David, I've been thinking 7-10#, but now I'm thinking 7-8#. I need some air at high altitudes. We may start with 7# and see what happens. Maybe 7# with the 3" down tube. I already have a flowmaster and 3" exhaust, I also have air ducts in the grill for fresh cool air. That should make it breathe easy. What kind of compression #'s would I be looking at with 7-8# of boost. My engine was rebuilt in 2006, maybe it has the newer head gaskets and better rings. My mechanic is too cheap to install new headbolts, so I can bet they are used. Thats what scares me, I really don't know whats in this engine, all i can say is, it starts right up and runs good.

 

Never gave it any thought that was where Banks had it set. At the time I had never heard of any head gasket troubles. So We'll see I've made some long hard pulls with it. It may have a lot more to do With how much You turn the pump up I'm not getting more then 1100egt.
How many different head gaskets are there on the market? I know from racing Fords what gasket You use can make a world of differents.

 

When hot-rodding a Cummins it's very common to retorque/OVER TORQUE the head bolts.

I would personally recommend pulling each heat bolt out individually and oiling it so you get a good torque reading.
Do it in the recommended sequence in the "book" and you should be fine.
Off of the top of my head I don't know if any of the head bolts go into a cooling passage but but Dave S. will.
If the bolt turns around more than the others with out increasing the torque load on the wrench STOP! That bolt has either reached it's elastic/stretch limit or the threds are trying to pull out of the block. BOTH of which are very unlikely.

I've never tried this on an IDI but I can't see why it wouldn't work.

I don't know what the factory rating is but I believe it's 90 ft.lbs. on used bolts, I think I'd go 105 as I believe that's what Dave did BUT he has STUDS.
Either way I think I would split the difference and torque them in two sequences.

I'm sure there will be lots of recommendations.

 

In an earlier post Dave said 88 thru 91 was torqued to 100, and 92 on for the turbo's was 110. My mech said he torques the 7.3 to 110. Tomorrow i will check with him. If he has them at 110 they should be tight enough. LOL maybe too tight.

 

From what I understand, the 6.9 head bolts are reusable as long as they are not corroded too badly. The head bolts on the outer perimiter of the block can get a little rusty over the years.

I do not however know if the 7.3 head bots are torque to yield. Might want to double check that.

$225 was for the 6.9L head stud kit. ARP is charging over twice that for the 7.3 IDI!

But the stock bolts on the 7.3 are stronger than on the 6.9, so you could safely go to 10 PSI and even peak at 15. If reliability is your first concern, I would limit the boost to 10-12 psi.

 

i only said that because thats what i was told by a friend. haha im obviously wrong judging by your response. can you explain to me what happens when you advance it? do you get more hp but less torque?

 

First where is the thermocouple located?
The standard location on the Banks kit was after the turbo if I remember right.
1100 degrees after the turbo is 1400 in the cylinder.


Head bolts do not go into the coolant jacket.


Injection timing determines where in the stroke the combustion event takes place.
The closer to TDC the gasses expand, the longer it has to push on the piston and the more power you get to take advantage of.
The stock setting was determined years ago with fuel that is very different from what we are running today.
The original timing method for the 6.9 even included measuring the specific gravity of the fuel to determine the cetane rating, which was then used to determine the optimum timing setting.

Tell most mechanics that today and the response will be, "Huh".

 

There is some wisdom out there that says that slighly retarding the timing after adding a turbo can help add spooling for the turbo. I time mine based on fuel economy and exhaust smoke and don't ask me the actual timing in degrees because I have absolutely NO IDEA where it is! All I know is that it starts, runs and hauls great.

 

And if you think about this for a second you will see why that makes sense.

If you inject the fuel a bit later in the stroke, there will be more fuel still burning and the exhaust will be hotter.

Hotter exhaust has more volume which when contained in the exhaust with only one way out translates to faster moving exhaust.

My thought, insulate the crossover and up pipe to keep the exhaust hot and moving fast.
Then advance the timing as far as I can so I can take better advantage of the extra turbo boost from insulating the exhaust.

What drives me crazy right now, with temps in the 20's both the timing advance is staying on longer in the morning and the much colder air going in the engine make it run so much better.

I can tell an intercooler needs to be in my near future, and I think I could really use about 3 more degrees of advance at heavier throttle applications.
Time to take the IP back to the injection shop and set the advance curve a little hotter.

Warning, anyone reading this that does not know, my engine is not a stock factory engine.
Some of what I do would result in a stock engine failure in a very few miles.
If you were lucky, the only engine damage would be blown head gaskets.
Not so lucky like me, it would be worse.

 

I guess you just can't leave well enough alone, can you?

... me neither. I just ordered a larger compressor side for my turbo today. Made it almost a full year before having to add another upgrade to the engine, heehee. Maybe this time next year I'll be ordering that so called "moose pump". Theres just no end to it.....

Yes I heard that logic about why to retard the timing slightly. Thats the only thing that made me even try it. I also read that more of the fuel can actually be burning on the way out of the engine, not much but some. That also means more push against the turbine because the exhaust gasses are still expanding on their way to the turbo. However my case I think it really was too far advanced because no matter how much boost there was, it just wouldn't clear the smoke, which was really annoying because most of the time I wasn't even pushing it hard.

I have to get a proper timing tool eventually.

 

after the turbo turn the pump up and upgrade nozzles

 

hey bud check the dates... think this might be the longest running thread on fte!!!

 

Man this IS an old thread.

So just thinking about some of the earlier posts, regarding emissions and warranty concerns. Does anyone know just how much the stock air intake and exhaust systems on these 6.9 diesels are restricting what the stock engine is actually able to pump through? Has anyone tried setting something up so that they simply breathe better? Did they notice any improvements?

Or am I way off in left field here?

 

FWIW, I ran My 7.3 for 175K miles with the wastegate set to 12PSI.

I just changed heads because of woofing. Failed exhaust valve stems seals/guides.

I doubt the boost had much to do with it. The OEM positive seals just don't allow enough lubrication.

 

why would you post on this thread? just start a new one next time instead of hijacking a old one.