1 fast z Posted November 16, 2005 Share Posted November 16, 2005 Ok, so I have been getting into disscussions with other engine builders about this. WIth say a big Block chevy, you want about 10 PSI PER 1000 RPM. Since the MAIN bearing is so large. But with a smaller bearing motor, such as the L28, It is not needed to have such a large Pressure of oil, right? The more oil pressure is not better, ie. Washes out bearings, takes HP to drive the pump, etc. So what is the LOWEST Solid Oil Pressure that can be ran, say at 7,000 RPM? I belive that 45-50 is PLENTY, and 45 would be fine, as I have run my L28's at this and had no problems. Just wanted to see what some of you guys thought about this. Quote Link to comment Share on other sites More sharing options...
Tony D Posted November 16, 2005 Share Posted November 16, 2005 Generally, this is the case as you stated. The general rule of thumb is 10/1Krpm, but recently with bearing coatings some have been going as low as 5psi. Depends on compresion ratio, and if you have an accumulator. I would get an accumulator, baffld oil pan be damned, $100 to provide that extra 1qt of pressurized oil just in case is well worth it IMO! Quote Link to comment Share on other sites More sharing options...
JMortensen Posted November 16, 2005 Share Posted November 16, 2005 I see that one the opposite way, maybe because I autox and do track days. On a long sweeper that accumulator only has a finite amount of oil. Baffled pan will continue to try and trap whatever oil is in the pan where it needs to be. Look at this thread here: http://forums.hybridz.org/showthread.php?t=103316. It shows a graph of the Accusump activation on a road course. The thing is open a lot. I question the ability of the oil system to fill it back up without a baffled pan in a sustained high g turn. I guess running both would be a good way to protect yourself. Or dry sump it. Then you'd have no worries at all... Quote Link to comment Share on other sites More sharing options...
Pyro Posted November 16, 2005 Share Posted November 16, 2005 I have always heard the magic number was 7psi/1K rpm. I also have a BBC and agree that it needs a bunch of pressure to keep that cam from going flat! After a few cam failures, I now have it idling at 45 psi with tight main a rod bearings (0.0015 -0.0020) and a high volume pump. I haven't had anymore oiling failures for over a year now. Quote Link to comment Share on other sites More sharing options...
Tony D Posted November 17, 2005 Share Posted November 17, 2005 I see that one the opposite way' date=' maybe because I autox and do track days. On a long sweeper that accumulator only has a finite amount of oil. Baffled pan will continue to try and trap whatever oil is in the pan where it needs to be. Look at this thread here: [url']http://forums.hybridz.org/showthread.php?t=103316[/url]. It shows a graph of the Accusump activation on a road course. The thing is open a lot. I question the ability of the oil system to fill it back up without a baffled pan in a sustained high g turn. I guess running both would be a good way to protect yourself. Or dry sump it. Then you'd have no worries at all... J, I autoX and do track days also. I would not be without an accumulator WITH my baffled pan. Either without the other is ASKING for trouble! That was what I was recommending in my above post. One turbo was all it took to convince me about that. I will not even hard street drive corners in a turbo without at least a 1/2 qut accusump unit in it! Plus, prelube is a neat feature... Quote Link to comment Share on other sites More sharing options...
1 fast z Posted November 17, 2005 Author Share Posted November 17, 2005 Well yea tony. You remember what happend at 7200 at the last hard corner of the MSA autocross event last year in ole silver! Yea, stock pan is no good for hard driving. I now use a baffled oil system. Quote Link to comment Share on other sites More sharing options...
Tony D Posted November 17, 2005 Share Posted November 17, 2005 Add an Accusump! Cheap Insurance, and you can prelube that hicomp monster before putting a load on it. Quote Link to comment Share on other sites More sharing options...
Silent Posted November 17, 2005 Share Posted November 17, 2005 on mine, 11 psi at idle, around 850-1000, depends on motor temp. at "indicated" it's about 38, at 6k its around 70 or so. factory oil pumps, or turbo pumps put out 11 psi at idle, according to the service manuals Quote Link to comment Share on other sites More sharing options...
Guest JZ82 Posted November 17, 2005 Share Posted November 17, 2005 My N/A 280ZX usually runs about 30psi at idle and then varies between 45-55 depending on RPM, 45psi being the average. Quote Link to comment Share on other sites More sharing options...
johnc Posted November 17, 2005 Share Posted November 17, 2005 On the NA 3L I ran in the ROD, oil pressure at idle (~2,000 rpm) was 40 psi and at 7,500 rpm it was 100 psi. This is how the high pressure was explained to me: A lot depends on the desired bearing clearances and how much cooling you want from the oil. A racing L6 engine needs to maintain at least 15 psi at the rod journals and the system pressure might have to be high to get this number. You also need a constant flow of oil on the valve springs to reduce heat buildup but you must to be careful about putting too much oil in the head (btw... the reason valve springs lose strength is from heat buildup). Unless some work is done, drainback on the L6 heads is OK for a mildly modified engine but poor on highly modified and high rpm engines. Quote Link to comment Share on other sites More sharing options...
1 fast z Posted November 17, 2005 Author Share Posted November 17, 2005 IMHO, 100 PSI is a bit much, ALOT of HP loss there, while driving that oil pump. Bearings may start to wash out, etc. THis is just my oppinion, and not to be taken as a hit upon you John. I ran 75 LBS on a motor once, then tore it back apart, and the bearings were REALLY washed out. Quote Link to comment Share on other sites More sharing options...
johnc Posted November 17, 2005 Share Posted November 17, 2005 I didn't build the engine and I'm not an engine guy so its no hit on me. Rod and main bearings were inspected after 15 hours of racing and they were perfect. The planned refresh at 25 hours was pushed back to 50 due to the good condition of the bottom end. Remember, every engine is different and builders can tailor a lot of things to meet specific racing requirements. Quote Link to comment Share on other sites More sharing options...
zbloke Posted November 18, 2005 Share Posted November 18, 2005 Just out of curiosity how would you go about improving the drainback of the L6 heads, smooth and polish the area around the valve springs to prevent pooling of the oil?, or are there other tricks? Tim Quote Link to comment Share on other sites More sharing options...
johnc Posted November 18, 2005 Share Posted November 18, 2005 I don't know for sure, but the head I had a lot of smoothing and polishing done. Quote Link to comment Share on other sites More sharing options...
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