Confusion - Ford Forums - Mustang Forum, Ford Trucks, Ford Focus and Ford Cars

XDSedan · 06-24-2002, 05:44

G'day, just a quick question....
I've read that the XF EFI Leaded puts out 111kW stock....
and XF EFI Unleaded puts out 121kW
How can this be? The leaded engine even has a higher compression. I thought that since leaded has a higher RON and also running at higher compression then it's be the more powerful one.... info from :
http://www.fordinfo.com.au/falconxf.htm

06-24-2002, 05:58

The info is wrong - the XE put out 111kw - all XFs were rated at 121kw leaded or unleaded. At least that is what Ford would have you believe.

Tote · 06-24-2002, 19:23

Many moons ago I was a government employee and they used to give me a new XF van every 9 months or so when they got to 40,000 KM
I had a leaded XF followed by one of the first unleaded ones.
Both vans were identical ie same diff ratios and 3 speed column shift manuals.
The leaded van would pull 145 at the top of Lidster hill near Orange if you hit the bottom @160
The unleaded van and the next couple of vans I had would be flat out at 100 at the top of the hill. XE vans had similar performance to the leaded XF but they were autos.
I would certainly say that there was a loss of power when unleaded was introduced.
Ah the things we do when we are young and stupid....
Regds,
Tote

06-24-2002, 20:55

yeah thats what i thort. the Leaded Fuel has more power. than unleaded. still i wish we could get BP 100 or AV130 at the pumps. they still use Leaded in the Arab Emerates. No problems there. Ppl are thick, running LRP on old cars, it just wrecks the motor. even europe is going bak to leaded. some ppl have started class actions against the Goventment and fuel companyies.

i will find the site for u guys.

James

06-25-2002, 05:06

The reason you notice a difference between the leaded XF and unleaded XF is Ford changed the cam profile and compression ratio to compensate for the lower RON - the unleaded had less torque - that's why it lost speed up hill - the max power obtained however was, according to Ford, identical.
XF leaded - 333Nm torque
XF unlead - 325Nm torque
These figures from memory so am open to correction if anyone can find the literature from back then.

Sundeep · 06-26-2002, 05:00

I thought the Unleaded EFI's lost 1kW?

Sundeep

06-26-2002, 07:22

sundeep> sounds right - but I don't think you'd notice one lost little killer watty...LOL

Futura97 · 06-26-2002, 07:26

Quote:

Originally posted by Cobra188
The reason you notice a difference between the leaded XF and unleaded XF is Ford changed the cam profile and compression ratio to compensate for the lower RON - the unleaded had less torque - that's why it lost speed up hill - the max power obtained however was, according to Ford, identical.
XF leaded - 333Nm torque
XF unlead - 325Nm torque
These figures from memory so am open to correction if anyone can find the literature from back then.

On this note... I think the vn-vt commodores where around 300-305Nm of torque?

Does this mean that an XF EFI should theoretically be able to tow better than a vn-vt? Or go up steep hills better? Or is this where kW come into play?

Cheers

06-26-2002, 07:32

xf_xr6> yes, assuming gear ratios are the same, the car with more torque is able to apply more force.

Dreders · 06-26-2002, 15:57

I have a 1985 leaded EFI XF and my brother has a 1987 Unleaded EFI XF. Mine is so much faster it isnt funny, you can feel the cam come on whereas my brothers car is just flat.
The power in mine is strong between 40-70 but first gear will push to about 85kph. My brothers car pulls from 35-50 with a lot less urgency.