Ejkej Posted April 19, 2012 Share Posted April 19, 2012 (edited) Guys, once again I need your help - Today I have driven my car for the first time after rebuilding the engine. It is a n42/n42 combo with flattops, itbs, 0,5mm overbored, ca 10,5:1 CR, around 210 psi on all 6 when warm,Oil is 10w60 castrol edge racing. After few miles I noticed that the oil pressure rises to almost 90 at the gauge and after lifting foot from gas pedal it slightly decreases. But it operates in a higher range than before rebuilding... When rebuilding a new oil pump was installed, ITM brand. I know there is a pressure valve in the pump that might be stuck, but maybe You have other suggestions? The engine isn't yet tuned - I am going to for a dyno session on Saturday to set AFR and timing for best effects, but is it safe with such a high oil pressure? Thanks in advance! Edited April 19, 2012 by Ejkej Quote Link to comment Share on other sites More sharing options...
Zmanco Posted April 20, 2012 Share Posted April 20, 2012 How are you measuring oil pressure? The factory oil pressure gauge is notoriously inaccurate. Install a mechanical pressure gauge (they're inexpensive here in the US ~$25 from Summit), even temporarily, to check what the pressure really is. The pressure valve is controlled by a spring behind the large bolt at the bottom of the oil pump. You might want to pull it out to make sure that everything is ok. Lastly, turn the ignition on but don't start the engine. The oil pressure gauge should not go beyond zero. I can't help you with your questions if this will damage the engine. Quote Link to comment Share on other sites More sharing options...
beermanpete Posted April 20, 2012 Share Posted April 20, 2012 A fresh engine will generally have more oil pressure than a worn engine. That being said, 90 PSI does seem a bit high. You should verify the pressure with a differnt pressure gauge (not an OE type). If the ITM pump is a generic OE replacement part the pressure should be the same as stock, about 60 PSI. I cannot say that the high pressure will or will not cause any damage but I reccomend verifying the oil pressure before running the engine much, especially at high RPM. Quote Link to comment Share on other sites More sharing options...
kaito Posted April 20, 2012 Share Posted April 20, 2012 The super thick oil is probably the culprit. Holy molasses batman! Quote Link to comment Share on other sites More sharing options...
FricFrac Posted April 20, 2012 Share Posted April 20, 2012 Guys, once again I need your help - Today I have driven my car for the first time after rebuilding the engine. It is a n42/n42 combo with flattops, itbs, 0,5mm overbored, ca 10,5:1 CR, around 210 psi on all 6 when warm,Oil is 10w60 castrol edge racing. After few miles I noticed that the oil pressure rises to almost 90 at the gauge and after lifting foot from gas pedal it slightly decreases. But it operates in a higher range than before rebuilding... When rebuilding a new oil pump was installed, ITM brand. I know there is a pressure valve in the pump that might be stuck, but maybe You have other suggestions? The engine isn't yet tuned - I am going to for a dyno session on Saturday to set AFR and timing for best effects, but is it safe with such a high oil pressure? Thanks in advance! Uh which is thicker - 10W60 or tar? As Zmanco stated the stock sender/gauge can be way out. Make sure you are measuring with a known working gauge. Once you know what your pressure is accuarately what is the pressure when you use oil designed for Earth temperatures rather than Mercury like 10W30? Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted April 20, 2012 Share Posted April 20, 2012 The super thick oil is probably the culprit. Holy molasses batman! No kidding! 10W60? wow. Quote Link to comment Share on other sites More sharing options...
Tony D Posted April 20, 2012 Share Posted April 20, 2012 Ditch the heavy oil, you are costing yourself horsepower. Verify with mechanical gauge. For all intents and purposes a straight 30 wt will handle your needs. The multi-vis is good for quick oil pump prime and pump-up to the top end. More important than high viscosity is the anti-scuffing properties of the oil. You can have 100wt in there and still wreck your cam without enough zinc in the oil! Quote Link to comment Share on other sites More sharing options...
Zmanco Posted April 20, 2012 Share Posted April 20, 2012 I began to wonder if maybe 10W60 was a typo, but it's not: http://www.castrol.c...ntentId=7018619 Wow, I can't imagine needing to operate an engine across such a broad range of conditions without being able to replace the oil with a different weight. For the original poster, as you can probably tell, in the US we just don't have oils with such a wide range. 20W50 is the most extreme that I've seen, and even that's becoming harder to find. BTW, this is a full synthetic oil. Most engine builders recommend using a non-synthetic oil to make it easier for the rings to seat. Some also prefer a single weight such as 30W. Quote Link to comment Share on other sites More sharing options...
Tony D Posted April 20, 2012 Share Posted April 20, 2012 Oh no...you just aren't looking in the right places Zmanco! Go to some Harley Shops and 20W70 and in some cases THICKER straight-weight is available! Air Cooled is a bit different than our mills, but generally higher viscosity is generally a cover for a compromise elsewhere... Quote Link to comment Share on other sites More sharing options...
Ejkej Posted April 21, 2012 Author Share Posted April 21, 2012 (edited) Thanks for your opinions! As for the oil - I decided to use this particular oil after recommendation of my friends, who have experience in building rally and race engines - I know it has different specs than oils recommended by the manual. However, I plan to use Motul LeMans 300V 10W50 - next time I will change the oil. After weekend I will check the oil pressure with mechanical gauge, I have checked the valve in the oil pump and it is working, however the spring used in a new pump seems to be "stronger" than the one used before rebuilding. Today I spent few hours on a dyno and have all set to following results: Max BHP: 206 at 6000RPM Max Torque: 253 at 5000RPM The number were ca 10 points better, but with higher operating temperature, the preignition knocking occurred around 5000, so we had to change the ignition map. The oil pressure was moving between 45-85 (reading the stock gauge). Edited April 21, 2012 by Ejkej Quote Link to comment Share on other sites More sharing options...
Leon Posted April 21, 2012 Share Posted April 21, 2012 As Tony said, you're keeping power away from yourself. Switch to a 10W-30 with ZDDP and everything will be happy. Quote Link to comment Share on other sites More sharing options...
Tony D Posted April 21, 2012 Share Posted April 21, 2012 Oils WAY too heavy. Guy running heavy oil are usually compensating for errors elsewhere. A most excellent marketing tool was Texaco Halvoline, when sponsoring CART cars (Buick Stock Block Turbos at the time...) Those guys had cases of 5W30 just like you find at any auto parts store. And that's what they ran in the race! Filled it one quart at a time from the same plastic bottles you could buy. Heavy oil wastes horsepower. The Datsun L has a very well designed oiling system. There is no need for the heavy oil. Quote Link to comment Share on other sites More sharing options...
Ejkej Posted April 23, 2012 Author Share Posted April 23, 2012 OK, I will go with oil with lesser viscosity next time I change it. Thanks! Quote Link to comment Share on other sites More sharing options...
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