I'd like some input about my timing map I posted if anyone has had a chance to look it over real good.

Thanks,
STEPHEN

 

Let's talk about timing split generalities.

(1) I have heard that Mazda runs about 15 for cleaner emissions.
(2) Negative split can cause pinging and detonation under load conditions. Under light loads it is less of a concern but will reduce power.
(3) Less split means more power. The NA engines are running 0 split or very close to it to develope max power. Turbo engines can also benefit form less split up to a point due to their higher combustion pressures and temperatures. You must have a very accurate timing control system to run true 0 split to insure against negative split.
(4) If running a J&S, split must be kept higher than the retard amount to prevent from going into negative split.

It is true that some parts of the timing map are not important since you will rarely or never be there. BUT, it is nicer to have a uniform map.

I run a J&S, so keep at lease 12 split when under strong boost.

Atached is a simply analysis of your split.

 

Thanks, Chuck

What do you think would be the best was of getting the neg split corrected? You think i should retard my leading or advance my trailing?

Thanks for the input,
STEPHEN

 

If the IGL is good, then you always adjust the IGT for the split. IGL first, then IGT for split.
Compare other maps on the forum to yours with similar mods. If the IGL is close, then change the IGT. It does appear that your high vacuum low rpm IGLs are screwed. Look at the base maps.

 

For what it's worth, the XS single turbo maps have negative split in many of the same cells you do. In the past I chalked that up to a hidden base map.

 

<<(1) I have heard that Mazda runs about 15 for cleaner emissions.

True, this is very important at idle.

<<(2) Negative split can cause pinging and detonation under load conditions. Under light loads it is less of a concern but will reduce power.

Under very light load conditions the stock Mazda timing maps have a negative split in some areas. This is to increase exhaust gas temperature and speed which therefore reduces turbo lag.

<<(3) Less split means more power. The NA engines are running 0 split or very close to it to develope max power. Turbo engines can also benefit form less split up to a point due to their higher combustion pressures and temperatures. You must have a very accurate timing control system to run true 0 split to insure against negative split.

Also true, to a point. I believe running zero split at full boost will not produce the most power. Tis is a myth because Racing Beat used to do it years ago. They did not have an ECU with the complexity to run two different timing maps for their cars.


<,(4) If running a J&S, split must be kept higher than the retard amount to prevent from going into negative split.
Very true.
It is true that some parts of the timing map are not important since you will rarely or never be there. BUT, it is nicer to have a uniform map.

I run a J&S, so keep at lease 12 split when under strong boost.

Attached is a simply analysis of your split. [/B][/QUOTE]


Nice analysis Chuck. I am experimenting with my timing maps also. Right now I am running an 8 degree split at full boost. (17lbs.)_

John

 

John,

Have you made any dyno runs testing only split? I am going for my second timing tuning runs this Friday. I have been very conservative with my tests. Only increasing a max of 2 degrees per session. I figure that when I go for my last dyno tests, I would disconenct the J&S and bump the IGT up and see what that does.

 

No,
As a matter of fact I haven't even run it in the quarter yet. Eventually I will get around to it. It's a good idea to bump up the IGT, as you know this only lessens the split but does not affect the total timing. I am still wondering how much total I can get away with but I am only going to keep fooling with the split right now also.......when I get a chance.
John

Keep us posted on your results.
Have you run your car in the quarter?? and Can you send me your adjusted fuel map??

 

John,

So are you saying that neg split while in vacume isnt much of a concern and may infact help minimize turbo lag???

XS programed my map with some negative split but its all during vacume.

Damn, now I really dont know what would be best.....I only wish I had a bad *** rotary tuner close by with a dyno.

Maybe I should just wait for the datalogit before changing anything!!!

Thanks guys,
STEPHEN

 

Stephen,

I never heard of negative split being good for
helping spooling, but retarding the timing and adding extra fuel will. Drag racers do it during staging when they have it reved up for launching. They have a control switch to turn this off and on. The DATALOGIT has the function to do this. It is hard on the turbos as it really heats them up.

You can do this to a less of a degree by running extra retard on the low end were your turbos are slow spooling.

 

I really am not sure. I can only say that it seems to be a touchy subject with a lot of people. Personally, I would monitor my knock readings while in the negative split zone. See if there is anything to be concerned about. I like to run no split during vacuum because I view it as being safer and my car is more efficient than stock so I really don't need increased heat for boost response. The factory timing seems to have very little negative split, only one or two degrees in only a fewe individual cells from what I remember. Anyway, I would bring up the trailing timing until you get 0 split in vacuum.

Come to think of it- CAll XS and ask to speak with their chief tuning engineer.
John