I just can't get my head round this so let's see if someone else can offer some insight. Green - 5-15 PSI Yellow - 15-23 PSI Blue - 23-30 PSI Red - 30 + PSI 1.5bar = 21.7 PSI Regarding the recirc valve and boost pressures. Forge quote on their website uprated recirc valves are supplied for at or slightly above original boost pressure yet both 225 and 250 applications are supplied with the green spring? Assuming they have a similar strength spring to the OEM valve, RST quote the 250/265 can run a stage one map ( 1.5bar ) with the original recirc valve unmodified. So in theory the Forge recirc can be fitted with a green spring for a stage one mapped 250 despite it only being rated to 15psi and the car running nearly 22. The only reason I ask is because my cars currently running the Forge recirc with the correctly specified yellow spring for my 1.5bar boost. However when logging boost data with the RsTuner pressure reaches 2bar during gear changes before the recirc opens? I've spoke to a few specialists and they are telling me the spring is too stiff in the recirc but going off the specs 1.5bar is rated at the upper limit of the yellow and nearing the blue spring? Dont fancy removing it again as it's a PITA just for the green spring to lose pressure so anyone offer some insight to this? Sorry if I've confused you tried to explain best I could!
The rating for the spring is "unassisted clamping force", not boost, I believe. I don't understand it all that well but the yellow spring works fine for the DV on my R26.
Forge are absolutely useless as per usual with technical help. So by unassisted obviously by the time you have boost pressure acting upon the rear of the valve then a green could easily hold 1.5bar? AdR26am have you logged your boost pressure during DV opening?
so it sounds to me like the uprated spring acts like a blanking plate being fitted and the lower spring acts like a standard recirc (with a stage 1 map) and could leak early when reaching peak boost.
Nope. I keep meaning to get the torque app now I have a HTC phone. Do you think that would be adequate? Ultimately I think a spring that is too firm would be better than one that's too soft. We all know these cars can run with no recirc/DV without eating their turbo.
True, however it does very much increase turbo lag as it's fighting 2 bar of boost before being relieved. Makes a smooth drive very difficult.
There is little use in fitting a very strong spring in the recirc valve. It only delays the point until it opens (engine needs to build up a stronger vacuum and more positive boost pressure before it opens up). Don't forget that if you fit the weakest spring, you still get that spring's clamping force PLUS the positive boost created by the turbo. Also, with regard to your datalogging with the RSTuner, did you register 2 Bar pressure as "Turbo Boost Pressure (Measured)" or as "Manifold Absolute Pressure"? The former is the boost solenoid's sensor right that registers boost at the beginning of your intake piping (end of turbo flange), while the other detects it after the throttle flap (inside manifold). Now the M3RS has a much more sophisticated boost control system than the M2RS which regulates boost also by throttle flap position, which leads to almost no possibilty in creating overboost inside the manifold (not even manual boost controllers can create overboost). So, while you registered 2 bar boost, this would be at the turbo itself, and should be no problem. It only indicates that your recirculation valve is slow due to its strong spring, and the vacuum needs to build up at the manifold together with the boost buildup in your intake piping. A stronger spring leads to a need for a higher boost pressure differential, and thus you see a 2 bar peak. Thus, my advice would be to switch to a weaker spring if you are not comfortable with it (there's no harm in running it this way, there is always more boost buildup regardless of springrate on the recirc, albeit to a slightly lower extent). Also, this whole "it might leak with lower rate springs" is untrue. I have yet to see boost leakage due to a weak spring (there is always your boost pressure on your valve). It is always due to a worn out seal.
TymenJ thanks for your time in writing that it's most useful. Obviously the only negative to the stronger spring is that allowing it to reach 2bar acting back on the turbo it will stall it more than a weaker spring setup? If I were to fit the lower rated spring could I expect an improvement in power response after each gear change?
Nope TymenJ is correct!. More boost means more preasure on the recirc valve which means more holding preassure.The stiffer the spring more vacum is neeeded to open up the valve.
hmmm would be good to see if anyone has tried a stage one map with standard and uprated recircs to see if it shows any difference.
It all depends on how worn the standard one is. I seen some megs were the power drops of too soon and was said it was down to leaking recirc valve
Mine is just on the standard recirc, 304hp and seems fine peak boost is about 1.3 on the chart I got from RS. Not even done 25k miles yet though so hardly had a lot of wear.
I think the recirc on my standard R26 is leaking, doesn't seem to pull much after 5500 rpm. Ordered a forge dump valve from cazan racing as I'm getting a stage one map before Christmas hopefully
Mine has been running 315bhp for about 18 months on the standard Recirc with no problems, current mileage is just under 40k.
I've got an OEM 265 and 225 recirc in the garage, they appear identical and the springs seem pretty similar in strength too. Anyway back to my original point I can't be arsed to take my recirc off again to switch the yellow spring for a blue so just gonna live with the slight over boost in the pipe work and subsequent turbo lag for now.
just checked the part number of a 225 oem recirc and the 265 one both the same part! why forge it? haha
