Engine Inlet Temperature

Looking through the visitor stats for this site, it seems that lots of people are interested in upgrading the intercoolers on the Ghibli. I have to admit that this is something that I looked into myself, since the stock air/air coolers seem a bit small compared with the huge aftermarket coolers that can be purchased for the likes of VW Golfs and Mitsubishi Evos.

So, I pulled up one of the data logs from my PLX Devices R-500, since I have it tapped into the air temperature sensor on the throttle body. This sensor measures the temperature of the charge air entering the engine, after it has been cooled by the intercooler. I have to admit that I expected the temperature to be in the range of 70 to 90 degrees since after going for an enthusiastic drive, the throttle body and plenum chamber are too hot to keep my finger on.


The picture above is a screen grab of the PLX Logger software charting the data in 2D. It's a bit rough... I've been having trouble getting reliable RPM data from the engine speed tap and so this needs to be multiplied by 5 to give the correct engine speed (I think I'm going to tap into one of the ignition timing wires instead). The MAP values are also a little bit out. However, the chart gives a good enough idea of what's happening and the temperature values are correct.

What you see is that at idle, when the car is stationary and no cooling air is flowing across the intercoolers, the inlet temperature is up around 50 degrees Centigrade. It's important to realise that the ambient temperature when these reading were taken was around 5 degrees Centigrade, so pretty cool. As soon as the car starts moving, the inlet temperature rapidly starts to decrease to a steady state around 30 degrees above the ambient temperature. When the car is driven hard at around 380 seconds, there are significant peaks in the inlet temperature. The temperature is quick to fall back to a steady state less than 40 degrees Centigrade.

I still need to capture some log data for summer temperature, but I suspect that steady state with an ambient temperature around 30 degrees Centigrade will be about 70 degrees Centigrade. This is less than I expected and my conclusion from this is that, unless the car is going to be raced on a track where the engine is kept at full load for a long time, then there's no huge benefit to changing out the stock intercoolers if the car is being run with 1.20 barg inlet pressure. Bear in mind that if the car is run on the track, there will be a good flow of air all the time over the intercoolers helping to keep them cool. The highest inlet temperatures are occurring when the car is stationary or moving slowly and increasing the intercooler size is not going to help this.

What I'm therefore thinking of doing is adding a cooling fan behind each intercooler, connected to the water radiator cooling fans. These fans generally only activate when the car is moving slowly or stationary so would be a good control for the intercooler fans. This should then keep the intercoolers at a relatively low temperature when driving around town for example, or when the car is cooling down after a hard drive.

Intercoolers

I've been doing a bit of research on intercoolers having recently found out a couple of things.

First was from Buddy at Wereld Auto who informed me that intercoolers from a VW Golf mark IV TDi will fit on the Ghibli, although the one manifold has to be removed and a new one constructed and welded on its place. The good thing about this solution is that it's cheap (these intercoolers can be purchased on ebay for less than €100) and they offer good performance since they're twice the thickness of standard Ghibli units. However, I don't like the idea of having to modify them.

The second option was hinted to me by Jorrit at Auto Forza. He informed me that the intercoolers on the V8 engined Quatroporte is about 30% thicker than the units on the V6 cars. I then happened to stumble upon a picture of a 3200 GT being sold for parts and noticed the intercooler... the location is identical to that of the Ghibli and Quatroporte and the configuration of the ports looked the same.


So I wrote to EuroSpares and enquired as to whether they had any second hand 3200 GT intercoolers and if they could check whether they fitted a Ghibli. They wrote back to inform me that they'd been informed from the factory that the Ghibli intercoolers will fit the 3200 GT (wrong way 'round but by definition, the 3200 GT intercoolers must fit the Ghibli (although the ducting may require a bit of modification)).


Above is the parts schematic from the 3200 GT. Compare the size of the intercoolers with those for the Ghibli in the schematic below.


So I'm tempted to try and source some 3200 GT intercoolers and get Jorrit to try fitting them when he's fitting my new bumber (when it arrives... it's been on order from the factory for about 2 months now!).

As usual... I'll keep you posted of any updates.

ECU Upgrade

Following a lead from Jarle in Norway, I started to investigate Kronenburg Management Systems as an option for upgrading the engine management system on my Ghibli to overcome the limitations of the OEM system installed by Maserati.

The Magnetti Marelli system installed by Maserati is very old compared with today's technology. To put it into context, this system was installed in Ford Sierra Cosworth cars back in the late eighties and early ninetees. The clock speed for this system is around 4MHz. Compare this to a modern laptop or desktop computer, which runs with a clock speed an order of magnitude quicker at 4GHz. In fact, you'd be luck to find a microprocessor that runs less than a hundred times quicker than that utilised in the OEM engine management system.

The effect of this is that the engine management system currently installed in my Ghibli makes significantly less decisions per second than the systems installed on typical modern street cars. Things happen and change very quickly in a car engine, particularly when it's reving at 7000rpm. That's over 100 revolutions of the crank every second, which is 25 detonations per second per cylinder.

The way an engine management system works is by taking a snapshot of the engine, which means recording the values of certain engine parameters at a moment in time by reading the output signals being sent from the various sensors located around the engine. The key sensors on the Ghibli are the inlet air temperature and the inlet air pressure for example. In order for the engine management to make decisions, it needs some reference data. This reference data comes in the form of look-up tables, which is just how people used to make complicated calculations in the days before electronic calculators. These are called maps.

A 2 dimensional map allows you to look up an answer if you know two numbers. Let's say that the inlet temperature is listed across the top row of the look-up table and the inlet pressure is listed along the left column of the table, the answer can be found by drawing a line down from the top inlet temperature value and a line across from the left inlet pressure value. Where the two lines cross is where the answer lies.

The answer tells the engine management system to perform a certain task. However, this answer is only applicable to the moment in time when the two input values were recorded, so if the system is too slow, by the time it carries out the response, it will no longer be applicable... a delayed response.

If there are more sensors, then the management system needs more look-up tables in order to know what decision to make, which takes more time. Also, the decision may require more than one response... for example the amount of fuel that is required and the time at which to ignite the fuel may need to be adjusted. Each additional response takes additional time.

My point here is that the quicker the management system can make decisions and respond, the more effective it is. In the Ghibli, it's obvious that the speed of the engine management system is not optimal, simply by virtue of the fact that TWO management systems are required, one to control the amount of fuel being injected and one to control when the fuel is ignited. So even when the Ghibli was being manufactured, it seems to have been recognised that processing speed was a limiting factor. Therefore, increasing processing speed should have a significant effect on the performance of the engine.

The next issue with the OEM management system is its lack of diagnostic capability. The only real way of determining if the system is making the right decisions is by measuring the performance of the engine, either by having a feel for the car or by sitting it on a dyno. The system does not have an easy way of monitoring what decisions are being made, except by taking the car to a specialist who can tap into the system and monitor what it is doing, which requires a degree of skill, technical knowledge and the appropriate equipment.

Modern management systems however offer a convenient way of monitoring what is happening. They generally have a convenient port into which you can plug a computer and with special software, you can record and review what decisions are being made.

Finally, if you recognise that sub-optimal decisions are being made, you need to be able to change the decision making process, which generally means altering the look-up tables or maps. Again, on the OEM management system, this is not a trivial thing to do and requires removal of the system and some special hardware to reprogramme the memory chips on which the data is stored. Also, the way this data is stored is not very user friendly, as it is stored in a way that is convenient for the microprocessor to read and not the car owner.

The beauty of a modern system is that all these things are possible. With modern software, you programme the data in a form that is easy to understand (using decimal numbers instead of hexidecimal or even binary code required for older systems) using a laptop computer. You can also record data from the engine, review it at a leisurely pace, determine what changes you want to make, update the look-up tables and see straight away the results... without having to go to a chip-tuner!

So, after contacting Van Kronenburg and discovering that they're a Dutch firm (much to my delight, since it means that they're local), I was a bit downheartened that I never heard back from them and it is then that I ordered the PLX Devices R-500 datalogger. However, I subsequently received an email from Buddy at Wereld Auto who informed me that he had been forwarded my enquiry from Van Kronenburg. Buddy is located pretty close to where I live (about a half hour drive) and can install and setup the KMS system on my Ghibli.


Above is a picture of the hardware which would replace the two OEM ECUs. He's given me a quote for fitting the system and I'm going to see if I can integrate the PLX R-500 into the installation to give me realtime feedback on the road. I've a feeling that the lambda probe that came with the R-500 is the same as that utilised by the KMS (a Bosch wideband probe) and I'll also see if I can integrate the Exhaust Gas Temperature (EGT) probe into the KMS, with maybe some feedback to prevent the exhaust gasses getting too hot and damaging the turbos.

The KMS can also control boost pressure, although I'm uncertain if it can tie into the TurboSmart solenoid valve. This would unfortunately make my E-Boost redundant, but I think the KMS would offer greater control over boost pressure with the added advantage of being able to tie in boost pressure maps with fueling and engine load.

I'm waiting to hear back from Buddy with answers to a couple more questions that I have, but if the price is right then I think I might go along with this option. The KMS is certainly much cheaper than MoTec and I like the idea of it being local, since if it stops working then I can go 'round the manufacturer personally to get them to sort it out!

Also, Buddy appears to have worked on a number of Maseratis, including a Ghibli fitted with a V8 engine from a Quatroporte in which the owner wanted the KMS system fitting. He also told me something interesting about the intercoolers from a Golf Mk4 TDi...