Safe EGTS & Boost Values for a 6.9l reman

[mankypro]

Ok I'm all gauged up now.

I've spoken to Dealers Diesel - the outfit that reman'd the engine in my truck - it was done in 99'. They could not tell me if they used studs or bolts on the heads, but did say that by 99' all the 6.9's were rebuilt the same way they rebuilt 7.3's? Does that mean that it's "turbo ready engine"? If I popped my valve covers could I tell if it was studded or bolted by looking at it?

In any case I'm not going past 8psi now when I can avoid it. I assume 12psi is "safe" still? Not that I'd run it up there with any frequency.

As far as EGTs are concerened, I've located my thermocouple at as close to #8 as possible, between it and #6 - in this location what should I consider safe temperature values? 1100 OK? Start backing off there?

Thanks

 

[DeepRoots]

1150 degrees and 12psi would be safe sure.

you should be able to tell if there are bolts easily. I doubt they used studs

 

[GenLightening]

Don't even need to do that, the lower bolts are visible above the exhaust manifolds.

 

[h2odrx]

Don't even need to do that, the lower bolts are visible above the exhaust manifolds.

Yes no need to pull the covers just look at the heads!

 

[mankypro]

Sorry folks, I don't even know what I'd be looking for - are the picks of studs on a 6.9/7.3 head somewhere to compare to?

 

[69oiler]

it's either a 12 point bolt head or a 6 point hex nut on a visible stud, below the valve cover above the exhaust manifold

 

[poolguy]

1150? I get 1200 before it shifts into OD when pulling out hard into 55 mph traffic. I've seen 1350 to 1400 when pulling a load up a hill!
Mine is drilled and tapped into the manifold just outside of #6 and the boost maxes out at 8lbs
I remember being advised not to worry about the temp., just drive it.
So I have and it still runs fine.

Chuck

 

[mankypro]

You know what they say - "Drive it like it was stolen!"

Sorry couldn't resist!

1150? I get 1200 before it shifts into OD when pulling out hard into 55 mph traffic. I've seen 1350 to 1400 when pulling a load up a hill!
Mine is drilled and tapped into the manifold just outside of #6 and the boost maxes out at 8lbs
I remember being advised not to worry about the temp., just drive it.
So I have and it still runs fine.

Chuck

 

[poolguy]

As a matter of fact, it was stolen a week and a half ago!
But I got it back.

Chuck

 

[mankypro]

I know Chuck - that was the purpose of the joke.

As a matter of fact, it was stolen a week and a half ago!
But I got it back.

Chuck

 

[DeepRoots]

well ya asked what was safe.
I personally can give the thumbs up to 1150.

I'm not gonna tell somewhat to run 1400 and it'll be fine.

 

[david85]

The piston material starts to melt at 1250, but combustion temperature will always be hgher than the pistons. Keeping the EGTs below 1250 is the limit that I hold to. The 6.9 head bolts are not very strong and I would personally not go above 10 PSI, but know of others that claim they can do 15 consistently.

The problem I (and others) have seen with the 6.9, is that a head gasket failure is not absolute. Instead what can happen is the fire ring gets pushed back from the high chamber pressures and reduced clamping force (head gets pushed up from higher boost). In my case, I saw no ill effects from the outside, still good power/compression, no pressure building in the coolant or anything.

But when I tore the engine down, I noticed that combustion chamber pressures that leaked past the damaged fire ring on the #2 cylinder had actually eroded the casting away on the head and block mating surfaces. Not much, but enough to require correction.

Like I said, the engine ran great and seemed to be fine, but all it too was a few seconds at 14 PSI to weaken the gasket enough to allow a breach in the fire ring for gasses to get in and do the damage over time.