Tedd

Hello all, I know this is pretty basic stuff, but I need some input from some of the more exerienced. I'm trying to tune my timing tables and have been stumbling a bit, I need to change my stock iron head/stock cam bin timing tables to ones that will work with aluminum TFS heads, Crane cam (#113931), and headers.

What I've been doing is:
Starting with the stock bin, I add an increment to the "entire" timing table(open throttle). Then I'll go for a data run using DataMaster to look for any detonation.

I have MAP, RPM and Spark Retard set on the DataMaster graph function, so I can see when the car is detonating at different engine conditions. I'll try to make the engine detonate during the run if it will.

When I'm done I'll export MAP, RPM and Spark Retard to Excell; Sort with regard to Spark Retard and collect only the data that experienced Spark Retard.

I'll then compare RPM vs. MAP for this group and decrement those paticular cells 2 times on the timing table that are experincing detonation.

At this point I'll add another increment to the entire timing table and go for another data run. And so on and on....

slowly I'm building up the tables where there is no detonation and lowering the tables where there is detonation.


I've done this probably seven times and I'm definatley getting more power out of the combo, but how many cycles of this can I go through? This motor shifts at 4000 maybe 4200 rpm, so there are alot of data points on the timing table that never get used under normal driving conditions, I add to the points that don't detonate so these points are getting higher than the probabley need to be. But if the motor never goes there, is there a problem with that?


Thanks for any insight you can shed on this!

Tedd Edmondson
tedd319@swbell.net



'95 4WD Suburban, $OD, 27C512, 16197427, BJYL, TFS heads, Crane cam (#113931), FelPro headers. 3.73 rear end

Grumpy

Trouble is you wind up tuned to the limits of detonation.
which is in part a function of fueling.

Doing your way get you to the running the most timing posible.

I suggest tuning to the min amount of timing consistant with max performance.

While it almost sounds like a play on words, it's very different when you get to the actual tables.

If you want to continue with what your doing, you could consider that a too much timing baseline, and then work back thru it with the other concept.

If your not worried about money and engine life, you might find a few more ponies tuning to the detonation limit of the mtor, but stand a real good chance of knocking the tops off the pistons if anything goes slightly wrong.

Tedd

Thanks for the reply Grumpy,

I have to start doing somewhere and I do seem to be making some progress, but I do see your point. Still it seems like I need to get the tables closer than the OEM settings before I try to squeeze a specific MPH from the lowest MAP reading. What about all those cells that arn't used. isn't this a decent way to get close?


Tedd

Grumpy

Don't ASSUME that the trend continues in what your seeing.

There are some rare circumstances that can goof up what you'd expect to see. ie

known/ expected:
30 40 50 60 70 80 90 100
20 24 24 26 26 26 26 26 400 RPM

But at first run the engine can be at 450 RPM and 90 K/Pa so you actually need:

30 40 50 60 70 80 90 100
20 24 24 26 22 18 14 12 400 RPM

This is the only real odd spot.

But at say 1600
You probably would want a table like in the second 400 rpm example.

Lots of the oem table have just completely screwy high rpm low bac advance numbers in them.

Tedd

Grumpy wrote:
Lots of the oem table have just completely screwy high rpm low bac advance numbers in them.


Thats what I would say to. those stock bins look horrible to me.

What other method can I use to get the most performance out of my timing tables? I know this must be an annoying question but other than the method I worked out I'm stumped



Tedd

novass

iTrader: (1)

I am sorta stumped on the timing advance issue also, I would really like some feedback too... I have done searches but still am hazy..

I also noticed stock the 305 bin has a heck of alot more timing than the 350 bins.