[thejeremyman9]

Originally Posted by AmuroRay

I’ll just point out that the CTS actually had positive fuel trims indicating it made additional power over the M2 lower box. There are also dunks of open intakes making more power than the stock box - even the M2 box. Take it for what it’s worth

Positive fuel trims doesn't automatically equate to more power... it just means you needed more fuel than the MAF/MAP thought you did. Higher MAF readings would be more correlted with more power.

[AmuroRay]

Originally Posted by thejeremyman9

Positive fuel trims doesn't automatically equate to more power... it just means you needed more fuel than the MAF/MAP thought you did. Higher MAF readings would be more correlted with more power.

You’re not going to find that on a MHD tune, but you may find that data on a stock tune or BM3 (but I think their Mac readings Mac out at 42lb/min)

On my tune, it reaches 352g/s- I may give another intake a try and see if it changes, but I doubt it.

[johnung]

Originally Posted by gameson

Expensive? What are the options? Can this stock oem part fail easily with bm3 stage 2 tune? Thanks.

The issue is not really the stock Diverter Valve will fail from a Bootmod3 Stage2 tune, it's that replacing it with a Turbosmart Blow Off Valve with manage boost better. DV and BOV are pretty much different names for the same thing.

I upgraded mine from the stock DV to the Turbosmart Plumb Back (quieter) model. When I drive in Sport Mode I can really feel the difference if I accelerate and then back off slightly and then give it more gas.

The DV would tend to dump more boost so when I tried to get back on it there would be a delay while boost built up again. But the Turbosmart seems to intelligently trim off just any excess boost, so when I press on the accelerator again the power is right there waiting, and the car just goes! Feels kinda like having a V-8 right in its power band.

So you don't have to upgrade from stock DV to Turbosmart BOV, but that's what to expect if you do.

The TS BOV cost is very reasonable but the installation is tight, especially one of the bolts so best to find someone who has done it before. Links below.

https://www.kiesmotorsports.com/prod...8;_ss=r?aff=22

[gameson]

Originally Posted by thejeremyman9

I went from stock IC to 5'' stepped IC to race is. There is no lag when you upgrade to a race IC. As Amuro alluded to, if you want to "reduce lag" or improve throttle response, you need to optimize the intake/inlet system. I recommend an inlet like MST v2, MPPK lower airbox bottom, and a dry drop in filter.

I've done numerous tests both qualitative and quantiative on different intake setups and that is my #1 recommendation. IF you want noise, i would say get CTS, but it provided no qualitative improvment in driveability or really any discernable difference in the data with my setup. For example, intake testing: https://f30.bimmerpost.com/forums/sh....php?t=1765289

Everyone seems incredibly paranoid about turbo lag when upsizing their IC. For a stock turbo car, especially once with inlet/intake upgrades as i mentioned, the difference in IC volume is negligible in terms of the time it takes to fill that air and what you would perceive as turbo lag when driving. I floor my car from a dead stop at idle all the time (no LC) and there is no lag, it surges forward nearly instantly.

It's very difficult to try and quantify turbo lag in datalogs, but look at these for an example:

Log with 5'' IC right before race install: https://datazap.me/u/thejeremyman9/3...&data=4-5-7-17

Log with race IC right after install: https://datazap.me/u/thejeremyman9/3...&data=4-5-7-17

The RPM where i go WOT is very similar in both logs (~2200 rpm) and you can see that with the race IC, the slope of the boost curve is actually steeper (builds boost faster) and it takes the same or less time from going WOT to reach boost target... Not sure what other evidence you guys want.

Edit: FWIW im still on stock DV. I may one day do a test like i did for intakes, but not in a rush at the moment.

how prone is stock turbo inlet for failure compare to stock charge pipe and stock turbo pipe?

[AmuroRay]

Originally Posted by gameson

how prone is stock turbo inlet for failure compare to stock charge pipe and stock turbo pipe?

It isn’t, that’s not why you change it out. It less restrictive, enough that there is a measurable impact on WGDC, and a power increase (based on another members dyno)

I changed my inlet and diverter valve at the same time and felt increased throttle response and more consistent power. And even though I’m on a custom tune, it feels like it pulls stronger to redline.

[gameson]

what's a good DV brand for N20? Thanks.

[AmuroRay]

https://f30.bimmerpost.com/forums/sh....php?t=1153103

It looks like the GFB is the only option for the N20.

[gameson]

Originally Posted by AmuroRay

https://f30.bimmerpost.com/forums/sh....php?t=1153103

It looks like the GFB is the only option for the N20.

i read here that DV and BOV is the different name for same item, but upon google, i found this....

https://www.urotuning.com/products/c...blow-off-valve
and the GFB
https://www.kiesmotorsports.com/prod...st-4-cyl-turbo

so what's the difference between the two? Thank you

[AmuroRay]

Originally Posted by gameson

i read here that DV and BOV is the different name for same item, but upon google, i found this....

https://www.urotuning.com/products/c...blow-off-valve
and the GFB
https://www.kiesmotorsports.com/prod...st-4-cyl-turbo

so what's the difference between the two? Thank you

a Blowoff will vent the excess air from the turbo to the atmosphere, giving it a cool/annoying sound vs a Diverter which will vent it back into the intake stream. As you can imagine, the throttle response should and would be better with a diverter, and it's quieter. I can barely hear my TS unit unless I'm absolutely trying.

[gameson]

Originally Posted by AmuroRay

a Blowoff will vent the excess air from the turbo to the atmosphere, giving it a cool/annoying sound vs a Diverter which will vent it back into the intake stream. As you can imagine, the throttle response should and would be better with a diverter, and it's quieter. I can barely hear my TS unit unless I'm absolutely trying.

thank you. another newb question from me

for this particular part, why aren't there many manufacturer make them? i mean if it help with boost and improve throttle response, shouldn't it be popular? like, look at charge pipe and FMIC, many brands are offering, including bm3 itself... but only 1 on DV

charge pipe doesn't offer hp, it only improve OEM plastic pipe, while this one actually would work better than charge pipe in my opinion as at least it does something to engine performance.

just wondering...

[johnung]

Originally Posted by gameson

thank you. another newb question from me

for this particular part, why aren't there many manufacturer make them? i mean if it help with boost and improve throttle response, shouldn't it be popular? like, look at charge pipe and FMIC, many brands are offering, including bm3 itself... but only 1 on DV

charge pipe doesn't offer hp, it only improve OEM plastic pipe, while this one actually would work better than charge pipe in my opinion as at least it does something to engine performance.

just wondering...

You asked a good question. It's pretty easy to develop a charge pipe or intercooler product by basically contracting with a supplier in China to put your brand name on one. There's a bigger market for them too. Not the same situation for a DV/BOV.

[johnung]

Originally Posted by AmuroRay

a Blowoff will vent the excess air from the turbo to the atmosphere, giving it a cool/annoying sound vs a Diverter which will vent it back into the intake stream. As you can imagine, the throttle response should and would be better with a diverter, and it's quieter. I can barely hear my TS unit unless I'm absolutely trying.

By those definitions the Turbosmart Plumb Back model would technically be a Diverter Valve, while the Turbosmart Dual Port model would be a combination DV & BOV because it partially vents to the atmosphere. 😀

[gameson]

Originally Posted by johnung

You asked a good question. It's pretty easy to develop a charge pipe or intercooler product by basically contracting with a supplier in China to put your brand name on one. There's a bigger market for them too. Not the same situation for a DV/BOV.

if you look at the parts, it's not hard to manufacture, it's just a brass piston, one spring and metal valve... anything, i find it strange and interesting that something like this, only 1 manufacturer offers it...

[sqwinny]

Originally Posted by gameson

if you look at the parts, it's not hard to manufacture, it's just a brass piston, one spring and metal valve... anything, i find it strange and interesting that something like this, only 1 manufacturer offers it...

It was shown that on the n20 after late 2014 and the timing chain guide revision the electronic waste gate was also upgraded and the GFB DV was deemed unnecessary for the stock turbo and its boost levels. Older cars experienced the boost holding issues however.

You have Go Fast Bits and the Diverter valve + upgrade, the CTS turbo blow off valve, and forge Motorsport used to make a blow off valve that was vent to atmosphere as well as a recirculating version.

As to why there are little companies making these parts, there is a limited aftermarket for them for the n20 as the n55 has a bigger market demand for aftermarket parts. As time comes and more people push the n20 more options will come alive, however 95% of people modding their n20 will go stage 1 or stage 2 off the shelf tune with a downpipe + intercooler + charge pipes and call it a day. I can count on my two hands on these boards the users with upgrade turbos on the n20. I'm sure there are more in the Facebook group.

[gameson]

Originally Posted by sqwinny

It was shown that on the n20 after late 2014 and the timing chain guide revision the electronic waste gate was also upgraded and the GFB DV was deemed unnecessary for the stock turbo and its boost levels. Older cars experienced the boost holding issues however.

You have Go Fast Bits and the Diverter valve + upgrade, the CTS turbo blow off valve, and forge Motorsport used to make a blow off valve that was vent to atmosphere as well as a recirculating version.

As to why there are little companies making these parts, there is a limited aftermarket for them for the n20 as the n55 has a bigger market demand for aftermarket parts. As time comes and more people push the n20 more options will come alive, however 95% of people modding their n20 will go stage 1 or stage 2 off the shelf tune with a downpipe + intercooler + charge pipes and call it a day. I can count on my two hands on these boards the users with upgrade turbos on the n20. I'm sure there are more in the Facebook group.

my car is built 05/2015, so it falls under this category, so you think it's un-necessary?

the reason i want to replace it is because i m replacing the turbo inlet to avoid cracked pipe that may cause expensive engine failure (changing the charge pipe and turbo pipe as well), and while at it, since accessing DV requires inlet removal, so i thought for additional low $100, i will just buy it as well for the same or minimal labor cost vs having a blown DV and pay double labor to fix it

[johnung]

Originally Posted by gameson

if you look at the parts, it's not hard to manufacture, it's just a brass piston, one spring and metal valve... anything, i find it strange and interesting that something like this, only 1 manufacturer offers it...

Maybe for the stock DV, but I think the guts of the Turbosmart are more sophisticated. The manufacturing tolerances are at a much higher level than with a charge pipe or Intercooler. Companies that do knockoffs want to tackle designs that are simpler. Complex types of parts tend to be done by companies that specialize like Turbosmart.

[sqwinny]

Originally Posted by gameson

my car is built 05/2015, so it falls under this category, so you think it's un-necessary?

the reason i want to replace it is because i m replacing the turbo inlet to avoid cracked pipe that may cause expensive engine failure (changing the charge pipe and turbo pipe as well), and while at it, since accessing DV requires inlet removal, so i thought for additional low $100, i will just buy it as well for the same or minimal labor cost vs having a blown DV and pay double labor to fix it

If you are any good with hand tools, you can change those pipes in your driveway. They are pretty simple. Plenty videos around on how to do the job via YouTube, Kies has one for the MST intake, but they are all the same.

The DV+ is a little complicated as the install isn't hard, there is limited space. This thread will help, otherwise most shops will charge 3-4 hours labor to install due to them removing the turbo 100% to install. It's not really needed, but the DV+ is more preventative than anything else under 20psi (OTS tunes are limited to 18-19 psi). With the larger turbo, the car sounds like a turkey/loud flutter in between shifts (6MT not auto 8AT).

N20 GFB DV+ installed without moving or touching the turbo! +quick tutorial https://f30.bimmerpost.com/forums/sh....php?t=1482708