 is about the max I see now.
 
I routinely pull a 12k pound 5th wheel in the mountains of southern Colorado (elevations up to 10,000'). I constantly watch my pyro to keep it below 1350 or so. If I don't, I can easily get to 1500. Stock except for the CAI, missing cat, and free-flow muffler.
 
Like its been said, dont use stock safe EGT's for anyting with timing, especially the Smarty timing.

On my truck with the Smarty Jr on TM2 I like 1300* to be my max cont and bursts to 1350* are okay for short periods. Since the cam install I have only gone above 1250* on one trip, and I was working the truck (70 mph, towing 2 trailers, GCWR 16. 5K, and pulling passing in 6th from 5-7K feet and 90-100% load). . It would hold 1250* or lower with the throttle at 90% or lower, but started creeping towards 1300-1350* at 95-100% throttle as I crept up to 7K feet.

I am working on a turbo upgrade that will hopefully keep my EGT's much cooler all the time. But like I said, I have only had to back down twice in the entire time I have towed with the Jr, and most the time I don't hit 1200* since the cam install.
 
I understand that advancing timing, fueling, and thus increasing cylinder pressures can change the entire dynamic of EGTs. One thing I don't understand is all the discussion about 1500 degrees "for long periods of time" in a stock truck. Stock trucks never see these temps. The fueling/timing parameters just won't get you there, or at least that's my experience. I've never been able to to 1350 in the hardest of pulls, loaded at nearly 30,000 gross. I think 1500 degrees in a stock truck is a bit of a red herring.



I easily reach 1400 degrees with my setup and it's completly stock fueling--no mods. I think it would go to 1500 or more if I didn't back off.

Jim
 
What if you have The Edge Mileage Max? What temperature is safe with it? I watch my temps all the time also and back off continuously when pulling a hill. I am pulling a 14 thousand pound 5er and the EGT can get up there easily.



Brian
 
The Mileage Max is a rail pressure box, which adds more fuel thru raising the pressure. I would try to limit your time above 1350* if the rest of the motor is stock.

Do you know if the MM boost fools?
 
What if you have The Edge Mileage Max? What temperature is safe with it? I watch my temps all the time also and back off continuously when pulling a hill. I am pulling a 14 thousand pound 5er and the EGT can get up there easily.



Brian



That one you had BETTER be careful with that one. IIRC its adding timing so what you are seeing for EGT's is not comparable to a stock tune. With added timing you are taking a big chance going over 1200-1300 for any length of time and 1500 for anymore than 30 seconds will be dangerous.
 
The rest of the motor is stock. I am not sure what you mean by boost fools? Maybe I should unplug the mileage max when I am towing and plug back in when I am not? It is real easy to get 1200 to 1300 EGT now. Usually I just gear down and be steady on the go pedal to keep the temps down. It is almost impossible to drive in 6th gear and keeping temps down they can reach 1500 if I don't pay attention.



Brian
 
That one you had BETTER be careful with that one. IIRC its adding timing so what you are seeing for EGT's is not comparable to a stock tune. With added timing you are taking a big chance going over 1200-1300 for any length of time and 1500 for anymore than 30 seconds will be dangerous.

Other than sooner ignition from better atomized fuel, how would it add timing?

Now there are several companies calling their mileage boxes timing/duration boxes due to the injector damaging stigma with pressure... But you can only adjust pressure if all you do is plug into the MAP and Rail PSI sensor...

But yes, stock max limits should be slightly lowered with pressure due to the nature of pressure igniting sooner.
 
Other than sooner ignition from better atomized fuel, how would it add timing?



Don't know for sure but assuming its does what it needs to adjust timing. This an excerpt from the Edge site and the description. It says it does timing, if it does then throw out the normal numbers around stock tunes. Thats the point I was making.



Developed and tested using innovative engineering techniques, the Mileage Max takes the bite out of rising fuel prices by optimizing the timing and pressure of fuel delivery, which has consistently been proven to improve not only fuel economy, but also horsepower.
 
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