Boost Controllers

Boost Controller Risks

Background: Since the boost controller thread started, I've received a large number of questions as to the safety and effectivenes of these devices. In order to answer some of these, I've put together two posts (the other should be going out simultaneously) which reflect my interpretation and opinions of the risks and returns which these devices offer.

Three significant concerns have been raised over the use of boost controllers on these cars (though they may not be real problems, or indeed there may be other issues which have not yet been brought up). The issues are Altitude, Heat and the ECU's response to Knocking.

Altitude:

Problem: At higher altitudes, where the air pressure is lower, there is a risk that a "dumb" boost controller will attempt to make up for the lack of ambient air pressure by piling on the boost (i.e. it will try to maintain a pressure reading without considering the drop in outside pressure). This, naturally, will lead to risks of running unacceptably high boost, or of overspinning the turbo.

Resolution: The straight HKS "EVC IV" doesn't deal with this issue. The "EVC IV atm" allegedly will, but I am informed that it is not yet on sale. If I was living in CO, I suspect I would wait for it to be available. Here in Michigan, it doesn't seem like a worry.

Heat:

Problem: If you're running high boost under high load in a hot climate, the air intake temperature may become "too high" (note: this is a value which remains unknown at this time), at which point the ECU will attempt to dial back the boost. The EVC, however, will ignore this and keep responding to the driver's right foot. The consequences of overly hot air entering the engine include detonation, with all its expensive consequences.

Resolution: So far, in my environment and with my driving style and having maintained a relatively low boost level (+ 1.25 bar), this does not appear to be a problem. The car has been taken to the track (prior to the EVC) and after 45 minutes of lapping in 80+ degree weather, boost had not been perceptibly reduced by the conventional ECU. That would indicate that the "too high" temperature is very high.

Further methods of clarifying this could involve an intercooler-exit air sensor, warning the driver to lift off when the temperature exceeded X degrees. IMO, this is either: (a) not very relevant, if the "X" temperature is drastically high or (b) a very sensible mod for all high-boost cars, if the "X" temperature is easily reached.

An alternative might perhaps involve a larger intercooler, hence delivering cooler air for any given boost level. My own solution is somewhat simpler. Because of the EVC's effect on the car's reflexes, a boost level which was previously merely "OK" now supplies ample response, so I simply keep the boost lower than I otherwise would have wanted. Lower boost -> lower heat, all things being equal.

Knocking:

Problem: When the engine knocks, the ECU attempts to both retard timing and cut the boost. The boost cutting signal will be ignored by the EVC. If the driver attempts to maintain full throttle with the turbo delivering high boost while the engine is fighting against knocking, at the very least, temperatures will climb dramatically.

Resolution: Currently, there seems to no technical fix to this. (a) You have to use good gas and (b) if you hear knocking, back off.

In the longer term, there are two additional answers. In the near future, a rework of the ECU code may be available (according to Scott Mo.) which would allow the "Check Engine" light to come on as a warning that the ECU was attempting to back off. Secondly, it _should_ be possible to isolate the signal which the ECU sends to the WGFV to ask it to open up the wastegate in an emergency, and use that signal to switch the EVC automatically from its "high" boost mode to "low" boost. A driver who ignored such warnings would have nobody but himself to blame.

For myself, I'm concerned but not worried about this issue. However, I probably will obtain the reworked ECU code when it's available, and would be interested in the signal-switching solution, though it lies far beyond my technical scope to implement.

So... How Risky Is It?

If you encounter situations where the ECU would be attempting to dial back the boost: High Altitude, Overheating, Knocking, then the EVC's failure to adjust will pose a risk. To answer Frank Amoroso's original question: No, it does not retain all of the factory safeguards.

If you use good gas, if you don't reach the "magic temperature" and if you live in the flatlands, the odds are that you aren't going to encounter enough risky situations to make it a serious threat, but that's ONLY if you don't run excessive boost, and even then, a _somewhat_ higher risk potential will now exist.

To my mind, the moment I start to tweak a car at all, I have to consider the balance of risk vs. reward (which I'll come to in an accompanying post). Given my driving and my estimation of the risks, I view the rewards to be more than sufficient to justify installing an EVC in my car.

Going up the Rockies in a fully laden car at max boost on a hot day with dodgy gas, the EVC will add to the risk, but there's no good in pretending that under those circumstances the EVC is responsible for all of the risks that are present.