So im gonna try and keep it short and simple guys. I got a 2002 vp cummins I just installed some compounds on. a 62/75 both Borg Warner and I got a set of DAP 150's. So I ended up having serious boost leaks which I addressed them all (I have a smoke machine) and the truck still wont spool. Laggy as it can be, I will see 50 psi only at redline (saw this with my single) and smoke under light throttle like a bad joke. Blocked wastegate to rule out. Not only that if I get on it hard pours white smoke like mad till I shut it off, will smoke out my shop parking lot. Doesn't smell like oil is getting burned through cylinders though? I see what looks to be oil coming from exhaust where the pipe pieces mate. The truck doesn't run like crap just feels naturally aspirated. Doesn't make sense I didn't mess with anything other than the manifold/turbos. checked blow by (ole filler cap on the valve cover) and doesn't move at all. Im clueless and ANY suggestions would go a long way. Thank you all and have a blessed weekend.

 

Could the white smoke be maybe from one of the turbo's leaking? Not sure if the BW's are ball bearing or not, if so they might need an oil restrictor on the feed line. Will it build boost throughout the rpm range, or will it stay stagnant and then spike at redline?

 

The turbos will progressively build boost through RPM range at steady pace. Then finally peak at redline. It’s not the normal turbo setup where as soon as it sees 15-20 psi and it rockets to peak boost. The oil return was linked a little so I re routed it but still may be a little kinked. Not near as much white smoke so it’s getting closer. Still baffled at the slow boost and low boost. Gonna fix the kink for good tomorrow and see how it goes.

 

A kink in the drain or even too small of a drain hose can cause oil to backup into the center housing, and leak past the seals. One time bigger is definitely better, too big of a drain line won’t cause any issues, and try to make it as vertical as possible, or a nice sweeping curve into the block/oil pan. As for boost, maybe a fueling issue?

 

So I fixed all the oil drain kinks. The turbo DOES NOT light in 1st gear... at all. ill see around 20 PSI until 2nd gear then ill see 60-65. The waste gate is blocked. At WOT I can see haze of grey smoke from exhaust. EGTs are higher than a stoner on 4/20 (1100-1200) cruising highway speeds 65-70. The truck is drivable I guess, but something is still wrong. So do I need an oil pressure regulator on the big turbo? I don't see why the little one wouldn't need one but the 75 would. And I heard that you actually want the wastegate to open to spool the big turbo? Seems like this is getting narrowed down.

 

Strange, high EGT’s usually mean too much fuel and not enough air, but too much fuel also means black smoke, and with temps that high it should look like a coal fire behind the truck. I can see having the wastegate on the big charger open, this way the small turbo spools and makes enough boost to efficiently spool the big one. If it’s trying to spool itself and the big turbo at the same time, that could explain the incredible lag and boost spike at redline when the two of them finally light off.
I know journal bearings don’t need restrictors on the oil feed, ball bearings do. It really depends on what the manufacturer calls for, though. They designed the turbo, after all.

Joe

 

Based on a quick search for rebuild kits, they appear to be journal bearings, so you shouldn’t need an oil feed restrictor to control pressure. As long as the oil can drain it should be fine.
I would try opening up the wastegate on the big charger and see how the truck reacts, and then figure out how to control the wastegate so it’ll close when the small one spools.

Joe

 

Ok thanks good to know about the oil restrictor I just read something about them but if I don't need it then I wont. The big charger doesn't have a wastegate its just a box turbo. My 62 is gated. Somebody told me that I should gave it hooked up, but set it up closed to spool the little charger and open it around 15lbs to help spool the bigger charger. I'm gonna do some tuning today.

 

The only journal bearing turbo’s that really need them are the China turbo’s. The seals are crappy so the flow of oil blows them out.
As for the wastegate, that also makes sense. The small turbo spools, which is the 20psi or so you said you were seeing and then it creates a restriction in flow preventing the big charger from spooling until there’s a tremendous amount of exhaust flow. I see there’s a lot more to compounds than just bolt the turbo’s on and crank the fuel up. Good luck with it.

Joe

 

So the white smoke problem is fixed and that was my major concern. I appreciate all the help and will look more into the slow spool time.