Well today I made an observation in regards to my boost reading which I dont know why I havent noticed this before. My boost reading is off by 1.5+ psi between my mechanical boost gauge and my EBC. I tested this multiple times in a couple of ways:

First, I turned off the boost controller (so I would only boost to the amount the WG spring would allow which was 5psi), then I would be in third and keep the vaccum as close to zero as possible on the boost gauge(this was done under partial throttle), since my EBC can record peak boost(even with not on) I wouldnt have to monitor both at the same time. So the result of this was a peak boost reading of 1.5psi from the ebc while a +/- zero reading on the gauge. I did this a few times and it was fairly consistent.

Second test I did was again leaving the EBC off, I did multiple boost runs in both 2nd and 3rd gear. Even before I hooked up the EBC, I saw the gauge pinned at 5 psi so I knew I should get the similar results. The outcome was again consistent with the first test and I got an average of 1.5 psi higher reading on the EBC than the gauge, highest reading was 2.5psi and it was never less than 1.5psi. This also supports why I see more than 6.5psi on the EBC with a 5psi WG spring when I have the ebc off. I read before that I should only be able to boost what the spring would allow with the EBC off so that raised my curiosity.

Now I'm trying to figure out any variables that could contribute to the difference in reading, I came up with the following:
1. Vaccum source: Gauge is pulling vaccum from a line after the TB, same line as my VI. EBC is pulling from the same source as the fuel pressure regulator. I am unsure if this is a factor since ultimately the vaccum is coming from the same source which is the IM.
2. Mechanical reading verse MAP reading. I believe that the ebc uses a MAP sensor to read boost, I don't know enough about MAP sensors to know how it works and if the electronic components in the EBC could affect the reading by this much.

My main concern is to figure out which of the two conponents is more accurate when it comes to reading boost. I would like to know which reading I would rely on to tune for power. Ideally it is safer to use the lower reading but at the same time I don't want to short myself with the possible 20-30hp from the 1.5+psi of boost.

Sorry for the long reading but this was something that I thought was interesting and would like to know some of you guys opinion/experience with this matter.
I also am think of borrowing my friend boost gauge and repeat the test to see if the results are consistent but that will be done at a later time.

 

I get a 1-.5 psi reading difference between my Blitz DTT boost gauge and my Greddy Profec EBC. They have different vacuum sources. I trust my EBC boost reading to be more accurate

I wouldn't worry about cheating yourself out of power. If you end up pushing 350whp @ 10psi or 350whp @ 11psi what is the difference? the most important thing is that it is consistant.

 

I'm not worried about power as much as what is more accurate. Yea it would be nice to get 350whp at whatever psi but for the piece of mind I was just curious to know which is the one I should go off of.

 

But it really doesn't matter which one you go off of. Boost itself is not really what your measuring, it is the power that the air being forced into the motor makes. Power is what your trying to indirectly measure with boost. What you need to be worried about is how much power you make with X amount of boost and you won't know that for sure unless you dyno. We talk about boost levels all the time, ie; "I want to build a turbo set up with 10-12 lbs of boost". 10-12 lbs of boost does not mean all that much unless there is a power level associated with that.

 

I understand your point and I wouldnt know what type of numbers I am putting down unless I dyno it but at the same like you said, I need to worried about how much power I make per X amount of boost but how would I know which boost to go off when the two arent the same? (which you answer in your first post). And also if I am using boost to indirectly measure power, wouldn't I want to know what boost level is really the correct one to get an idea of the potential numbers?
Knowing which of the two reading is more accurate in terms of the amount of "boost" vs power would be helpful and help me understand easier if I'm making the right amount of power that I should at that boost level. I mean I wouldnt wanna say "o I dyno 350 @8psi when it actuality it more like 10psi" (2 psi can be a decent amount of hp, you dyno a difference of 20hp-ish per psi from the difference in ecu alone, granted the variables were different). Each setup will obviously produce a different amount of power per psi of boost but I guess I just want to get the most precise "measurement" and not try give out wrong information.

 

Most likely the difference is the vacuum source. I bet your VI and gauge are tapped off the brake booster vacuum line since it is an easy one that is right after the throttle body. I think the vacuum line for the fuel pressure regulator is better. Try switching the gauge to the fuel pressure regulator and see what you get.

My whole point about the boost not being that important is that you need to dyno to really know what type of power your putting down. Then you really know where you stand as far as how much power you get per psi.

I get about a 5hp difference per psi between the stock ECU and JWT, not 20whp.

 

I don't understand the concern. As long as the boost is consistent from one run to the next (not fluctuating) what's it matter if your gauge is reading 10psi or 45psi, as long as your power is within a safe range so you don't blow the motor.

 

If you knew justin you would understand the problem....

 

Lol Ben. I"m just being **** about this thats all plus since I havent had much experience with a EBC I thought it may be an issue but apparently it isnt a big deal. End of discussion.