egt temperature question

[SPR1NK]

I put a pyrometer on my 6.9 earlier this week and I'm hoping to put my turbo on this weekend, but I was wondering what appropriate egt temperatures are for a N/A 6.9
I've been seeing 700-800* on acceleration and 550-650* cruising at 60-65mph in 5th gear with zf5
Is this normal temperatures for this engine? Or is there something I should be checking into to find out why it's so hot before I turbo it?

 

[IDIoit]

the only thing thats going to make it hot is turning your fuel pressure up.
youll get a bit hotter when your turbo goes on.
stay under 1200*
if you get close, mount an innercooler.

 

[SPR1NK]

So where she running right now should be fine then?

 

[IDIoit]

You're good

 

[PwrSmoke]

My advice is as follows:

Maximum Short Term: 1100F (short term means 5 minutes or less)
Maximum Sustained: 900F (a long, hard pull up the mountain)

Your numbers seem typical and nominal to me.

 

[IDIoit]

My advice is as follows:

Maximum Short Term: 1100F (short term means 5 minutes or less)
Maximum Sustained: 900F (a long, hard pull up the mountain)

Your numbers seem typical and nominal to me.

for N/A or turbo or both?

 

[PwrSmoke]

Both. Melted pistons are melted pistons. While the upper numbers I listed are more or less generic, in terms of the structural limits of the engine, how they are achieved would be different. I imagine you'd have to be radically overfueled and smoking like a locomotive in an NA engine to sustain those high numbers but they are just about right for a turbo truck with the fuel setting near the optimal spot. I could see a NA truck with a max load going up Eisenhower on a summer day might hit 1000F at times but in a short term run, that much EGT would indicate an overfill situation based on what I know.

I admit my experience with NA 6.9/7.3L is limited (since I only drove mine that way for a short time in '87). I did drive my 6.2L GM (a pretty similar engine really and a useful comparison) for a couple of years as an NA with a pyro in the right manifold. 800-900 is about as hot as that truck would get (or I would let it get) and that was just below the point where it was rolling excessive coal.

FWIW, the numbers I listed are generally those I adhere to on my turbo truck and they are based more or less on what I perceive as the structural limits (which apply turbocharged or not) ... with a little safety factor.

 

[icanfixall]

Some of whats posted above is correct but some is not close. As for turning up the fuel pressure.. Nope... We don't turn up the fuel pressure when we turn up the fuel delivery volume. The pressure stays the same. But the reat is spot on. Turning up the fuel and turning up the fuel pressure is like timing a dimes width or a dimes thickness. We sometimes say the wrong thing but mean the same thing. This is something I deal with on a daily basis. Wifey will point to the right and tell me to turn left. What I found works great is to drive straight forwards and come back later.....

 

[fsmyth]

Both. Melted pistons are melted pistons. While the upper numbers I listed are more or less generic, in terms of the structural limits of the engine, how they are achieved would be different. I imagine you'd have to be radically overfueled and smoking like a locomotive in an NA engine to sustain those high numbers but they are just about right for a turbo truck with the fuel setting near the optimal spot. I could see a NA truck with a max load going up Eisenhower on a summer day might hit 1000F at times but in a short term run, that much EGT would indicate an overfill situation based on what I know.

I admit my experience with NA 6.9/7.3L is limited (since I only drove mine that way for a short time in '87). I did drive my 6.2L GM (a pretty similar engine really and a useful comparison) for a couple of years as an NA with a pyro in the right manifold. 800-900 is about as hot as that truck would get (or I would let it get) and that was just below the point where it was rolling excessive coal.

FWIW, the numbers I listed are generally those I adhere to on my turbo truck and they are based more or less on what I perceive as the structural limits (which apply turbocharged or not) ... with a little safety factor.

I have a '91 7.3 N/A that has NO trouble getting to 1150 - unloaded, WOT, 3rd/4th gear. No smoke. Made me very nervous when I first got it (am used to a 5.9L turbo Cummins) and I have to watch it getting on the freeway. Dunno if PO messed with the fuel screw, but timing seems about right (rattles until high-idle kicks out, then quiets down). ~300 idle, 600-700 at city speeds, 900 or so at 55. Really starts climbing over 65.
<als>

 

[79jasper]

^ I would say something is "wrong." Try a new air filter.

Sent from my SM-T537R4 using Tapatalk

 

[fsmyth]

^ I would say something is "wrong." Try a new air filter.

But that would be too EASY <grin>. Thanks, I will look at that. I wrapped the original with a foam surround when I first got the truck. Didn't think it would be a problem. Will take it off and try again.

 

[The Warden]

youll get a bit hotter when your turbo goes on.

Actually, I disagree...if you put a turbo on and don't do anything else, the EGT's should stay about the same or go down. Extra fuel adds to the exhaust temperature; extra air by itself will actually cool things down a bit. Of course, that doesn't factor in the permagrin/right foot factor

I imagine you'd have to be radically overfueled and smoking like a locomotive in an NA engine to sustain those high numbers but they are just about right for a turbo truck with the fuel setting near the optimal spot. I could see a NA truck with a max load going up Eisenhower on a summer day might hit 1000F at times but in a short term run, that much EGT would indicate an overfill situation based on what I know.

I've never done it myself (installed the pyro at the same time I installed the turbo), but from what I've heard from people who installed pyros on naturally aspirated engines, they'll actually run hotter than turbo engines, even with a 100% stock pump ...in fact, I remember some people being unpleasantly surprised by how close their EGT's were getting to the danger zone in what they thought was normal driving, particularly at high altitudes. I've always believed this, but hearing those experiences put my belief in stone...a pyrometer should be factory equipment on ANY diesel truck. The lesson I learned from what was reported was that, just because the truck left the factory set up the way it was, doesn't mean that there's no danger of meltdown. You would think that they would have set up the engine conservatively specifically to avoid meltdowns (and resulting warranty claims); seeing those reports was a big eye-opener for me.

I have a '91 7.3 N/A that has NO trouble getting to 1150 - unloaded, WOT, 3rd/4th gear. No smoke. Made me very nervous when I first got it (am used to a 5.9L turbo Cummins) and I have to watch it getting on the freeway. Dunno if PO messed with the fuel screw, but timing seems about right (rattles until high-idle kicks out, then quiets down). ~300 idle, 600-700 at city speeds, 900 or so at 55. Really starts climbing over 65.
<als>

Based on reports from others, I'm not suprised by those numbers. Like 79jasper said, a dirty air filter can really effect EGT's, and that foam surround will REALLY make a difference...I would start by ditching the foam and seeing how things do. But, unfortunately, it'll only help so much...the best thing you can do is keep your foot out of it, and seriously consider going the turbo route...

 

[PwrSmoke]

Good post Warden. I did a little reading on the NA thing too after this post and it appears high EGTs are the norm for NA trucks. In some of the material I have from the '90s, Jim Bensen, the guy that invented the ATS system, said a turbo kit actually made the engine MORE reliable when it had moderate fuel settings because it was running more air thru the engine and dropping the EGTs. Now that I think about it, with regards to my old diesel Blazer, my low readings were probably due to conservative fuel settings and a light vehicle more than any indicator of "low EGTs because it's NA" as I stated. Some notes from my GM project were of a discussion I had with a GM engineer over the 6.2/6.5L engines who told me that when they offered the first turbo 6.2L and 6.5L (before they went to the DB4 pump), they tracked engine reliability on those engines and found reliability actually went UP in the higher GVW trucks by a considerable margin. You take a 140 hp/245 lbs-ft NA engine in a 1-ton truck: you know that with a full load, you will have only two foot feed positions... all the way up or all the way to the floor. How does that impact engine durability, especially considering the 1150 EGTs noted above (which the driver won't realize because there is no pyro)? Install a turbo, power goes to an easy 190-200 hp/400+ lbs-ft and suddenly, you no longer need to pin the pedal every time you need to move. Plus, you are moving more cooling air to the engine. This passes the logic test.

Yeah, you're right about he pyro too... gauge one on the dieseohaulics guide to the galaxy.

Speaking of air filters: gauge two should be an air filter restriction gauge. Air filter restriction on diesels, especially old-tech diesels, is an important topic.

 

[IDIoit]

Speaking of air filters: gauge two should be an air filter restriction gauge. Air filter restriction on diesels, especially old-tech diesels, is an important topic.

and the only gauge available is like the one thats mounted on the filter of my PSD right?
the way toy make it sound, i should have one in a pod next to my pyro and boost gauge

 

[PwrSmoke]

and the only gauge available is like the one thats mounted on the filter of my PSD right?
the way toy make it sound, i should have one in a pod next to my pyro and boost gauge

Google "filter minder" they have many different styles, including a remote one for the dash. You want one that has a range of 10 inches of water on the low side and 25 on the high (up to 30 is OK too). For maximum power, you want to clean/change filters at 20 inches, but 25 is the normal time. Some of the big engines go to 30 inches, but they have large, very robust filters