Wrong assumptions:

You cannot compare what you see with a compressor and gauge vs what actually happens in the manifold lines to the MAP sensor with the amount of air that flow through a Turbo System of that size and magnitude. I have seen these test done externally and they mean absolutely nothing. Real test is on the vehicle while its running monitoring the line pressure before and after and logging via a scan tool what the PCM is reading from the MAP sensor.

You can measure the MAP line before and after the valve and they are same. With that said the MAP is seing the max of 22-24. The Valves do start openning at 20 lbs, that is what its calibrated to do, but you can still hit 30 lbs of boost reading through the AIH plug. I have the facts to prove it on my own vehicle.

I'll gladly pay for shipping and you can send it my way, instead of it being wasted away, I will put it for a good use!

 

i here alot of mpg questions, and my mileage didnt change with or with out the boost tube, i was getting 15 mpg with the boost tube and the dual map relieve valve this past fall, but the oncoming of winter blend diesel and autostarts for 45 min a day are whats killing my mileage. my truck is probably running through a quarter tank of fuel just trying to warm up.

 

I couldn't find your product using this link provided by Amiller93... Its on Pure diesel power or dfusers web site. I didn't look under every rock, but if it was a snake it should have bitten me! Maybe you could send a link that goes directly to it.

I've posted a pic here of my boost valve so we can see if we're talking about the same thing. It was only on my truck for about 300 miles. It was installed along with my new turbo at Browns Valley in N CA, and I listened to it whistle all the way up the Grapevine as it vented boost to the MAP, and had it removed in LA when I had to (it's a long story) do some more to my truck at Diesel-Tune. If you want this valve just PM the shipping info and it's yours. It's easier if I just pay the shipping, it's not very much to send UPS ground.

In principle, I see no difference between a zener diode and the valve in this pic! They both try to perform an "ideal limiting" function by letting the MAP see the actual boost up to a given threshold (say 22 psi) and then give a constant output for boosts exceeding 22 psi, thereby avoiding the SES due to over boost. Unfortunately, these devices start to limit their outputs before the threshold is reached, it's just the way the real world works versus the ideal one that we'd all rather be living in. Turns out, that zener diodes can more closely approximate an ideal limiter than can a spring loaded valve, but that's an even longer story from my days working on the air data flight computer for the F-4 aircraft at Mac Air.

"You cannot compare what you see with a compressor and gauge"

My measurements were accurate to 0.5 psi, and if I remember correctly, this valve starts venting at 16 psi! I used a tissue over the vent to see when it started venting.

"what actually happens in the manifold lines to the MAP sensor with the amount of air that flow through a Turbo System of that size and magnitude."

How much air do you think is flowing through this 3/16" line to the MAP? Well, if it wasn't for a relief valve inserted in the line their would be zero, because normally it's just a static line with no flow, so the MAP can accurately sense the true boost inside the intake manifold. When a relief valve starts venting air from this line, there will sure be some flow in the line, and the more it vents the higher the flow rate will be. This dynamic flow situation is nothing like the OEM static one, and it will definitely effect the pressure the MAP sees. I can only imagine the effects of the turbulence that's now in the line which was designed for measuring static pressure.

"Real test is on the vehicle while its running monitoring the line pressure before and after and logging via a scan tool what the PCM is reading from the MAP sensor."

What do you use to monitor the line pressures if not a pressure gauge?

Please read my post to Amiller93 regarding the feedback control of the wastegate. If you don't agree it works as I've stated, please provide your explanation. Unless you know its pertinent parameters such as feedback loop gain, various time constants, etc... you're at best guessing how it might react when you try to fool it with your leak tube, and I doubt that it can even be fooled very much anyway because its a feedback system not an open loop controller.

One final observation based on my 8 years of towing experience. I'm pretty sure (95%) that there's not just one single boost threshold (say 22 psi) that results in an over boost SES. Nominally, if you exceed 22 psi for some number of seconds you'll get the SES. However, the exact psi and # of seconds is determined by the PCM based on load and even gear selection. I can get the SES at a lower boost and with a shorter time constant in 4th than in 3rd than in 2nd. This data was taken while towing up long grades. So, even if you had an ideal limiter, you'd have to pick some compromise threshold at which to limit and that wouldn't be correct under all driving conditions.

 

"What do you use to monitor the line pressures if not a pressure gauge? "

We read boost pressure via a Scan tool what the PCM what seeing thru the MAP sensor.

The Valve you show is not one of our products, so I am curious to see what it ws doing. Please send it to the dfuser address listed on our site attn: Bill.

Thx.

 

Heres the boost tube http://www.puredieselpower.com/catal...esel-p-90.html

 

Your previous post said...

"Real test is on the vehicle while its running monitoring the line pressure before and after and logging via a scan tool what the PCM is reading from the MAP sensor."

I understood the logging part using the scan tool, but you also refer to monitoring the line pressure before and after? What does "line pressure" refer to, and what does "before and after" refer to? I assumed this meant you were monitoring the line pressures on both the intake manifold side of your relief valve and on the MAP side of the valve, so that you could measure how well the valve was limiting the pressure seen by the MAP.

amiller93 provided this link.... Here's the boost tube http://www.puredieselpower.com/cata...iesel-p-90.html and I now see what your two headed relief valve looks like, but there was no explanation of how it works. Does each valve vent at a different pressure? If not, why use two valves? I could find no shipping info on this link, so I'll still need that to fill in the UPS form.

Here's an aircraft analogy for the MAP sensor, it's called an altimeter. A static port on the fuselage is connected via a static line to a pressure sensor in the cockpit to measure altitude. Air flows across this static port due to aircraft motion, just as the air in our intake manifold flows across the static port to our MAP. As long as no air is allowed to flow into this line, it can measure the static pressure in the flowing air stream. However, if air is allowed to enter this line (which happens with a relief valve in the line) it perturbs the boundary layer interface at the static port resulting in a combination of both static and dynamic pressures being measured.

 

"I understood the logging part using the scan tool, but you also refer to monitoring the line pressure before and after? What does "line pressure" refer to, and what does "before and after" refer to? I assumed this meant you were monitoring the line pressures on both the intake manifold side of your relief valve and on the MAP side of the valve, so that you could measure how well the valve was limiting the pressure seen by the MAP. "

You are correct.

MAP: The Manifold Absolute Pressure sensor provides instantaneous pressure information to the engine's electronic control unit (ECU). This is necessary to calculate air density and determine the engine's air mass flow rate, which in turn is used to calculate the appropriate fuel flow.

In this case we are not disturbing the air flow, but controlling what the MAP sees so the PCM does not go in defuel mode. Measured before and after the Dual valves, the MAP sees a max of 22 lbs consistantly through out the test we ran w/o distruption to air flow. Where as the Mainfold continued its climb to 31 lbs. The added air helped keep exhaust temps down at that level.

The second valve was added to accomodate bigger turbos of which with enough exhaust pressure were creating a burst of 30+ lbs almost instantly. One Valve could not control such a fast burst.

There is also a mis-information out there that by bleeding this air through the MAP line you are loosing boost. WRONG- The Manifold was still reading the same value of pressure generated by the Turbo with and w/o the valve installed. The difference it tripped the PCM and went into de-fuel mode.

My address:
dfuser.com llc
attn: Bill
108 Evergreen Road
Georgetown, TX 78628

PS: This is a very healthy discussion!

 

After reading several of the replies to this thread, i see that it has been hijacked badly, from being started as a discussion of the Boost tube used on the wastegate control side of the turbo, to now a discussion over the MAP relief system. I think it is a great discussion and Dfuser and Ernest have pointed out the good and bad sides of using a "pop-off" style relief. Ernest have you ever looked at using a MAP regulator? I had a relief valve at one time, and you are right it does affect the MAP pressure in spikes. I had it plumbed in on the MAP side of my boost gauge T-tap, and i could watch the gauge jump at 22ish psi when it activated. Still set a SES light. The regulator i have now (www.itpdiesel.com) works like any other regulator, it just regulates 23-24ish psi to the MAP and that is it. No boost leak, and no SES light. It could be the fix to your problem.

 

Ok, I've got this much...

Bill ??????
108 Evergreen Road
Georgetown, TX 78628

But, I'm pretty sure that UPS needs a last name when I fill out the shipping form.

Too bad we didn't have this conversation last fall, I could've dropped the valve off at your place on my way to Austin, I'm in Rockport now, but I'm getting ready to head east to the Smokin event.

BTW, my valve added 12 HP on back-to-back dyno runs with and without it, at Browns Valley RV. So I know they work to avoid defueling!

"In this case we are not disturbing the air flow"

In my altimeter analogy, I was referring to the air flow at the static sensing port, which for us is inside the intake manifold. With no relief valve, air never enters this line, and it can sense true boundary air static pressure. When air is allowed to flow into this line, all bets are off, and no one can tell you for sure just what combination of static and dynamic pressures exist at the port due to the unpredictable turbulence that the inflow of air is causing.

But, I readily admit that we're not talking about making a pilot crash due to an inaccurate altimeter reading, but rather what is probably just a second order perturbabation to the MAP reading.

"There is also a mis-information out there that by bleeding this air through the MAP line you are loosing boost."

Well since you had to bring this up, it sure seems like a boost leak to me. Like I said, my valve sounded like a train whistle all the way up the Grapevine, and all of that air had to come from somewhere. In my case, I wanted to lose boost, but not listen to the noise. I'll agree, that a valve doesn't lose much boost, maybe not even enough to measure with a typical boost gauge. That's why I developed (see my post above) my homemade wastegate management system. If you tow 80% of the time like me, YOU DON'T WANT BOOST MORE THAT 20-22 PSI, because it will wear your turbo bearings out faster, make that MUCH FASTER!

 

I had something shipped ups without a last name before, idk why it didnt have a last name but it just said john.

 

249K miles on original setup of Engine Turbo and Transmission. Make sure you ship it to dfuser.com LLC Attn: Bill should be more than enough.

 

"...it has been hijacked badly, from being started as a discussion of the Boost tube..."

I thought this thread was about relief valves all along, once I figured out this "boost tube" was in the line to the actuator and not in the line to the MAP like the old Superchip "boost tube" was, I tried to address why I think it has little if any effect due to the closed loop feedback control of the wastegate. If anyone thinks my post about the PCM control of the wastegate using a bang-bang feedback control loop is not correct, please let me know.

"Ernest have you ever looked at using a MAP regulator?"

No, because I don't let my boost exceed 20-22 psi using my homemade system shown on my post above. I know I referred to a 12 HP gain, but that Browns guy stuck that valve on my truck so fast I didn't know what he was doing until it was too late to stop him. He insisted on doing the second run for free to demo the difference the valve made. I was trying to be nice because I still had work for him to do on my truck.

 

I appologies for participating in the "Hi-Jacking" piece. In many cases installing a boost tube will cause one or 2 things on top of just adding more air.

1. Intake Manifold Air pressure exceeding maximum allowable measured by the PCM
2. Exhaust pressure exceeding maximum allowable measured by the PCM

The intent of the Boost Tube both on the Powerstroke and the early Cummins forcing more air for cooler running Engines. There is a safe limit you can drive that to and still run a healthy Engine. Most chips and programmers dumps too much fuel and not allow enough boost and air to balance the output of the engine.

In the Powertsroke case any "GOOD" method that works to defer any pressure above allowable measured by the PCM based on the aplication need will work. Incase of ernesteugene he found what works for him, and we should leave at that. He had a part that was added to his system that did not do what he was looking for. It very well possible the value of that specific valve was not correct for his need or may have been faulty. I can only speculate.

For those that choose to either disconnect the MAP line or add the Tube, it does what it should. Enjoy it!

 

Ok, I'll address as...

dfuser.com LLC Attn: Bill
108 Evergreen Road
Georgetown, TX 78628

...and put it in the UPS when I go to town tomorrow, I'll PM the tracking number. I'm not sending the hoses to simplify packing, unless you really want them.

Before my homemade boost spring, my boost would sit at 26+ for many miles at a time when pulling long grades, and sometimes into very stiff headwinds. Even on the flat, it stays between 12-16 psi all day long. I think going above 20 psi increases the wear exponentially, and doesn't even buy me much on my early 99 due to its 2" intake boots vs the 3" ones on the later trucks. I was just working the turbo harder to heat the air with little if any additional flow.

In fact, I pull grades better now at the lower boost, but I'm not sure if I'm getting cooler air at the same flow rate or my TAG II is helping the flow or some combination of the two because I did both mods at the same time.