Let have a technical discussion on optimum performance tuning for a N/A FE.

[Barry_R]

Still need to address the BTU content/potential of the fuel - or just "lock" the fuel part of the equation.  Not all fuels work best at a specific A/F ratio.  Some work better at a richer or leaner mixture, and many release energy at different levels, speeds and temperatures.  An example would be a good race gas, which, contrary to some opinions, burns very fast and releases a lot of energy.

To get those characteristics other parameters are pushed back - such as emissions, and shelf life.

[cdmbill2]

Back in the day when I had my 69 Mustang E/SA 428 car we played with the boosters in the carb using some of the special version Ford had produced for various applications in order to improve mixture distribution. These boosters had small tabs cast onto the od of the booster at the bottom of the venturi. Maybe someone here has pictures of some of these. Of course we also played with the air bleeds along with the PVCR channels to adjust for cylinder to cylinder variation as indicated by plug reading. Indexing the plugs is really important in my view to make those samll adjustments more visible and repeatable.

Having eight AFR bungs in the headers as Jay mentioned really can help with that kind of tuning now that we have the technology available so relatiively inexpensively.

I'm way out of touch with what is legal in Stock eliminator classes these days. Can you run an ignition that allows you you tailor individual cylinder timing curves/ Maps? The dyno is best for that as it'll take a ton of drag strip passes to accomplish what you can in one or two days of dyno flogging.

All of this assumes you are trying to set record's or qualify at the top of the list. Otherwise getting the car to be consistent and working on your driving is way more important for going rounds.

One other note you will never be able to get a car to run as fast at 3000 DA as it does at sea level if the sea level tune was optimal or close to it, but  neither can anyone else.

[69Cobra]

Back in the day when I had my 69 Mustang E/SA 428 car we played with the boosters in the carb using some of the special version Ford had produced for various applications in order to improve mixture distribution. These boosters had small tabs cast onto the od of the booster at the bottom of the venturi. Maybe someone here has pictures of some of these. Of course we also played with the air bleeds along with the PVCR channels to adjust for cylinder to cylinder variation as indicated by plug reading. Indexing the plugs is really important in my view to make those samll adjustments more visible and repeatable.

Having eight AFR bungs in the headers as Jay mentioned really can help with that kind of tuning now that we have the technology available so relatiively inexpensively.

I'm way out of touch with what is legal in Stock eliminator classes these days. Can you run an ignition that allows you you tailor individual cylinder timing curves/ Maps? The dyno is best for that as it'll take a ton of drag strip passes to accomplish what you can in one or two days of dyno flogging.

All of this assumes you are trying to set record's or qualify at the top of the list. Otherwise getting the car to be consistent and working on your driving is way more important for going rounds.

One other note you will never be able to get a car to run as fast at 3000 DA as it does at sea level if the sea level tune was optimal or close to it, but  neither can anyone else.

Yes the ignitions that are allowed today will let you map out timing curves and adjust individual cylinder timing as well.

[TomP]

The ignition box can control individual cylinder timing? Or is this an EFI multi-coil deal?

 The way i've seen that done on a SuperStock car was timing was checked on each cylinder, mark the balancer in four equal spots (hopefully TDC is equal in each too!)  and check every cylinder. Any variation and you need to grind one side or other of the terminals in the distibutor cap.

I had to do that with the Mallory crab cab i used to run.

[69Cobra]

Honestly I'm not 100% sure Tom. I've never tuned for individual cylinder timing. I know the ignition system can do it but I don't know if that's for EFI only. I've wondered how it would adjust individual cylinder timing with one coil and a dizzy.

[Barry_R]

In order to do individual cylinder timing it would need a cam position sensor to tell it where the number one plug was.  After that it can drop timing as directed from subsequent cylinders.  This is done here by using a crank trigger for plug firing signal and by removing all but one trigger blade on an MSD (or other) magnetic distributor - turning the distributor pickup into a cam position sensor.

[machoneman]

This has been a fascinating thread. No longer drag racing here but today's equipment would have helped a ton with trackside tuning.

Question: I understand well the method of individual cylinder tuning.  But, what is the primary reason why it is necessary to wring out max. hp?

Is it the unevenness of cylinder loading due to varying ports (intake, head, both) flow characteristics of end ports versus center ports in carb'ed applications (EFI would eliminate this variable), varying combustion heat in different cylinders, etc.?
Have never heard a good answer as to the major factor, or factors, at work here.     

[jayb]

MSD Digital 7s can do individual cylinder timing adjustments, based on a reference from cylinder #1.  You have to put one of their spark pulse sensors, which is essentially the same as the clip from a timing light, over the #1 spark plug wire.  The sensor is actually a donut shape, so it doesn't clip on to the plug wire, you have to pull one boot off the #1 plug wire and thread the wire through the sensor.  Then there is a cable, fiberoptic I think, which goes from the sensor to a port in the MSD Digital 7.  You have to tell the MSD what your firing order is, and then the software in the MSD will allow you to retard timing in any of the cylinders.  I used this setup on my Mach 1 when I was running the supercharged engine, which was carbureted.

I think there are a lot of factors at work when it comes to causing variations in the individual cylinder fuel or timing requirements.  Variations in the intake manifold and headers comes to mind, as well as fuel distribution.  By the way, fuel distribution issues are not automatically cured by 8 EFI injectors, because there can be significant variation in the injectors themselves.  Also temperature differences from cylinder to cylinder caused by variations in the cooling system could come into play, small variations in pistons or combustion chambers from cylinder to cylinder, etc. etc.; the list goes on and on.  My efi-guru friend Dieselgeek has seen remarkably large variations from cylinder to cylinder in fuel requirements even with individual runner sheet metal intakes and EFI setups.  So the more tunability you can put into individual cylinders, the more likely you will be able to squeeze out more horsepower.

[machoneman]

Cool and thanks for the reply Jay. Dieselgeek's findings are quite interesting too as one would think (fancy that, eh?) with IR intakes and EFI cylinder-to-cylinder variations would be at a minimum.

[69Cobra]

MSD Digital 7s can do individual cylinder timing adjustments, based on a reference from cylinder #1.  You have to put one of their spark pulse sensors, which is essentially the same as the clip from a timing light, over the #1 spark plug wire.  The sensor is actually a donut shape, so it doesn't clip on to the plug wire, you have to pull one boot off the #1 plug wire and thread the wire through the sensor.  Then there is a cable, fiberoptic I think, which goes from the sensor to a port in the MSD Digital 7.  You have to tell the MSD what your firing order is, and then the software in the MSD will allow you to retard timing in any of the cylinders.  I used this setup on my Mach 1 when I was running the supercharged engine, which was carbureted.

I think there are a lot of factors at work when it comes to causing variations in the individual cylinder fuel or timing requirements.  Variations in the intake manifold and headers comes to mind, as well as fuel distribution.  By the way, fuel distribution issues are not automatically cured by 8 EFI injectors, because there can be significant variation in the injectors themselves.  Also temperature differences from cylinder to cylinder caused by variations in the cooling system could come into play, small variations in pistons or combustion chambers from cylinder to cylinder, etc. etc.; the list goes on and on.  My efi-guru friend Dieselgeek has seen remarkably large variations from cylinder to cylinder in fuel requirements even with individual runner sheet metal intakes and EFI setups.  So the more tunability you can put into individual cylinders, the more likely you will be able to squeeze out more horsepower.

Thanks for that explanation Jay. I've seen the sensors on the #1 wire and I knew it had something to do with the individual cylinder timing but I didn't know what else was involved to make it work. So basically as long as your mechanical advanced is locked out and you have this sensor and the ignition box programed correctly that's all you need for this to work?

[jayb]

That is correct.

[fe66comet]

Really if you wanted the ultimate ignition system you would go coil on plug with a custom box. I have made custom circuit board systems for other applications before but not for that. I would use the Caddy variable timing circuit as a basis for my build. And use a standard ECM for controlled access.

[69Cobra]

Really if you wanted the ultimate ignition system you would go coil on plug with a custom box. I have made custom circuit board systems for other applications before but not for that. I would use the Caddy variable timing circuit as a basis for my build. And use a standard ECM for controlled access.

Yeah that won't fly in Stock Eliminator lol

[fe66comet]

Than no variable timing is truly legal.

[69Cobra]

DISTRIBUTOR
Any battery-operated, stock-type ignition permitted. Crank trigger systems prohibited unless OEM distributorless ignition. Distributorless ignition must retain OEM number of coils. See General Regulations 8:3.

COMPUTER/DATA RECORDERS
Original OEM computer may be replaced with aftermarket computer. Data recorders permitted. Other than OEM or OEM-replacement computers prohibited. See General Regulations 9:1, 9:2.

Well according to the rule book. You might be able to do something like you're talking about but the MSD box would have to be able to operate the individual coils because I couldn't use an ECU if it didn't come with one the way I'm reading it. You would have to use the distributor as the "crank trigger" and figure out if you can make the 7730/7720 MSD box control the individual coils. I guess I just wondering what are you gaining by doing this?