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Panathaole
3rd July, 2019, 05:37 AM
Hi

I am trying to understand how correct tuning work's

I start with the Fiat 1.3 mtj

Engine have 1248 cc capacity so

1248/4=312
Compression 17.6:1
And turbo rise air pressure 1.4 + 1 atmp = 2.4

if I rise the turbo pressure to 1.55
i have 1+1.55=2.55 * 17.6=~45 max iq

The torque limit is~20nm I must add ~25% to have
25nm

I am thinking correct unlit now?

Panathaole
3rd July, 2019, 08:00 PM
no one pro can say if i am wrong or right?

morgano
3rd July, 2019, 09:51 PM
That numbers would be aproximate if instead the engine compression rate you would use afr.

Panathaole
3rd July, 2019, 10:33 PM
This numbers is from Fiat 1.3 66 kw 90 hp

At technical specifications....

So i am in the right direction?

mexanico1971
4th July, 2019, 02:24 AM
Hi
For what I can understand , your calculations are right, but there is more variables that you have to take in count !
Car are remapped by constructors base in pollution and power demands limitations .
I do not have EVC training or other engineering school .
All I know is based in this last 14 years of study and doing .
IAW 6Jf was one of my first ecu study"s in the beginning of this and other forum Ecuconections
But basic is
Driver demand / throttle position , RPM, temperature and pressure

BRS

Panathaole
4th July, 2019, 04:44 AM
Thank you...

I just want to start learning correctly about tuning,

Not just increase volume by 10% or 15% etc just in luck....

morgano
4th July, 2019, 08:10 AM
As i told you the engine compression relation is not part of the equation to calculate the fuelling, you must use instead desired lambda/air fuel ratio (afr).

Panathaole
4th July, 2019, 03:43 PM
You have to use the compression ratio to find out the max of iq, right?

morgano
4th July, 2019, 04:01 PM
No, compression ratio of engine has nothing to do with air quantity or turbo. It is how much the charge is compressed into the chamber.

What you need to calc the max iq is the max air quantity you can put in chamber and divided it by the desired air/fuel ratio.

Then what you have put into chamber gets compressed by piston run (in your engine 17,6:1) but that’s all. The compression ratio is to be taken in account if you raise too much turbo presure and head gasket cannot handle it, then you need lower the compression ratio to be able to handle more boost without engine exploding :) more or less, so you can understand the basics.

Panathaole
4th July, 2019, 10:08 PM
I am little confused now...

I have 1248cc / 4 = 312 cc

So I have 312 cc air in the chamber....

The turbo pressing the air in the chamber, and add how much more? (If I have turbo pressure 1.4)

I must have 312+312*1.4 I am correct?

morgano
4th July, 2019, 10:41 PM
Yes that calculation is the proper to know approximate air in cilynder. Then divide it for 16 to get maximum injection quantity with afr 16.

Panathaole
5th July, 2019, 05:03 AM
The 16:1 is for all modern diesel engines or for the specific one?

I see for stage 1 this engine giving..

Hp 110(90)
Torque 25(20)

To rise the torque I must increase the original + 25%? (20nm + 25 % =25nm)?

morgano
5th July, 2019, 08:37 AM
For 110hp the torque would be over 250nm that numbers you use are not real.

For ANY diesel the afr should go greater than 14,7 (stochiometric). You decide how much. The more, more economical... you must based on knowledge and experience do a balanced tune power/economy.

Forget the percentage way if you want to do something good and balanced.

Panathaole
5th July, 2019, 09:33 AM
I saw that numbers (90->110 hp ~20->25 nm) in a sites from a tune company.... they gives that numbers as stage 1 improvement...