2003 cobra timing map?

[MattACK]

How many folks in here tune their own cobra, or tune cobras with SCT PRP?

I'm going to start tuning my stock one, and am looking for suggestions for how much the stock timing map can be adjusted. Any help would be appreciated.

--Matt

 

[racebronco2]

How many folks in here tune their own cobra, or tune cobras with SCT PRP?

I'm going to start tuning my stock one, and am looking for suggestions for how much the stock timing map can be adjusted. Any help would be appreciated.

--Matt

It can adjust it all you want. Generally on 91 octane 13psi and 21 degrees.

For every octane above 91 you can either add 1 psi or 1 degree of timing.

For every psi above 13 you will need 1 octane higher fuel or reduce timing by 1 degree. If you are less than 13psi you can add 1 degree of timing for every psi below 13.

For every degree of timing added you need to add 1 point of octane. For every degree of timing you take away you can 1 psi of boost.

If you add any of the three (octane, timing or boost) you must also add or subtract one of the three (octane , timing or boost).

Add boost = reduce timing or increase octane
Add timing = reduce boost or add octane
Add octane= increase timing or add boost

The above is safe for most cars. You really need to get on a dyno to get the best combo of the three.

 

[MattACK]

Awesome... thanks for the tips.

What about midrange and low-end timing? I'm sure it is sufficient as is, but are there areas that can be improved?

 

[watman02]

It can adjust it all you want. Generally on 91 octane 13psi and 21 degrees.

For every octane above 91 you can either add 1 psi or 1 degree of timing.

For every psi above 13 you will need 1 octane higher fuel or reduce timing by 1 degree. If you are less than 13psi you can add 1 degree of timing for every psi below 13.

For every degree of timing added you need to add 1 point of octane. For every degree of timing you take away you can 1 psi of boost.

If you add any of the three (octane, timing or boost) you must also add or subtract one of the three (octane , timing or boost).

Add boost = reduce timing or increase octane
Add timing = reduce boost or add octane
Add octane= increase timing or add boost

The above is safe for most cars. You really need to get on a dyno to get the best combo of the three.

not to throw wrench into the works but does the above rule hold true if the compression ratio is higher?
my mach 1 has 10.1:1 i believe and most people will only run about 16 deg timing max under boost due to the weaker piston and rods.
Im wondering what your thought on this would be if i added 1 lb of boost should i take away 1 deg of timing or add 1 octaine ?

 

[racebronco2]

Awesome... thanks for the tips.

What about midrange and low-end timing? I'm sure it is sufficient as is, but are there areas that can be improved?

My tuner added timing once the car went wot. I'm not sure how much timing he added. You really need to get on a dyno to verify if it's helping or not.

 

[racebronco2]

not to throw wrench into the works but does the above rule hold true if the compression ratio is higher?
my mach 1 has 10.1:1 i believe and most people will only run about 16 deg timing max under boost due to the weaker piston and rods.
Im wondering what your thought on this would be if i added 1 lb of boost should i take away 1 deg of timing or add 1 octaine ?

On my car 1 degree of timing almost equals one pound of boost. I would think so just you would be starting with timing or boost. Be careful tuning the Mach, as you should know for some reason some of them are harder to tune than others. Your knock sensors might need to be adjusted for sensitivity. I know more than a few 4v's that the vibration of the blower cause a false knock in which the ecu pulled timing.

 

[leegro1015]

One thing we are missing here is commanded a/f ratio. Leaner less timing 12.0 or leaner. 12.0 or richer more timing for example. So racebronco what a/f ratio are these based on?

 

[Demonio]

Subing

 

[racebronco2]

One thing we are missing here is commanded a/f ratio. Leaner less timing 12.0 or leaner. 12.0 or richer more timing for example. So racebronco what a/f ratio are these based on?

You never want to be in the 12's. On my car it's in the mid 11's. It jumps a little plus or minus. 12's on the dyno will not hurt anything but on the street it takes alot long to hit 6000 rpms.

The numbers above are only a guide and considered to be safe with most cobra's.

I would like to see where you read leaner less timing, richer more timing. I have never heard that before.

 

[leegro1015]

You never want to be in the 12's. On my car it's in the mid 11's. It jumps a little plus or minus. 12's on the dyno will not hurt anything but on the street it takes alot long to hit 6000 rpms.

The numbers above are only a guide and considered to be safe with most cobra's.

I would like to see where you read leaner less timing, richer more timing. I have never heard that before.

Maybe the way I put it was a little misleading. Basically that you can obtain the same power with a lean a/f and less timing as you can with richer a/f and more timing.

 

[racebronco2]

Maybe the way I put it was a little misleading. Basically that you can obtain the same power with a lean a/f and less timing as you can with richer a/f and more timing.

Lean is dangerous and rich is safe. Lean with the same timing will always make for power, until it blows up. Say the car is running low 11's a/f. Change timing for max power, back off 1/2 to 1 degree. Lean out the a/f til you get it to around mid 11's for a blown cobra. If you lean it out to low 12's it will make more power. Take timing away and it will lose hp. If you have a small vacuum leak of a line blows off your engine is done. Is you car tuned for lean and less timing or is it tuned for rich and safe?

 

[leegro1015]

Lets take a look at this... Kenne Bell's tune calls for 11.00 a/f and 23° of timing for 03 cobras(optimal). But most tuners in CA will tune for 12.00 and 18-19° of timing. It all depends on where you lock your a/f on the dyno, then add timing till it stops making power then back off a few degrees.

 

[MattACK]

The short of it is that any fuel you add past the stoich 14.7 is to assist in cooling the cylinders. Any A/F ratio below 14.7 will result in unburnt fuel, this unburnt fuel cools the cylinders so theoretically you can add a little more timing, but it isn't very rational. You're robbing peter to pay paul in that situation. Rich conditions = less power, so we add timing.... why not just leave it where it was. Better ways to make power than to push the envelope.

 

[cj428mach]

in for later

 

[ctgreddy]

on my car I'm running a ported eaton with roughly 15lbs of boost and 93 octane and am running 21 degrees. I keep my target afr around 11.6.