ION Redline Aftermarket Supercharger Pulley Information
The Saturn Ion RedLine (RL) features the 2.0L Supercharged ECOTEC (LSJ) motor. The supercharger is the latest generation Eaton M62 helical roots style positive displacement supercharger and offers a maximum of 12 psi of manifold pressure for a 40% increase in power. The latest generation offers a more efficient low-end power and improved durability from a more precision made zero-contact assembly. Also the supercharger is configured with an internal bypass valve to lower off power loads resulting in less power used and higher MPG ratings when cruising. The intake manifold that the supercharger is mated to is an all aluminum port matched intake manifold with an internal water-to-air Laminova heat exchanger intercooler. This style of heat exchanger is more efficient than even that of a bar and plate intercooler and offers more compact packaging. When the whole package is configured together and controlled with a high speed PCM it produces 200 HP and 200 lb-ft TQ for a very solid and reliable powertrain package.

As is the case in every consumer’s quest for “more power” the common ideology is that the more air you can stuff in a motor the more power you will get out of it. This is a solid way of thinking as long as it’s adhered to with attention to both the needs of the air (oxygen) and the needs of a combustible (fuel). Other factors contribute to the whole process like spark and it’s timing, but for simplicity sake focus will be directed to just air and fuel (mixture). In the case of the RL the fuel needs are addressed 100% by the PCM and sensor input based on the mass of airflow entering the engine. The M62 supercharger based on the relationship of the engine rpm and rotor speed addresses the air needs of the motor. This leads individuals to assume that by spinning the supercharger faster that it will also increase the air entering the motor and by ideology make more power. This assumption is inaccurate and will only lead to a loss in power, and increase in heat and drastically reduced supercharger and engine life.

To understand why this is the case (as contrary to ideology as it sounds) it’s very important to fully understand how a positive displacement helical roots supercharger works and its respective limits. Positive displacement helical roots superchargers are literally one-way valves that move a fluid from one place to another. The way the valve works is that it is of a specific size and can move a specific volume of fluid through itself by creating a bucket that is first exposed to one side then contained in the assembly and then exposed to the other side through constant rotation. How this is possible is based on the design of the rotors that are counter-rotating and intermeshed. There is no physical contact between either the rotors or housing of the supercharger, but the clearance is so close that at high speeds not even air under pressure can escape. Also the actual profile of the rotors is almost like a 4 leaf clover and is aligned in a way that the ‘lobe’ of one is in the ‘recess’ of the other as they rotate. By moving a larger volume of air into an intake manifold than the motor can consume the supercharger begins to cause backpressure against itself and the intake valves. This backpressure continues to build until it’s many times that of atmospheric and in the case of the RL 12 times so. Thus you have more air entering the motor and it results in more power than it would naturally aspirated.

The pressure in the manifold is in a direct relation to how much volume the supercharger puts in it and how fast. When correctly matched through gearing to engine rpm the supercharger will offer a substantial increase in volume at low engine rpms and as much as two or three times that by redline. The supercharger however can only operate so quickly because of physical size limits and mechanical bearing limits. As the pressure in the manifold increases it generates heat from both compression and action against the rotors and this heat becomes increasingly more of a problem as rotor speeds increase. This is a key factor in why roots superchargers tend to be so inefficient in the range of 60-70% compared to that of a Turbo in the range of 90% efficient. Basically as you increase rotor speed you see diminishing returns to the point that the actual volume of air is lower at higher rotor speeds than it would be at a lower speed.

The M62 supercharger at 12psi by redline in a 2.0L motor is already very close to it’s maximum operating speed needing around 30 HP to operate producing 180degree charge temperatures. Obviously the intercooler addresses the extreme charge temperatures, but increasing the rotor speed much more will only take additional power to do and measurably increase charge temperatures.

Will a smaller diameter pulley make more power? Possibly, but there are other more reliable and safer ways to make equal if not more power than can be made with a smaller pulley. When a pulley does become available it will have to be no more than a few percent difference in size or by redline the heat generated will cause blower failure from heat expansion and contact. In a warm weather environment or abusive driving conditions I would never suggest a smaller pulley because heat build-up will result in even quicker failure.

For now opening up the exhaust track and providing more than atmospheric pressure to the open side of the blower are the only easy ways to gain power. A possible M91 swap would also result in more air volume and at a lower pressure and temperature, but it would take serious work. Finally the other option would be N20, but I can’t stress enough that is MUST be plumbed AFTER the supercharger along with ANY form of fluid other than air or it will delaminate the rotor coating and dramatically reduce power.

I have been tuning M45, M62 and M91 blowers on Hondas for a number of years now here in the humidity-neglect high California desert. I have seen everything happen to them and every attempt to make more power by people and most of the time all that results is an expensive piece of junk that can’t even produce the advertised power because of physical damage from failing to understand how they work.

Also as of my last chat with Hondata no M62 supercharger strapped to any Honda motor has even produced more than 280 HP and that’s with cams, exhaust and hondata PCM so don’t expect anything magical out of a RL because it’s already been tried on a motor that statistically is exactly the same as the LSJ.


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-Adam Chant
http://www.scdyne.com
"Tune it or lose it!"

If Eaton roots blowers don't make more power with a smaller pulley then why does it seem to work so well with the 3800 S/C?