I'd like to find out what are some common manifold pressures are of different engines, at idle, and at full throttle. I'm interested in N/A, blown, engine displacement, and number of cylinders. ??
Also, does the load on N/A engine increase or decrease as pressure goes down? Should the timing be advanced or retarded as engine load increases?
MAP Pressure in Different engines
Moderators: JeffC, rdoherty, stieg, brentp
The same concepts hold true w
The same concepts hold true whether the engine is NA or boosted. Anytime the manifold pressure goes away from vacuum, the engine load increases.
With NA motors the "maximum" pressure is 100KPA, which is atmospheric pressure- I.E. the throttle is completely open. With boosted engines, the effective atmospheric pressure is increased, so you just see pressure beyond 100Kpa.
My turbo with 8.0:1 C/R idles with 23 Kpa, Full throttle is 220 KPA (about 17-18 lbs of boost)
Generally speaking timing should be retarded as pressure goes up, and be advanced as RPMs go up. Take a look at my ignition curve under the files section to get an idea.
Brent
With NA motors the "maximum" pressure is 100KPA, which is atmospheric pressure- I.E. the throttle is completely open. With boosted engines, the effective atmospheric pressure is increased, so you just see pressure beyond 100Kpa.
My turbo with 8.0:1 C/R idles with 23 Kpa, Full throttle is 220 KPA (about 17-18 lbs of boost)
Generally speaking timing should be retarded as pressure goes up, and be advanced as RPMs go up. Take a look at my ignition curve under the files section to get an idea.
Brent
My N/A goes past 100 KPA
My 4.6L idles at 28KPA, and 32KPA with A/C on. If reved high and hard pressure will go past 100KPA, I noted it goes as high as 117KPA. It won't go past 100KPA if reved high but steady (squizing the throttle instead of flooring it). What's up with that?
Under what conditions will pressure go lower than the idle pressure? Say to 10 or 5 or 0 KPA? At such low pressures, what is the best thing to do, advance or retard? If I was tunning fuel injection I'm guessing I'd inrich to cool down the engine.
Does it make any sense on N/A engine to make your map past 100 KPA?
AL
Under what conditions will pressure go lower than the idle pressure? Say to 10 or 5 or 0 KPA? At such low pressures, what is the best thing to do, advance or retard? If I was tunning fuel injection I'm guessing I'd inrich to cool down the engine.
Does it make any sense on N/A engine to make your map past 100 KPA?
AL
In screen shots section you h
In screen shots section you have timing being advanced as pressure goes up.
http://picasso.org/mjlj/images/ignition ... ig_tab.png
Yet you said timing should be retarded as pressure goes up. Did I misunderstood something or ignition map in screenshots section is wrong? Please help me out.
AL
http://picasso.org/mjlj/images/ignition ... ig_tab.png
Yet you said timing should be retarded as pressure goes up. Did I misunderstood something or ignition map in screenshots section is wrong? Please help me out.
AL
That is a screen shot I used
That is a screen shot I used for my test bench, not something for use on a car. I see that it can be misleading.
Review the ignition configuration I'm using on my turbo 4AG- download it from the files section and load it into the configurator.
Thanks,
Brent
Review the ignition configuration I'm using on my turbo 4AG- download it from the files section and load it into the configurator.
Thanks,
Brent