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GMR Design produces state-of-the-art supercharging solutions with inspiration drawn from years of experience in military aircraft engineering. As such, questions about what we do, how we do them, and how they impact your vehicle, are common. We’ve collated some of the most frequent queries regarding the science, maintenance and impacts, to help you better understand the benefits of GMR’s supercharger technology.
An unwritten law that sets a quality upgrade apart from a cobbled together set of aftermarket parts, includes that all vehicle management systems retain their integrity. By that we mean all the vehicle’s safety systems that were integrated ‘at birth’ (i.e. chassis, engine management and maintenance), must remain in place to look after the vehicle after the upgrade:
ENGINE MANAGEMENT SYSTEMS (ECU/PCM)
This is also important as many aspects of the vehicle’s safety systems rely to a greater or lesser extent on the ECU/PCM for information and/or operation. Many, if not all cars built these days have an incorporated ‘drive by wire’ throttle system. This is regarded by some as an over-complication of a simple process. What is misunderstood is the part this system plays in the overall safety of the vehicle. For instance, traction/torque control/stability controls are all governed to a degree by the ‘drive by wire’ throttle. Just because the driver mashes the pedal to the floor does not necessarily mean that the throttle will open to the same degree. In a millisecond the ECU will calculate the most efficient throttle plate angle for engine speed, car attitude and grip available. Far from being a hindrance to the driver, it must be considered a friend as it’s taking into consideration far more aspects than an average driver is able to assimilate, especially on the way to work in the morning when he or she is thinking about the kids, the troubles at the office and the events of the previous evening, etc! Whilst we humans are thus otherwise occupied, the Engine Management System is keeping a constant watch over the safety of the vehicle.
There are many systems built into the ECU solely for engine protection and emissions. Again, these cannot be compromised. The ‘knock’ and ‘lambda’ sensors play a huge part in how the vehicle drives, the fuel economy and not least engine safety. Any omission or changes to these systems must spell danger to the purchaser and should be avoided.
SPECIAL IMPORTANCE: The open/closed loop lambda system
For all the extra air being ingested when under boost, it is vital that the Air/Fuel Ratio is maintained to levels that are vital for the safety of the engine. These are under low load ‘closed loop’ conditions (AFR 14.7:1), high load ‘open loop’ (13.2:1 max torque to 12.5:1 max power). Should any irregularity to these be seen by the lambda system, it will bring on an Onboard Diagnostics (OBD) code showing either ‘lean condition’ (can cause detonation) or ‘condition rich’, which can severely deteriorate the catalytic converter. Should either condition be present an immediate code is shown. It will also identify the offending bank and the associated condition.
The knock sensing capacity of the AMV8 engine is also key to its ability to make timing allowances for lower grade fuel (unlike its bigger 12-cylinder brother, which cannot change its timing to accommodate such a change). Therefore, this system must also remain completely intact with no interference from an ‘outside party’, namely another ECU, etc.
CHASSIS SYSTEMS
These must include ABS, any stability control programmes, anti-skid, traction/torque control, etc. Any changes to the operation of these systems would render the upgrade a ‘downgrade’, and have no place on the commercial market as a road car. This is not the case for track cars that operate under different rules and by different drivers.
OUR PROMISE
Here at GMR we take special care to ensure that all of the above are retained. Our systems are integrated to run alongside your car’s existing system and in no way affect the complex monitoring systems in place as set out in the OBD2. Nothing is hidden and should any of the engine systems be outside these parameters then the PCM/ECU will bring up the associated warning, as it would prior to the upgrade.
Normal maintenance procedures and service timings can be adhered to. The only additional requirement is to examine the supercharger belt at service: 24000 miles or 3 years whichever comes first. In addition, the supercharger gearbox oil will need changing after 250,000 miles!
Our development car has completed over 77,000 miles in supercharged form (@ early 2016). The clutch has covered 57,000 miles (including many test drives and track sessions) with no detectable deterioration in either feel or travel. This is indicative of the benefit of the conversion, as the car now only has to do half as many gear changes as it used to, due to the greatly increased torque available at low RPMs in the higher gears. So much less use of high RPM gear changes means that the net result is substantially less shocks and stresses on the drive train as a whole. That said, we are not recommending supercharging your car simply to extend clutch life!
Our forced-induction engine produces the same torque at 2,500 RPM as the normally aspirated engine would at 5,000 RPM using less fuel. This is achieved, not by halving the revs, but by using innovative water-cooling technology to reduce waste (the Geyser) as well as reduced internal drag, throttling and friction losses to contend with.
Simply raise the rev limit, add another 1,000 rpm and get more power, easy right? Well, let’s examine this in more detail. The added inertial loads placed upon the engine internals can be calculated by dividing the rpm increase between the original limit and the new proposed limit by 100, giving a percentage, then squaring the result.
Therefore, an increase of 1,000 rpm equates to 10 x10 = 100%. You can bet that 100% increase in loading will not be within the acceptable design limits of any production engine and certainly not with any degree of reliability! So, this can be disregarded for a standard engine. Though perhaps more viable at a glance, increasing the bore, stroke or both provides a limited performance improvement and is comparatively costly to achieve just 10-15% increase.
Forced induction however, can safely double the engine’s power, retaining the original RPM limits without doubling the structural loads placed upon the components. It’s not necessarily all about getting a bigger bang, it’s far more important to make the bang last longer, thus increasing torque. This is why we chose this method.
As well as being cheaper than fuel, water is far better at cooling air: it has six times the ‘latent heat capacity’ (i.e. ability to absorb heat) of fuel. It also has the convenient side-effect of steam-cleaning the inside of the combustion chamber, removing the carbon deposits that cause ‘hot spots’, which can cause knock. So, by adding water to the charge instead of fuel, a substantially leaner fuel/air mixture is possible under load, because no fuel is wasted through use as a coolant. The result is comprehensive efficiency gains, an improvement in fuel economy, increased output at all engine speeds, and cleaner exhaust emissions.
You can view the ordering process in more detail on the Products & Ordering page. The steps are as follows:
1: 15-minute vehicle diagnostic check
2: Complete the order form
3: 50% Upfront payment to secure
4: Agree fitting date
5: Balance paid on collection
6: Enjoy!
Fall in love with driving all over again. Contact GMR Design for more information or to discuss supercharging and upgrades.
