Feedback on Boost pressure

[Danbonzo]

for that drive pressure you should be making alot more boost IMHO

I agree 100%

 

[Dzchey21]

Well that ain't the problem then, again it goes good, I just think there is more in it. I know of 2 ways to plumb gate. I have a line off cfm to input of reg. then output to gate. on top of gate is vented to atmosphere. I believe Tad plumbs another way but I was told pressures are erratic and hard to dial in. Again hear say. Too late now but I'm going to try bypassing regulator by closing down line from reg. to wastegate. and see if I can get boost to go up. I'll just be careful with the EP.

If you want my honest opinion... your making way over 25 psi of boost...

Sounds like the factory map sensor might have taken a dump on you, the computer WILL create a value if it has to.

before you go any further verfiy with a boost gauge or oil pressure guage or some sort of mechanical gauge that you are only seeing 25 psi of boost.

Then why do tuner only trucks tend to make more power than trucks that are gated with just a tune? I don't know enough about this stuff to say for sure, but the trends point to stock trucks with stock turbos and no gate making more power than the same setup without a gate.

I am still learning all of this as well. It's hard for me to see it though. All gated trucks that have been on Dunbar's dyno do lower than not gated trucks with the same setup. That is all.

To a point thats probably true.

The reason for it i believe is because we were OVER estimating on hard we were driving stock turbos. Turns out at 55 psi of boost the turbos are turning some decent pressure ratios and might not actually be out that far out of the map...

That being said a truck that can still maintain 55 psi of boost with 70psi absolute drive pressure will make more power than a truck with 55psi of boost and 80psi of drive. The problem is being able to gate the drive pressure and still maintain prior boost levels.

 

[Jeff@Spartan]

I have made logs before that show that boost and drive are pretty damn close at peak boost on a hard pull from 65-70 MPH. I think it's within 6-8 psi. I want to say 49 psi of boost and 55-56 psi of drive. The worst ratios are converter unlocked at high RPM. Cruising on the interstate it is pretty much 1:1.

I have logged runs on Dunbar's dyno also, but I can't remember what I saw. My truck makes 38ish psi max on his dyno. I want to say the ratio isn't quite as good as it is at 48-50 psi of boost.

 

[Danbonzo]

Of course I want your honest opinion Dustin I wouldn't of put it out there if I didn't. LOL

This is gonna drive me bat$h!t now, I won't sleep a wink tonight.
Anyone else have any ideas? or better yet actual readings?

 

[Jeff@Spartan]

Are you looking for readings from another gated truck, or a non gated truck?

 

[Danbonzo]

Are you looking for readings from another gated truck, or a non gated truck?

Gated of course to compare.

 

[91turbogsx]

I was seeing 45-48 without a gate. Unsure of EP at the time. Now with the gate I can barely crack 40 psi with EP at 70-75. But I am still in the middle of playing with it.

 

[Danbonzo]

I was seeing 45-48 without a gate. Unsure of EP at the time. Now with the gate I can barely crack 40 psi with EP at 70-75. But I am still in the middle of playing with it.

40 psi MAP? or MGP? there is on average difference of around 14.4 psi (varies from, elevation, temp, etc..) between them, with the MAP reading higher so its important that we discern between the two. MAP adds in absolute (barometric pressure) I think this is what misleads many people.

 

[91turbogsx]

98% sure it's MGP.

 

[Jeff@Spartan]

Why would someone use MAP to monitor boost? We've made it pretty obvious that MGP is boost.

 

[Dzchey21]

so your reading absolute pressure on both boost and back pressure, easier at a glance to see how close to a 1:1 ratio you are

 

[91turbogsx]

And I do know the EP numbers add atmospheric pressure as well.

 

[91turbogsx]

so your reading absolute pressure on both boost and back pressure, easier at a glance to see how close to a 1:1 ratio you are

That is actually a good idea that I didn't think about. Beats doing all the math. LOL

 

[Dzchey21]

That is actually a good idea that I didn't think about. Beats doing all the math. LOL

but the problem i found is that MAP maxes out at 36 or 38psi total so it doesnt do you any good, unless your guys's is different then mine

 

[91turbogsx]

So what is the point of the PCM reading the MAP sensor when it maxes out before stock boost levels are reached?

 

[Danbonzo]

so your reading absolute pressure on both boost and back pressure, easier at a glance to see how close to a 1:1 ratio you are

Bingo

 

[Danbonzo]

So what is the point of the PCM reading the MAP sensor when it maxes out before stock boost levels are reached?

I'm guessing because it wasn't designed to be used like we are trying to utilize it, as a tuning tool. It's oem intent may have just a systems readiness device is my guess, who knows (anybody know a Ford engineer?). Its a good question that as of late has been bugging the sht out of me! I never bothered recording all these same parameters on my truck in stock form cause there was never a need to. It would be extremely beneficial if I had benchmarks I could go back to. What do they say, hindsight is always 20/20....

 

[Danbonzo]

so your reading absolute pressure on both boost and back pressure, easier at a glance to see how close to a 1:1 ratio you are

to expand on that point D: when I'm testing I'm typically making steam and covering a lot of ground in a hurry.

Factoid; At 75 mph your covering approximately 46 yards/second. or about half the length of a football field. Not wise in my view to be staring at gauges and playing calculator.

 

[Dzchey21]

Thats why data logging is nice

 

[Jeff@Spartan]

:whs: