Volumetric Efficiency
 

I have been corresponding with Harvey regarding setting up a volumetric efficiency graph for tuning the SVX. After getting into this more, I am thinking that the volumetric efficiency calculated by Harvey might not be applicable for a turbo charged or supercharged application, since there are significant pressure drops and drops in efficiency in a FI engine than an NA engine. I think that the best way to calculate VE would be to tap into the MAF and log some real data to help narrow down these values. In fact I think that these values will certainly change even after an intercooler is added, and if any exhaust modifications are made. So this is something I would need to consider as the car modified even further.

Any thoughts on how to best log data from the MAF?

Thanks

Chuck D.

I am rather in the dark here. Could you please detail as to how the VE was calculated by Harvey. There are many factors involved and each would require a finite value and the allocation of these values in accordance with the application i.e. forced induction and by what means, or normally aspirated.

The MAF will give you air flow values but exactly how do you wish to relate these to VE as such?

I dont see how calculating Volumetric efficency will benefit you in tuning. What you need to know is AFR and load values, and then use the knock sensor system that came with your car to adjust accordingly, chances are you will be running close to stock timing, so maybe michael will be able to help you out.

Exactly Phil,

I am trying to ascertain what BS has again been handed out here to a member, hence my reference to finite figures. VE can only be indicative as a ratio/percentage.

It is unlikely that the extent of hot air excreted, will ever come to light. The VE of the expediter is beyond question.

Cheers, Trevor.

The Question was:
What is the best way to log data from the MAF...??

Im interested to know aswell

Cheers,
Jake

The wide band that SVXFiles and Mychailo both have (okay, so I've still got Mychailo's:rolleyes: ) both have datalogger features. If you go back and check some of Mychailo's posts, you'll see he was able to measure MAF voltage vs rpm. There really shouldn't be any reason why you can't tap into any of the lines coming out of the ECU (as long as their voltage levels are sufficient).
-Bill

V eff
 

Thanks for the replies. Exactly my thoughts. VE will be different for every kind of intake exhaust application. Probably best to use the MAF. I'll check what was done before.

The reason I need it is that electromotive uses volumetric efficiency as a tuning table. I did not think I would need it either, but now that I think of it, it makes sense. The electromotive software does not use an MAF, and calculates mass air flow rate by knowing the pressure, temperature, and rpm of the motor. In order to convert from rpm to mass air flow rate, volumetric efficiency will be an important part of the equation. Although the efficiency may be from the plenum where I take my air pressure reading to the cylinder instead of the entire motor.

Thanks for your input

Chuck D.

Then it utilizes a map sensor, which will calculate load, and let you to apply a set knock AFR for that load. IT does utilize speed density right?
phil

What a waste of space.:rolleyes:

Harvey.:mad:

Chuck if they only enter the VE to 150%, then I would think that they only want the engines VE characteristics, to tailor the maps to the way the engine breathes through the rev range. without the added boost included. Any boost that you add, will just be automatically included in the map set up.

So the figures that I gave you would be the engines characteristic VE curve.

Harvey.;)

Not so Harvey. It has now been ascertained that VE as a finite measurement, which is not a feasible expression was suggested only as method of describing an unknown factor in the absence of a MAF signal. Thus the original dilemma caused as a result of you suggesting VE in finite terms, has been put to rest.

Quote:- "I am thinking that the volumetric efficiency calculated by Harvey might not be applicable for a turbo charged or supercharged application,"

As I said --- It is unlikely that the extent of hot air excreted, will ever come to light. The VE of the expediter is beyond question.

Trevor. :rolleyes:

The ECU obtains a signal from the MAF on the basis of current flowing in the signal line, rather than voltage, which varies as compensating factors adjust and runs 12-14 volts above ground. The current is directly proportional to the mass of air flowing.

Therefore if you were to insert an ammeter in the signal line you should be able to secure a useful proportional measurement, which you could plot. I would guess that only milli amps will be involved. The resistance of a moving coil, or digital instrument, should not effect the signal and in fact will be compensated for.

Gonna give it a try.
 

I might give that ammeter a try. First I may do some trial and error stuff as Phast suggests. I've got a wideband, EGT, and knock sensor, so I should be able to hone in on the correct fuel to add. I'm also looking at LANs timing numbers for his stage III supercharged engine (a little tuned down), and his high boost AFRs.

Again thanks to everyone for your help. I appreciate all the help I can get. :)

Greetings Chuck,

I was not able to give you the required info on the MAF by PM as your mail box is full. Please do not delete any VE figures you have on file.

Cheers, Trevor. ;)

My Box
 

Sorry about that. I went a cleaned up my box. Thanks.