So I've read that the Bullitt can detect differing grades of fuel and adjust operating parameters to offer up to a 25 hp boost in power (iirc), has anybody explained how the system works (is it just a software upgrade or is it a hard/soft upgrade to the standard system in the GT). CAI aside, I see the Bullitt is also fitted with retuned damper as well.

 

It would have to have revised knock sensors. That's the only way I know of to "detect" octane ratings. It detects knock and retards the timing. Thats how most other cars do it with premium/regular fuel capability. There really isn't an octane rating sensor out there.

 

I'm just not sure if it can be done with the current knock sensors installed in the regular GT's. Maybe it is all software... I don't know.

 

I've seen everyone post this and it is wrong.

The Bullitts adaptive octane sensor does NOT boost HP by 10-15-20-25hp

It can add UP TO 10FT-LBS in the 1000-4000RPM range

Quote:

Engine performance is further enhanced through the use of an innovative adaptive spark ignition system, new for the 2008 Mustang.

The system can sense, within a few seconds, what type of fuel is being injected into the motor and adjusts the spark to provide maximum torque at any given speed – and as much as 10 pounds-feet more between 1,000 and 4,000 rpm.

Bullitt can run on either premium or regular fuel. Ford recommends premium fuel for optimum performance, but the adaptive spark ignition will adjust the spark to burn regular fuel without damaging the engine.

Sounds like the change is not just Bullitt, but not confirmed by anyone yet.

 

The car features the first use of an open-element air filter in a factory-produced, fuel-injected Mustang. Inspired by Ford Racing, the intake is tucked neatly behind the driver side headlamp, mounted in an air box that was tooled up specifically for the Mustang. The hood liner was extensively modified to provide a full seal to the air box, ensuring that the engine is fed a steady diet of cooler air.

“Colder air reduces intake losses,” said Randle. “The new cold-air intake has shown a reduction in rise over ambient temperature from 50 degrees down to 17 degrees Fahrenheit. That equates to more horsepower and more torque in all driving conditions.”

Engine performance is further enhanced through the use of an innovative adaptive spark ignition system, new for the 2008 Mustang.

The system can sense, within a few seconds, what type of fuel is being injected into the motor and adjusts the spark to provide maximum torque at any given speed – and as much as 10 pounds-feet more between 1,000 and 4,000 rpm.

Bullitt can run on either premium or regular fuel. Ford recommends premium fuel for optimum performance, but the adaptive spark ignition will adjust the spark to burn regular fuel without damaging the engine.

“With all the improvements we’ve made to the engine and the taller 3.73-to-1 rear gear, the Bullitt will plant you firmly in the driver’s seat when you stand on the throttle. We’ve seen zero to 60 times drop by up to three tenths of a second,” said Randle. “There’s also plenty of power on tap at any speed. The car definitely feels lighter on its feet, and it is.”

The custom-designed exhaust system continues Mustang’s traditional use of a true dual-exhaust system with a new H-pipe specifically developed for Bullitt. The all-new mufflers, featuring larger 3.5-inch chrome tips (versus the 3-inch tips on the standard Mustang GT) are tuned to minimize backpressure, maximize horsepower and provide the Bullitt with its powerful exhaust note.

“We wanted to get the exhaust note as close to the original movie car as possible, so we based it on a digitally mastered DVD,” said Randle. “We wanted something that would rumble your heart, literally buzz you – and the Bullitt team delivered.”

 

I suspect there is new logic in the software using similar knock sensors. If you were to add some logic to the current software to allow it to switch spark tables based on frequency of knock.

Right now it just takes spark out (or adds it) actively based on knock. But it's always referencing the same tables for the intial spark value. If after a certain amount of knock, it switched to a different table for it's starting point, it wouldn't be hard for all of this to work.

If you put in high octane, after a certain amount of time seeing no knock, it would switch to the higher output tables. It may be even smart enough to recheck 'octane' after it sees an increase in the amount of fuel in the tank. That way it knows you added new gas and it could be higher octane (or lower)


This is just a guess and I will look into it further.

Ken

 

Ken:

Any comment on whether or not the 05-07's can get any extra HP or torque by running higher octane? This has been discussed at length, but I don't think there is a definitive answer out there yet.

 

Dynamic compression is really what it comes down to, higher octane fuels allow the ignition to fire later in the compression stroke than would be possible with a lower octane fuel, effectively altering the compression ratio fo the engine (despite the actual mechanical compression ratio of the engine), with more compression you get more power and fuel economy.

This is different than advancing/retarding the ignition based on engine speed and load (altough all this stuff is related). Here it is a matter of choosing a point where to best fire the igntion so that the correct cylinder pressure is achieved at the right time based on the burn rate of the fuel.

 

Ok??

 

Lol, maybe I need to space things out a bit.

Mechanical Compression Ratio: This is a fixed relationship based on the maximum volume of the cylinder at BDC compared to its volume at TDC.


Dynamic Compression: This is the actual compression ratio of the engine based on its volumetric efficiency relative to its maximum volume at BDC compared to its volume at TDC. You can also effectively alter the dynamic compression of the engine by changing the point at which the plug fires, as an example if you wait to fire the plug at some point after/before top dead center, then the observed compression of the engine will be lower since the volume of the cylinder will be larger at that point.



I need to edit things a bit for completeness/clarity, but hopefully you get the idea. late ron this morning I'll try and get things straightened out (along with an example showing volumetric effciency)

 

On the stock tune? No. Ignition timing is clipped on the stock tune. You should actually make less power on 93 vs. 87 with the stock tune.

You can get additional torque since the timing is only clipped up high. It's up to the knock sensors to add this additional timing required. From 3,000 RPM up, the stock tune can only add 2 degrees of timing. Not enough.

 

I understand dynamic compression and all the stuff you are trying to clarify. My question is, what does it all have to do with Bullitt tuning, or octane ratings? What is your point for explaining how compression works?

 

Ken, the clipping your talking about... I assume your talking about the knock advance Limit/rate settings and how they drop as RPM's increase. I kinda thought that maybe some revised settings with this was what Ford was talking about. For those who are inevitably scratching their heads at what the heck I am talking about... the stock ford computer has the ability to, in the absence of knock, add timing as it can. as Ken said, below 3K rpm's it can add 8 degrees of timing, but once it goes past 3K, it can only add 2 degree's.

I don't think that a low/high octaine timing and fuel maps would be all that hard to impliment. I know that GM does a high and a low ocatine timing map with the Atlas, Vortec, and LSx series of motors. in function, it basically ends up using the Low ocatine map as a starting point, and slowly adds timing until it either hits knock or hits the value on the High Octaine map. However, I don't see Ford changing the way they write the PCM's just for one car.

 

Lol, I started on this tangent and was going off the edge there and I meant to round out that post with how you can tune the engine to take advantage of different octane ratings and why thats different from tuning with the ignition for best power (but 3:00 am came up pretty quick) and just decided to start from the most simple point and intended to progress from there.

Now that I think about it, that would have been a pretty lengthy post (and not very Bullitt specific).