As far as mileage goes with the DT/BPV yes, a lot of that will depend on how naturally heavy your foot is and just your overall driving style, and you're right, no need to over think it, the slightly stiffer spring simply cause's the butterfly to be fully closed just a little early under WOT. it shouldn't effect anything under normal conditions....unless you of course accelerate with a heavy foot, and that's why the description on the website says "may" cause a loss in fuel mileage.

As far as tuners are concerned, I can see them being neutral or not ness. wanting to promote a product that isn't theirs, but not recommending it seems a little weird, the modifications to the BPV that Chad does shouldn't effect tuning at all unless it is changed "after" a tune (either added or taken off) simply because changing the BPV may change air flow characteristics, but that should be it, but you really don't want to make anything but minimal or "have to" changes after a tune anyway.
(IMO you would think the verification of the butterfly alignment and possible removal of any yoyo effect in air flow would be something a tuner would recommend, but, I can see how someone may say it isn't needed, esp. post facelift since the stock BPV's seem to be better then)

 

Unless you are having a problem with your stock BPV I would not go to the DT unit. If I had to do it again I would probably go with a stock BPV and varify it's fully closing and opening before I installed it. The DT BPV does cure the yo-yo problem that some people get with the stock BPV....mostly caused by a weak or worn spring.

I drive with a light foot...and I lost 2mpg right after installing the DT BPV. That's just my experience though......

 

Thanks to both of you. The stock one does work OK. I suspect some yo-yo under certain circumstances, but getting rid of that may not be worth it in other respects. I've not had it off and suspect the stop screw could be adjusted to close a tiny bit more based on its position compared to the DT valve. Moving the stock valve with my finger is much easier than the impossibly stiff DT. So, there is quite a difference, that would undoubtedly translate into unnecessary waste of fuel and driveability problems when full boost is not needed.

Thanks again for your comments.

--Russ

 

I said it all depends on the car and the mods it has and how it reacts to things. every car is different and if there is not a problem, don't fix it. If there is a problem, then yes upgrade. some cars don't have a a yo-yo...then they add a pulley, it now has a yo-yo OR it has a yo-yo and you add a pulley and it's gone. every car is different. but we see a lot of broken stock springs.

MPG all comes down to driver. a 2 mpg loss is a lot and i'd look at other things that could be causing this. we normally see less than 1 mpg loss on a lot of cars and i can tell you we move a lot of these. the biggest call i get is it caused a check engine light, which the valve can not do. I go over the install with them and it comes back to a intercooler boot not on right normally or something like that. if you had a small vacuum leak it could hurt MPG. also ECU rests will help some times. we had a driver here at theshop gain MPG when we put a pulley onto his car, so it all really comes down to the driver.

 

I agree, every car is different. I think the reason I saw a 1-2mpg drop on my fuel mileage was mainly because my stock BVP had a broken spring in it, and it would NEVER fully close, even when you were hard on the gas. With no boost, I was not making as much power....and not burning as much fuel.

I might have seen the same kind of MPG reduction if I would have just put a new stock BPV back on the car....who knows.

 

OK: 70 MPH with cruise control gets me 29 MPG. My overall mileage with all kinds of driving is 25.5. I drive at 2-3,000 RPM most of the time, except an occasional WOT just for fun. The car is nice and smooth with proportional power increase as the throttle is gradually depressed. The only problem is I get yo-you briefly after slowing down, and then speeding back up again.

So, My real, unchanging question is; will I sacrifice EITHER mileage or proportional throttle/power response as described above if I install the DT valve? I have never had the OEM valve off.

I will not install if freeway mileage drops from 29 to 26 or 27, for example, or if my over-all average drops from 25.5 to 23.5. I would install if everything stays the same and get rid of the yo-yo effect.

So there you have it. Maybe nobody has ever tested or experienced this before, but I thought it would be worth asking.

Thanks.

 

I don't think anyone can deny that with the DT BPV....you are going to loose SOME mpg......their site says 1-2mpg. With a stiffer spring, it's going to build more boost with less engine load.....that's just how it's designed to work. Yes...it depends on how heavy your foot is.....but unless you never press the pedal down more than a 1/4 of the way.....chances are, you are going to loose some MPG....maybe not enough to notice, but you will loose some. In the grand scheme of things...it's really not that big of a deal.

 

Thanks - great answer. I would also expect to lose some proportionality of throttle, in that a small increase in throttle will cause abrupt acceleration, and more sudden let-off on lift. Wife may not like riding with me through town with a full cup of coffee. The best of all worlds would be just enough spring tension to fully close and fully open - proportionate to throttle setting.

Looks like it's time to try it and see.

--Russ

 

I didn't notice that my throttle got any more touchy after I installed the DT BPV.

 

Oh - great! If I end up installing, will report. By the way, what mileage do you get - normal freeway driving etc.

06 R52, Koni FSD, 15% pulley, CAI, upper and lower braces, under tower plates, RMW dyno-tuned, Pulstar Spark Plugs, MSD ignition and wires, Engine and lower control poly bushings, 22mm rear bar, DOS copper intercooler, ATI superdamper, 18X8 Signature Autobahn rims, Continental DWS 215x40x18. All Amsoil lube and fluids, PS Pump covered and ducted.

 

denatured alcohol would have been better. acetone will eat through plastic pretty quickly.

 

I get around 20-22mpg city, and around 27-28mph highway. That's actual fuel burned by miles driven...not going off of the gauge listed MPG.

 

Any change in mileage should be directly proporsional to power output. The mileage hit people see should be due to the car not being so anemic at lower rpms. That is, with the same throttle input there is more acceleration and less mileage. If you change your habits to accelerate the same as before I don't see how it would use more fuel. Certainly not freeway driving.