EGT Thoughts

[6 Nebraska IDIs]

Yea, I wish you would have too David. 25psi out of a T4 turbo on a diesel engine with the displacement ours have is at or beyond its efficiency point. Thats why I don't understand why you keep talking about pushing it over 30psi. Thats just nuts man. Even with an intercooler its going to be difficult to keep the intake air temp down, not even gonna come close to efficient. Yea your turbo will push that much pressure, but you get to a point and you're just blowing hot air.
The turbo in my Eclipse will push 37-38psi, I know because I've done it, but its no longer "efficient" past about 28psi. So I turn it down to 25psi and call it a day.
Also, just to apply something specifically to this thread. My brown truck never went over 1000* until a couple days before the engine blew up for the third time. At the time the engine blew the EGTs were right around 1150*
However, my Eclipse Idles at 1050*, it never cools down below that, it cruises at 1500* and I've pegged the pyro at 1600* a couple times. If you don't know what a turbo Eclipse has for an engine its a 4G63T Diamond Sport 4cyl gas motor with a cast iron block and an aluminum head. Yea, thats right, an aluminum head.
I think every engine is different, because I'd never ever run an IDI at the temps my Eclipses engine cruises at, much less where it runs at WOT.

 

[dyoung14]

Yea, I wish you would have too David. 25psi out of a T4 turbo on a diesel engine with the displacement ours have is at or beyond its efficiency point. Thats why I don't understand why you keep talking about pushing it over 30psi. Thats just nuts man. Even with an intercooler its going to be difficult to keep the intake air temp down, not even gonna come close to efficient. Yea your turbo will push that much pressure, but you get to a point and you're just blowing hot air.
The turbo in my Eclipse will push 37-38psi, I know because I've done it, but its no longer "efficient" past about 28psi. So I turn it down to 25psi and call it a day.
Also, just to apply something specifically to this thread. My brown truck never went over 1000* until a couple days before the engine blew up for the third time. At the time the engine blew the EGTs were right around 1150*
However, my Eclipse Idles at 1050*, it never cools down below that, it cruises at 1500* and I've pegged the pyro at 1600* a couple times. If you don't know what a turbo Eclipse has for an engine its a 4G63T Diamond Sport 4cyl gas motor with a cast iron block and an aluminum head. Yea, thats right, an aluminum head.
I think every engine is different, because I'd never ever run an IDI at the temps my Eclipses engine cruises at, much less where it runs at WOT.

Im gonna try and get the egt gauge back in it here soon and get my girlfriends camera and make a few videos of me finishing th head gasket off, it was leaking bad today to the outside of the engine, but got it sealed up with stop leak gonna run it easy till i get my girlfriends truck were i can drive it instead, then i will blow the head gasket out of the truck for yall

 

[6 Nebraska IDIs]

Ouch, really its leaking that bad?

 

[dyoung14]

Ouch, really its leaking that bad?

It was leaking about a gallon every 50 miles or so but i poured stop leak in it and it stopped it, as long as it holds off for a couple days i will be fine then i can blow it up and park it

 

[towtruckdave]

***?

Why dont you just replace the head gaskets and still have a good motor?

It was leaking about a gallon every 50 miles or so but i poured stop leak in it and it stopped it, as long as it holds off for a couple days i will be fine then i can blow it up and park it

 

[dyoung14]

***?

Why dont you just replace the head gaskets and still have a good motor?

I was kidding im not gonna blow the damn motor, just finish the head gasket off by making a very entertaining video, i have a gasket set under my bed, but there is no since in putting the gaskets into a worn engine, it needs a complete overhaul

 

[towtruckdave]

Poor truck.....

So do you have another victim, I mean engine, to throw in there?

 

[dyoung14]

Poor truck.....

So do you have another victim, I mean engine, to throw in there?

Not yet, i think im gonna slowly rebuild this one, i got an unlce that can put the pistons on a lathe and cut the tops for FREE! so that will lower the compression, then all i got to do is come up with some studs, and rings mains and rod bearings then it will be good

 

[MidnightBlade]

Why do I have the sickening suspicion that a certain someone on here's now going to make a point of pushing his EGT's as high as possible and proclaiming success after one or two runs before his engine blows up?

David, oh David, i think you were summoned

 

[dyoung14]

David, oh David, i think you were summoned

Always am, only problem with that is i do it constantly every single day many times a day so its more than once or twice

 

[Diesel JD]

If nothing else you've proven that many 6.9 IDIs can take a level of abuse none of us ever suspected they would for a short period of time. No way it would last 500,000 miles like that though, even from brand new. That is unless you had the rotating assembly balanced to 5000 rpm, ceramic coated the pistons and studded everything and upgraded the valve springs and used 7.3 rockers. If you did that you could probably drive it like you do long past your interest....that would be my guess. How much do you want to take off the pistons? Playing it safe or going for a big reduction in compression? In any case ceramic coating would be a good idea.

 

[dyoung14]

If nothing else you've proven that many 6.9 IDIs can take a level of abuse none of us ever suspected they would for a short period of time. No way it would last 500,000 miles like that though, even from brand new. That is unless you had the rotating assembly balanced to 5000 rpm, ceramic coated the pistons and studded everything and upgraded the valve springs and used 7.3 rockers. If you did that you could probably drive it like you do long past your interest....that would be my guess. How much do you want to take off the pistons? Playing it safe or going for a big reduction in compression? In any case ceramic coating would be a good idea.

I was thinking around .035-.040 and studded, then mactching the weight to every piston and rod then also get it balanced to 5000 rpm, and a few other tricks me and the girl friend decided to slowly build it the way we want to and drive her truck till it gets done,

I never expected it to last as long as it did, but i think it proved us all wrong, and yet even with the head gasket leaking to the outside i pour stop leak in it and imm still drving it so its still not dead

 

[BigRigTech]

I had my 351W dyno'd last summer, when we switched from the "house" carb to my 750DP carb we saw a severe lean condition when Danny attempted the first pull as the main jets were too small so he shut it down....He turned to me and asked "what did you say is in this thing for pistons?".........."Forged" was my reply.....He said we might have a problem if they were cast....Short or long term - anything over 1200F is just flirting with disaster as far as I'm concerned. We have a 3306 mechanical Cat torn down at work for a rebuild at work, all 6 pistons are cracked bad in the same place...My guess is someone has played with the pump to crank up the HP as it's a road line paint truck and it's heavy....

 

[Brianedwardss]

Keep us posted David. These numbers you're playing with are Insane. I get chippy when I have to push mine to the 2850 rpm limit of my IH pump. I can't even FATHOM 4,000+ rpms AND 25+ lbs of boost in a 6.9l IDI. The term 'blow up' is vastly over used, but at that operating parameter, I'd be shakin in my seat anticipating a

And then a nice from the truck as it said it's last words. Atleast you got a lady who supports your cause, whatever it may be!

 

[dmaxjoe]

I'm no expert by any means, but I have owned a few different types of diesels. My duramax I felt ok with up to 1400*. My mercedes was factory stock and when loaded with 4 people and luggage. On a steep grade I hit 1350*. My 6.5 chevy would hit 1250 pulling my tt up a grade. My 91 7.3 NA I will not let get above 1050*. My personal limits are based on other people and engine design. I have noticed that a turbo engine the egt's drop faster when letting off of the pedal than they do when NA. My mercedes and my 6.5 chevy were factory stock so I figured thats the way they wanted them to run. If I had a turbo on my 7.3 I would probably go 1150*-1250* for short bursts. It has been said before " Put your hand in a pizza oven for a few seconds no problem. Leave it there too long and you will get burned!"