Neutral Balance Shafts
- Less vibration. As the tech article explains, these shafts cause a cancellation vibration that works against you at higher rpms. These neutral shafts eliminate the HP loss incurred from creating this vibration. They keep your engine safe at high rpm.
- Less weight. As pictured below the ZZP shafts are lighter than stock. Lighter cars perform better in every way.
- Less rotating mass. Balance shafts spin at twice engine speed. HP required to spin an object rises exponentially with speed. Balance shafts on built engines can spin in excess of 16,000 rpm!
For a good explanation of the function of balance shafts, read our tech article about Engine Balance and the Balance Shafts.
The best solution for building a performance motor is removing the balance shafts entirely. This requires changing to an electric water pump and plugging rear oiling holes. For most people, changing to neutral shafts is the best solution.
These shafts help you in 3 ways.
So how much HP is saved?
This is a difficult question to answer because the truth is that it depends on a variety of factors. With any neutral shaft HP is gained at higher rpm because you are not creating a counter vibration for the car. The higher the rpm, the more HP is saved and it rises exponentially.
With the ZZP shafts, HP is saved because you are not spinning as much weight. The faster you spin your engine, the more HP is saved. With our competitor’s shafts HP is lost here.
If you look at kinetic energy formulas, you get an idea of how engine speed plays a roll.
KE = 1/2 (M * (V * V))
Let’s say it takes 1/2 HP to accelerate the shafts to 2k engine rpm. It would then take 2 HP to accelerate them to 4k rpm in the same amount of time or 8 HP to spin to 8k. Every time you double the speed, it requires 4 times the horsepower to accelerate in the same amount of time. Considering these shafts are spinning twice engine speed, you can see why it’s so critical to run a light shaft.
Compare the ZZP neutral balance shaft to our competitors. Their shafts weigh 2.5 times what the ZZP shafts weigh! This is actually more than the factory shafts weigh, costing you valuable HP.
Fits the 2.0, 2.2, and 2.4 liter engines.
The ATI balancer doesn't give HP gains but it does keep the motor from vibrating apart. It should be considered for RPM over 7000 in a 2.0. It should be considered mandatory for over 7200 rpm. In a 2.2 or 2.4, it's need 500 RPM sooner due to the longer stroke.
The neutral balance shafts are for very high RPM applications and should be considered for anything over 7500rpm (500 lower on 2.2/2.4).