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External oil cooler on boosted Nsx?

Geez! Dry sump...

You really need to update your build thread!

It was a waste. I would like to turn this car back into a 3-season daily driver like I had it 11 years ago. I'm concerned about the pump/belt robustness for DD duties, so I'll probably go back to the conventional pump. I still have a brand-new housing and pump gear that were ported and then WPC-treated. I can adapt my thermostat and oil cooler setup to it pretty easily. That and the huge oil separator/storage tank takes too much space that I need for another turbo layout revision....

The build continues!
 
A Band-Aid on the coolant side may be more of a problem than it's worth. Why? You're adding additional restriction to this coolant loop and it may end up bypassing the OEM cooler and now the supplemental cooler, rendering about the same overall oil temp drop effectiveness as OEM. Like electricity and air, coolant takes the path of least resistance, and more will preferentially flow through the heads and block than the oil cooler. It may be worthwhile to try, but you'd need a large, low-restriction cooler to probably make any difference.


To completely solve the problem, you need to completely get rid of the weak, restrictive oil cooler and rely on dedicated oil-air heat exchanger(s)!

Besides a completely custom oil system, you'll need to cap the coolant supply nipple by the TB, and then make a blanking plate for the coolant return to the block (pictured below). When I made this aluminum plate a few years ago I was concerned if it would leak or not. Well, when I pressure-tested my coolant system it held steady at 20 psi. No problems leaking over the past few years.

My Mocal thermostat is set for a min oil temp of 180F (to start boiling off the blowby condensate and help the oil live longer), and I can pretty much set the max temp to whatever I want on the street/track (600HP and ambient temp of 100F). The heat limit becomes me, not the car....

Dave

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A Band-Aid on the coolant side may be more of a problem than it's worth. Why? You're adding additional restriction to this coolant loop and it may end up bypassing the OEM cooler and now the supplemental cooler, rendering about the same overall oil temp drop effectiveness as OEM. Like electricity and air, coolant takes the path of least resistance, and more will preferentially flow through the heads and block than the oil cooler. It may be worthwhile to try, but you'd need a large, low-restriction cooler to probably make any difference.

"MAY end up bypassing" so you dont know .In theory yes but i will test it.

To completely solve the problem, you need to completely get rid of the weak, restrictive oil cooler and rely on dedicated oil-air heat exchanger(s)!

Restrictive OEM oil cooler ? i will pass this one

Besides a completely custom oil system, you'll need to cap the coolant supply nipple by the TB, and then make a blanking plate for the coolant return to the block (pictured below). When I made this aluminum plate a few years ago I was concerned if it would leak or not. Well, when I pressure-tested my coolant system it held steady at 20 psi. No problems leaking over the past few years.

My Mocal thermostat is set for a min oil temp of 180F (to start boiling off the blowby condensate and help the oil live longer), and I can pretty much set the max temp to whatever I want on the street/track (600HP and ambient temp of 100F). The heat limit becomes me, not the car....

I agree that one ! Mine "max effiency turbo build" does not have any external coolers . I dont need it ! Another car what has same set does not need that either ! AND he is tracking /racing it at summer almost every weekend . 3-4 laps in any circuit max oil temp 125 C (alarm).

Operator
 
By all means test it out!

When I rebuilt my engine I engineered a dry sump setup for it due to oil requirements for my high piston rod loads at low RPM. The OEM pump could not supply the volume required. The semi-sequential semi-compounded turbo setup ala Audi's bi-turbo diesel gives me a 2:1 pressure ratio at low RPM and high RPM. It is a max efficiency turbo build like yours.

Anyways, tuning has proven to be above my abilities and I've removed the turbos. As such, there was no need for the complicated oil pump and reservoir. I went back to a rebuilt OEM pump that I modified for efficiency. I still ditched the OEM cooler. Measuring oil pressure in the front head OEM location, my oil pressure has increased a good 20 psi at a given RPM (below 6k of course when the bypass opens up) before/after the rebuild. Before/after bearing clearances were similar. My engine was in top shape before the rebuild. I attribute the oil pressure difference to a restrictive OEM oil cooler and oil filter design. I use a Canton inline oil filter now with a similar media and surface area as OEM-style filters... it just has a replaceable catridge.

So yes, I do have proof the OEM oil cooler is restrictive for oil flow!
 
By all means test it out!

When I rebuilt my engine I engineered a dry sump setup for it due to oil requirements for my high piston rod loads at low RPM. The OEM pump could not supply the volume required. The semi-sequential semi-compounded turbo setup ala Audi's bi-turbo diesel gives me a 2:1 pressure ratio at low RPM and high RPM. It is a max efficiency turbo build like yours.

Anyways, tuning has proven to be above my abilities and I've removed the turbos. As such, there was no need for the complicated oil pump and reservoir. I went back to a rebuilt OEM pump that I modified for efficiency. I still ditched the OEM cooler. Measuring oil pressure in the front head OEM location, my oil pressure has increased a good 20 psi at a given RPM (below 6k of course when the bypass opens up) before/after the rebuild. Before/after bearing clearances were similar. My engine was in top shape before the rebuild. I attribute the oil pressure difference to a restrictive OEM oil cooler and oil filter design. I use a Canton inline oil filter now with a similar media and surface area as OEM-style filters... it just has a replaceable catridge.

So yes, I do have proof the OEM oil cooler is restrictive for oil flow!

OK good to know ! Good work . I have build engines only using TODA pump . So starting point is better than yours . Street car like 95+% NSXs are i woud not remove OEM oil cooler ..it is heater too!
When oil temps go higher than 80-82 it is cooler , before that it is heater ...it like natural thermostad with no valve !
OEM oil system is good starting point and it will not give you normaly any issues . But if you start modifying stock oil system you (not you:)) shoud measure before/ after oil pressure !
Using AN10 fittings ( like most sets)with no by-pass holes will drop your oil pressure 15-20 psi and relief valve opens too earlier and that will couse serious problems in long term use !
Using colder coolant in OEM cooler shoud help to cut oil temp rise. If you are cruising external coolant cooler gets less air and it i s less effient. More speed better effiency ! Natural thermostad
again ! I will Place 3 K-temp probes (calibrated) in that system. 2 for coolant one for returning oil from OEM cooler. But i hate to wait 4 months !
 
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I hear you on some of the aftermarket NSX oil cooler offerings. It's clear a few vendors don't understand oil systems very well. You do though.

My dry sump used 16AN hoses. One fitting was $50 :eek: My modified OEM is now 12AN. I wouldn't say the TODA gerotor set is better than what I currently have :wink:, but it does appear to be a good product. I wouldn't hesitate to use it.

You're right - the OEM oil cooler acts as a small heat source to the oil during engine warmup. It's only good if you make short trips and don't let the oil temperature warm up sufficiently to evaporate the combustion blowby condensates.

That doesn't apply to me based on:
1) How I use this car
2) My extremely effective air/condensate/oil separators
3) The piston ring package and gaps I used
4) How well I seated the rings after the rebuild
5) How frequently I change the oil (it's cheap insurance)


On your coolant heat exchanger - I recommend placing the cooler on the passenger side like Mark did at the top of this page:
http://www.mscperformance.com/thermalpg1.html
There's no need for fans like you said before, but I recommend you block off the alternator cooling hole with a blanking plate in the engine compartment to make it even more effective. If you don't have a full rear underbody you have plenty of engine compartment cooling without this hole.

Dave
 
Mac Attack & Operator

This is a very interesting conversation however a little alarming for the right reasons.

I have the SOS oil cooler kit, should i be worried? Should i remove it?

I have a fully built, low comp stroker build with lovefab turbo kit.
 
Mac Attack & Operator

This is a very interesting conversation however a little alarming for the right reasons.

I have the SOS oil cooler kit, should i be worried? Should i remove it?


I have a fully built, low comp stroker build with lovefab turbo kit.

NO you dont need to remove it ! Take sandwich adapter out of engine and drill 3x6 mm holes to adapter . Then your oil pressure is same like OEM.
Still oil cooler works ! about 60 % of oils runs tru oil cooler ! OIL Flows no slower than it use to be what is good thing ! It works , i have tested !

LOOK how big are OEM oli holes ! 17 mm . AN 10 Fittings are 11,5 mm ! So OEM Flow size is 2 times MORE . Yes ! Alarm shoud go ON !
 

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I have the SOS oil cooler kit, should i be worried? Should i remove it?

I have a fully built, low comp stroker build with lovefab turbo kit.

The only way to answer that is to know if you really need it or not. You may have a built engine and run a turbo, but what are your maximum oil temperatures on the street or track? Some measure in the oil pan or right at the pump discharge pre-cooler to get the maximum oil temperature, but I prefer to know what the temperature is post-cooler(s) just before it supplies load-bearing capacity to the crankshaft main bearings. That is the real temperature you need to know.

How was your engine built? What are your bearing tolerances? Have you modified anything else that would alter the oil passageways? Are you using a OEM-sized pump, or did you need to upgrade based on larger bearing clearances?

If you are just puttering around on the street in a cool climate and your engine was rebuilt to OEM clearances, then there is probably no need for the cooler. It's a vital failure point and I would just remove it. At the minimum, the SOS braided oil cooler lines have had documented failures on here and I would make sure to replace those with something better. Braided hoses make it hard to inspect, so you need to keep up a regular replacement schedule.

Otherwise, if you know or feel you need a cooler, you can modify the adapter like Operator explained above with a larger bypass and larger lines. Even this may not matter depending on the oil cooler itself (with small inlet/exit fittings). If you don't want to make the bypass holes larger and bypass the extra cooler, then you can do one more thing that I don't really recommend either - add a spring shim in the oil pump bypass plunger.

As Operator explained in a previous post here, if you add a restrictive cooler then you decrease the pump speed (engine RPM) where the bypass valve opens up inside the oil pump housing. You have effectively increased the oil pump "backpressure" in simple terms, and as engine speed (pump speed) increases, the additional backpressure will force the engine oil to bypass the engine and be diverted back to the pump suction. So, if the OEM oil pump began bypassing oil at 6k RPM, you may begin bypassing oil at 5500 RPM, or something like that. Obviously, the oil pump is no longer supplying the oil volume and pressure the Honda engineers designed into our engine at that point, and bad things can happen. Sure, there is margin built into it due to manufacturing tolerances and reliability concerns, but it's obviously not a good thing when you're putting out double the power the engineers designed either. Who knows? You can reduce the oil pump bypass in this situation by adding a shim under the spring to the oil pump bypass plunger. You'll have to pull off the oil pan to get to it and break loose the allen plug holding it in. You'll need a new crush washer and, heck, a new OEM spring too.

I don't recommend this route either. You've heard of oil pump gears "resonating" and shattering in some NSX's, right? The problem alone isn't cheap oil gear material, or some magical RPM we shouldn't exceed, it's really due to oil pump gear cavitation. When the oil pump spins fast enough and it can't get the oil volume it needs at its suction, then it will begin cavitating. That is the magical thing that happens and will cause the gear to shatter. Sure, reducing RPM or getting a better gear will help keep it from physically shattering, but the problem still remains that the right amount of oil isn't getting supplied to the engine, whether you have the fancy gear or not. So, if you increase the bypass spring pressure, you reduce the bypass back to the pump inlet at 6k RPM. Depending on the shim you use, you may delay bypass back to the pump suction by 500 RPM or more. That's a bad thing, because it may increase the propensity for oil pump cavitation. Again, who knows unless you test it. Good thing Honda did when designing this engine. I think they did a great job. It can be easily messed up by the best. Look at all the oiling problems BMW has had with their V10 M engines just a few years ago.

Based on your oil temperatures, if you don't need the cooler, I would just take it off. If you know you need it, then consider doing what Operator suggested but optimize the cooling and bypass needed.

As a data point, when I was in the process of re-engineering my oiling system earlier this year (removing the dry sump and fancy cooling setup), I didn't even run an oil cooler at all. Not even the OEM oil cooler. This wasn't track duty, just "enthusiastic" street driving this past summer in ambient 90F weather and ~550 crank HP. The maximum oil temperature just before entering the engine was 220F and acceptable for me.

Dave
 
Thanks Dave,

That is great info.

I live in the UK so the weather never really gets that hot, We may hit around 30 degrees, maybe a little more in the summer months, which i think is about 86F

I do track my car but i don't track my car like some guys. I will go out do maybe 6-10 laps, come in, let it cool down, have a chat, check fluids and go back out with a warm up lap or two. I'm never really on it for long periods of time.

I do have the upgraded oil pump kit offered by SOS which i believe is the larger billet gear and spring mod.


I added it mainly for safety and for good practices (paranoid) to keep temps down and not cook things, I think what your going to tell me is with UK weather and because i'm not out half a day at a time without a break then it's not something i really need to worry about and actually may be causing more issues than good?


I do have the AEM Infinity ecu, i do have oil pressure/temp safety maps that will restrict rpm perhaps i would be best relying on this as a safety net instead of adding a cooler?

What i'm trying to do with my car is build something with lots of reliability and safety so i can enjoy the experience instead of having to drive it being paranoid.


The tolerance the engine is being built to is 0.036mm which is in the middle of Honda Tolerances. We are trying to get every bearing as close to that given the options of bearings available from Honda.
 
I looked at the SOS website, and indeed, their oil pump bypass has been shimmed to increase maximum pressure by about 10 psi. Furthermore, the gear thickness has been increased by 0.06". I sold my old oil gear set and can't measure it, but I believe it was probably around 0.5" thick. Let's say the OEM gear is 0.6" thick, then the SOS gear is 10% larger, and being a positive displacement pump, will therefore supply about 10% more flow than OEM at the same speed.

If you are using Honda bearings and building the mains to the middle of the Honda OEM band (0.036mm like you said), and 0.05mm middle band for the rods, then you shouldn't need any extra oil pump capacity. A little extra volume won't hurt (you have an oil supply for the turbo), but too much is bad.

The reasons why too much oil flow and pressure is bad are:
- It takes additional pumping power to supply the extra oil volume and maximum pressure. You reduce engine net power output and heat up the oil a bit more because of pump losses. Not really a big deal overall.
- You place extra stress and wear on the aluminum pump housing requiring more frequent pump rebuilds. Not really a big deal either.
- You place extra stress (10 more psi) on all the oil sealing places (O-rings, machined faces, etc). Do you know how many O-rings are in this engine to seal the oil? You've probably seen all the bags and how much these little suckers all cost.
- Most importantly, the reason I gave in a post above - oil pump cavitation. You've increased the bypass setpoint where it dumps oil from the pump discharge back to the suction. You've also increased the oil pump volume, so the propensity to cavitate will be at an earlier RPM than OEM. Look at my used housing below. There are some intricate details in this pump housing to direct and compress oil flow that even a lot of engineers wouldn't understand. When I went back to a new OEM oil pump, it took me quite a bit of time to modify a new oil pump and improve a TINY bit on what Honda did.

It's another long-winded post, but I think you're just fine for your engine rebuild with what you have. However, I would remove the SOS oil cooler just because you probably don't need it, and the oil lines they used have failed here a few times. You could replace the lines of course, but I would just keep it simple. You've had enough bad luck already. Just monitor the oil temps (there's a lot of good advice on here), and reinstall it if you need it later.

Also, I don't recommend you increase the engine redline above 8k RPM thinking your oil pump will be OK.

Just my $0.02.

Dave

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Unless you want to spend over 10 minutes to properly warm up your car before driving it, I wouldn't use solely an air:eek:il cooler and would retain some form of air:water (stock or aftermarket) for the reason of it warming up the oil faster. It's not a great route for a street car IMO unless you are diligent about your warm up procedure.

Turbo NSXs have been tracked for a long time now. Shimming an upgraded billet pump with the stock cooler and a secondary inline air:eek:il cooler has been a proven reliable and effective combination. Going with a wider pump with more flow is far better and can justify a larger cooler. If you're making more than 400whp, a built motor is pretty much a requirement. Upgrading the oil pump should be mandatory in anyone's turbo build.

The only way to answer that is to know if you really need it or not. You may have a built engine and run a turbo, but what are your maximum oil temperatures on the street or track? Some measure in the oil pan or right at the pump discharge pre-cooler to get the maximum oil temperature, but I prefer to know what the temperature is post-cooler(s) just before it supplies load-bearing capacity to the crankshaft main bearings. That is the real temperature you need to know.
I disagree. FWIW, no professional race team or engine builders that I know of solely measure the post cooler temperature. While it's good to measure post-cooler to know the effectiveness of your cooling system, you really need to measure how hot your oil is getting, which is in the oil pan or pre-cooler. it doesn't matter if your oil is a happy and cool 180*F entering the engine if it spikes to 300* and is breaking down, thinning out, and losing shear strength and viscosity from the heat the engines power is making. This is an unrealistic extreme example, but the temperature that really matters is the temp of the oil that the bearings are seeing.

Your comfortable 220*F pre-cooler could be quite a bit higher depending on how efficient your cooling system is.

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Hey, we all bring unique insights and our own knowledge/experience to the table. I'm not an engine expert, but I do know from personal experience building my engine what seems to work or doesn't work. I've done a lot of unique things to a C series engine that others haven't, or have but haven't published on the internet. I'm also a very technical person, and as a result of that, need to understand from a very basic level how things work before I talk about it.

From my experience over the summer, I didn't need a diligent warmup procedure. I let it idle for about a minute in ambient 85F weather and then I'd just drive it, monitoring oil pan temps. Compared to what I remember before I took everything apart :redface: completely removing the OEM cooler/heater required an extra 3 minutes to warm the oil temps up from 85F to 180F in my pan. Not a big difference, and is due to the reason I explained previously - it's a small cooler/heater!

Anyways, I don't really care about oil temps when it's cold. The cold oil provides plenty of load-bearing capacity - the only thing you need to worry about is the difference in thermal expansion coefficients between the various metals when the engine is cold (P2W, etc). That's why you take it easy driving around until the engine is up to the steady-state operating temperature the engineers designed everything to. Well, that and if your oil has a lot of moisture in it on a startup if you didn't boil it off before shutting down. Water and fuel don't work as good as oil lubricating internal engine parts. That was evidenced by the previous owner of my NSX when examining the old main and rod bearings when I rebuilt the engine. They obviously took it on very short trips around town, or didn't change the oil frequently enough.

Oil can regularly withstand 500F, not sure why you are concerned with an "extreme" of 300F before breaking down. Actually, when routed through turbo bearings it can see over 1000F. There is no way oil is breaking down at 300F like you say. Now, it does lose it's load-bearing capacity like you said, and is why that is the critical temperature to know just before it re-enters the engine.

But you're right - no professional team will measure just post-cooler. They instrument everything as they should. Weight and packaging is extremely important, especially on a race car. Why go with an over-sized cooler if you can get away with a smaller, lighter one that doesn't need a large restrictive air opening to cool it? To do that you need to know pre- and post-cooler temperature. Makes sense, right? If I were designing race cars that is what I would do too. But, the OP asked if he need a cooler or not. I provided my recommendation that he doesn't based on his expected usage as well as the known documented failures on here with his supplemental cooler. He's monitoring and has feedback to the EMS based on oil temps so he can reinstall it if he ever needs to. It's not a big deal to remove or reinstall it.

I think I've demonstrated in my above posts the rationale and logic why a larger volume oil pump and an increased discharge pressure are not necessary for a rebuilt turbo engine running OEM-spec clearances. Actually, I've subjectively explained with sound engineering logic why it can be worse instead of saying every built engine needs one. I'm pretty confident this information has never been clearly explained here, or on very few other forums. Uninformed hot-rodder logic is "bigger is better" and you need to spend money on stuff to be cool (no pun intended). You really don't for some scenarios. My own build has certainly proved that.

You must have inadvertently missed the part in the same paragraph below where I stated 220F was with no engine cooler at all, not even the OEM one! That was a good closing argument in my recommendation to the OP.

Happy Holidays everyone!
 
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Oil temps are very important when it's cold because it's far thicker than when at its operating temperature and can cause damage if revved or loaded when cold. I cringe when I see people revving their cars right after starting it cold.

While a turbo runs at 1,000*+, the oil does not get that hot. Heck, the surface temperature of bearings are well over 300*, but when the oil itself is saturated and 300*+, synthetic oil does start to shear and break down.

For his use, he probably does not "need" the extra cooler but I personally feel it's better for him to have it. Nothing wrong with us disagreeing. For those who don't live in the cold and sleeting island of the UK, and who live in the hot south, an external cooler is far more crucial. For those that track their cars competently, heat and oil heat management is a top priority, especially when effectively keeping the car near redline. VTEC takes a lot of oil volume and pressure away from the bearings. Turbos, tracking the car, being a fast driver, and hot climates really taxes the oiling system of the car. Billet oil pumps, shimming them, and wider than stock oil pumps have been the tried and true, proven solution for track cars, high end turbo cars, and especially time attack and track turboed NSXs. This isn't a "hot rodder logic" but decades of testing, development, blown motors and destroyed bearings. Again, as you lose 1 or more of these aspects (hot weather, track use, competent driving, high revving, forced induction), the issue is greatly reduced.

Yes I did miss that part, my apologies. Many street cars don't have any form of oil cooler, but once tracked, oil temps become a severely limiting, damaging factor. I don't recommend tracking an NSX (especially turboed car) with no oil cooler, and highly recommend an aftermarket cooler, especially since NA cars can make oil temps shoot up over 280* on a 90* track day.
 
Oil temps are very important when it's cold because it's far thicker than when at its operating temperature and can cause damage if revved or loaded when cold. I cringe when I see people revving their cars right after starting it cold.

While a turbo runs at 1,000*+, the oil does not get that hot. Heck, the surface temperature of bearings are well over 300*, but when the oil itself is saturated and 300*+, synthetic oil does start to shear and break down.

The modern premium fully-synthetic multi-viscosity oils with all those additives work well. Heck, when I hit the start button on our newer 3.5L direct-injected Honda engine in 0F ambient weather with 0W-20 synthetic oil, the sucker immediately revs up to 2500+ RPM for a good 30 seconds or so - just after starting! I'm pretty sure all of us here would cringe when we hear an engine revving excessively right after it was started cold, or an excessive load placed on it. However, what is a "excessive," and what kind of RPM or load is allowable? I'm confident my warm-up procedure without a oil cooler/heater will result in a long life for my engine. I'm not concerned about the minimum 50F oil in my case when I start the NSX. Colder than that and I just don't drive it. I custom-designed the old dry sump pump and bearings to be able to take a large load at low RPM for my old semi-sequential, semi-compounded twin turbo setup. I had a friend at FEV make a dynamic engine model so I could be sure of it. Because I wanted to use my old Ti rods, we discovered that the small end would have too large of a stress if I bushed it for the full-floating pins. So instead of removing material and bushing the end, I matched each piston pin weight and had them DLC-coated to eliminate the change for galling. Another area was to optimize the piston-head squish clearance with our high modulus-of-elasticity Ti rods and stackup of tolerances, and crank vibrational/torsional deformations. You can see, I've gone from basically no engine knowledge to almost too much in the past few years for my build. Way too much time wasted....

As far as maximum temps again, a turbine can get over 1500F, and heat conduction/convection can lead to a small surface area that the oil sees of near 1000F. The oil "cokes" basically and leaves deposits. This is very important to turbo makers and they make oil recommendations based on all their testing of leading oils. However, this is a very small amount of oil overall that is in contact with the rare extreme times you have an exhaust that hot (besides racing where you typically change oil after a weekend anyways). I'll say it again, good, modern, fully-synthetic oils do not break down at 300F. Change viscosity - yes. But they don't "break down." Look at some free internet Mobil 1 test data. I also want to know what the oil is doing right before entering the engine for another reason - what is the maximum temperature your engine bearings are physically designed to? 350F? That's a good upper limit for aluminum bearings like Honda OEM, and 350 F is WAY above the protective alarm setpoint the OP will be using.

I see that a lot - VTEC taking a lot of oil volume and pressure away from the bearings. This is downstream of the main bearings (but upstream of the rod bearings) and AFTER a restricting orifice in each bank, so it doesn't affect pressure much on the main bearings. Rod bearings, yes, and is why I wanted to be careful for my design. That's why you see more spun rod bearing problems on our engines than you do main bearing problems.

Some vendor here should really make a proper oil pan design with real baffle doors instead of a simple plate that also restricts reflood to the pickup once a cornering load is clear. I would add that to the list of aspects you listed below (hot weather, track use, competent driving, high revving, forced induction). Blown oil pump gears probably occurred first when the pumps cavitated from a momentary lack of supply in a corner. I guess a simple plate helps in that one scenario, but a larger oil pump, or increased pressure, or even keeping it cooler won't help the engine in that scenario.
 
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For his use, he probably does not "need" the extra cooler but I personally feel it's better for him to have it. Nothing wrong with us disagreeing.

I think in general, you and I agree. My recommendation specifically for the OP, knowing his engine luck so far and the SOS prone-to-rupturing oil lines he's using, is to skip it for this rebuild and see how high his temps get on the track. I think I've said it enough here already, so I'll be quiet now. :smile:
 
Most cold-start procedures rev that high and adjust the timing to quickly heat the cats for emissions. 2,500rpm isn't "high" or an issue, and actually isn't a bad RPM to help warm the car up and build heat quicker. What I meant by "excessive" are those people who take a dead cold motor and then redline it to impress their friends. Also going full throttle isn't good on a cold motor. Redlining and going full throttle putting a lot of load on your car, shortly after starting it, even in 50*F weather is really not good (not saying that you do that), but oil is quite a bit thicker even at 100*F than it is at the measured 212*F "operating temperature" as used industry-wide to measure oil viscosity in Cst.

How much power did you make on the Ti rods? They have been known to fail around 450-500whp.

According to chemical engineers at a few different major oil companies, synthetic oil and its additives do start to break down at 300*F. Their flashpoints are usually around 375-475*F. Here's a pretty old test: http://www.speedtalk.com/forum/viewtopic.php?f=1&t=31363

Here are the approximate observed temperatures at which the various oils started to vaporize/smoke, which indicated the onset of thermal breakdown:

5W30 Pennzoil Ultra, API SM = 280*
5W30 Mobil 1, API SN = 265*
10W30 Lucas Racing Only = 290*
5W50 Motorcraft, API SN = 275*
10W30 Amsoil Z-Rod Oil = 300*, the BEST in this test
20W50 Castrol GTX, API SN = 275*
5W20 Castrol Edge w/Titanium, API SN = 280*
10W30 Joe Gibbs XP3 NASCAR Racing Oil = 280*
5W30 Castrol GTX, API SN = 280*

10W30 Valvoline VR1 Racing Oil, silver bottle = 260*, the WORST in this test
0W30 Brad Penn, Penn Grade 1 = 280*
5W30 Royal Purple XPR = 285*


Here are the “averages” for the onset of thermal breakdown with these 12 oils:

Full synthetic oils = 282*
Semi-synthetic oil = 280*
Conventional dino oils = 272*


NASCAR engines are quite impressive. Making over 160hp/L from pushrod (and until recently, carburated) V8s. They often race for hours with oil temps above 300*F, but the engine is specifically built for this and rebuilt after every race. Plus they consume GALLONS of oil during a race. By the end of the race, the oil's shear strength is way down and the oil has broken down quite a lot. They run at this high of an oil temp for aerodynamic purposes, with as small of an opening as possible for the least drag and most downforce possible. It's really not a good idea to run a modern synthetic at this temperature. I've had 6-hour races where I ran Mobil-1 in a S54 BMW I-6 at 300*F for the entire race and the oil was toast by the end of the race. Also those engines were also rebuilt frequently. The engine did last, and would probably be fine for many more track days to come, but the oil did break down with more wear on the engine than what one would consider 'acceptable'.

Due to the NSX's very small oil pan, it really doesn't need or will benefit from an overly complex baffle design. If you increase the capacity (which is another very important thing for high demand uses -tracked cars, turboed cars, turboed track cars), then you do need something more complex than the typical top plate. Top plates are quite effective at preventing oil from sloshing up on the 'shelf' of the left side of the oil pan during long right-hand corners. Unfortunately most of them are not seam-welded and often have a gap where the plate meets this 'shelf' -thus greatly reducing the effectiveness of keeping oil in the deep sump in right hand corners. Ideally, you want the top plate to be flush against and seam-welded to the 'shelf'. While most baffles aren't ideal in this regard, all of them do a great job at allowing oil to drain back into the sump, so I disagree with your comments of 'restricting reflood'.

I agree baffled oil pans should be added to my list of stresses on the oil system, however from a cooling standpoint they are not exactly related, in that: you can starve the sump of oil with a good driver on sticky tires in an NA car on a cold day with ideal oil temperatures -and spin a rod bearing without a baffle, but you can also overheat, breakdown, and thin-out the oil on a turbocharged car at the track with a bad driver on street tires who doesn't push it in the corners to never have a oil starvation problem, but the oil can cause problems on a hot day with inadequate oil cooling. Now put them together, a good driver on sticky tires, with a turbocharged car, on a hot day with inadequate oil cooling and no baffle, and that's a recipe for disaster. I can't count the amount of blown NSX motors due to one or many of these factors (as well as tuning and bad luck) but it's probably over 15. I don't take oiling, turbocharging, or cooling lightly.

I think in general, you and I agree. My recommendation specifically for the OP, knowing his engine luck so far and the SOS prone-to-rupturing oil lines he's using, is to skip it for this rebuild and see how high his temps get on the track. I think I've said it enough here already, so I'll be quiet now. :smile:
I'd agree to that. I also don't take oil lines lightly, however I must say that i'm not aware of SOS oil line issues or the OP's engine troubles. If there's a problem with the lines, I'd recommend reaching out to and calling www.bmrs.net and telling them the fitting size and hose length of his current lines and replace them with the aircraft-grade, lightweight crimped lines. BMRS is what the majority of NASCAR, Prototype, and Formula car teams use. They aren't cheap, but I wouldn't skimp on anything in the oil system of a car, especially high pressure lines feeding the bearings.
 
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I know why Honda does this on the new engines. It is balancing a reduction in emissions in exchange for a shortened engine life. Nothing is free. There is always a tradeoff when engineering something. I still don't like to see it rev up to 2500 RPM when the engine is at 0F.

There is a wide variety of synthetic oil bases out there.

The "good" ones that don't break down at 300F and are continuously rated for duty above 300F are:
Diakyl benzene
Polyalkaline glycols
Dibasic acid esters
Polyalphaoletins
and the good ones I use... Polyol esters which can even intermittently go above 625F. Redline 5W30 synthetic is one of these and has a NOACK evaporation loss of only 6% over a 1 hour test at 480F (sorry - I rounded up to 500F before. My memory isn't what it used to be since I last looked at this stuff years ago.):smile:

Standard Mobil1 isn't that good (it's common knowledge they use inferior basestocks), but look - they even advertise protection up to 500F :biggrin:
why-mobil-1-keeps-engine-running-like-new.jpg


If you're concerned about your race engine oils breaking down at 300F, then tell the engine builders to stop using those low-tension rings. They'll laugh because the rings give them power in exchange for ring life, increased oil contamination due to blowby, and increased oil consumption. The engine builders know what they are doing... balancing power and engine life for whatever duration they need to use them. My NSX engine wasn't designed with that in mind. I expect at least 50k miles on my particular ring package.

I only had ~3k on my stock rods at ~550-600WHP before the turbos were removed. I would say only about 50 miles worth at WOT. I had a minimum of 350 ft-lbs of torque from about 2750 RPM to 8K RPM, with a peak of just over 400 ft-lbs. Every edge of the rod was radiused to relieve stress, the rods were ground in a specific orientation (I forget now) when I matched their weights, and then peened again to relieve surface stress. I guessed a bit on the material properties in the dynamics tool we used, but it said it would be fine at this torque/power. If it didn't break then it won't now. I'm significantly reducing power and focusing on variable-runner-length ITBs next... just for fun as a design/engineering challenge.

Well, this has been fun, but it will be my last post here. Need to do other stuff.
 
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Have you done any UOAs in your motors? Synthetics from M1, Castrol, Pennzoil, Redline, Amsoil, etc... Will all show signs of additive loss and breakdown when subjected to sustained 300*F temperatures. I wouldn't assume the marketing nonsense and believe the oil will not break down and will work great up to 500*F. Well before then the additives and viscosity will be so out of its operating range that it would not offer much protection.

I'm glad to hear your motor held together but it would be interesting to know if those modifications strengthened the rods to any significant degree. Stock rods are a ticking timebomb on the street and quickly fail when pushed on track or the drag strip. I probably would just put time and $ into quality forged rods when trying to push those power levels rather than risking it with modified stock rods.
 
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I dont leave anything in half way ! New sandwich adapter to NSX or any "big" oil-filter engines AN10 or AN12 size ! This is part of new NSX oil cooler kit what is ready soon.
 

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Alright guys, but the diameter of the oil filter hollow bolt is also just 15mm. The bolt where the oil filter is mounted to. So this is the oem bottleneck.

Anybody ever thought about the Comptech adapter. It goes instead of the oem oil/water cooler and has a super big fitting. AN14 no problem

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Alright guys, but the diameter of the oil filter hollow bolt is also just 15mm. The bolt where the oil filter is mounted to. So this is the oem bottleneck.

Anybody ever thought about the Comptech adapter. It goes instead of the oem oil/water cooler and has a super big fitting. AN14 no problem

The Comptech adapter and TiDave's adapter are 12AN. That's the biggest you can go with the limited spacing between the two oil ports on the OEM oil pump housing.

When I removed my dry sump I modified the OEM housing and welded fittings to it. User Costa has also done something similar in the past. If I remember I'll take some pics and add them here later.
 
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