Doubt about how much air enters cilynder

[camil]

Hi.

I know this must sound stupid to most of you, but it's a newbie question.

How can i know how much must i raise the boost to meet the air needed to burn my target IQ?

Or said another way, how can i know how much IQ can i inject on a given rpm range knowing the boost on it.

I'm trying to learn from scratch using a 207 HDI 1.6 110PS

My guess is:

Each cilynder is 400cc, i will assume a VE of 80%. So it shows each cylinder take 320cc on each stroke.

Ok, this at Atm. pressure is around 320*1.19(air density) mgh, so around 380,80mgh, is this right?

When turbo boosts and pressure goes up, my guess is that i must multiply that 380,80mgh by 1(bar Atm.p.)+x(bar boost produced by turbo). So let's see with numbers.

If turbo doesn't boost mgh should be 380,80. -> (320*1.19)*1=380,80
If turbo boosts 500mb mgh should be 571,20 -> (320*1.19)*(1+0.5)=571,20
If turbo boosts 1 bar mgh should be 761,60 -> (320*1.19)*(1+1)=761,60
If turbo boosts 1.5 bar mgh should be 952 -> (320*1.19)*(1+1.5)=952

How far is this (my guess) from tuning reality? Is there another/better way to know it?

Thanks

[mrf]

Post of the screenshot of the map you are trying to adjust.

[camil]

Post of the screenshot of the map you are trying to adjust.

Thanks but i'm trying to understand the theory, not yet adjust any map.

[camil]

I asked this in a couple other forums and no one seems to know the answer. It seems everybody "just raise boost" on their own without any scientific method or without knowing exactly why and how much. I can't believe this can be true.

Is this a top secret or everybody does "lotto" boost raise? :)

[Morette]

You might find that many people do it the opposite way, boost is raised to a safe level, then IQ set to what you want, and checked by lambda or smoke limiter maps.


"Or said another way, how can i know how much IQ can i inject on a given rpm range knowing the boost on it."-

this will be in your lambda or smoke limitation map

[Stanton]

I asked this in a couple other forums and no one seems to know the answer. It seems everybody "just raise boost" on their own without any scientific method or without knowing exactly why and how much. I can't believe this can be true.

Is this a top secret or everybody does "lotto" boost raise? :)

That's not strictly true now is it ;)

You have been advised on ecuconnections forum to log MSHFM and plot increase in air flow with increase in boost. You seam to want to fight this.

You CAN'T calculate or guess airflow without at least exact VE for a given boost and temp rise ob charge for that boost, aswell as basic engine geometry. Simply, you font have this data so logging a physical parameter is the only way. This also happens to be the best way.

[physyc]

85% of the "tuners" here works with hacked ecm titanium. they just load a file in the (poor) database and raise it in %, what answer do you expect? That is 'pro' tuning today on this forum....

Introduce yourself to some real chiptuning forum. and maybe you will get a clear answer. this is a great forum, don't get me wrong. and there are some Real pro's active. but don't expect them to share that stuff here... Here they talk about updating tools, ecu connections, pinouts maybe, etc...

Meanwhile read on some turbo papers. try to find the pressure map for your turbo. lurn about pressure ratio, mass flow, speed lines, choke lines, etc...

Or as the pro's would do here...
Raise the pressure, when you get into limp mode raise the limiter and turn off DTC lol
And never forget nr 1 rule in chiptuning: No smoke = No power!!!!lol

[camil]

@physyc

thanks for the docs, really interesting :)

@Stanton

hahaha, i just wanted to read as much opinions as i can, and then think about all them, i thank you for offering yours, but please let me decide when opninions are enough to satisfy my curiosity ;) I know, datalogging :) My lexia3 is comming today by dhl, but i like theory too, not just the cold data from datalogging :)

@Morette

Just what i thought, most people use "lotto" boost raise :)

Thanks to all.
Camilo.

[mrf]

Thanks but i'm trying to understand the theory, not yet adjust any map.
How you change that map depends on how it's laid out.

Is it RPM vs MAP? And is the data in injector pulsewidth? Is the fuel pressure constant or MAP dependent?

Is it RPM vs MAF?
Is it RPM vs Load?

All of this makes a difference in how you adjust that map. In a MAF car, you don't have to 'add more fuel'. The ECU will figure it out based on the MAF signal. But you may have to target a richer AFR depending on how much boost.

[camil]

http://img856.imageshack.us/img856/4632/turbomaps2.pnghttp://img337.imageshack.us/img337/3777/turbomaps1.pnghttp://img209.imageshack.us/img209/5179/turbolimit.png

These are the maps in my learning victim :)

[Morette]

@Morette

Just what i thought, most people use "lotto" boost raise :)

Thanks to all.
Camilo.


It's not a guess, (but maybe some people will just guess). You can go through compressor maps, and find out what it suitable.


A turbo should have a good working range, your method would be to find the minimum possible boost and set this.

It is as if you are working backwards, you have a power you need, and then have to find out the boost to run.
The other way is set the boost as high as possible but safe, then tune the IQs, and find out the power later.

[spawns3]

And never forget nr 1 rule in chiptuning: No smoke = No power!!!!lol


That rule is for the "pros" in chiptuning , because they don't know how to use a calculater

[mrf]

These are the maps in my learning victim :)

OK, great. What are the X and Y axis labels? I'm guessing the Y axis is RPM? What is the X axis? And what do the data values represent?

[ominimicu]

as a reponse to camil and other members of the comunity. i would like to add to the first post:

calculations are in part correct. but air density needs a variable called air temperature. Also the total IQ needs to me divided in mg per Stroke.

Also when the engines are designed they calculate the caloric energy needed (Joules) to move the piston, and they always, always go rouding it up the energy is never exact but superior.

Durin air feeding you got boost pressure whhich you multiply but you do not have mg/hub whic is air debimetry, quantity.

The Maf takes care of that acording to current air temperature. And even if we sum all this up the IQ will still be altered by the readings of the MAF.

[spawns3]

OK, great. What are the X and Y axis labels? I'm guessing the Y axis is RPM? What is the X axis? And what do the data values represent?

Map 1&2 X axis - mg
Map 3&4 X axis - ?C
Map 5&6 X axis - ATM pressure
Map value - Mbar (atm pressure + Turbo)

[camil]

Ok, then tried doing the opposite way.

Investigate installed turbo on car, GT1544V

Made calculations based on 135HP target. And plotted them on the map.

Target Nm 240, 177lbft.

Range from 2500 to 4000, with AFR 17:1

Calculator program gave as suitable the GT1544, and gave me this numbers.



----------------------------2500rpm---------4000rpm
HP ---------------------------84---------------134
PSI------------------------15.25-------------15.25
Pressure Ratio---------------2.10--------------2.10
Airflow lb/min----------------8.71-------------13.94
Torque Nm-------------------240---------------240
If i understood well how this can be worked from here, the PSI is the boost neded to make the airflow, and results in that pressure ratio 2.10

15.25 PSI is around ...

15 psi equals 1034 mbar (hPa)
16 psi equals 1103 mbar (hPa)

... 1051.45 mbar.

Does this mean i can achieve that target torque 240nm with boost no need to go higher than 1051mbar from 2500-4000rpm?

I used for the calcs 30?C ambient temp, sea level p atm, VE 90% as it's 16V, 17:1 AFR and 0.36 BSFC as suggested by calculator for diesel.

Pretty app this Garret Boost Adviser for the iphone :)

What do you think?