I believe I have decided on the turbo setup that I want to run. I believe the 30r that I previously planned on getting will put too much stress on the engine and require an upgraded shortblock and clutch (I don't want to go there again, yet...). So Ive decided on running a stock mount turbo: either an FP Green or a TD06-20g. So for the time being, I'm going for a solid stage 2 setup which will be able to handle the larger turbo later on. Also, I'd like to try something a little different on this setup with the EWG. So here is the projected mods for the stage 2 setup... --UR EWG Up-Pipe with 38mm Tial wastegate --HKS downpipe (Non-bellmouth design is similar to the UR downpipe and should leave plenty of room for the wastegate) *See picture here* --Cobb Accessport 2.0 I want to get the EWG and up-pipe first, and then get the AP and the Downpipe later. My question is: Can I run an atmospherically dumped EWG up-pipe without engine management? My concern is that, at WOT, a portion of the exhaust will be bypassing the rear o2 sensor. But if Subaru o2 sensors read similar to other manufacturers, the rear o2 sensor is only used to ensure that the cats are functioning properly. So if this is correct, AFRs are controlled solely by the pre-cat o2 sensor and the EWG up-pipe will not affect AFRs. Also, are there any downsides to the EWG (besides noise of course, lol)? Thanks in advance, John
EM first will most likely be the majority response....and with good reason. Can't comment on the EWG though, sorry, I am sure others will have more knowledge to share though...
Yeah, I will be doing the AP, but I was wanting to do the EWG first (if there will be no EM issues with it).
You're right that the rear O2 doesn't serve much of a purpose. But as for running external wastegate without EM, not sure that's such a hoppin' idea; how are you planning to control boost? Also, why an EWG in the first place?
I wanted to run the EWG for better boost control with the Green or 20g. If the pressure of the wastegate spring is the same as the stock spring, will the factory BCS control boost correctly? While I'm at it, does anyone know what the factory wastegate spring pressure is?? I was thinking it was 11 or 12 psi, but I can't remember.
Highly unlikely. The same amount of arm movement/opening won't yield the same change in boost as it would on the stock turbo... Think it's right around 7. (on a 2.0 at least)
That makes sense. So not only would I need the Accessport, but I would also need a protune to run the EWG. What effects would a higher spring pressure have on spool? If I had the car protuned for the new wastegate I would think that a stiffer spring would cause faster spool due to later opening.
If the boost controller is doing its thing it shouldn't open until needed regardless of spring, I think... but one of the tuners can chime in on the details.
Oh yeah, I forgot about that. Because you wouldn't be able to have 19psi on a 7lb spring otherwise. Im hoping Milo will chime in about this. I'm pretty sure he got his turbo with the 19lb wastegate spring.
my spring is rated at 19psi but on the dyno, it started to open at about 14 psi IIRC... the boost controller lets it stay shut longer
Quoting Cobb's Calibration and Tuning Guide: If the rod coming out of the wastegate actuator is shortened, it will pre-load the spring inside the wastegate actuator increasing the pressure level at which the actuator will allow the wastegate valve to open and the total boost pressure that the turbo can generate will increase (as long as the turbo is still within its efficiency range). This pre-load will also limit how far the wastegate valve can open. Pre-loading (shortening) the wastegate actuator rod too much CAN POTENTIALLY CREATE A MECHANICAL BOOST CREEP ISSUE THAT CANNOT BE TUNED OUT! So, with a stiffer spring, your max boost goes up and you change the dynamics of the waste gate. More tuning.