Hi all, I have been toying with the idea of a re-map. However I was just wondering, why would the car not have been mapped like this to begin with by Renault if it gives around 50bhp more and better fuel consumption? What are the drawbacks? What am I missing?!
Let me answer you to this one. I will start by saying first that my previous job was petrol base engine calibration in Renault. So, I believe I have some knowledge on the subject. First of all, the company (here Renault, but any car manufacturer) wants some very reliable cars to decrease the money they spend on servicing. So they leave some safety margins on all parts. In the case of a turbo petrol engine, the limitations are: - turbo speed and boost pressure - maximum peak pressure inside cylinder without knocking - knock limit which is not the audible limit tuners usually tune at - pressure ramp inside cylinder - temperature at engine exit and most important at kat entry (this is why all the cars run rich at full load, richer than we think they should) - spark plug temperature. Over all this limitations, you have the drivetrain limitations like maximum torque, maximum ramp of torque to protect gearboxes, shafts and diffs and in the end all the filtering for drivability. We don't have to forget that some rich grandma can drive this cars, so they have to filter all the torque requests. So, this gives you the OEM calibration. After we calibrate an engine, it has to pass some reliability tests which are draconic: 600 hours of full speed (basically you run the engine 250rpm below rpm limit), 450 hours of ramps (you accelerate from idle to full load in 20-30 seconds and back) and the most harsh test is when we also cycle the water temp inside the engine between 0 to 110, while the engine goes to full load and back thousands of times. When you remap the car, you loose most of this safety margin, pretty much all the drivetrain limitations and some of the drivability features. And to really gain something, you decrease the back pressure and loose the cat which really gives you a genuine increase and map for that. After you map the car, if you are civilized and know how to treat it properly, you should still be safe, but not as safe as the producer considered you should be. There is no free lunch, so gaining something makes you loose something else. S.
It's all down to exporting the cars to different countries that have different qualitys of fuel. That's why when you have a remap they tell you to run 99 Ron fuel.
Thank you for taking the time to give that very detailed reply Bulardas So it's basically removing the margin of safety, but unless you drive it like an idiot you'll pretty much be ok. I'm not sure it needs more power anyway to be honest!
That, my friends is a tip top answer right there. No Bullshit, just pure knowledge. We are not worthy! Still getting mine mapped and decatted in April mind
It's also a game of luck, I do track days with people with R26s who are running theirs at stage 2 285/300 and have done over 60 very very hard track days and are fine,
It's worth bearing in mind that a respected tuner (let's say RS Tuning as that's where most of us here go) will also leave a margin of safety with a custom map - obviously that margin is reduced from the manufacturers map, but generally anyone who is into cars enough to remap one will also run it on super unleaded, maintain it properly etc. Some people running a standard car are probably much more likely to have problems, because they run it on the cheapest supermarket fuel, change the oil at 12,000 miles even if that takes 3 years to rack up, and don't maintain it until something breaks or falls off. I've been on the RenaultSport forums since 2009 and in all that time have only read of the odd engine going, and those weren't even all mapped. With these cars the engine is the thing you should least worry about, they are pretty solid and the safe limits are well known. I've racked up 28,000 miles now with the F4R engines and the only issue I've had in all that time is a knackered lambda sensor. I'm trying to think of anything else that's gone wrong with an engine or electrics, even a fuse, but I can't.
Ive done over 40k in my RS250 since i have owned it in the past 2 years and other than having to get the engine stripped due to flood/water ingestion the actual engine has been faultless.
From what I've read that was in the early days, isn't the accepted 'safe' limit 300lbft on standard internals?
your spot on mate I was only talking to rstuning and WoN about that and they confirm what you just posted +1 mate
I'm running stage 2 on standard internals. Going for rod bolts and injectors just to add another margin of safety. Personally think luck plays a big role too!
Does this mean that you test multiple engines in various climatic tests ? Also running multiple different Ron/Mon contents ? Curious how the det is monitored ? Not having a go , just want to know more.
Thats nice burlardas. Also if u improve your oem components (decat, turbo, IC, internals, etc) for shure that safe margin is not the same, and youre aviable of geting more power safely
Ok, I will try to tell you more, but if you have specific questions about, let me know. Someone asked about the different fuels. I'm never worked on the Sagem ecu in the 225, I only worked in the Continental version from the 250, which I know pretty well. The Continental has 4 different fuel levels, so ignition, fuelling and boost are tuned based on the fuel the ECU is recognising. And then, you have another strategy that chooses which fuel you are running. Think of this as a switch. I'm not speaking about a certain tuner here, but a lot of the maps I've seen for the 250 are not keeping this feature. Because the tuners don't know the logic behind this maps, they just put the same ignition numbers and fuelling in all maps. So doesn't matter what fuel are you using, your car will push the same ignition, which is a pretty big caveat in the tuned files. If any of you have the possibility to look in your own tuned maps, you will see I'm right. And then, there a lot of other jewels in the stock ecu, that it seems none of the tuners know how to use it. The simplest example is the nice launch control that Continental has inside. Everything is there, you just need to enable it and set it up correctly. It works a charm. But no one is offering it. Or the 4 fuel maps, so you could tune normal, premium and race-fuel inside the oem ecu and have the power accordingly. Or race ESP mode where you don't kill all your power, just what you need to keep the wheels not to spin. But again, the most of the tuners, just pushes for 3-4 extra degrees of ignition, more boost and maybe put in place the AFR which is sad for a calibration engineer like me. What Haomaru said, it is true. When you change parts on the car, you move the safety margin. The biggest problem you have is the kat. It is very temperature sensitive and makes a lot of back-pressure. Once you remove that, you are not that temperature limited and you can also run leaner, so there is also your mpg improvement. But with the kat on, I don't see any place where you can get better mpg through a map unless you "fry" the kat. Removing the intake limitations also helps a lot. But running more boost just pushes the turbo on the edge. I'm not saying you should run more boost, I'm just saying that you need to know what are you gambling. But the biggest discussion is about the safety margin, reliability and life time. A lot of people here say they are mapped for xx miles and the car still goes strong. Let's face it! Most of you just run like anyone else on the highway with a limited blast once in a while on a B-road or a track day. If you sum up all the fullload time your engine seen during his like, you will see it is under 2%. But if you choose to live in Germany for example or track your car all day long, you will start to see how much your remap is pushing the limits. Or, if you install a remap from a genuine company from Germany, they will give you less power than the companies here, because in Germany people pushes the car a lot more. Bottom line: I'm pretty confident that none of the remaps widely available will be able to run a 24h endurance race with a stock engine. That is the ultimate test. Also the weight of the car is pretty important. If you have 2 cars, a stripped one and a full-fat one carrying also 4 person on board and they run the same remap, the same power both, the full-fat one will throw a conrod first, because the increased weight keeps the engine more on the high-load areas and also forces more all the parts. S.
Nope, All i know is they do it now. I would love it as well just for the flames/pops/bangs but i don't think i would actually use it for launching, Clutchs are expensive enough.
This stuff is mega interesting ( at least to me ! ) The rod issue. Have you any insight into what is causing the rod to fail ? Was any testing done moving the torque to different RPM loads ? For instance , I think from admittedly limited exposure to results that the engine is under huge stress by relatively large amounts of torque at lower levels of RPM. If this is moved to a higher level so the RPM can dissipate it more would this help.
Very very interesting information bulardas. Shame you never tested the 225 engine . Surprised about the 250 having 4 fuel maps and launch control though. @OP I has some pretty amazing gains from my 225 engine because of the decat, exhaust, induction and remap, its running 270bhp & 301 lbft reliably .
The explanation is pretty easy and you don't need any testing, is just physics. Hp = (bmep * L * rpm) / const where: Hp = horse power bmep = brake mean effective pressure L = engine size rpm = engine speed const = some other constants What breaks an engine is BMEP which is the actual pressure inside the cylinder. This cracks pistons and bends rods. If you read my first post here, I said that the engines have some limitation of BMEP and ramp of BMEP, but nobody knows this limitation or measures this in anyway. If you keep rpm constant, in order to increase the power, you need to increase BMEP accordingly and the difference is very big inside the piston. But keep in mind that usually the turbo has a lot of air at low rpm, so you can get to very big BMEP values. And there goes your rod. Is there any single clip on youtube with a Megane III with launch control? Can you share it please? S.
Interesting. How do manufacturers know what BMEP will bend things if they dont test it ? I am not trying to be argumentative , just curious. Did renault test some to destruction then wound it back ? Or simply said the BMEP in a 172 is X , so we should be able to go Y and then extreme test ?
Any given amount of torque (let's say 200 ft lb for example) exerts more stress on the Conrod at lower engines speeds than higher engine speeds. I believe this is because the lower the engine speed the longer amount of time the rod is exposed to that bending force (torque). Higher engine speeds mean that the rods are only exposed to the torque/force/load for microseconds at a time. Hope this makes sense
I realise you have a very bad opinion about the automotive industry. So, I will try to shed some light here. Any producer knows well before he draws any line for the next model, what weight, power, performances the car will have to a very great detail. Renault is one of the best producers into this from what i meet. They know (around minimum 80%) how many screws and weld points the car will have even before they know how it will look. Going for engine alone, the first things we know when we start to develop a new engine is engine capacity, exact performance we want from the engine (a graph of power and torque), what euro norms has to meet, the weight of the engine, the final cost of the engine, the fuel consumption. And then we start to develop the engine to stay within those boundaries. When you have the torque curve, you know what BMEP will be inside the engine. And once you know what, you can design a rod to withstand those forces and then to simulate all the forces to see how it will hold. When we first build a new conrod, we know within 1% of tolerance which is the max load it can stand and it really breaks there. If it can hold more then what we want, it means it has more material which makes it more expensive and heavier. And we extract that out. Back in the 80s, when engineers couldn't simulate on PCs all this things, they had to do all the parts bigger than necessary because they didn't know what loads and necessities where there. So this is the reason why older cars withstand a lot more abuse without problems. When CAD/CAE/FEM (pc aided simulations) were available, engineers managed to check what benefit comes from each gram of material, each screw, weld point. And now, I will tell you something that most of you don't understand or realise. Today, all the manufacturers care only about fuel economy (which translated to CO2 emissions), the general emission (if it is eu5, eu6...) and cost. Maximum power is just a by-product of the whole project. Or to put it in a different perspective, we spend 2-3 years to develop the emission side and maximum 2 months to make the maximum power. Why? Because you can always sell a car that should have 250 and has only 245hp, but you cannot sell a car that should be Euro6 and it is only Euro5. S.
I dont have a bad opinion of the auto industry ! I just want to learn. I have a quest for knowledge. Interesting points on the designed for job , rather than the old school over engineered ! Do you know what BMEP / Torque the 225/r26 engine can take ? Can you find out ? I guess it might be hard now you are a LJR ?
I don't think bulardas means you personally andy , but the public in general I guess , yeah I would like to know that too , we know what rstuning/WoZ think it is, be interesting from a manufacturing perspective.........
So is he saying there's not enough room for a re-map then and best left alone, I can see where this will go, everyone removing their maps.
No I don't think that at all Steve, though it does highlight (to me at least) the level of expertise that's involved and the importance of getting the work done by people who are experts in the field of mapping if you choose to do it. I think we all know it carries a risk but minimising that risk is key.
