Ed,
This fall I began researching an upgrade that would lower the EGT's on our 8.3. It turns out that the engines major issue is that it simply cannot breath. According to the turbo calculator on the BD Diesel website, the 8.3 requires well over 1,000 CFM but the Holset only produces around 425 CFM. I bolted on a Borg Warner SV366 from BD Diesel Performance who specially modified exhaust flange to adapt to the existing exhaust flange/brake. The result was EGT's dropping from 1,350 to 1,050, fuel mileage is now consistently over 10 mpg, up from 8. The fuel plate is now a number 5 which brings the H.P. to around 460, and torque near 1,000 lb/ft, Max EGT's 1,150. We have put over 5,000 miles on with this setup with absolutely no issues. I was able to adjust the off-idle and medium range fuel to accomplish a near smoke-free acceleration.

Billy T

You can call me if you would like the details

Thanks Billy, do you recall what your turbo boost pressure was before and what it is now after mods?

I have the 5.9l but issues are similar! Throttle plates can make a world of difference for sure. I am in the process of turbo evaluation now. I was going to advance the timing but it is way to hard on the engine and I would probably blow a head gasket unless I changed to ARP headbolts. Cylinder pressures go thru the roof.

I will probably run this engine out and replace it with a 6.7L or maybe a built 24 valve common rail engine. 8.3L is just a bit longer and a lot heavier!

Billy those mods sound interesting. I will be in NE Texas last week of Jan, then heading around the gulf to Florida. We will try to stop in to see you on our way through.

Billy

That mod sounds great. Ours runs great but not a mountain climber. Would like to discuss the upgrade.

Ed

Hey all,
The boost was 24 stock, 30 Banks Stinger & I estimate 40 or so now. My boost gauge tops off at 30 but before the next trip I will temporarily mount a 60 pounder to check it out. From what I was reading on the Marine blogs, it should be 40 - 45 PSI. I set the timing on 12 BTDC when I had the head off a few years ago to mill out the broken exhaust manifold bolts.

On our last trip we encountered a long steep grade, the one where they add a truck lane, actually accelerated up the grade, EGT peaking at just under 1,150.

Steve, Helen got your message today. Please gives us as many days notice that you can. We have hookups at work and three extra full hookups at the farm, would be great to see you guys again!

Billy T

Thanks Billy. We are looking at Jan 29-30 or 30-31 whichever is best for you. Looking forward to the visit!

It sounds like you went through the exhaust bolt job a while back. We did not pull the head for mine, the poor guy drillled and tapped 9 bolts with the head in place! A job for a masochistic contortionist for sure.

Hope to see you soon!

Billy curious where you located the EGT sensor, did you also rep[lace the exhaust manifold with a 2 or 3 piece style?

Thanks

Ed, I always measure EGT's just before the turbo. I did have to replace the exhaust manifold but went back with the stock Cummins unit but I did take the Dremel to the ports to match them to the cylinder head. I wasn't sure how a multi-section manifold would perform with an exhaust brake developing 60 PSI of back pressure. The manifold was so pitted that it would not have sealed for very long, we had already replaced a couple of individual gaskets. The cylinder head surface was just as bad so I had the machine shop perform a valve job a mill all surfaces, they did an outstanding job.

I measured the maximum boost pressure today at 40 PSI.

Old vs new manifold,





Shows comparison between old and new manifold and how much it shortened. Good thing the bolt broke because if it didn't the tab on the head would have broken off, that has happened on other 5.9L.





After all said and done I find a crack developing, same place as the last two manifolds cracked but in this case found it before it got into the exhaust area

That new manifold looks a lot better. The old one looks rather primitive to me. The ports are small, sharp corners and the main runs are small. The ports on the new one are bigger and more radiused. Should be way better flow.

I am amazed that the castings shrink that much over time. No wonder the bolts are getting cramped. I will talk to my father one of these days about this. (A metallurgist from way back, he'll bury you with face centered cubic vs body centered crystals, austenite, heat treating, cast iron alloys, nodular iron, wrought iron, malleable iron vs steel.)

I might be tempted to do more work on my coach but not now! I'm finding it to be REALLY easy to work on lately. Just drop it off at the shop, do some heavy lifting and signing with my pen and on home!

Good luck with those projects.