Low Mount Turbo System (II)

[Lextreme II]

From my personal experience. The LMTS worked pretty good. I had used Nissan turbos and they were not in the best of shape. I had oil leak. I wonder if have brand new turbos like the Garrett GT28RS (rated 320-350 hp each )how would it perform. With T3 (.48 A/R ), they responded very well. I know STS is using the Rear-Low mount system, but i wonder if they have any issue with the oil return. Anyone have the inside information on the oil return? I know they use Tilton oil pump for their oil return. If the oil issue is solved, i think it pretty project. What do u think?

There couple of issues should be considered:
1. Oil Return
2. Fitmentship
3. Clearance.

 

[Murphy]

This seems like a good place to ask you - you say in the original article that "low mount turbos will not allow you to lower your ride." From the photos though it didn't seem that they projected all that far beneath the car. How much ground clearance do you actually lose with the low-mounts?

 

[Toysrme]

On my ES, the original setup was with the turbo at oil pan level (It was pumped to the pan), tho when I twin turbo in the next few months I will scrap that setup. It's not just STS, if you search hard enough, you can find a bunch of aftermarket companies that are doing low mount systems at various points on the exhaust.
If the oil returns still have some downhill slope to it without many turns you'll be fine. A T'd 3AN line would be as large of a supply as I would feed them. I would be weary that 4AN would flood them when the pressure rises.
STS, has to use an electrical oil pump to push the oil back into the bay. They choose to shoot it through an oil cap, but when you cover any type of distance you have to pump it. A side note, mechanical pumps can draw oil a long way, electrical pump's not very far.

It's not going to drain horizontal. If you can get some slope to it, you're OK. Even if it drops just two inches down to your oil pan tap, as long as the return line is big enough & doesn't have any restrictions you're fine.

 

[rarson]

Standard journal bearing turbos can take a lot of oil pressure. I feed mine off the outlet of the oil pump. I have a feeling that, were the return at a slight up-angle, I'd still be able to have proper oil flow.

Ball bearing CHRA's require LOW oil pressure. On my car, I would use a banjo bolt off the head for the oil feed. This I think would require you to have a gravity drain. I don't think a pump on the outlet would be feasible because you'd have to fine tune it to the point where it pumps as slow as gravity would drain it. Otherwise you might get too much oil passing through or not enough.

 

[stevechumo]

I have an idea on the oil return issue on the low mount turbo although I haven't tried it. I might get an oil pressure gauge and measure its psi from the turbo's oil return line to an external dump pan, in the free-flow-gravity condition. Since the car is jacked up, I should have enough clearance to test it. After I know its reading, hook an oil pump, with the oil gauge after it, to its return line and adjust it as according to the free-flow-gravity condition. Will anyone try this?

 

[Toysrme]

There isn't any psi from the oil return.

 

[Lextreme II]

How about self-contained turbo?

 

[rarson]

I don't see why it wouldn't work, but again, you'd have to control the pressure on both sides, and you'd have to make a new heat exchanger setup. Keep in mind that this will be a lot easier with journal bearing CHRAs.

 

[stevechumo]

There isn't any psi from the oil return.

But I think there're at least some light pressures besides the gravity pull. That's why the oil is pumped from the pressure sensor below and up. Although the pressures might be lost in the center housing, however, there're still some forces more than the natural gravity. This could be seen by observing the oil return line at priming the turbo. The first few cranks produce no oil, however, when the turbo is fully primed, the oil is pushed out the hose with some forces along with the cranks. Due to the newer turbo designs, the oil pressures should even flow more freely in the center housing, which means less pressures loss.