If u had $7000 to spend on a 6.9 to make it better and more hp output what would u do?

 

i would say scrap the 6.9 and go buy a powerstroke. the 6.9 are not made for the boost from adding a turbo and there is only so much that you can do to those old motors

 

if i had 7000 to spend on a motor, it would not be a 6.9. i agree with outdoorsman. i drive an old 7.3 because its cheap. the new power stroke is the way to go.

 

ok then $4000 to spend, and if u can put a 7.3 powerstroke in my 1985 u go ahead, be my guest.

 

i dunno if i had 7000$ to spend on a moter i would do what dave s. did to his that thing is really sweet!

 

Head studs, turbo, intercooler, gauges, 20+ psi boost, zf5 or 6. Can't beat it.

 

i'll probably get slapped, but I'd drop a Cummins 12v in mine.

 

I Would Do The Cummins Thing Also My Ford Is O.k But My Buddies Run Circles Around Me... Sorry Jim

 

Yup, that right there! I gather he whups on the cumminses AND the powersmokes, and IIRC he only has about 5 grand invested in his.

With the leftover dough I'd take a nice vacation!

 

Use a late 85, 86 or 87 6.9 engine.
Find a very good machine shop, the one I used builds lots of race motors.
The machinist was able to clean up cylinders with .007 taper in them doing a .010 bore.
Check every surface for straight and true, correct as required.
Magnaflux everything, mic everything, replace anything that is questionable.

After you have all good engine parts to use.
Minimum bore to straighten out the cylinder wear.
Line bore as required.

Hypereutectic pistons, milled .040 to drop the stock compression ratio.
.040 drops the compression to 20.25 to 1 and keeps the cold start manageable.
.080 drops the compression to 18 to 1, but you will have cold start issues in northern climates.
I used hypereutectic pistons for better heat resistance and .040 off the top to keep cold start problems low because I plow snow.
It has to start at 2 AM in the winter no matter how cold it is outside.
Lower base compression lets you run more boost and more fuel.

Polish crank.
Balance the rotating assembly to over 4000 RPM.
New bearings
New cam
New lifters
New oil pump
Rebuild oil cooler
7.3 rockers
7.3 valves (inconnel valves are preferable)
New valve springs
New push rods
New rings
ARP head studs
ATS turbo
Header wrap on everything you can wrap before the turbo
New grade 8 bolts in the intake and exhaust manifolds (part of the high boost solution, double stock torque)
New 7.3 turbo injectors (I am running DPS Stage 1 injectors)
7.3 turbo injection pump (I am soon going to a DPS modified IP)
Run the timing as fast as you can without having a Power Stroke rattle.
Run as much fuel as you can out of the IP.
Turn up the max RPM to at least 3800 RPM
Max out the turbo boost pressure
Spray copper gasket maker on both sides of the valley pan where it doubles as intake gaskets, high boost will cause a failure in that area.
Spray copper gasket maker on both sides of the exhaust manifold gasket, high boost will cause a failure there as well.
Use NAPA part number 31311 exhaust gaskets in the cross over to manifold pipe connections, high boost will cause failures there as well.

An intercoooler would be a good addition, but I did not have room for one, my snow plow mounting bracket would block all the air flow through it.

Gauges you need to watch, don't forget to cool the turbo before you turn the engine off
Pyrometer installed in the exhaust manifold.
Boost gauge
Oil temp gauge
Manual coolant temp gauge
Manual oil pressure gauge

Build ram air intake on truck
Minimum 3" exhaust no muffler, bigger is better

Save the extra money to rebuild failed driveline parts, U joints and driveshafts don't last long.
Also the extra money will be required at the fuel pump if you run it hard, I can get below 10 MPG rather easily.

The IDI engine is an excellent engine to turbo charge.
You just have to address several areas that were designed for no boost if you want to get wild with boost pressure.
I am sure I would be addressing several areas again if I went over 30 PSI boost, but I am also rather sure it could be done.

Running boost that high would take dropping the stock compression down to 18 to 1 and make below zero starts rather hard if not impossible without being plugged in

As a test I did start my engine at 10 below this winter without being plugged in, but it did take several tries and after glow to keep it running for the first 45 seconds after it did start

 

Dave i have a 1984 6.9 and you said one should use 85,86, or 87 6.9. What is the difference between mine and those?

 

Even the early 85 blocks have a possible weakness in the block heater area.
Use of the block heater may cause cracks in the block over the block heater.

I would not want to put a lot of money in a block that may crack next winter.

Defined area for the dip stick to enter the block and a counter bored block heater location are the newer style 6.9 block.

From PLC7.3, (Thanks Pete)
6.9 blocks up to serial #u2u17900 had a thinner casting around the block heater. It is very common for these blocks to crack.

6.9L Old Style Block
Block Casting Number:

On left side of block (beneath oil cooler) 1805440C1
Note: Some 440 blocks are truly new style and must be visually inspected by raised donut around the block heater, frost plug (right rear). Old style below serial number 173828.
Visual Identification: *No counter bored area for block heater
*No defined area on side of block for dip stick
*Thickness of cast iron around block heater 3/8" (.375")
Head Bolts: *7/16, 12 point socket is used to torque head bolts
*Block tapped with 7/16-14 for head bolts
6.9L New Style Block
Block Casting Number: 1807996C1 Note: Some new style blocks have casting
number 440. Above serial number 173828.
Visual Identification: *Has counterbored area for block heater
*Very defined relief area cast in side of block for dip stick tube.
*Thickness of cast iron around block heater 15/32" (.470")
*Latest style (not all new style 6.9) has ribs around head bolts, rear two on left side go from head gasket surface to pan rail - same as 7.3
Head Bolts: *Same as old style 6.9

 

A tiny bit off topic but seems like a perfect place to ask...

Dave, what are the weaker points on the 7.3L design that should be addressed before turbocharging? I know in the 6.9's it was a good idea to use studs but even ARP doesn't make them for the 7.3L...I know dps performance makes them but $675 is a little steep in my opinion. I already have weak oil rings that I will have to fix in the future (valve stem seals and a new CDR only minimized my smoking issue). I plan to do some performance upgrades reguardless even if I can only get 1 rebuild out of a 7.3L... Your knowledge would be appreciated, thanks...

 

Weak points are the cylinder wall thickness, boring .020 without using sleeves is like Russian Roulette with 4 bullets in the six shooter.
.020 is the smallest oversize piston I have seen.


21.5 to 1 compression is the next thing if you want to run big boost.
Head bolts are still to weak to run big boost numbers.
Milling the pistons would help, but then you have cold start issues if you go very far below 20 to 1.
Without recalculating everything I would say that would be about .020 off the piston crown on a 7.3 to stay above 20 to 1.
That should put you about 20.375 to 1.
With stock head bolts, you should be able to run close to 20 PSI with no problem reliably.

If you are planning to stay under 15 PSI boost, the only thing I really see as a problem is the cylinder wall thickness and boring the block to get new cylinder walls for the rings to seat on.

I have seen reman engines with a .020 bore and no sleeves, but if SCA was not run and maintained religiously I would say that is a big risk.
Even if it was used, I still think it is at least a small risk.

Want to run boost over 20 PSI, head studs and milling the pistons is the only game in town to do it reliably.

Want to go over 30 PSI, now we are talking O ring head gaskets, head studs, milled pistons, intercooler, custom IP and lots of dollars.

I would hate to put 4,000 dollars in an engine only to loose it to cavitation a year or two or even three later.

Even though I do run mine right to the edge, I think I will be seeing 200,000 miles out of the rebuild as a minimum mileage, at least that is what I am shooting for.

 

Thanks Dave! I knew I'd get a good list from ya. I don't plan to go too crazy but if I have to re-ring my engine in the future I will see about milling pistons, head studs would be imparative then. I'll try and keep below the 15psi . Once we get into summertime I will get into more preventative maintenance and my turbo install. Thanks to this forum I'll be able to jump in on my own without worries of goofing something up