Turbo boost RS265

Sorry that I don't know the specifics of the RS265, but I try to help with what I can.

That you have lower boost on first and second is fairly typical; Renault actually programs some of their petrol turbo ECUs such that the max. boost pressure is lowered in 1st and 2nd gear, and obviously there's also the fact that there is less load on the engine on lower gears which may result in lower boost as the turbochanger needs a good load to work against to provide full boost. However, I do not know if Renault did limit boost on the first gears on the 265. It would not surprise me if they did as they have done this on many engines.

Full boost going just above the 1 bar mark - again, sorry that I don't know what the 265 is originally supposed to be making but the number you are quoting does not sound far off at all. The older 225 engines make max boost of 0.9 bar although officially it's 0.8 bar, so counting in the extra power of the 265 (main difference in the engine vs. a 225 is VVT and a slightly bigger turbo + naturally it has different mapping) it would seem logical it would be making just over 1 bar max boost.

Hopefully someone with a stock 265 can chime in and confirm if I'm right or wrong here.

 

Do you have the rs monitor, I had something similar but only because it was in snow mode instead of sport or extreme.

 

Check if you can move the actuator arm. Mine got stuck and thats what caused the issue for me.


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The waste gate actuator will not directly determine the max. boost on these engines or on any modern EFI engines as the boost control is achieced by utilizing an electronically controlled solenoid valve which is fitted between the pressure source (inlet manifold, boost pipe or similar) and the actuator is in turn controlled by the ECU's boost map.

Typically the "gate pressure" will be roughly half of the maximum boost in the original setup. You might start to "bleed boost" if the actuator preload is too low though; the exhaust gas pressure inside the turbine's inlet area will then start to force the wastegate open even before the solenoid is open as the pre-tension of the actuator is too low to withstand the exhaust gas pressure.

By having the actuator arm adjusted "wrong" you can get boost pressure bleed as described, but on the other end of the spectrum you might also get undesirable overboost especially under high engine loads as the movement range of the actuator arm doesn't leave enough room for the actual wastegate "flap" to get fully open. This can lead to serious engine damage because the built-in fail safe systems of the engine are not able to function properly.

Unless your engine has modified induction, intercoolin, exhaust, head work done, the factory setting on the wastegate actuator should always be the preferred setup as it is the ECU with the solenoid valve doing the actual adjusting of the boost the engine is allowed to make under different loads.

Typically on most Renaults I've seen dyno plots of have the max boost in the mid range, slightly tapering off towards the top end but holding steady-ish compared to many of the direct ignition engines we have now. Most modern engines will always be running less pressure at redline than they do in the mid range; this is due to turbo sizing, inlet/exhaust system optimization and factory ECU tuning where maximum tractability and system stability is almost always preferred instead of highest possible hp figure.

P.S. I do hope someone can tell us what the max. boost setting normally is on the 265 engine.

 

Hi guys. I've been just lurking here quite a long just reading these interesting and excellent posts, but as you are still waiting for an answer to this one maybe I can try. Would you be surprised if I told you that the answer is 1.5 bar in sport mode?
Max. boost in Meg 250 is set to 1.3 bar and Meg 225 to 1.2 bar.

As an example this one copied from the 265 / 275 Renault press release:

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6. ENGINE AND TRANSMISSION

Mégane Renaultsport 265 is powered by a new-generation 2.0 16V turbocharged engine (F4Rt). With the Renaultsport Dynamic Management in Sport mode, it delivers peak power of 265hp at 5,500rpm and maximum torque of 360Nm at 3,000rpm.

With 80% of peak torque available from as low as 1,900rpm, acceleration is smooth and responsive, thanks to a twin-scroll turbocharger and continuously variable intake valve timing.

Raising the bar to 265hp has seen maximum turbo pressure increase by 0.2bar to 2.5bar. Changes have also been made to the air intake in line with the higher pressure and running temperatures.

Sport mode delivers a 15hp hike in maximum output to 265hp, plus an extra 20Nm of torque. This takes the power-to-weight ratio to an exceptional 191hp per tonne and ramps up performance, too: the 0-62 mph time is brought down to six seconds dead, while maximum speed rises to 158 mph.
---
Or this one, page 26:
https://www.renaultsport.co.uk/media/2842/renault-sport.pdf

 

That 2.5 bar pressure quoted is absolute pressure, which means 1.5 bar of boost pressure on top of atmospheric pressure which is as close as makes no difference 1.0 bar.

I'm surprised by those factory quotes though as I have seen boost blots and live runs with boost gauge fitted of 225s and they don't seem to reach that 1.2 bar quote mentioned above. 225s running 1.1 bar boost are seen hitting 240 hp+ on the dyno too.. It would be useful if actul drivers of these cars would report the kind of pressures they have measured themselves on stock vehicles and maybe even remapped ones.

FWIW wife's Clio III TCe wasn't close to factory figures on dyno either regarding the boost pressures and that car didn't even show any overboost feature being present even though that was very much promoted by Renault when those cars were new. The official figures aren't always in line with reality when it comes to cars, power output and boost etc. They should be close though so it'd be interesting to hear from more people around here.

................

Kimbe, nice to see you here bro

Would you mind sharing with us what kind of boost pressures your F4Rt engine is giving currently and what it was making originally, if you don't mind me asking?

 

*boost plots

I don't really like the timing feature of this forum that doesn't allow editing typos off of my posts...

 

Yeah, been lurking here a while just looking if someone could sell me some cheap Meg 250/265 engine for my Clio .

Superfly mentioned this mk2 Meg so let's take another example. I have a mk2 Laguna GT that has basically this same mk2 Megane engine. This following statement can be found from the Renault technical material:
"Derived from the engine in the Mégane Renault Sport, the 2.0T for the GT version develops 205hp and gives priority to the pleasure of everyday driving. Thus at least 90% of its maximum torque is available between 2,250 and 5,250rpm. This engine was developed to meet the requirements of D-segment customers, notably in terms of driving pleasure. It is a less radical version of the original, with maximum boost pressure reduced to 2 bars."

Before my Lag was mapped I took some measurements with Fastchip RSTuner and the max. boost pressure was pretty much there what was specified by Renault, giving around 1 bar as stock (pic attached if I just get it here). So I don't know how or with what that 0.6 bar was measured that was mentioned by Superfly in earlier post, but to me it sounds to be too low if that supposed to be the maximum achievable pressure. But of course, in generally, those measured values are always dependent on where and how and with what device those were measured, so those can vary a lot.

Also had some problems at some point when occasionally boost pressure climbed up too much (roughly 1.4 bar) and ecu went to limp mode. Nowadays it runs near 1.2 bar max.

 

That's good info right there, kimbe.

One thing I just thought of is that some of the irregularities of reported boost pressures might be due to differences in method of measurement. Let's assume one has an accurate analogue boost gauge. It will show noticeably different readings depending on where the boost feed is coming from - for example whether it's coming from before or after the intercooler (!)

Where is the factory boost sensor located BTW? If people are running aftermarket tools that measure pressure directly from the inlet manifold, for example, the pressure there will be less than what is produced by the compressor measured right at the compressor outlet.

Hmm. Kimbe, do you remember how the boost curve is on your car or how it was when stock - does it hold up until top end and by how much does it drop at redline? Just trying to get some guidelines for when I get the chance to do some data logging on one certain 225.

 

Not an expert at all, but I think the stock turbo (TD04-14T) does not hold up very well, or at least could always hold up better. It's quite a long since I took any log files, but I managed to dig some old ones. One example attached. Hope it still stays readable.

It is a full throttle acceleration using 3rd gear, starting at speed about 40 km/h and ending about 125 km/h. Max. values can be seen on top of the picture. Red line is engine speed, green line is gas pedal position and so on, just like stated on the left side of the image. So max turbo pressure during this acceleration was around 1.24 bar and starts to drop more clearly somewhere close to 5000 rpm. .

 

Just read this are you sure the max boost is 2.5 bar ? That is a very high boost pressure, even on my race Impreza I only ran 2.2 bar when I absolutely had too and normally ran between 1.6 and 2.1 depending on weather conditions and event and that was on a full race engine I would be surprised if these run 2.5 bar but happy to be corrected.

Out of interest are the turbo's on the 250 also twin scroll ?

 

Well, that is what Renault claims, so maybe we just have to trust it. But, like TurboJ stated earlier this 2.5 bar is absolute pressure (atmospheric pressure plus gauge pressure) which is about 1.5 bar boost pressure. Even in Renault material there are sometimes mentioned 2,5 bar and sometimes 1,5 bar when talking about the same thing (max. boost pressure). So let's not get confused about these differently given values. And also that this pressure was given to 265/275, 250 should be 0.2 bar lower as Renault says.

Yep, twin scroll turbos.

 

That makes more sense, that's marketing blurb the real figures then will be 1.3 and 1.5 bar which is more normal. What sort of figures are people remapping to on none forged internals ?

 

The torque curves on these are pretty good with a better turbo the curves could be changed dramatically interesting. Are your internals and gearbox standard Jamie and what turbo are you using ?

 

I had an Owen Developments GT3076 which was modded with a bigger compressor wheel and very high spec internals and the way it made boost was unbelievable. I made over 2.0 bar of boost by 2650 rpm. On a similar spec smaller turbo with a twin scroll input it would be mental.

 

Hi I was having a bit of trouble with boost pressure just dropping off turned out being a faulty FORGE actuator I have attached both graphs 1st one being the forge actuator and 2nd being the standard mk3 rs actuator as you can c massive difference between the 2