This is, in large part common sense.
The intake system from the factory, on ANY car, is not going to be that bad from a performance standpoint. The OEM is under fantastic pressure to generate the most power it can while creating the least amount of emissions possible that it can from an engine. Part of that recipe does NOT include a restrictive intake path. If you're seeing unreasonable power gains from an intake system on a modern car, then that system is doing something wrong--- even if "wrong" produces power on the dyno.
The lotus airbox is NOT that restrictive. It is however, big, heavy, hard to service, and complicated. A large reason for some of these factors is consistant with other OEMs in that they're trying to regulate intake sound, ie reduce it *substantially*.
Aftermarket intake designers tend to not care about sound, and that helps to reduce size, complexity, weight, and in many cases make service easier. Aftermarket designers do care about airflow, but so does the OEM! It's common to see a slight increase in power in the upper RPM registers with an aftermarket intake, but you should NOT see a huge gain. If you do, you know the designer of the inlet intentionally or
UNintentionally manipulated the fuel and spark management with the intake.
In the case of your intake, I have shown the MAF values vs stock. Clear as day, measured air is more than 10% reduced. This means the ECU will provide LESS FUEL and MORE SPARK at a given RPM and throttle position than it did prior to the installation. It does this because it uses airflow and RPM as the primary drivers to determine load. Lower MAF values, like your intake provides at given RPM, equate to lower load in the ECU. Lower calculated load requires less fuel and more spark for a proper burn. Manipulating calculated load is NOT the correct way to make power.
I'm not making assumptions. It's right in the data. Your intake will data log more spark and atleast 2 points leaner AFR at WOT than the stock airbox on a stock tune in addition to 10+% less metered airflow... It makes sense what's happening, it just doesn't make sense to do it this way
As for motor failures, I don't have any numbers in front on me. Don't care to. I'm not trying to use a scare tactic to move parts. I just like things to be correct. Contact Lotus USA and inquire. I know they have a list. There have been several drivetrain claims denied once they learned of the installation of that inlet, because they understand exactly what I'm saying here. They've seen it first hand.
It is perfectly evident that the intake makes a mess out of the tune. It's been further discovered that simply rotating the offset KN filter impact trims and measured MAF values at various RPMs.
I posted about the problem with that intake quite a good while before Julian asked us to design a replacement. We actually hadn't planned on it, but he asked, the car was here, and we like fixing problems
. Fortunately, we have a dyno and several years of experience with tuning these cars on MAF, undestand Lotus ECU tuning pretty well, etc and came up with a decent part that retains an external air source, is easier to service, light weight, and most importantly does not make a mess of load calculations in the ECU...
Sorry for the long post. It's important to explain "the why" in all this. We've also worked very closely with our friends at VSA in california on identifying the issues here. Between the several Evora S and NAs that they have to work with and what we've done in our shop, I have an enormous database compiled of logs and many - many pulls on the dyno. The homework has largely been done...