Reply With QuoteHow big are your oil return lines to the pan, do they have a straight shot. Drains that don't work well can cause oil to go out the exhaust.
I just received a 500 ci RaceAero EFI twin turbo engine. The engine is a fresh rebuild and was running when shipped. We put it on the dyno and both turbos leak oil out the exhaust. We tore the turbos down and the seals and bearings seem to be within spec tolerances. Now we're going to do a leak down test to make sure we're not getting pressure from the crankcase. Any ideas on what is causing the turbos to leak??? frown
How big are your oil return lines to the pan, do they have a straight shot. Drains that don't work well can cause oil to go out the exhaust.
The drain lines look like 1/2" out the bottom and go directly to the oil pan. The lines in are -6 size, much smaller. The turbos are Garrett T04Bs. The oil pressure now is 77 psi cold and 69 psi when the engine is warmed up.
Sounds like your drains are too small. To give you a comparison, I was running -4 oil feeds with 5/8in drains on RayJay 375 E-10s. While I'm not too familliar with the Garrets, I know they are bigger and it would thus stand to reason that they might have bigger oil passages. If you're puking oil, its usually because you can't drain it back fast enough (providing that your seals are still good). The reason you can't drain it back fast enough might be the drain hose I.D., or too much crank case pressure. If the crankcase is under pressure, the oil will be held up in the drain tubes and eventually back up and overcome the seals in the turbos. Something to think about. I'd swap to bigger drains, and take a good look at your crankcase ventilation.
I don't know about this next suggestion, but you could run it past a couple of the guys and see what they think. Where are you pulling your oil off the motor? If you are pulling closer to the pump on a larger gallery, you could be getting too much oil to the turbo as well. I pull my oil from the front most plug in the oil gallery on the drivers side of the block. By then, all of the mains have already gotten their oil, and the I.D. of the oriffice is smaller than the usual oil pressure sender location right above the filter pad.
I hope that helps, and feel free to post up a pic of your setup. I'd love to see pics of more FI setups.
Good luck,
Chris
Chris is right. Drain lines to the pan should be minimum of -10 AN also.
I have -12 on mine.
It's all been covered, one last thing the fittings in the pan need to be above the oil level and in the middle of a main journal.
Thankyou for the excellent responses. We checked the oil lines and the inputs are -4 with -8 output. We're going to upsize the outputs to -10 or -12, put the turbos back together and see what happens. We did the leak-down test and two cylinders are at 12%, the others @ 10%. Both valve covers have oil breather caps and appear to be free flowing. The sparkplugs have a little soot, we think the engine is running rich, but no sign of any oil on the plugs. Will keep you posted.
Jim:
Sounds like there are some good suggestions. I have the larger lines on my oil returns as well and it drains above the oil level in the pan.
Did you receive the info I sent out to you?
Sounds like a nice project, Good Luck!
BG
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