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Discussion Starter · #1 ·

I've recently listened to the Smoking Tire Podcast with M-Engineering and found it very informative and has raised questions in my mind. I wanted to speak to a community about tuning and what actually happens if I were to send my 720s ECU for a tune. I stumbled across this forum in hopes to better understand what will happen and what the expected outcome will be.

1. Why should I tune my ECU? Is the stock tune not good? Is there something I am missing that I will only find once I unlock the ECU?
2. They spoke about adding in additional safety features. What extra protection will I get over my current 720s features? I feel this is a strong selling point and has me worried about my stock 720s. Or is this mainly if I were to track the car (haven't done to date).
3. With increased performance, will I not run into issues with my engine? I assume power is added through boost pressure?

I hope this is the correct place to post this question. First time posting and this old boy is not that great with technology, however want to learn more as I have an inquisitive mind.

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Discussion Starter · #7 ·
Hi Both,

thank you ever so much for taking the time to give me such a detailed response. I read both and had to go away to do a bit of reading. I hope it’s okay to ask for a bit more information regarding your answers. As there is a lot I want to understand, wish I became an engineer, but 52 year old me just doesn’t have the time or patience anymore.

First off Mike, awesome to hear about your experience! Thank you for sharing. Must have been a dream to work everyday in the home of these supercars. Based on your reply sounds like you were quite involved in the engines?

I went through my owners manual and service schedules, but couldn’t find anywhere a mention of a EGT sensor. How is EGT measured?
My first set of questions are around your points of the car running such extreme lambda. Why are they doing that? What is this component protection and what needs protecting?

I would like to touch on the other points that you both raised after the EGT/protection topics. Still researching, but it’s better to hear from the experts

Hi Bobsfurniture and others who are interested to tune,

I am going to back up what @M-Engineering is saying here, but I think there is a need for more technical info, as to be honest the forum needs it. Phh where to start, so lets get into it. As having a McLaren background and working for the company in the UK, I have seen a few things/lucky enough to learn more than the average having worked with some very experienced people who have been technical support for years on end.

There seems to be a lot of people worried about tuning their McLarens due to "reliability". From experience, I can tell you, these cars yes have their gremlins which most of the time small electrical issues, however, the engines are STRONG if maintained properly and some technical common sense being used, yes there have been some instances of cracked liners and thrown rods, but from the cases I have seen, have mainly been because of poor maintenance, abuse or poor tuning. I think its fair to say that there are some poor tuning techniques out there, which I have seen myself, and having dedicated about a year to learning how to tune this particular platform, great benefits can be found in tuning these cars if done properly.

While the stock mapping as already mentioned is good, there are some negatives within the tuning which could do with some refinement, such areas include the fueling, McLarens run far too rich with a minimum of .67 Lambda on full throttle under certain conditions (Component protection), running fueling so rich, can actually INCREASE EGTs to around 800c, so while this might cool down combustion temperatures the temperature of the exhaust gases is significantly increased putting extra heat into the turbos, manifolds (which is probably why some have cracked P13 upwards), oil, etc is obviously not a good thing, which is why tuners like me, and M-engineering fine tune this area which actually results in much lower EGTs at full load by about 50-60c. (730-740c).

The ECU strategy is mainly operated on requested load and EGT modelling, once a certain EGT is seen by the ECU, (850c) component protection will come in and you will be running .67 lambda. (9.98-10 AFR) or so, this is detrimental for power and of course EGTs, (exhaust gas temperatures). So as I said above, this is an area that is greatly improved to around .79/.80 Lambda with tuning, and from the amount of logging I have done, these cars after a few pulls will kick into component protection mode anyway, and mainly maintain this very rich operating condition. As the too rich lambda will generate the high EGTs and its a never ending cycle from there on in unless you allow the engine to cool for a significant amount of time, so tuners will opt to change this map to keep EGTs under control.

Another area that is optimized is the ignition timing, the profile as stock is as said, aggressive but well controlled knock strategy that will pull timing to protect the engine from any damage, so this isn't a problem, ignition timing is a key factor in making more power, but we have to be safe with it and use the right amount as it will be destructive on any engine.

Boost is another aspect of tuning which is cranked up a little, approx. 18-19 PSI (tuned) depending on the platform but we will use 12c/650 as an example. This is also an area that is closely monitored. The ecu has a MAP sensor limit which needs to be set correctly, once we set this limit, the boost will not exceed, and is there to protect the turbos running too much boost into the engine, if the fueling is good, then the engine can see higher boost levels/timing without any issues, the problem is when intake air temperatures get too high and boost is not limited by poor tuning (example map below), I have had a car come to me with boost vs IAT maps still requesting full load/boost to the engine at temperatures above 90c, which is totally asking for trouble and this is the point we are making here, if the tuning is done correctly, there is really nothing to worry about, I have just tuned my McLaren myself and I am really happy with the results. Its so much better, I am hitting the dyno on Friday and I will post in this thread the before and after dyno results.

Example of stupid and unsafe tuning of a Load vs IAT map.

View attachment 227675

My advice to all McLaren owners would be to tune their cars, but, make sure it has been done by someone who knows that they are doing, just as an FYI, tuning these cars do not need to be done by a McLaren expert, they run the same ECU has some Audis and VWs. If someone knows how to tune those well, they can also tune McLaren's well.

To summaries the tuning process it consists of: Raising map limits, fueling, Boost, ignition timing, torque changes, there are various maps within these areas, but this is mainly all that is changed, tuning is like making a 5* meal, with the right amount of ingredients, its fantastic.

The engines can take the tuning if its done properly. Its really nothing to be scared about also regarding the warranty issue, the way this is checked to see if the car is tuned is by using the calibration area (map segment of the data's checksum vs McLarens) once the data within the ecu is changed, the checksum also have to change, McLaren stock calibrations all use the SAME checksum, so its easy for them to check if the data is stock or not, but if you take the car for any warranty work I don't think warranty voiding is an issue if you revert to stock via BENCH flashing and you keep the RPM limit standard, you will be fine and it will in the main go undetected, because if you exceed the RPM limit stock, that will show in diagnostics and its obvious, its pointless changing the RPM limit of these engines anyway as there is little power after 7500 with stock turbos, bigger turbos its obvs another story.

In terms of safeties, the ecu from factory have these anyway (Knock, Fuel trims and some others) but m-engineering have been smart and added more just incase for the sake of people who do not understand what is going on.

Open to any questions so please ask, I hope you found this interesting,

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