Tuning Help

[Jim]

Nope you are not missing the point at all.

However if the factory tune already runs MBT why change it? If the only changes you are making are at WOT (to the factory operation) it only makes sense to change the ignition timing at WOT. If you are starting with a new engine that you don't have any tuning data for then you will need to tune it at all points, including part throttle. The OEM manufacturers put a lot of effort into getting the engine spark to run at MBT whenever it can.

The "WOT tune method" is not a complete engine tuning method, it is only a small subset of one.

For info on dynamometers you'll have to speak to a dyno manufacturer of someone who has one in their workshop.

[macka'sxr6t]

  Jim said:

Nope you are not missing the point at all.

However if the factory tune already runs MBT why change it? 

The OEM manufacturers put a lot of effort into getting the engine spark to run at MBT whenever it can.

<{POST_SNAPBACK}>

But we're not really running a stock tune anymore other than to initially fire the engine and idle speeds, are we?

Would'nt the MBT change from the stock tune, once you've added more boost and fuel across the entire rpm range?

So there would be a need to revise all MBT's and load points throttle postions etc.

To achieve the best tune possible?

macka

[Jim]

I can't speak for everyone doing a tune but my guess is that most of them are running the factory tune for fuel and spark about 90% of the time, perhaps more. If they only change the boost tables a little bit, they wouldn't need to change the fuelling or spark tables at all as I believe the factory maps cover overboost spikes and therefore would cover a slight increase in boost anyway.

At part throttle your max boost is mostly controlled by the thottle, so in these regions it is hard to add more boost without significant engine hardware changes.

I've answered a lot of questions, so here's one for you, tell me more about your backyard project. I guess it's a Nissan CA18DET that's going into something. Am I right?

[macka'sxr6t]

Sorry Jim, for taking so long to get back to you.

Thanks heaps for answering my questions

My project is a CA18DET conversion into a Nissan TRX.

Just finished putting together some basic fuel and ignition maps, and I have just a little bit of wiring work to do on the harness.

Hopefully won't be to much longer before I can fire it up.

macka