Are the differences in boost due to quality control of the Eaton chargers or something else?
An update on what I have posted previously regarding the charger problems, as I've been asked quite a lot questions about this issue. And additionally I obviously need to explain and somehow "correct" my other statement: IMHO every pulley below 3.0" is definitely the charger's death, and on "German Autobahns" or with heavy race usage additionally definitely the death of a stock engine...
At least it CAN be the charger's death and will shorten its and the engine's life under the circumstances I name below:
I obviously didn't explain that exact enough: every Eaton charger has 2 rpm limits that are safe, a continuous rpm-limit and a higher temporary rpm-limit.
Again, a 2.9-3.0" pulley is the smallest I would recommend for a heavy usage like "running above 8000 rpms all the time"
And here we go, in Germany it's not a problem to run for e.g. 10-15mins near or at the rpm limiter in 6th gear on an empty autobahn (e.g. at night) ... And we have customers doing this.
Then (with a pulley <2.9") the charger is above the continuous rpm-limit for that time and can start to pump mechanically (don't know if this is the right translation) and the screws get too near each other and the housing, and the worst case that can happen is shown on the pictures.
I know that there are cars with <2.9" pulleys out there doing fine, also we have tuned cars with such small pulleys over here, but it always depends on the usage of the car and how you drive or better, how often and how long you drive above the charger's continuous rpm-limit.
Another issue is the boost the charger produces. A stock S240 usually makes 0,5-0,55 bar (7,25-7,95 PSI) boost with a stock pulley. Now you always have to consider, that an engine like the 2ZZ-GE with a compression ratio of 11.5:1 was not build as an SC engine and that it’s just not healthy to run it with a much higher boost (Keywords: MEP (Mean Effective Pressure) or IMEP (Indicated Mean Effective Pressure)). Bun here again it depends on the usage.
Definitely running above 0,7-0,75 bar (10.15-10.9 PSI) boost with a stock engine (stock compression ratio) and externals like stock IC, exhaust, catalyzer etc. may work only just when you use the power only from time to time, but definitely not under sporting conditions.
So, apart from the charger's rpm limits, running with a smaller pulley than 2.9-3.0 (depending on the different boost caused by the production differences of the chargers) and so with a boost above 9 PSI makes more changes necessary, that then naturally depend on what one wants to achieve, under which conditions someone is driving and also, in which country
BTW Apart from tracks like NARDO in Italy e.g. or other (round) high-speed tracks you normally never run with such a high load and rpms for a time like you can do that on an empty autobahn. That’s a fact.