Hello Ken, We to own a 1994 motorhome with the 8.3 in it. It is a Barth Sovereign, 3Pms 6' that tips the scales at 31,000 lbs., She sits on a Spartan IC chassis. Over the last 15 years I have tried many improvements that incrementally upgraded the performance on this coach. I installed called EGT and Boost gauges first then as a Banks Dealer, I naturally installed the Stinger system. Stock she ran max EGT's in the 900 degree range, 24 PSI Boost. After the Stinger system, boost went to 30 and EGT went to 1250, 1350 on a very long, hard hill-climb, I did verify the that the timing, using spill port method, was at 12 degrees, stock for my engine.



We ran this way 60,000 miles and when, knowing the "cork" in the system was the tiny turbo, I replaced the HX35 with a Borg Warner SV366 from BD Diesel Performance, also a dealer for them. The EGT's went from 1350 down to 1050 on the same hard pull. After the turbo test I went ahead and installed the #5 fuel plate which brought the EGT's back up on a hard pull but I adjusted it down to 1250 max. Fuel economy went up an average of 2 MPG from 6-8 MPG to 8-10 MPG, we even logged 10.67 in 2017 on our way back from Nova Scotia on primarily two-lane highways through small towns. The downside of the larger turbo is that it is non-waste-gated so I spent a lot of time doing trial and error adjustments to the aneroid but got it pretty damned good, a puff of smoke leaving a stop and clear exhaust after that, max boost recorded was 40 PSI, cruise boost was 4-5 PSI. With a calculated 450 HP, we ran this configuration for 50,000 miles.



The coach now has 180,000 miles on it, about three years ago I noticed an oil leak where the timing gear case met the engine block, apparently a common Cummins issue. Last week I dropped the engine and transmission out of the coach and stripped it down to replace the gaskets and crankshaft seal. In the process I replaced the injection pump which had developed it’s own leak at the throttle shaft and with that many miles on it, I was going to have it rebuilt but made a steal of a deal on eBay. I purchased a ReCon P7100 Marine Injection pump from a 8.3 CTA 450- M engine. Basically the same pump and governor but tuned for the 450 HP engine, the biggest difference is the timing spec for that engine, it is 24 degrees BTDC.



When I first started the engine on the stand the first thing I noticed was a distinct change in the idle sound, it was crisp and throttle response was instant. After running it for a few hours and assured myself that there were no leaks, I lifted it back into the coach. The road tests, two at ten miles each, flat land, were quite impressive, throttle response is instant, where I had to wait for boost to build before, it comes up instantly now. Normal acceleration is with much less throttle now, a puff of smoke upon leaving then clear after that. Boost rises smoothly to 38 PSI, EGTS seem to top off around 1150, but other than hard acceleration with my truck in tow, no hard sustained pull. Cruising EGT’s have risen from 850 to 1050 which tells me that the fuel is burning more completely in the combustion chamber. As soon as we get the all clear, we will go visit in-laws in Kilgore, the rolling hills on I-20 in East Texas pose some good, albeit short, pulls which will get me more conclusive data.



The only negative I see now is the same complaint, if you want to call it that, of light white/blue smoke on cold start. This clears up as soon as the engine reaches operating temperature though. I am anticipating another mile or two per gallon improvement too, maybe a pipe dream but it seems to do a lot more work with less fuel.



Billy T