engine mapping

[woollymoof]

Hi all,

Say you have a good map for your engine. You then change the runner lengths or plenum volume or shape or whatever, do you then have come up with a new map because of the likely change in VE across the rev range?

Cheers,

Kirk Veitch
Swinburne University of Technology

[woollymoof]

Hi all,

Say you have a good map for your engine. You then change the runner lengths or plenum volume or shape or whatever, do you then have come up with a new map because of the likely change in VE across the rev range?

Cheers,

Kirk Veitch
Swinburne University of Technology

[Igor]

I'd think so. The enigne might still run, but is isn't a good map anymore.
If you don't have access to a dyno anymore you could model the engine in one of the simulation packages and see how the map changes with geometry. Then apply those relative changes to your current map. Just a idea though, we haven't tried that so all caveats apply.

Igor
Delft University

[Dan Deussen @ Weber Motor]

If anything in your induction, exhaust, or fuel delivery system changes you will have to remap both fuel and spark. If you don't go through the process of properly recalibrating the maps, you might actually see a decrease in engine performance, even though your new system could be superior to the old one.

A dyno is the only way to find out how your change really effects the engine's performance.

Daniel Deussen
www.walbro-italy.com (http://www.walbro-italy.com)

[Charlie]

IMO the best thing to do is make these changes and then watch your A/F ratio closely while dynoing. If it does not drop below a range where you should still be close to peak power, the comparison is fairly good. Timing is important too, but in these engines you reach an ultimate timing barrier where you don't make much more power. Basically, I believe if you see a big improvement or a big decrease in performance without a tune, it is valid. Small changes aren't conclusive.

But when changing things like runner length and cam timing, you should be looking for trends more than ultimate performance anyway.

You can also map your VE vs RPM curve and make changes in the engine MAP accordingly, to get closer to the proper tune.

-Charlie Ping
Auburn University FSAE (http://eng.auburn.edu/organizations/SAE/AUFSAE)
5th Overall Detroit 2003
? Overall Aussie 2003. http://fsae.com/groupee_common/emoticons/icon_smile.gif

[Frank]

timing won't change much at all

if: it uses TPS as load site input;
then: throttle size most important

plenums dont make much difference

runners make a little difference, but not too much

the change of restrictor has a pronounced effect

exhausts don't make too much difference

fuel pressure and injector sizing, can be corrected by overall trim, but it is certainly not a fix, just a start

[Matthew]

don't forget cylinder to cylinder distributions, thoose will change for most configurations.

-Matthew Hetler
hetl0020@umn.edu

[woollymoof]

Hmmm, thanks people

Cheers,

Kirk Veitch
Swinburne University of Technology