LS engine turbo feed size
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LS engine turbo feed size

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    Junior Member Huffa350's Avatar
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    Default LS engine turbo feed size

    What would the correct size oil feed lines/restrictor size be for twin Borg Warners on LS 5.3 wet sump engine? I have and was recommended 4an hose with no restrictors, I am told the borgs have built in restrictors but they still look like 4mm holes. I have been running main bearings and wondering if the turbos are bleeding too much oil off. Am been told by some to drop to 1.5mm restrictors

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    Or Seth, either one Budweiser's Avatar
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    Hey Huffa, it's Seth, we've chatted a bit on LS1Tech.

    I couldn't tell you what is the best for your specific turbos. But, I ran 2 4AN feeds on my twin journal bearing turbos. They were tapped from the oil pressure sending unit port on the top of the flywheel end of the engine, non restricted, and I had 50psi at idle on a modified stock oil pump. I just shimmed the relief springs in the pump with washers. IIRC, about 0.120" of shim.

    I chose this setup based on the success the other jet boat guy I told you about.

    My thoughts... if there is sufficient oil volume at idle to build acceptable pressure, it's likely good with increased RPM too. For the engine anyway. If there is some good reason to run restrictors for the turbos' benefit, that's a whole different thing. But, I don't think it would have a impact on engine oiling.

    Just my thoughts.

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    Junior Member Huffa350's Avatar
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    Hi Seth, cheers for that. The outfit who supplied me with the turbos say no way to any smaller than 3mm as will cook the bush, but me mate has bush turbos, beargo so not borgs but he only runs about a 1.5mm restrictor, he runs the exact same sump as me and never had an oiling issue with either engine or turbos, so that got me wondering

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    Or Seth, either one Budweiser's Avatar
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    Quote Originally Posted by Huffa350 View Post
    Hi Seth, cheers for that. The outfit who supplied me with the turbos say no way to any smaller than 3mm as will cook the bush, but me mate has bush turbos, beargo so not borgs but he only runs about a 1.5mm restrictor, he runs the exact same sump as me and never had an oiling issue with either engine or turbos, so that got me wondering
    I'd really hate to see you have issues with another engine, so I'm not making conversation without taking the gravity of the whole situation into account. And, I'm not any sort of authority or guru in the matter either. That said, I don't think you've had an oil volume problem, that restricting the turbo feeds would change.

    Correct me if I'm not remembering accurately. You've had 2 engines fail. The first one had issues with the center (thrust) main bearing, and the second spun a cam bearing and bearing material gummed up on a lifter and stuck it in the bore, hanging the valve open... or something like that. To my recollection, there wasn't an issue with the main bearings in the second engine. Is that correct?
    Last edited by Budweiser; 10-29-2017 at 09:33 AM.

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    Or Seth, either one Budweiser's Avatar
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    Side note, I know you've posted here before. Did the site not let you log in with your old user name?

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    Junior Member Huffa350's Avatar
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    Yea I forgot password and my email has changed so couldn't retrieve it. I have had third engine go since we last spoke. Kind of managed to save it in time, the sump had a crack so I let the oil go after about an hour or so running to repair it and it was grey. Pulled engine down to find bearings starting to go. So its had new bearings installed, new lifter trays relieved to help with drain back and oil drain backs from the rear of heads to sump just in case

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    Or Seth, either one Budweiser's Avatar
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    Quote Originally Posted by Huffa350 View Post
    Yea I forgot password and my email has changed so couldn't retrieve it. I have had third engine go since we last spoke. Kind of managed to save it in time, the sump had a crack so I let the oil go after about an hour or so running to repair it and it was grey. Pulled engine down to find bearings starting to go. So its had new bearings installed, new lifter trays relieved to help with drain back and oil drain backs from the rear of heads to sump just in case
    Oh jeez Huffa. I'm real sorry to hear that. Lot's of questions...

    • Which bearings were showing wear? Cam, main, rod? And, was it all of them or random? Pics?
    • Was this the same block from the damaged cam/lifter bore engine?
    • Did you ever start logging oil pressure?
    • Do you have an oil temperature gauge? If so, what temp does it run at?


    Man, I'd really like to figure this out and start hearing about victories.
    BTW, I'm sending you a PM.

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    Junior Member Huffa350's Avatar
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    Thanks, I pulled a couple of shells, cant remember now if it was big end or mains I looked at as was a while ago now, however it had marks. The engine went back to the supplier/builder who has been so great over this issue. He stripped engine completely and told me it was starting to go on the mains. It is the same engine that run the cam bearing, I believe these cam bearings are still fine. I did have a capillary oil temp gauge at the time, but oil temp never got up as hardly ran the thing. So I have the engine back in and have just had the ecu hooked up to data log, also the builder extended the sump now holding about 7.5 litres. I just ran it the other day on trailer in water ready to go for a run to discover rear main seal pissing out, fark me! So got that off in the boat last nigjt by lifting the rear of engine up to get the two bottom bolts out, will get a new seal

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    Junior Member Huffa350's Avatar
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    One picture of a shall I had
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  12. #10
    Or Seth, either one Budweiser's Avatar
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    Quote Originally Posted by Huffa350 View Post
    Thanks, I pulled a couple of shells, cant remember now if it was big end or mains I looked at as was a while ago now, however it had marks. The engine went back to the supplier/builder who has been so great over this issue. He stripped engine completely and told me it was starting to go on the mains. It is the same engine that run the cam bearing, I believe these cam bearings are still fine. I did have a capillary oil temp gauge at the time, but oil temp never got up as hardly ran the thing. So I have the engine back in and have just had the ecu hooked up to data log, also the builder extended the sump now holding about 7.5 litres. I just ran it the other day on trailer in water ready to go for a run to discover rear main seal pissing out, fark me! So got that off in the boat last nigjt by lifting the rear of engine up to get the two bottom bolts out, will get a new seal
    The reason I ask about the oil temp is, I'm half way curious if it's running too cool for the oil you're using and the relatively stock automotive bearing clearances. Too cool can be worse than too hot... or so I've read. I haven't had to deal with that issue personally, but it may be worth some consideration. Typically, a purpose built engine will have greater bearing clearances than stock automotive clearances. If your engine is essentially a stock bottom end deal, it may be worth eliminating the oil cooler. At least for some testing, to see what the temps get up to and if it's even needed in the first place. Just thinking out loud.

    Also, is that a front sump oil pan? I thought you had a rear sump 8qt pan, out of a Holden Commodore or something. No? It's just my logic, but it feels somewhat imperative to have a rear sump pan. Does it not?

    Sorry to hear about the rear seal. At least you don't have to drop the pan and pull a main cap like a small block. Easy enough to do with the new design, especially in a boat.

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    Junior Member Huffa350's Avatar
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    Yip I've left the cooler disconnected the last engine just to eliminate that, water temp runs in good operating range so dont think its cold oil. Yes it is a front hump, I realize thats not perfect but all the rear humps fouled on the bottom of hull. My mate has successfully run with the same sump for years completing races and marathons without ever having an oiling issue on his twin turbo

  14. #12
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    Quote Originally Posted by Huffa350 View Post
    Yip I've left the cooler disconnected the last engine just to eliminate that, water temp runs in good operating range so dont think its cold oil. Yes it is a front hump, I realize thats not perfect but all the rear humps fouled on the bottom of hull. My mate has successfully run with the same sump for years completing races and marathons without ever having an oiling issue on his twin turbo
    Good info. I'll let that soak in a bit and see if any bright ideas arise.

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    I usually run the commodore 8qrt pans, but ls3 camaro pan is the same now just has the in pan relief valve you have to block off and the bosses on the side for the oilcooler. New deal runs the ls3 pan, new pulloff with pickup/windage tray was only 120 shipped then i put 10an return bungs on it. Had great luck with the commodore pan , i expect the same from this ls3 pan. Theyre both central sumped but baffled really well. That shell looks like its lost pressure to it a few times, time for better pan or accumulator.
    Last edited by IMPATIENT 1; 10-29-2017 at 07:45 PM.

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    Junior Member Huffa350's Avatar
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    Thanks impatient for your thoughts. I hear what you say about the pan, but the bit I don't get with my engine is how the pan could cause that when all I did on the last engine was tune and run up and down a flat and wide tidal river in a straight line, no tight turns or turning at speed, not even abusing it really. I do have an accumulator to go on, but felt I needed to find the cause of the issue rather than bandaid it, in saying that I'm so over it I might have to just go with it and if it keeps my engine going for more than a couple hours I'd be stoked! Whats going to be the cheapest way for me to dry sump? What do you think about my turbo feed size and the possibility of them bleeding too much oil off the system?
    Last edited by Huffa350; 10-30-2017 at 08:40 AM.

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