Torque Limits of the VR38DETT Rods

A couple of bent rods

Everything has a limit, a point where it will fail. The VR38DETT has been proven to be a strong engine when modified, seeing over 1300 wheel horsepower in several cars.  In stock form 480-485-530 horsepower at the engine, the VR38 should last the life of the car. However, if you start to increase horsepower, you will shorten the life of the engine as you are putting extra stress on the components above and beyond their design loads.  Recently there has been some discussion on NAGTROC about the limits of the VR38 engine in the Nissan GT-R, with several tuners chiming in with their experience.

When we talk about cars, and engines, everyone always quotes horsepower. It makes 150 hp, 500 hp, 700hp, however we don't normally measure horsepower what we are measuring is torque and rpm.  Horsepower is a calculated value from torque(ft-lb) x rpm/5252.  The constant 5252 comes from (33,000 ft·lbf/min)/(2π rad/rev).


The above pictures were from SP Engineering, of an VR38DETT that has a couple of bent rods in the engine. They say they have seen some engines with 525 awhp, and 530 ft-lb with bent rods on cylinders 3 and 4 with no signs of detonation. There are a lot of engines out there running more power and torque than this Eventually if you make enough power, this ends up happening. .

I have aftermarket turbos 700 whp and 680 torque on 100 octane. Car was running amazing for the last 2k miles but the torque just too much, rod let go on at full throttle run 5500 rpm.

At 700 whp, you are making 60% more power than stock to the wheels, stock 2009-2011 Nissan GTR's do about 420 horsepower to the wheels.When you break a rod, it does nasty stuff. A lot of the time, everything is destroyed.  When you have a really bad day, nearly the entire engine is junk. The broken rod takes out the block. The piston takes out that head. The rod takes out the crankshaft. Broken chunks of metal go into everything. From the turbochargers, to the oil coolers.  At that point, you are spending a lot of money to replace parts.

There are always doubters, always people that won't listen to tuners with more experience. They want to make all the power they can, and they eventually break the engine.  If you are aiming high, you should try and do it right the first time, and put a good aftermarket piston and rod in the block. However, we are always going to have the "hp on a stock block" guys.  A lot of the Toyota Supra owners of old were nearly  like this. They would brag how much power they could get out of the stock bottom end. When they broke it, another short block from Toyota was cheap, and they would start over.  There were several Supras over 1000 hp on the stock bottom ends, but when pushed hard or raced, the smart guys went with built bottom ends. I've personally pushed more than 700 whp out of a stock RB26, but at that level, everything needs to be perfect, because in their case, the piston is the weak point.  FFF as MotoIQ and Eric Hsu like to call them, might spout off anything about x part doing xxxx power, but in the real world you will see failures. Some of those same guys will try and hide those failures.  If you do it right the first time, your failures at high power, high load conditions are going to be greatly reduced. Every engine has a weak point, but normally it can be fixed.

Cosworth piston top, stock VR38 piston bottom

Popular choices for pistons for the Nissan GT-R VR38DETT are JE, CP, Arias, Greddy/JE, Mahle, and Cosworth.  Popular choices for rods are Carillo, Cosworth, Pauter, Crower, and Arrow.

Source: NAGTROC