Oil Pump Upgrades

While the stock oil pump setup is more than adequate for street use, those who track their cars heavily or have modified their ECU to raise the RPM at which fuel cut kicks in should seriously look at upgrading their stock oil system.

There are two main problems. First, under extended high-RPM use (some techs as Honda has said mid-8000 RPM range) the stock oil pump gears spin so fast that they actually expand, which brings them out of tolerance and causes them to get stuck and shatter. This is bad. The second problem is that under high-RPM operation during extended periods of high G-forces it is possible to induce oil starvation. This has happened to a few owners, usually when hammering through the banked turns at a track – quite a few road courses use an infield section as well as one half of a NASCAR oval – and usually also running on R compound tires.

   

      

        
 
          
Happy NSX oil pump gears 
        
 
          
Unhappy NSX oil pump gears that revved too high 
      
    

The solution to the gear issue is simply to upgrade either the gears themselves or the entire pump unit. Comptech offers both – stronger replacement billet gears for $475 or a high-volume oil pump with the billet gears for $975 (exchange). Comptech’s estimated install time for these parts is 10-11 hours when starting with the engine in the car.

   

      

        
 

          Comptech billet oil gear set 
        
 
          
Comptech high-volume oil pump 
      
    

Oil starvation is a bit harder to solve. To fully understand the issue, you need to understand how the system works. The NSX, along with almost every other street car in the world, uses a "wet sump" oil system. The "sump" is the bottom of the crankcase where the oil collects after being pumped to the engine. On a wet sump system, this oil that collects in the oil pan is pumped directly from this pan back into the engine. Under high G-forces, it is possible for the oil slosh to one side, away from the oil pump pickup tube. In some situations the oil pump feed tube will no longer be submerged, which means the pump will suck in air instead of oil. Once that happens, your engine will feel as good as new… because you will have to replace it with a new engine.

In a "dry sump" system, a scavenge pump moves oil from the sump at the bottom of the crankcase into a holding tank (usually located low to improve the center of gravity). The main oil pump takes oil from the bottom of this holding tank and pumps it back into the engine’s system of oil passages. The advantage of this system is that it prevents oil starvation during hard cornering. With the dry sump’s large vertical storage tank, you’d have to turn the car upside down to keep oil away from the pickup point. Most race cars use a dry sump system unless it is prohibited by their series rules.

So what can be done about this problem on an NSX? Dali Racing offers a high-volume baffled oil pan with the goal of preventing the oil from all sloshing away from the pick-up. It is $500 but you get $100 core charge back if you send in your undamaged oil pan.

Anyone seriously tracking their car, however, probably ought to consider installing a device like an Accusump. What does an Accusump do? Two things. First it acts as a pre-oiler to pump oil to the engine when you start the car. Second, if it detects a loss of pressure from the main oil pump, it will pump some oil to the engine. Figure $200-$300 plus installation.

On initial start-up when the valve on the oil side is opened the pressurized oil is released into the engine and therefore pre-lubricating the engine prior to start-up. The Accusump holds whatever oil pressure the engine has at the time that it is shut off. After the engine is started and the oil pump has taken over, oil is pumped back into the Accusump. This moves the piston back and pressurizes the Accusump until it equalizes with engine’s oil pressure. While driving, if the engine’s oil pressure is interrupted for any reason, the Accusump releases its oil reserve again, keeping the engine lubricated until the engine’s oil pressure comes back to normal. This release of oil could last from 15 to 60 seconds, depending on the size and speed of the engine. In racing or hard driving conditions, the Accusump will automatically fill and discharge when needed as you corner, accelerate and brake.

The Dali oil pan and Accusump should be all 99.9% of owners ever need, but anyone building a true race car may want to just put in a true dry-sump system while they have the whole car apart for modifications anyway.

Performance