Injector pump timing with turbo? Boost pressure?

[frdtrckmnrich]

I have been told that with gas motors that have 7psi or more of boost require timing changes. So my question is, If i am acheiving 15psi of boost on my 6.9 do i need to make a timing change?

I ask this because i think i went thru another set of headgaskets. Yes it is studed, and the head and block surfaces have been checked.

Anyone have an idea as to how much boost these motors can handle?

I am really getting sick of doing head gaskets every 2 months.

 

[Mr_Roboto]

15 psi is too much for a stock IDI.

Gassers retard timing as boost increase to prevent pre ignition (auto ignition). This can happen because the fuel and air are compressed together. Diesels being direct injected this does not occur.

 

[sassyrel]

frdtrk--keep the boost below 12 psi----under full load----and run a pyro---and keep that below 1200---before turbo----

 

[Joejohn]

get some head studs for that 6.9. They will hold 15psi and last. Also I am not being judgmental on gaskets but I think fel-pro is the best.

 

[Hyde]

He said he has studs

 

[Mr_Roboto]

I didn't notice the first time that there were head studs. Maybe they are not being torqued tight enough?

 

[frdtrckmnrich]

Torqued to 90 ft/lbs.Felpro gaskets are being used.
My egt's have never exceeded 1100, and my probe is at the "y" in the up pipe.
So is 15psi too much?

 

[suv7734]

15 PSI is generally considered too much due mainly to the compression ratio. I don't see many specifics on your truck other than a 6.9 with studs. What has been done to the IP etc? Where have the gaskets been failing? Same place both times? When you say the heads and block have been checked what specifically has been checked? The reason I ask is I saw you other post regarding the coolant tank and there are a number of things that could be related.

 

[frdtrckmnrich]

The gaskets have been blowing from the cylinder to the water jackets on the rear of the block primarily. There is evidence that the front is doing the same but has not completely blown. The heads and block have been checked for warpage and they come out true. No the precups are not protruding.

As for the injection pump, I removed the triangle side cover. I then turned the screw up 3/4 of a turn. That is all that has been done to the motor. I did this when i installed the turbo.

I really appreciate your help. Any and all ideas will be considered/checked out. I really like my truck, this is the first diesel i have ever owned. When it runs it is absolutely wonderful. But at this rate i am seriously thinking of selling it. I don't relly want to but if i can't get this figured out it just might happen.

Thanks again for everyone's help.

 

[icanfixall]

Any boost over 12 lbs is lost because the air is so heated by the compressor wheel that it makes no real hp. The temp reaches 300 degrees as I'm told.

 

[Diesel JD]

Gary may be correct about the thermal loss of efficiency as he knows his stuff, but it should hold 15psi without going through a set of gaskets 2 or 3 times. Something is wrong with the studs, the torque settings on your wrench, the torque sequence, the gaskets the block or the heads. The question has always been is it efficient to run high boost...most say no, or is it conducive to engine longevity...that is under dispute...but there are guys that exceed 12 psi of boost on stock bolts on this forum and go years without blowing a gasket. Something is not right! Now you have to find out what that is.

 

[frdtrckmnrich]

Well that is why i am posting this. I need ideas, I know something is wrong. I also think it should hold it especially with the studs(i thought that was thier purpose).It has only hit 15 twice and neither was for more that 2-3 minutes.

 

[82F100SWB]

15 psi shouldn't kill HG's... My engine has about 170K miles on the factory gaskets and bolts, and has seen 15 psi for the last 20K miles or so, it hasn't been driven easy, and when it has been towing, it's been most often in the 10K+ range, and I have not had an issue, heck, as the temperature sinks further below the freezing part, I make more boost, at -30 and colder, I can easily make 19 psi....

 

[Diesel JD]

You ask about your injection timing...I doubt that is the cause of your headaches but running an extremely advanced injection pump will cause problems of one type or another. Have you had yours timed? I think these trucks do just fine with a turbo and the timing specs adhered to 1.5*ATDC at 1400 by the lumy method or 8.5* BTDC with the pulse method. I wasn't trying to insult your intelligence or your skills by insisting something isn't right. I guess I just am agreeing with you that what you are doing isn't abusive and it shouldn't be a problem, just too ignorant, especially at a distance to suggest a cause. I do hope you get it figured out. Are you sure there isn't something wrong with those studs? Some of the guys at Olds-diesel had problems with these things giving out on them.

 

[Joejohn]

Heck my pops is running 15psi on his 7.3idi with over 350,000 miles on it and the head gaskets and heads have never been touched. He has had good luck with his truck and its all stock except the turbo upgrade, I would for sure do some checking. I bolted my heads down and the next morning the stud nuts were loose because the head gasket compressed so slowly. Double and triple check. Make sure your torque wrench is accurate, it may need an adjustment. Check the deck on your block to make sure it is flat as well as the head surfaces. Also if you leaking around the coolant passages a bit of RTV will always help. These are some other things you may consider.