Turbo Compressor Maps

[inferno 1]

I appear to have over looked an obvious issue on my turbo project. I assumed the ecu would cope with say a max of 10psi easily, overlooking the fact that my T3 will produce more airflow/s than the standard t25, which would cause it to run lean.

 

So my questions are where to find compressor maps for the 2 turbos, standard t25 and standard escort rst trim t3, and how to use them to work out the on boost %rise in fuel needed.

 

this will determine the next step, whether to use a rising rate fuel regulater, a fifth injector, or full blown management. Does any1 know of a chip i could just plug in the standard ecu and have it mapped for my engine?

 

I need to get this sorted out pretty fast, and i cant warrant spending vast sums of money i dont have on a complete management setup at this point.

 

any factual info ill be gratefull for.

cheers, tom.

[Doof 11]

Surely that amount of airflow is more to do with the head and inlet tract than the turbo...wont a T25, T3...Tn flow the same amount of air through the inlet at the same boost pressure, only generating less heat and doing it at less rpm (turbo rpm).

 

Increasing the size of the turbo can't suddenly make the head flow more air at the same boost levels...

[inferno 1]

That was my initial thoughts too... but ive been told again by some1 else this isnt the case.

 

the t3 pushes a larger volume of air at the same pressure so im told...

 

Any turbo tuners to clarify this? short of bolting it on and wiring it up im lost and ready to learn...

[Doof 11]

Yes but this can only be down to the larger outlet from the turbo. I'm almost certain it isn't the case. The head will be the limiting factor and so the size of the turbo is irrelavent because it is the head that causes the pressure increase.

 

If both turbos were spooled up with no pipes attached, just pumping into the atmosphere then the T3 would move air, but it is impossible to move more air through the same restriction without increasing the pressure.

[inferno 1]

doof if your wrong can i dangle your nuts in the compressor wheel at full chat if my engine goes bang?!

 

personally i agree with you.

 

does anyone dissagree?

[bales 1]

If you think about it from a purely fundamental point of view, when you are using a turbo you are in effect putting the same volume of air into the cylinder as a N/A engine but it is more tightly packed e.g pressurised hence there is more oxygen in it.

 

So the engines VE is being improved not because you are flowing more air but because the air you are flowing is pressurised. So whether you are boosting at 7psi or 25psi you arent physically flowing any more air through the head, as the head is the main restriction to flow, you are just adding a greater "mass" of air as it is under pressure.

 

So I would have though a bigger turbo will generate more pressure at less revs than the smaller one, but ultimately (as Doof said) the head is the restriction of the airflow capacity so you wont be flowing any more air than standard.

 

All IMO

 

Thats how I think about it anyway

[inferno 1]

hmmm

 

Perfect touch seem to think i need to adjust fuelling, RPM motersport dissagree.

 

wtf :S

[Doof 11]

You only need to adjust fuelling if the air density in the cylinders goes up...through more boost, cooler charge density or better flowing ability (ie headwork).

 

The T3 might heat the charge air less than the T25, thus it might require and adjustment in fuelling, depends on boost levels and the specs of the chargers / intercoolers.

 

...i think.

[sonofsam 5]

Thinking about it mate, how many people have done T3 upgrades on Fiesta's and the like and not worried

about changing the fuel map.

 

I would of guessed upping the boost and a larger displacement engine aswell as whats been said

were the only major concerns of needing more fuel.

 

 

 

Did you make a decision in the end