[335dlci]

Originally Posted by Whitbread

Here's a nice video demonstrating the sound well

Basically, when the turbo(s) get big enough on a diesel, you run into the effect where letting off at high boost creates a condition were the turbo is trying to force more air into the engine than what it can swallow immediately after removing the load on the engine. So the air ends up going backwards through the turbo. It's obviously very detrimental to the life of a turbo and should be avoided. Normally on a stock-ish diesel, the turbo will decelerate fast enough that this condition doesn't happen. But when the turbo rpm's and/or wheel sizes are pushed well beyond stock, the increased inertia will slow the deceleration of the turbo causing the barking behavior.

To combat this, TurboSmart makes a controller that ties into the tps sensor and will trigger a blow off valve to operate when you lift off the throttle pedal. This gives a path for the air to go that would otherwise try and go backwards past the compressor.

Dumb question. Having it tied to your TPS without a egr block off would cause it to dump if the throttle would happen to close for egr gas to flow. Wouldn't it be better to get a pedal position input instead?

[Whitbread]

Originally Posted by 335dlci

Dumb question. Having it tied to your TPS without a egr block off would cause it to dump if the throttle would happen to close for egr gas to flow. Wouldn't it be better to get a pedal position input instead?

Sorry, I should've said the accelerator pedal position sensor instead of the TPS. My car doesn't have a throttle body anymore so I forget that everyone else isn't set up the same.

[TDIwyse]

Originally Posted by Whitbread

... In fact, I'm actually rather horrified at the amount of surge and barking I'm hearing now that was hidden before. It legitimately needs one of turbosmart's diesel bov kits (or a borg Warner EFR with their built in bov and turbosmart's controller ).

Interesting. I've noticed the sound of the compressor and turbine bypass behaviors, but haven't noticed what I'd consider barking.

My understanding of bark is that the intake air gets backed up, and when the turbine drive pressure drops (due to rapidly removing fuel for example) the intake air can flow backwards. Supposedly this can be made worse if the turbine is undersized compared to the compressor.

Would be interesting to log rpm/boost/EMP during bark to see if we can measure the phenomena.

[lnxguy]

Compressor surge is a bad thing.

[Whitbread]

Originally Posted by TDIwyse

Interesting. I've noticed the sound of the compressor and turbine bypass behaviors, but haven't noticed what I'd consider barking.

My understanding of bark is that the intake air gets backed up, and when the turbine drive pressure drops (due to rapidly removing fuel for example) the intake air can flow backwards. Supposedly this can be made worse if the turbine is undersized compared to the compressor.

Would be interesting to log rpm/boost/EMP during bark to see if we can measure the phenomena.

I never noticed any of the bad turbo noises with the modded oem airbox, but now with Dave's intake, I'm hearing all kinds of stuff I've never heard before. At certain midrange rpms with heavy throttle, I can hear the turbos are walking the surge line. When letting off at full boost under 3.5krpm I very clearly hear it bark, letting off at 4+krpm, I don't hear any barking.

[EvanTheBruce]

Originally Posted by Torqu3

Glad to hear you're still working at it and tweaking the design! Even if it has zero performance benefits, as long as it doesn't hurt performance and is priced in my budget, I'd likely buy it when I pick up your turbo-back exhaust just to hear the glorious turbo music. Stop making nice things! You're financially ruining me.

If you haven't seen my vidoes already, they are a good reference as to how David's exhaust sounds. I just ordered his Intake today and expect it sometime in the beginning of January. I'll be sure to get another video of the car and also a in-cabin driving video comparison of before and after.

[TDIwyse]

Originally Posted by Whitbread

I never noticed any of the bad turbo noises with the modded oem airbox, but now with Dave's intake, I'm hearing all kinds of stuff I've never heard before. At certain midrange rpms with heavy throttle, I can hear the turbos are walking the surge line. When letting off at full boost under 3.5krpm I very clearly hear it bark, letting off at 4+krpm, I don't hear any barking.

Thanks.

Yes, I've ran a cone filter setup off and on for several years and agree the intake sound is much more pronounced.

The rapid transition at high boost mid rpm operating condition you describe is one I try to avoid, so is likely why I haven't heard the bark. From earlier diesel engines I learned to try to avoid rapid transitions of fueling from the skinny pedal.

Based on this description it seems like looking at EMP vs Boost can give insight to indicate conditions where this would occur (adding MAF data would also be interesting and could give an idea where the surge line is on the compressor map).

http://www.dieselarmy.com/engine-tec...ff-valves-bov/

"As long as there is a ratio of slightly less-to-more drive (back) pressure than boost, the turbocharger continues to produce boost and everything hopefully runs smoothly. When the throttle is let off suddenly, the drive pressure goes away almost instantly."

[TDIwyse]

Originally Posted by TDIwyse

...
Based on this description it seems like looking at EMP vs Boost can give insight to indicate conditions where this would occur (adding MAF data would also be interesting and could give an idea where the surge line is on the compressor map).
...

For my own curiosity I pulled up a full fueling 4th gear log from this Fall to look at the shift/fuel letoff transition behavior. It looks like in this condition the EMP stays higher than the Boost across the whole transient run. Using TestO with a faster sampling rate would give better information, as the Torque based log might be missing something.

[BB_cuda]

Anyone that has installed in airbox want to comment on fuel mileage?

I have driven from Houston to Baton Rouge and noticed cluster indicated mileage down about ~3 mpg( 39 vs 36 at 70 mph). I may have a mix of data though. Pumped a half tank before trip so I may have gotten winter mix of fuel now. Also I pumped at a station I don't often go to. Station is a nice clean Exxon though but I normally run Chevron.

I know Whitbread did a cross country drive after install.

[ASBSECU E93]

Happy New Year to me

[iaknown]

Good news coming soon..... It has been confirmed this revised intake is worth power

[ASBSECU E93]

That sound is glorious

[Whitbread]

Originally Posted by BB_cuda

Anyone that has installed in airbox want to comment on fuel mileage?

I have driven from Houston to Baton Rouge and noticed cluster indicated mileage down about ~3 mpg( 39 vs 36 at 70 mph). I may have a mix of data though. Pumped a half tank before trip so I may have gotten winter mix of fuel now. Also I pumped at a station I don't often go to. Station is a nice clean Exxon though but I normally run Chevron.

I know Whitbread did a cross country drive after install.

Hard to say on my end. When I left michigan on my trip to California it was -4F and didn't get over 32F until somewhere in SW Oklahoma. I was also doing 80-85mph for most of my drive which isn't the best for fuel mileage either. My first tank was the lowest at 34mpg and last half tank fill up from Pheonix to LA was 41mpg. I slowed down to 72-75mph average due to to heavier traiffic for that leg though. Since I've been out here, I've been running the HPR renewable diesel, so another changed factor.

Side note though - I can't wait until that stuff is available nationwide, it's

[335dlci]

Originally Posted by Whitbread

Hard to say on my end. When I left michigan on my trip to California it was -4F and didn't get over 32F until somewhere in SW Oklahoma. I was also doing 80-85mph for most of my drive which isn't the best for fuel mileage either. My first tank was the lowest at 34mpg and last half tank fill up from Pheonix to LA was 41mpg. I slowed down to 72-75mph average due to to heavier traiffic for that leg though. Since I've been out here, I've been running the HPR renewable diesel, so another changed factor.

Side note though - I can't wait until that stuff is available nationwide, it's

Hpr is pretty limited here as is. I can't wait until we have more stations. My closet Hpr station is about 60 miles away.

[BB_cuda]

Maybe I just got a tank that was a little off perhaps. My run back to Houston was back where it was supposed to be. I put in 9 gallons of Chevron with same optilube XPD I've been running for many months. Running same 70-73 mph, the 41 mpg stayed pretty steady for ~ 200 mile flat run. Not sure if the car is adapting now or what.

[iaknown]

Here's the info you've been waiting for

Special thanks to BPC for finishing testing on this so we can finally publish some gains. As you can see the revised filter element design was very successful, the intake is worth over 15hp and about 25 ft. lbs of torque on a Stage 2+ car compared to the stock airbox. And did I mention the sound is amazing?

[EvanTheBruce]

Originally Posted by iaknown

Here's the info you've been waiting for

Special thanks to BPC for finishing testing on this so we can finally publish some gains. As you can see the revised filter element design was very successful, the intake is worth over 15hp and about 25 ft. lbs of torque on a Stage 2+ car compared to the stock airbox. And did I mention the sound is amazing?

I am assuming that we would have to have our Stage 2+ tunes optimized for this intake? I just had my car tuned by BPC back in November when I added your exhaust. I'm thinking a true dyno session by them is in order to get the most from your intake and your exhaust.

[335dlci]

Originally Posted by iaknown

Here's the info you've been waiting for

Special thanks to BPC for finishing testing on this so we can finally publish some gains. As you can see the revised filter element design was very successful, the intake is worth over 15hp and about 25 ft. lbs of torque on a Stage 2+ car compared to the stock airbox. And did I mention the sound is amazing?

What other mods were on this vehicle? Awesome work Ian!

[ASBSECU E93]

I KNEW my butt dyno wasn't wrong

[Owen81]

Originally Posted by iaknown

Here's the info you've been waiting for

Awesome! PM sent!

[TDIwyse]

Originally Posted by iaknown

Here's the info you've been waiting for

Special thanks to BPC for finishing testing on this so we can finally publish some gains. As you can see the revised filter element design was very successful, the intake is worth over 15hp and about 25 ft. lbs of torque on a Stage 2+ car compared to the stock airbox. And did I mention the sound is amazing?

Good stuff iaknown. That increase in whp is very similiar to what I measured with PerfExpert when modifying the OEM intake and reducing pre-turbo pressure drop: http://www.e90post.com/forums/showpo...4&postcount=33

The stock setup becomes restrictive when increasing air flow much beyond stock levels.

[iaknown]

For those of you who have this installed, what size gap are you measuring in this area between the lid and radiator support? Seems your gaps are a little larger than mine.....