ENGINE REBUILD and machine shop

[WOTURBO]

I am looking at rebuilding an 06 short block, only a stock rebuild. What pistons, rings and bearings are the majority of people using? Cummins or Mahle pistons and rings? Cummins or Clevite bearings? If anybody was going to do one upgrade out of an exhaust manifold, intake setup or a cam which would they pick?

Also does anybody know of a decent machine shop in the Portland OR area?

 

[Joseph Donnelly]

Cummins and Mahle are both good. The shop has to be better than decent for good ring seal at 35 psi boost, and a very smooth head gasket surface per Cummins specs. Most shops think it is "smooth" when it looks like a concrete road.

 

[WOTURBO]

Joe, what kind of things should be looked at to make sure you get good ring seal?

 

[CKelley1]

you need the cam to get rid of part of the in-cylinder egr. I use pdr but colt stage II or a Hamilton is good. for the intake, get a complete takeoff from a 6.7 and add a psm kit. exhaust manifold, if that one is ok leave it alone, if you are worried about it, get a three piece one. to get a good ring seal, the machine shop needs to be a good one to get near minimum tolerance and true uniform shape on the walls when they bore it. the next size piston over stock is 0.5mm. because I have so many cummins engines I have an account with them at mechanic rates, the cummins parts cost me about 15% over aftermarket so I stay cummins.

 

[jelag]

A lot of OEM production engine manufacturing uses a brush hone to finish off the bore... a good example is that if you run a clean dry red rag into a normal bore/hone cylinder the rag will catch on the cross hatch after being finished honed... but on that same block you run a brush hone down the bore after 8-10 strokes of the brush.... it removes all those burrs that caught the rag... now the rag moves through the bore...

When we were re-manufacturing truck air compressors.. a leak down test on a bore/hone new compress compared to a bore/hone/brush hone compressor showed that the rings were seated better and showed less leakage... after the brush hone process... and I know most of the OEM's who build gasoline engines brush hone as a final step...

Do any of you know if this process in the diesel helps seal and break in the rings better....

 

[Joseph Donnelly]

I have gotten good ring seal with a "brush" hone with the little abrasive balls, but that was with chrome Cummins rings ten years ago. I don't know what rings are being sold these days for Cummins B engines. For a bore and hone job, I would go to a good race machine shop since they will understand boring and honing for best ring seal.

 

[jelag]

Joe.. the guys I've interviewed for some work in the race shops have this swollen head about how good they are.. but I've found 2 and picked one... who's been doing basic light truck and diesel work for the past 10 years..

I assume with the cost of these pistons it seems to be more cost effective to sleeve and re-ring stock pistons over going to .020" over size... if the pistons are in good shape...

I'm going to have the guy use either the ball style or brush style to finish the bore.. I'm convinced its a better finish.. on the truck compressors.... they were moly rings.... but there was a measurable difference.... with the leak down testing after we ran them on the dyno...

 

[Joseph Donnelly]

Besides the obvious areas for piston problems, including the skirts, the ring lands could be worn. Thus, I would get new pistons myself.

 

[JJPage]

This is who I would contact in the Portland area, if they can't accommodate you, they will certainly point you in the right direction.
http://sourceautomotive.biz/