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I wanted to open a thread about sensible tuning options for the S65/CL65 with these main goals in mind:
- reliability
- drivability
- as close to stock as possible
I started with a Renntech tune plus heat exchanger and pump upgrade. I am very satisfied with the results. (675hp/1150Nm) The car is as drivable as ever but it storms forward much more urgent when you want it to. The only "disadvantage" is the fact, that you hear the turbos a little more because they spool faster and earlier. It is a price you have to pay for the gains. I know, for most people it won't be a concern but I want to mention it at this point because you have to keep the nature of these cars in mind, which is comfort.
What I am looking for now is some input where to go from here.
Either improve the cooling and try to go for more hp or improve the transmission and go for even more torque?
Every bit of cooling you can throw at the car is definitely a good idea, but my main concern is the problem that comes with it: relocating the intake system. The options available are not to my taste. An open intake is loud and sucks in either hot air from the engine bay or is completely exposed to the elements in front of all the coolers. Going over 250km/h on the autobahn a lot of the time, I will not risk damaging my air filters and destroying my engine/turbos. So open filters are not an option for me.
Brabus has a nice intake system for the W221, but I bet I can almost buy a new car for the price of it, in case I am even able to order it separately.
The space in the engine bay is unbelievably cramped on the W221, I do not see a way to relocate my air filters. So what about going down the SL65 Black Series route? As far as I know, the intercoolers are the same as the ones on regular AMGs but they added two additional heat exchangers. Combining that with a second Renntech pump, like they do on their SL65 BS, might be a valid option for cooling. What do you think about that?
If I were able to get 750 hp out of the car without adding a lot of stress to the components, I would be happy. By the way, I am able to use 102 octane fuel, in case this makes a big difference.
Last edited by black-series; Jul 22, 2017 at 04:17 AM.
Aside from improving the IC, one of the best ways to get more power is to remove the stock air filters and replace them with new intake ducts and cylindrical filters in front of the radiator.
I personally do not like the idea of the intake duct solution for several reasons:
- Running my car on the autobahn all the time near its top speed leads to massive stone chips on the whole front of the car, you should see how much damage this causes. There is no way I want to expose the last protection for the turbo chargers and engine to this punishment. Rain becomes a big issue during high speed driving as well.
- I am not a fan of these filter in general. First of all, small oil particles will always travel towards the engine internals and often do cause major issues, especially sensor reading faults. It may work for many but I know enough people who had major problems after some time.
Another problem is dirt that gets carried into the engine internals. Everything comes with a price and more air comes with the price of more dirt traveling through the bigger holes in the filter. I do not want that to be honest, the gains are not worth it in my opinion.
Is anyone running his car with more than 1200Nm of torque and could share his experience?
I am considering to remove the current limitation (1150Nm) in 4th and 5th gear and go all in (1230Nm). I will probably need a transmission upgrade after some time, but that is acceptable to me. My only questions are, is it worth it acceleration-wise and will I have to worry about other parts like axels, differential and so on? I would appreciate any input on this matter
Is anyone running his car with more than 1200Nm of torque and could share his experience?
I am considering to remove the current limitation (1150Nm) in 4th and 5th gear and go all in (1230Nm). I will probably need a transmission upgrade after some time, but that is acceptable to me. My only questions are, is it worth it acceleration-wise and will I have to worry about other parts like axels, differential and so on? I would appreciate any input on this matter
I haven't worked on my intake sytem, for the same reasons as you. I am worried about ingesting bits. K&n type cone filters flow more by filtering less.
There is also no doubt that the intake system on the M275 is a horrible bottleneck and also a big heat source when in slow moving traffic.
I may try this method at some point, but as I have distronic I get even less space so it may be difficult.
To tackle intake temperatures I have meth/water injection which works well. I also have the updated pierburg cwa200 and a swirl pot header system as suggested by welwynnick!
My opinion on on the gearbox is, remove the limiters and when it goes bang, strengthen the bits that break, the boxes are common and there are lots of bits for them.
Last edited by alexanderfoti; Jul 24, 2017 at 12:43 PM.
I haven't worked on my intake sytem, for the same reasons as you. I am worried about ingesting bits. K&n type cone filters also flow more by filtering less.
There is also no doubt that the intake system on the M275 is a horrible bottleneck and also a big heat source when in slow moving traffic.
I may try this method at some point, but as I have distronic I get even less space so it may be difficult.
To tackle intake temperatures I have meth/water injection which works well. I also have the updated pierburg cwa200 and a swirl pot header system as suggested by welwynnick!
My opinion on on the gearbox is, remove the limiters and when it goes bang, strengthen the bits that break, the boxes are common and there are lots of bits for them.
At the moment I can't complain about my cooling situation. Since I added the additional HE to the intercooler circuit and upgraded the pump I stay below the critical 70 C charge air temperature. Sure it is always better to get the temperatures down as low as possible, but as long as my engine management is not pulling power due to heat, this is fine by me.
Thank you for your input on the gearbox. Do you think I will notice the additional 100 Nm? I mainly care about speeds between 150km/h and 300 km/h. Or will the car even become slower because of esp intervention?
What about the differential? Does it hold the power?
At the moment I can't complain about my cooling situation. Since I added the additional HE to the intercooler circuit and upgraded the pump I stay below the critical 70 C charge air temperature. Sure it is always better to get the temperatures down as low as possible, but as long as my engine management is not pulling power due to heat, this is fine by me.
Thank you for your input on the gearbox. Do you think I will notice the additional 100 Nm? I mainly care about speeds between 150km/h and 300 km/h. Or will the car even become slower because of esp intervention?
What about the differential? Does it hold the power?
Yes, that is my aim as well, to keep it below the point it pulls timing/boost.
I am sure 100nm will be noticed in the midrange. In the higher gears the gearbox should be OK with the increase. I would do it to mine.
I have not heard of any issues with the differential of tuned cars.
I would be surprised if you get esp intervention at 150km/h+
May I ask, how much you paid for your Renntech ECU tune?
As for the intake improvement, the only solution I really like is the one brabus uses. No one can beat their solutions in my opinion, the money they are able to put into research and development is visible in all of their products. That is exactly how I would like to do it but with original Mercedes air filters. This would be my perfect setup.
That setup doesnt help on the restriction side, only the intake cooling side.
I am not entirely sure about that. At low speed you might be right because the cones have a larger surface area, bigger diameters and are less restrictive. But at high speeds the added ram air effect of the brabus scoop is superior to the open cone solution. The cones start to create turbulences and ultimately blockage (partial) of air at high speed. Not only for themselves but for the coolers behind them as well. The brabus scoop is able to create a nice constant pressure in front of the filters that forces air through.
I am not entirely sure about that. At low speed you might be right because the cones have a larger surface area, bigger diameters and are less restrictive. But at high speeds the added ram air effect of the brabus scoop is superior to the open cone solution. The cones start to create turbulences and ultimately blockage (partial) of air at high speed. Not only for themselves but for the coolers behind them as well. The brabus scoop is able to create a nice constant pressure in front of the filters that forces air through.
Ah yes, you make a good point. I did not appreciate where that actually was on the engine bay.
It should be relatively eays to replicate the function ?
Ah yes, you make a good point. I did not appreciate where that actually was on the engine bay.
It should be relatively eays to replicate the function ?
Well, you would have to laminate the whole intake system which probably takes a lot of time. The two airboxes, the scoop, the channels from scoop to the airboxes. You even have to cut a part of sound isolation out of the hood to make room for the scoop. Brabus covers this part nicely with a carbon fibre plate. A genius solution to make that much required room in the engine bay.
Did anyone do a ecu tune first and a tcu tune a little later? I would like to know how big the difference is after an ecu tune. Theoretically without tcu tune the torque should always be limited to 980Nm by the transmission so basically no gains in torque over stock. With tcu tune a torque gain of 200Nm should be available (in case it is not limited by the software of the ecu)
I plan on doing it in that order. I do belive that the torque Limiter in the tcu is higher than 1000nm as you say you have noticed a difference with the remap on its own, so that must be the case.
I plan on doing it in that order. I do belive that the torque Limiter in the tcu is higher than 1000nm as you say you have noticed a difference with the remap on its own, so that must be the case.
Yes, the difference is huge, so I guessed it must have been the torque increase. After talking to another big Mercedes tuner (Väth) I found out that the transmission control unit is the master in torque limitation. Lets say ecu allows 1100Nm, it will momentarily increase torque over 1000Nm but as soon as the tcu recognizes that it is too high, it will limit it back down to 980 Nm. That process goes on over and over again, ecu trying to increase torque because it thinks it is ok to do so, tcu limiting it back down again because it thinks it is not ok. That is what I was told.
Yes, the difference is huge, so I guessed it must have been the torque increase. After talking to another big Mercedes tuner (Väth) I found out that the transmission control unit is the master in torque limitation. Lets say ecu allows 1100Nm, it will momentarily increase torque over 1000Nm but as soon as the tcu recognizes that it is too high, it will limit it back down to 980 Nm. That process goes on over and over again, ecu trying to increase torque because it thinks it is ok to do so, tcu limiting it back down again because it thinks it is not ok. That is what I was told.
Its also not a fixed limit. There will be times at certain parts of the rev range where the gearbox is not limiting tourque, but the engine does not make it.
EG the map will bring the power on earlier in the rev range and adjust boost pressure control to make it longer in the rev range, at the expense of misfiring etc.
Its also not a fixed limit. There will be times at certain parts of the rev range where the gearbox is not limiting tourque, but the engine does not make it.
EG the map will bring the power on earlier in the rev range and adjust boost pressure control to make it longer in the rev range, at the expense of misfiring etc.
You are right, it is a complex interaction between ecu and tcu with no fixed limits. But I think it is true that the full potential of an ecu tune can only be achieved if the tcu allows the torque to go trough which means going for an ecu tune as well.
You are right, it is a complex interaction between ecu and tcu with no fixed limits. But I think it is true that the full potential of an ecu tune can only be achieved if the tcu allows the torque to go trough which means going for an ecu tune as well.
I, potentially, agree.
However, I have to send the TCU to the USA to get it mapped and that makes me nervous.
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