tuning for economy

[Simon]

Whats the best way to make the standard 302 most efficient (economical)?
A 600cfm Holley or the standard ford efi setup?

Simon

I ask because our petrol is about 4+ times more expensive than the US

 

[Dave Wood]

I doubt that you could get better drivability and fuel mileage than what you can achieve with the EFI that is on the later 5.0s. I had an '89 GT( heaviest version) and regularly got 29+ driving in the 80mph range. You would want the mass flow and not the speed density. The MF is very tunable for almost any modification while the SD can only adapt to about a 10% change in airflow.

 

[Eric]

Simon

EFI provides better control over air-fuel ratio based on conditions. That is how you get better gas mileage with EFI over carburation (EFI holds a big advantage in the emmisions area, which is really why it is used). It is, however, a misconception that EFI is more fuel efficient than carburation, theoretically speaking. In both cases, fuel is being accurately metered. EFI is just more adaptable, since pulse width is tuneable over a wide range (and managed by a computer) whereas a jet must be manually swapped out. And, because of the adaptability of EFI, if you get down to the nitty-gritty of tuning, you can realize more power than with carburation.

I would go with EFI (and, in fact, am doing so on my 351W). Multipoint is better than throttle body, all things being equal.

Eric

 

[Randy V]

Simon,

Like was said earlier - the EFI system will most likely give you the best overall economy.
A 600 CFM carburetor is probably just a bit on the large side for best economy - but that's not to say you can't get there with that carb either.. Holleys can be very tuneable. Of course since it's a pressure differential device, it will be impacted by changes in barometric pressure / altitude / temperature...
If you're planning on driving through any high altitudes, you may want to consider installing the Ford 5.0 Intake / injection system along with an EEC-IV computer like the A9L or A9P. They're not hard to wire up and are really pretty darned good systems..

 

[Jack Houpe]

I doubt that you could get better drivability and fuel mileage than what you can achieve with the EFI that is on the later 5.0s. I had an '89 GT( heaviest version) and regularly got 29+ driving in the 80mph range. You would want the mass flow and not the speed density. The MF is very tunable for almost any modification while the SD can only adapt to about a 10% change in airflow.

Dave I agree with you on your politics but will disagree with you on MAF over Speed Density, MAF you will alway have a restriction in which the EFI computer communicates how much CFMs are passing and at what rpm range to deliver. The beauty of Speed density is less restriction (CFM per given event) which with the correct amount of fuel delivers more HP. Just my opinion. Yes MAF is easier to tune but then again is something easy always the best?

Jack

 

[Paul Thompson 'Hooligan']

Simon -

After fitting Kinnsler throttle bodies with Accell management to Roy Smart's GTD40, driveability improved no end (esp in traffic) and fuel consumption was noticibly less. On a run he could get 20+ mpg and that was often with some spirited driving enroute. Bearing in mind that the motor was not at the lower end of power output, I'd say EFi every time.

Also, with EFi an overrun fuel cut function will help too, as each time you come off the throttle when decelerating, the fuel can be cut above a preset level of rpm. Every little helps....:thumbsup:

In addition, with EFi it is possible to have a road/track switch, whereby the road position has a leaner, less agressive, more fuel conscious cruising map and in track mode, well that's self explanitary. I know people will say carbs can be tuned for either mode but try doing it at 'the flick of a switch'...

I have added active fuelling to my GSX1400 and with the fitted lambda sensor, I can select between two target Air-Fuel-Ratio (AFR) Maps at the flick of a switch. Result is 0 to 60 in less than 4 secs and almost 50 mpg when required if cruising.

 

[Paul]

Simon -

After fitting Kinnsler throttle bodies with Accell management to Roy Smart's GTD40, driveability improved no end (esp in traffic) and fuel consumption was noticibly less. On a run he could get 20+ mpg and that was often with some spirited driving enroute. Bearing in mind that the motor was not at the lower end of power output, I'd say EFi every time.

Also, with EFi an overrun fuel cut function will help too, as each time you come off the throttle when decelerating, the fuel can be cut above a preset level of rpm. Every little helps....:thumbsup:

In addition, with EFi it is possible to have a road/track switch, whereby the road position has a leaner, less agressive, more fuel conscious cruising map and in track mode, well that's self explanitary. I know people will say carbs can be tuned for either mode but try doing it at 'the flick of a switch'...

I have added active fuelling to my GSX1400 and with the fitted lambda sensor, I can select between two target Air-Fuel-Ratio (AFR) Maps at the flick of a switch. Result is 0 to 60 in less than 4 secs and almost 50 mpg when required if cruising.

50mpg in a GT40??? How could that be?

 

[David]

50mpg in a GT40??? How could that be?

It's not, you're misreading it. He's talking about a bike. It's a bit poor mpg at cruise IMO for a bike but then it's unfaired and that makes a huge difference. My VFR gets better with carbs but it's 650cc less and faired!

 

[Cliff Beer]

Any carburetor struggles to maintain the optimal AFR across the full rpm range and throttle settings. In fact, no carburetor can do it really well. Why? Because fuel transitions from different circuits, through different orifices, is affected by the position of the throttle plate (hence "accelerator pumps"), different jetting, etc. and all of it results in a compromise and sub-optimal AFR under the various loads and rpms. EFI is much better able to maintain optimal AFR under the various loads and rpms. Of course, this ability depends on a range of sophisticated sensors.....throttle position, air flow, engine temp, rpm, the O2 sensor, etc. All these inputs are processed by the ecu and an optimal AFR is determined and then implemented by the pulsed injectors.

You'll get far better tunability and fuel efficiency from EFI.

That said, I still like four IDAs on top of a Ford V8 and that's where I'm going with my drive train soon. Of course, our benzine is cheap on this side of the pond....