Lower oil pressure with new forged ls1,single turbo.
09-20-2007, 03:18 PM
#21
Correct me if I'm wrong, but I don't see a reply to the bearing clearance question posed in post #2. OEM is around .0018 and sometimes motors are built a little looser for a different application. So what are the rod & main clearances? With more space between the metal, the pressure will be lower.
Mine was built a little looser (.002-.003) and I have similar pressure as yours. I'm still using generic 10W30 dyno oil for break-in as I only have ~500 miles on the motor.
Try something like a 15W50 or 20W50 viscosity (non-synthetic if the rings haven't seated) to see how your oil pressure reacts.
Mine was built a little looser (.002-.003) and I have similar pressure as yours. I'm still using generic 10W30 dyno oil for break-in as I only have ~500 miles on the motor.
Try something like a 15W50 or 20W50 viscosity (non-synthetic if the rings haven't seated) to see how your oil pressure reacts.
09-20-2007, 04:14 PM
#22
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Jim,
Im trying to get that info but the engine was built over a year ago and the builder said it would take some time to dig up that info. He also recomended 20W50. Any down side to running that thick of oil. Will it still be okay for the turbo?
Im trying to get that info but the engine was built over a year ago and the builder said it would take some time to dig up that info. He also recomended 20W50. Any down side to running that thick of oil. Will it still be okay for the turbo?
09-20-2007, 06:22 PM
#23
Originally Posted by SPRAYED 01
Jim,
Im trying to get that info but the engine was built over a year ago and the builder said it would take some time to dig up that info. He also recomended 20W50. Any down side to running that thick of oil. Will it still be okay for the turbo?
Im trying to get that info but the engine was built over a year ago and the builder said it would take some time to dig up that info. He also recomended 20W50. Any down side to running that thick of oil. Will it still be okay for the turbo?
09-20-2007, 09:11 PM
#24
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I'm running Shell 15W40 Rotella in my 3800 mile TSP stroker, along with my old TSP ported oil pump from my old heads/cam motor. Anyways, when the oil is still cool I get AWESOME oil pressure. When my oil temp gets to around 205-215 (normal operating temp) I only see about 32-33 pounds at idle. I also use a WIX 51042 filter, which supposedly is one of the best filters around. The pressure does come up and I'm seeing 45 psi by 2500 rpm when its hot, but I did notice this same phenomenon with my new motor. I'm not too worried about it.
09-20-2007, 10:37 PM
#26
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IMO pressure isn't as important as proper oil flow. You only need so much pressure to keep the oil in the bearings, anymore than that is overkill. You do however, need to have at least a certain amount of oil flow. Since pressure and flow are inversely related at X amount of oil, if you increase the clearances without increasing the total flow (oil pump's ability to pump essentially) then your pressure will obviously drop. Tighten the clearances, and pressure goes up accordingly. If all of that is true, then your oil pump is flowing the same amount of oil it used to but the motor is looser, and thus your pressure is lower....BUT your engine is getting the same amount of oil it used to, so it should be fine. This is of course assuming that the pump is functioning properly and your o ring is undamaged, etc.
Also, Personally, I don't like 10 psi per 1k rpm rule of thumb, as that doesn't really hold completely true in the real world.
Think about it: Say your car idles at ~1k, it should have 10 psi? No. Say it idles at 1k with 30psi...so at 6800 it should have 88psi? I don't know about you guys, but my car doesn't go up that high.
IMO, if you have reasonable pressure at idle, and it obviously goes up as RPM increases, you shouldn't be worried. Especially if you use a good high quality oil.
Also, Personally, I don't like 10 psi per 1k rpm rule of thumb, as that doesn't really hold completely true in the real world.
Think about it: Say your car idles at ~1k, it should have 10 psi? No. Say it idles at 1k with 30psi...so at 6800 it should have 88psi? I don't know about you guys, but my car doesn't go up that high.
IMO, if you have reasonable pressure at idle, and it obviously goes up as RPM increases, you shouldn't be worried. Especially if you use a good high quality oil.
09-21-2007, 12:13 AM
#27
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Originally Posted by SPRAYED 01
What psi do you see at full throttle?
In the mid to high 50's.... to be honest with you though at full blast I'm really trying to pay attention to other things than my oil pressure
09-23-2007, 08:08 PM
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I switched to 15w-50 mobil one today. It does not go any lower that 30psi at idle which is better. At full throttle its pretty much the same, about 50psi.
09-24-2007, 01:19 PM
#31
Not according to the inquiries I made after my motor was built. Shop #1 indicated they build them at .018mm and they'll grow to about .025, shop #2 indicated I should have used stock clearances if I wanted stock pressure, shop #3 (whom I bought the new ported oil pump) didn't think it'd be a big deal, but recommended using 5w30 or 15w50 oil (the latter when racing).
http://www.z06vette.com/forums/archi...p/t-75982.html
Another statement I've read is not to use the 10psi per 1000RPM, but 10psi per 100HP.
http://www.z06vette.com/forums/archi...p/t-75982.html
Another statement I've read is not to use the 10psi per 1000RPM, but 10psi per 100HP.
09-24-2007, 01:55 PM
#32
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Think problem really sucks. The car runs and drives great,no leaks or wierd noises. So im kinda stuck. Do i leave it alone or do i rip the oil pump out and put a different one in there with the hopes it helps. I just got done with the setup and really dont want to rip it apart again. I just want to know what guys with similar engines with similar clearances are see for oil pressure.
09-24-2007, 01:56 PM
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Jim what oil are you using and how many miles do you have on your motor right now. What are you thoughts? Are you going to call your oil pressure normal or look into making it higher?
09-24-2007, 02:20 PM
#34
I only have maybe 600 miles on the motor. Still using generic dyno 10W30, but I've changed the oil & filter three times already. I wasn't planning on switching to synthetic until 1200-1500 miles and not worry about the oil pressure until then. I have some German Castrol 0W30 stockpiled from the last motor and I'll start with that. If I have to use 15W50, then so be it.
I'm not worried about my idle oil pressure. I haven't made up my mind whom to believe on what oil pressure I need at WOT and/or a specific RPM range. I built the motor to turn 7200 easily, though.
I'm not worried about my idle oil pressure. I haven't made up my mind whom to believe on what oil pressure I need at WOT and/or a specific RPM range. I built the motor to turn 7200 easily, though.
09-24-2007, 02:35 PM
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My oil pressure issue I was having with my 408 is partly due to loose clearences, and the ported oil pump it had on it. I replaced the pump with a melling m-select with the high pressure spring, and it consistently reads ~10psi higher than it used to (both mech and electric), and it ramps to a higher pressure faster when revving.
09-26-2007, 07:04 PM
#37
I think the pressure you are seeing is perfectly fine. With the clearances that you listed your right around where you should be. Plus your running synthetic oil. Your not going to get high PRESSURE. Oil flow is more important than pressure. 40psi while cruising is fine. 25psi at 600-800 idle is okay also. Just let it go and enjoy the car. Thats also why you see a lot of HIGH FLOW pumps not HIGH PRESSURE pumps.
09-26-2007, 09:04 PM
#38
I'm totally new to LSx engines but I still trust in the theory of 10psi for every 1000rpm's. And no that doesn't mean you should have 10psi at idle, but it means you'd be SAFE with that low of psi. If you spin it to 7grand, you should have 70psi. I've built many small and big block Chevy engines. All had bearing clearances of .0025-.003" and all of them maintained the above pressures. Never had a problem. Now that being said, pressure is really just a measurement of the resistance to flow of the oil thru the engines galleys and bearings. You really need to talk to some pro-engine builders who've used those clearances on LSx engines. That is the only way I'd feel safe in going WOT. Maybe your oil pump can't push that kind of volume thru those kind of clearances. Honestly, with the cost of these new mills, I wouldn't take any chances... that's just me.
