the initial kits developed an oil leak which I have previously advised. The most suitable engineering fixes have been applied to all of these kits, however there is still a report of some leaking in one of the kits.



Following these issues, we have done a thorough analysis of the cause of failure, and have finally made a decision to rectify the situation. The problem relates back to a design decision we took when we opted to use engine oil to lubricate the internal gears/timing mechanism of the compressor. This seemed “valid” at the time, as it is one of the acceptable ways to provide the lubrication, as recommended by the compressor manufacturer. Subsequent testing indicated this was OK, as I have outlined before. As it turns out, this decision was crucial. It is now evident that the choice was bad due to the following factors:



Viscosity of the oil. The viscosity of the RX-8 engine oil can vary from one user to the other, but generally the RX-8 uses a lower viscosity of “most” engines, so the lubrication we are using is not ideal.
Heat of the oil. The oil temperature of the oil returning to from the oil cooler / filter system is rather hotter on a rotary engine – as is a well documented fact. If this is added to the extra heat introduced during the compression of air, we are getting elevated temperatures. This temperature has resulted in one case of a seal failing and replacing with a Viton seal (higher head range) has seemed to fix the problem.
Volume of oil. It would appear that way too much oil is being bled off the main oil pressure feed into the supercharger, and this is exacerbated by the next point.
Design of the oil return to the sump. This design had the oil returning to the sump through an open cage bearing, very “similar” to a ball bearing turbo lubrication system. The high RPM of the bearing combined with the fact of reasonably low pressure (compared to a turbo lubrication system) prevented the adequate passage of oil from the compressor to the return line and on to the sump.


Prior to the gear driven setup, we always used a “sealed” system for providing lubrication to the compressor. This is the other method recommended by the manufacturer. This proved effective (albeit a simpler drive), and proved itself over some very “highly stressed” dyno tuning session, the most vigorous being the engine dyno sessions extracting the 340 & 360 HP figures. A sealed system is what is used on the transmission and differential of all (or vast majority of?) vehicles.



So – the solution is fairly obvious – leave the engine lubrication system alone (apart from the remote mounted oil cooler – no problems), and use a sealed lubrication system for the compressor filled with a controlled oil. The oil will be provided to you to, or at the least specified so you can procure a small amount of your own. It might be problematic to send oil… Future compressors will pre-filled and sealed prior to shipping.



The other part of the solution is very, very simple. The braided line the feeds the oil will be replaced with two simple bungs (1/8 NPT bungs) to seal the fittings, and the return cover at the end of the blower will be replaced with a cap, sealed by the existing o-ring arrangement.