Considering Ideas For 6.9 Rebuild

[k_williams1982]

I spent almost two hours talking to Justin tonight about my current motor and what all I can do to it. I mentioned a couple things that we both were unsure of, and found out some things that I didn't know. I'll list what I plan to do with this motor and I'd like some advice and/or pointers from you guys about what you think, and if I should rebuilt this differently. I also have a few questions that I hope someone might know the answers to.

Going to have 6.9 block bored .060 over, stud the heads instead of bolt, put my current ATS turbo back on, try to find the "DD" injectors (Believe they're "DD" - ones used in a stock '94 7.3), put on a 7.3 injector pump, and might use the rods and the crank from a 7.3.

My next thought is to install 7.3 heads onto the 6.9 block. Justin told me tonight that the 6.9 uses 7/16" bolts and the 7.3 uses 1/2" bolts. After some debate about this, we came up with two ideas to pull this off, I'd have to do one of two things... (1) Have the machine shop drill and retap my 6.9 bolt holes on the block to the 1/2" OR (2) Contact ARP and see if I can get a set of studs that are 7/16" on one end, and change to 1/2" at the block surface for the heads.

I was thinking that it would help the engine "breath" easier to install 7.3 heads (since I'd be boring it over just a little over half the difference of the 6.9 and 7.3 - Would that mean I have a 7.1? lol) if the 7.3 has bigger valves.

Does the 7.3 have bigger valves than the 6.9, and if there is a difference will it be enough to make these modifications worth it? Justin mentioned that the exhaust manifolds might be restrictive. Is there any place to get manifolds that allow better exhaust flow into an up-pipe to the turbo and will I even have enough room to pull this off?

Is there a difference in the stroke of a 6.9 and 7.3 crank, or is the crank the same? If there is a difference, can a person make the 7.3 crank work in a 6.9?

I'm just curious what all I can do to this engine to make it a better engine or even make it almost one of a kind. I don't plan on during all this right away. It'll be something that I do little by little and take my time on. Thank you for any advice or pointers that can help me.

 

[seawalkersee]

Not 100% sure on all of the questions, but if there is a difference on the head studs, just use the adapter washers that fit in the holes. They will cover the hole and work just fine to use the smaller stud. 5.0s need them to run the 5.8 heads.

Chris

 

[typ4]

Valves are all the same size, proper guide work and new springs and rockers are the most important. 7.3 heads seem to crack more often in my experience. the 6.9 has a non emission precup which should make more power.
I ported my heads and manifolds on the exhaust side a little, doesnt take much and with a turbo it is not that important, a good seal is by far more important.
The crank and rods are the same, I wouldnt bore it 60 even tho bigger is better, do just what cleans it up, say 20 or 30, that gives you another build or 2 down the road

You cant go to a 1/2 inch stud in the 6.9 block, not enough thread engagement to hold,the 6.9 arp studs will give you all the reliabilty you need.
There is only one replacement injector for all non turbo applications according to my source and then the g codes for turbo.
Did I hit all you questions/
Gotta build a buggy motor now ,back later.