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Oil Cooler for 350Z

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  • #16
    Clint I am in and out today for moving but hit me up on AIM
    Andrew M Brilliant
    Aerodynamicist / Race Engineer

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    • #17
      Loose caboose - do you have a 350Z and a 370Z? What's the issue: High oil temps or low oil pressure on track?

      Clint/Andrew - I could be wrong but I don't see how raising the water pressure will have a significant impact on oil temp OR oil pressure. I understand Andrew and it's an easy/cheap test to possibly determine if there's something else going on but maybe its my lack of understanding on what issue everyone is talking about but either way it's important to have an oil temp and pressure gauge and monitor both. If you have high oil temps, work on the cooling system. If you have low oil pressure, work on the oiling system.

      Andrew - 300*F oil is pretty darn hot... More oil ambient cooling surface area than water? Dang...

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      • #18
        370s are notorious for there high oil temps, kojima and i are working on a oil cooler setup that should eliminate this issue for track day usage. I was just trying to get more insight as to what Drew was referring to

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        • #19
          Originally posted by GreyFocus View Post
          ^btw just curious, what oil cooler are you running? it seems to be harder to find oil cooler kits that fit nismo 350s
          Mine is kind of a combination of a couple kits. Mishimoto oil cooler parts and one of those cheap ebay oil coolers which I am replacing in the next few weeks with an Earl's oil cooler. I mounted mine on the bottom of the bumper reinforcement bar. Not the best location but no need to worry about the mass dampner getting in the way.

          BTW - I used a higher pressure radiator cap on the SRT-4 and it helped a little.

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          • #20
            Originally posted by GreyFocus View Post
            370s are notorious for there high oil temps, kojima and i are working on a oil cooler setup that should eliminate this issue for track day usage. I was just trying to get more insight as to what Drew was referring to
            What heat exchanger are you using? Setrab and PWR seem to be some of the best stuff out there. Brown & Miller Racing Solutions for hoses are also arguably the best ss lines you can get.

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            • #21
              we were most likely going to use a Setrab core, something along the lines of 12x12 in size, off to the side in front of the wheel well with the fender liner vented, mounted up with custom bracketry, shrouding/ducting, and maybe even a slim fan on the back with a cabin switch.

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              • #22
                Billy,

                Sorry if the post is verbose and confusing, Im on my way out.

                My $.02. If your finding a lot of heat getting into the oil then it stands to reason the oil is getting access to something hot that water isn't. If the block casting is the same, water pump is the same and that is happening in the block (which I wouldnt assume either) it would stand to reason to me at least that the issue is your making more heat than you used to and getting localized boiling. If so, coolant pres helps. If its happening in the head, it could be something else (many other things). If it was happening in a bearing I assume you would have found out. It can be surprising how much more heat is generated by a few more horsepower when your talking about riding the knock limit. You cant just increase flow to solve the issue because velocity = pressure you can actually drop the pressure by flowing more, this is the old "your flowing too fast to cool it down" thing without the lack of understanding of whats really happening..

                If you cant change the size of the passages you know where that takes you. Most likely its the head, maybe. But even that I find that just as interesting. So I would want to eliminate localized block heat first if its easy and cheap. Then start trying a million things with the head. This is all assuming you had some decent oil cooling in the first place, which it sounds like it didn't.

                There isnt a linear relationship of the temperature of a metal when your riding the limit of localized boiling. It will be a sudden jump in temperature once you start boiling water and the ability to transfer heat goes away real fast. Oil won't boil until a much higher temperature and if say you have an oil passage and a water passage next to eachother you wont see much in the water temp if the rest of the system is ok and the oil will jump in temperature. So something like that can possibly go un-noticed in your pre production tests for something like a 20 hp bump next iteration of an engine they dont apply the same test rigs they do when they designed the thing originally. All those passages get a spec for min pressure and its tough to maintain when your talking about tight packaging and raising base pres is sometimes an easy solution. But so is an oil cooler...
                Last edited by gixxer_drew; 10-08-2011, 05:44 PM.
                Andrew M Brilliant
                Aerodynamicist / Race Engineer

                Comment


                • #23
                  Originally posted by gixxer_drew View Post
                  Billy,

                  Sorry if the post is verbose and confusing, Im on my way out.

                  My $.02. If your finding a lot of heat getting into the oil then it stands to reason the oil is getting access to something hot that water isn't. If the block casting is the same, water pump is the same and that is happening in the block (which I wouldnt assume either) it would stand to reason to me at least that the issue is your making more heat than you used to and getting localized boiling. If so, coolant pres helps. If its happening in the head, it could be something else (many other things). If it was happening in a bearing I assume you would have found out. It can be surprising how much more heat is generated by a few more horsepower when your talking about riding the knock limit. You cant just increase flow to solve the issue because velocity = pressure you can actually drop the pressure by flowing more, this is the old "your flowing too fast to cool it down" thing without the lack of understanding of whats really happening..

                  If you cant change the size of the passages you know where that takes you. Most likely its the head, maybe. But even that I find that just as interesting. So I would want to eliminate localized block heat first if its easy and cheap. Then start trying a million things with the head. This is all assuming you had some decent oil cooling in the first place, which it sounds like it didn't.

                  There isnt a linear relationship of the temperature of a metal when your riding the limit of localized boiling. It will be a sudden jump in temperature once you start boiling water and the ability to transfer heat goes away real fast. Oil won't boil until a much higher temperature and if say you have an oil passage and a water passage next to eachother you wont see much in the water temp if the rest of the system is ok and the oil will jump in temperature. So something like that can possibly go un-noticed in your pre production tests for something like a 20 hp bump next iteration of an engine they dont apply the same test rigs they do when they designed the thing originally. All those passages get a spec for min pressure and its tough to maintain when your talking about tight packaging and raising base pres is sometimes an easy solution. But so is an oil cooler...
                  I think the OPs question is a worry about his oil pressure dropping due to an install of an oil cooler. I could be wrong but he hasn't replied since.

                  While I agree it won't hurt to try it, and its cheap and easy, I still feel you're trying to change the roll stiffness by playing with the roll center rather than simply attacking it head on with springs.

                  If the OP has oil temps issues and is worried about oil pressure drop from a cooler, he would probably be fine with simply going with an oil cooler.


                  Then again, this is often why I dislike tech discussions online.


                  0.02

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                  • #24
                    I think your taking what I'm saying like I'm disagreeing with your solution. I am just trying to add a little additional insight (hopefully). I mentioned having a reasonable amount of cooling there is a pre-requisite and mentioned I didn't know how much cooling we are dealing with. I don't disagree with you at all, I would probably put a bigger oil cooler on first and then start playing with everything else to understand. I was broadening the scope of discussion, I agree his original question had already been answered. I found the tangent to be an interesting topic.

                    I'm simply trying understand why the 370z is suddenly generating more heat in the oil than the 350. I think its just two different ways of thinking a driver and an engineer, in real life they should work together. I enjoy tech discussions, though they tend to go all wrong on the web when they would be just fine over a beer.
                    Last edited by gixxer_drew; 10-09-2011, 06:38 PM.
                    Andrew M Brilliant
                    Aerodynamicist / Race Engineer

                    Comment


                    • #25
                      Originally posted by gixxer_drew View Post
                      I think your taking what I'm saying like I'm disagreeing with your solution. I am just trying to add a little additional insight (hopefully). I mentioned having a reasonable amount of cooling there is a pre-requisite and mentioned I didn't know how much cooling we are dealing with. I don't disagree with you at all, I would probably put a bigger oil cooler on first and then start playing with everything else to understand. I was broadening the scope of discussion, I agree his original question had already been answered. I found the tangent to be an interesting topic.

                      I'm simply trying understand why the 370z is suddenly generating more heat in the oil than the 350. I think its just two different ways of thinking a driver and an engineer, in real life they should work together. I enjoy tech discussions, though they tend to go all wrong on the web when they would be just fine over a beer.
                      I'm not taking it as disagreeing, but rather taking it like my example (dealing with roll stiffness w/roll centers rather than springs first). I'm all for additional insight and its worth looking into for sure. -Again, why I hate internet tech talk sometimes.

                      I don't know the differences between the 370 or 350 internally, maybe the wall thickness is smaller/smaller water jackets due to an increase in bore (or is the additional 0.2L from stroke?), are the coolers the same, what about frontal area for the water cooling intake, or if there's an Air to oil heat exchanger for engine oil, are they the same design, if it's water-oil cooler, is it the same size/design, there are tons of possibilities why the 370 makes more heat than the 350 on track.

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                      • #26
                        Originally posted by Stuntman View Post
                        I'm not taking it as disagreeing, but rather taking it like my example (dealing with roll stiffness w/roll centers rather than springs first). I'm all for additional insight and its worth looking into for sure. -Again, why I hate internet tech talk sometimes.

                        I don't know the differences between the 370 or 350 internally, maybe the wall thickness is smaller/smaller water jackets due to an increase in bore (or is the additional 0.2L from stroke?), are the coolers the same, what about frontal area for the water cooling intake, or if there's an Air to oil heat exchanger for engine oil, are they the same design, if it's water-oil cooler, is it the same size/design, there are tons of possibilities why the 370 makes more heat than the 350 on track.
                        I kind of assumed people could rule out most of those things on their own and presented it as another thing to think about. We are probably approaching the point of talking this to death though, may be best to continue by PM or email. I hope the water pressure comments added some insight for people, I feel its often neglected to consider as part of the equation.
                        Last edited by gixxer_drew; 10-10-2011, 03:44 PM.
                        Andrew M Brilliant
                        Aerodynamicist / Race Engineer

                        Comment


                        • #27
                          Thanks for the question. Sorry for the delayed response. I have a stock 350Z with no oil temp guage, which I probably should remedy before I do anything else. Anyway, the oil pressure seems o.k. (60+ psi at 1,000 rpm on a hot day); but I have heard enough from other Z owner's to get me to thinking about "an ounce of prevention." I am not a heavy duty hot shoe, however, so perhaps I should worry less and drive more. Curious though about what kind of "on throttle" oil pressures are considered too low.

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                          • #28
                            Get a cooler, I found out the hard way on my first track day a few years back... Granted, my case was based on running conventional oil, in 95+ degree heat, doing fairly high rpm (4500-6600) lead and follow excercises without keeping a close eye on the water temps - so I'll add inexperience as a factor too. Regardless, the cooler is a great idea, but I've heard claims people are using the largest AN lines and fittings they can find, and that could have an effect on the pressure. I use a cooler with AN 10 hose and think its the most common (Stillen fits a AN 8, Nismo specs AN 10 on their coolers). IMO, Nissan should have spec'd both cars with a cheap cooler, but I understand 90% of the owners will never tax the engine that hard.

                            As far as pressures, they should be higher than 14 psi at idle and 45 psi around 2000 on a warm engine.

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                            • #29
                              The 350 and 370 share essentially the same block. The VQ35 evolved into the VQ35HR which is a taller deck, longer rod version of the standard VQ35. They have the same heads. Now when they went to the VQ37 the kept the tall deck block and made the stroke longer. However, the head is a new design that includes variable valve lift in addition to timing. This is another load added to the oil system. The spark plug diameter was reduced to give better cooling of the combustion chamber and this raises the detonation limit. Both engines share a tiny oil to water heat exchanger that I feel is not enough. All of the VQ engines are very difficult to get 100% of the air out of the cooling system. There are some specific tools and procedures that make it much easier to bleed the system, but the basics have to be there as well, like a proper swirl pot, bleeds from the radiator and coolant outlets with a return to the water pump inlet.

                              I can see Andrew's thinking that if you are having a localized boiling problem in the heads, then improving the cooling system should take some heat load off the oil. Instead of steam insulating the combustion chambers you would now have coolant conducting the heat away which drops the cylinder head temperature, which was essentially oil cooled due to the localized boiling.

                              My experience with the RB26 engine shows that engine makes crazy oil temperature and needs a very effective oil cooler. It is hampered by a cylinder head that leans towards the exhaust side and has poor drainback. Since the oil is pooling over the exhaust ports, the oil temp goes past 150C in only a few laps. To keep it cool look at a NISMO Super Taiqyu R34. That setup works well.
                              We point your tires in the right direction!

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                              • #30
                                Originally posted by M-Workz View Post
                                The 350 and 370 share essentially the same block. The VQ35 evolved into the VQ35HR which is a taller deck, longer rod version of the standard VQ35. They have the same heads. Now when they went to the VQ37 the kept the tall deck block and made the stroke longer. However, the head is a new design that includes variable valve lift in addition to timing. This is another load added to the oil system. The spark plug diameter was reduced to give better cooling of the combustion chamber and this raises the detonation limit. Both engines share a tiny oil to water heat exchanger that I feel is not enough. All of the VQ engines are very difficult to get 100% of the air out of the cooling system. There are some specific tools and procedures that make it much easier to bleed the system, but the basics have to be there as well, like a proper swirl pot, bleeds from the radiator and coolant outlets with a return to the water pump inlet.

                                I can see Andrew's thinking that if you are having a localized boiling problem in the heads, then improving the cooling system should take some heat load off the oil. Instead of steam insulating the combustion chambers you would now have coolant conducting the heat away which drops the cylinder head temperature, which was essentially oil cooled due to the localized boiling.

                                My experience with the RB26 engine shows that engine makes crazy oil temperature and needs a very effective oil cooler. It is hampered by a cylinder head that leans towards the exhaust side and has poor drainback. Since the oil is pooling over the exhaust ports, the oil temp goes past 150C in only a few laps. To keep it cool look at a NISMO Super Taiqyu R34. That setup works well.
                                i thought the VQ37 didnt get a oil-water heat exchanger till the 2012 370z model year? unless its in a spot i havent found yet on my car, i have a 2010 370

                                and in regards to bleeding the air out of the cooling system for the VQ, why is it so diffecult?

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