Max boost in the modern age

[82F100SWB]

In normal weather, I was running 14psi peak on my 6.9, at -35, due to the denser air, it was closer to 18. Stock engine, 168K miles, stock bolts, stock HG's, locally built pump, turbo injectors, pretty advanced timing... I put about 40K miles on it like that, no issues, If I ever get a round tuit and play with the thing again, I will put 20 psi through it just to see what happens... Currently it languishes in the back yard without a turbo...

 

[david85]

Not enough oil pressure to support more than 14 PSI? Haven't heard that one before.

As for not being able to reach 20 PSI, thats more a limit of the fuel system and the turbochargers that are available out there. Companies that made turbochargers for these engines knew that 8 PSI was enough to make the IDI the most powerful diesel on the road in its day. They also knew that going any higher would risk reducing the reliability of the engine.

Simply put, if you want to go beyond 10 PSI, you are going to have to either modify your turbo extensively, or make a new turbo kit from scratch.

More recent developments suggest that a performance camshaft might also help. Can't wait for that to come

82F100SWB

Did that 6.9 have head studs or was it bone stock?

 

[82F100SWB]

100 % bone stock; as far as I know, it's still on factory head gaskets. But, the history of the truck before 04 is unknown to me, all I know is prior to that it was last plated in 00, and parked due to a bad IP combined with a very rusty body.

 

[f-two-fiddy]

Says who

Is that why it says "I break wrist pins" under Your avatar?

 

[1320Cummins]

Is that why it says "I break wrist pins" under Your avatar?

HAHAHA Catching on Ah in all truth I suspect it was a defective pin. I ran the motor at 20psi for only the first couple days of its life maybe 150 miles.
I knocked the boost down to 14psi and all was well for about two months and then I had the failure on #1. I pulled that head and was able to warranty all four pistons in that bank as well as the valey pan, head gasket and pan gasket I only had to purchase one used rod. I am wanting to pull the glow plugs and plug the holes in the attempt to lower the compression a bit.

Knowing what I know now I would have shaved the pistons and used IDIT rods. But, I knew NOTHING about the IDI 7.3/6.9 when I built this motor other than I was going to do something special.

 

[Agnem]

I'd really love to see someone do a GP elimination experiment, perhaps replaceing the GP's with a grid heater. I know a healthy IDI will start in summer temps without GP's at all if you crank it enough.

 

[david85]

I'd really love to see someone do a GP elimination experiment, perhaps replaceing the GP's with a grid heater. I know a healthy IDI will start in summer temps without GP's at all if you crank it enough.

That would be very easy to test if some on had a working block heater and it wasn't freezing outside. My engine will fire off as long as its warm to the touch. It can do a dead cold start if its sitting out in the sun on a hot summer day without touching the glow plugs. And thats with 20 thou taken off the pistons.

I guess all you would have to do is take some dead glow plugs, cut the tips off (or use champions since they do that automatically) and wield the stem hole shut. Then take a grinder or small lathe to them to smooth the plug off

The stems are metric 10x1.5 if memory serves. If bolts could be found with the correct thread and length, then they could also be used, but again the ends would have to be turned to get the proper shape to be able to seal in the head without damaging anything.

 

[typ4]

What I meant by the oil pressure comment is pertaining to the width of the rod bearings, I know there is a formulas out there to calc this and it would be easy to squeeze the oil out under high cyl. pressures.
Now if we could maintain 60 -65 lbs of oil pressure it wouldnt be an issue.
I dont know if 40 will do it.

 

[ameristar1]

Is there a way to raise the pressure up? Does the pump have a relief spring that can be changed?

 

[david85]

I remember hearing of some one that had problems with his IDI making too much pressure (over 100 PSI). This was an isolated case (so I can't verify it), but he said the PO put some sort of spacer on the oil pressure relief valve spring. However, we also know that at idle speeds the oil pressure drops well below stock blow off pressure. You could probably get the pressure higher up past 2500, but if you were to make a moster low end torque motor, it could overload the bearings.

In fact I have wondered about this myself. In theory, My truck could hold 50 MPH @ 1200 RPM for what I hoped to be crazy high MPGs. The engine and transmission will do it on flat ground without issues, but I'm worried about oil pressure not being enough.

It seems if this is a real problem, then a modified oil pump would be the answer. It is a simple device relatively speaking, but the tooling required to do it right isn't cheap. I wonder if putting a smaller drive gear on it would do the trick?

 

[icanfixall]

A stock oil pump puts out 18.2 gallons per minute at 3000 rpm. I shimmed up my new regulater spring 70 thousands and usually see 55 lbs at 2000 rpm hot... On a cold startup I see 75 lbs at 1000 rpm.... Never is the warm idle under 25 lbs. This shim trick is not for the everyday guy working on a motor either...

 

[91f2504x4]

I am still hitting 18psi on hills, especially with a load and hitting the throttle a good bit. I see 15psi pretty consistently on quick take offs. I have never held into it beyond 18psi, so I am not sure if it will build anymore boost, it just seems to sound a little different, and I hate to push the engine any further than that. I would like to hook it to a sled and see what it would do, but I will wait til next year for that.

My newer truck hits 37 psi on any quick take off, I wonder how the old IDI would like that.


BTW
I get to drop the tank tomorrow and clean everything out and see if she will get fuel after all that slime is cleaned out.

 

[6 Nebraska IDIs]

This shim trick is not for the everyday guy working on a motor either...

Thats exactly why I didn't want to touch that one. lol

 

[65sixbanger]

Crash86 has not posted in a few weeks.

His truck still runs great

 

[65sixbanger]

A stock oil pump puts out 18.2 gallons per minute at 3000 rpm. I shimmed up my new regulater spring 70 thousands and usually see 55 lbs at 2000 rpm hot... On a cold startup I see 75 lbs at 1000 rpm.... Never is the warm idle under 25 lbs. This shim trick is not for the everyday guy working on a motor either...

So is this inside the pump where the gears Are?