6.9 Build-up

[Ironman03R]

Heres the first pics of my engine build. Here it is hangin after being steam cleaned and degreased. Next step is to pull the heads for head work.

I've built lots of engines but have never had an IDI apart, this is going to be the "test engine" so I dont want too much money in it. If anyone has any advise on putting one of these together let me know. I'll keep posting pics as it progresses.

 

[CSARebel916]

What do u plan on doing with this engine?

 

[seawalkersee]

What kind of head work? What compression? Forced induction? What kind of injectors? What kind of pump?

Chris

 

[Ironman03R]

Ported heads, Studs, Hypermax turbo, My injectors, My pump, possibly intercooled. Gonna check cost of machining pistons, I may skip that right now. When I get the heads off I'll see what the pistons and block look like.
Stage 1 is to get it built, running and and in a truck.
Stage 2 power adders and hope it dont go BOOM!

 

[Agnem]

Take 50 - 60 thou off the piston tops. That seems like a no brainer idea to me at this point. You'll be able to stuff more air in later.

 

[schoelta]

Dumb question, but can you just machine your stock pistons, or do ou need new one that are shorter than stock?

 

[DeepRoots]

paint it red, it makes em faster.

 

[icanfixall]

About shaving the piston tops. It is "possible" to mill them any amount but.... When I needed to do this I bought a set of Mahle 1441800WR std. These are the big pin type. They were way too tall for the block macnining I had done so... I talked to the Mahle engineer named Eric. He told me to buy a low comp piston and mill no more than 18 thousands off the tops because the pin is machined 10 thousands higher in the piston so that alone will lower the piston in the bore. The stroke stays the same too.... Otherwise the top compression ring will suffer from the heat because its now closer to it. All.. And I mean all the Mahle pistons, even the original ones removed from my 89 motor have a crown thickness of between 560 and 580 thousands. So there is plenty that can come off but outside of what they recommend you are on your own. It can be done but what will happen taking off 30 or 40 may turn into something noboy wnats to read about. Now if we were just racing or pulling with a piston that was milled 40 or 50 may be something somebody would like to try. Somebody needs to be first. I think I was with the head porting and I know I was running with the pistons as much as 47 thousands up above the block. The maximum amount From Navistar is 31 thousands. Every piston showed a valve mark but you couldn't feel it or measure it. I don't recommend that close of a clearance to anyone but you see it can be done but... As bearing wear the clearance deminishes and suddenly CRASH.... My current set of Mahle low comp pistons part number 1441711 have 12 thousands milled off the tops and then ceramic coated with Tech Line CBX.

 

[Ironman03R]

More pics of disassembly. All looks good inside, really clean, this engine has swallowed a couple glowplugs over the years but pistons dont have any cracks. I had 3 injectors come apart when I removed them and the tips all have ash deposits from WVO/WMO.
It had Felpro head gaskets that were holding up fine the the 12psi of boost. I noticed that the paint was burnt of the heads above each exhaust port, no visable damage inside from the 1300* EGT's it was seeing. Possibly more than that due to the fact the probe was not all the way in the pipe, it was in the factory Hypermax spot but had a reducer bushing in it keeping it only about 1/4" in the pipe.

 

[david85]

This brings back all sorts of memories of my rebuild earlier this year. I had a glow plug tip mark one of the pistons as well. Good luck with your build

 

[LCAM-01XA]

these metal brackets that hold the rockers in pairs, are they stock parts? When I pulled my driver-side valve cover I did not have those under there, haven't checked the passenger side but expect the same situation. Are they really needed, or are thy just a 6.9 thing the 7.3 can't even use?

 

[Diesel JD]

Ivan that's the "strap type rocker" which was used on the 83-86 6.9s. Your truck as well as all 7.3 IDIs and 87 MY 6.9 engines have the pivot type which is supposedly an upgrade. Ken at DPS has a tech article on the issue. I keep wondering when somebody is going to get real serious about a build and order a set of custom pistons at around 18-19:1 compression with plenty of meat on them so the upper compression ring doesn't suffer nor does the dome of the piston as it might when you shave pistons too much.

 

[Ironman03R]

Someone has replaced the strap and rockers on the #2 cylinder. I thought about upgrading them all but they all look good so I dont think I'll worry about it. I did notice the valves stems have pitting on the stems, I've seen this in SBC's but it usually was due to valve lash not adjusted corectly

 

[FordGuy100]

Looks real clean man . How many miles were on that motor?

How about a set of custom rods, just a little shorter maybe of a stronger metal (billet?). That way you dont have to worry about taking off metal off the top of a piston . They would probably be more expensive though.

 

[tractorman86]

that would be the right way to do it justin but getting custom rods made wont be cheap at all. maybe someone needs to see if C.A.T. will do ithttp://www.catpep.com