Hello folks, Currently I have a 97 Lincoln MKVIII that with my mods runs to the same power level of the 300hp 4.2. Not bad but not overwhelming. Since my son would like to have the Lincoln, I think its time to take another look at a base XK coupe. The question I have off the bat is should I stick with the 4.2 or go for the extra 85hp of a 2010 + XK? from what I'v read, the 4.2 seems to be some 2 mpg more than the 5.0 in overall driving. I'v always liked the fact that the MKVIII gets a solid 25mpg running 75-85mph over the interstate runs I do occasionally. I do custom mods on about everything I own so I'm wondering if their are some basic mods that can be done to the 06-09 4.2 engine that could yeild some 20 - 30 hp without putting codes in the PCM. The 85hp of the 5.0 is enticing but I'm not sure I want to pay for it with a millage lose. Thoughts?

 

Your key points are about fuel economy and doing basic mods to increase hp without a loss of mileage. When I bought mine, I didn't care about fuel economy. And I suspect that neither did most of us on this Forum.

Maybe an XK isn't a good choice for you. Especially now, when the prices are crazy high. And the cost of gasoline is skyrocketing.

You're not the first person to ask about modifying an XK, and some Forum members have successfully done so. But modifying an XK won't give you the same driving experience as an XKR, as the supercharger provides low-end torque that simply can't be matched by the normally-aspirated XK. I'd put the money for the XK mods towards buying an XKR.

And no, you can't simply slap a supercharger on an XK.

 

According to the UK brochures, the 4.2 XK combined mpg is 25 and the 5 litre is 25.2 so it is actually better.

Having owned both in XKR format I would definitely recommend the 5 litre over the 4.2. They are just a better all round car.

 

With 100cell cats , x-pipe intermediate pipe and ecu tune my xk was enough to get just over 101mph and a 1/4 mile time of 13.7 .which is knocking on the door of a standard 5l

Have you considered a 4.2 xkr ?? Not only are they are very tunable in the right hands but also have larger brakes then a 4.2 xk and firmer suspension

 

So I’m clear, you are considering buying either a 12yo+ car. The car is a GT. Not a sports car.
And the cost of entry to this particular car is higher than many.
And the cost of maintenance is higher than most.
And if not maintained, it will be a significant headache and wallet ache.

And you are worried about fuel economy when you play with the V8??
How much are you willing to spend on ‘mods’? Because you will need to spend a significant amount to improve the performance of this vehicle…. which will dwarf the amount spent on fuel.

 

About 2 years ago I bought a 2010 XK Convert. with 52K miles. It's my intown summer car, but did take it on a 400 mile trip already.
Got 23.5 mpg keeping the speed limit (75mph), around town it's about 19+ mpg if I keep my foot off the gas pedal.
I bought the car for enjoyment, never even though about mpg
I just bought a new Lincoln Aviator, 200 hp. twin turbo 6, ratings are 18/24, much better the the Ford Expedition I traded in that gave me 8/18.

 

xtriggerman, what do you run for octane in the Lincoln? I see online 87 but since you have mod's perhaps you are running higher octane. Regardless, the XK requires 91, for me here in Florida that is hard to find so I use 93.

Can be a factor, especially if you have 2 mpg as a major decision criterion. Not a criticism, we all have our decision matrix and vary to which data points are important.

 

Thanks for all the replys! The MPG angle is not a major concern but being a diesel guy' I like the efficiency of power to fuel consumption ratio as anyone would that doesn't have an abundance 0f (retired) disposable income. I like working on my cars. The Lincoln mods were 2.5" SS cat back dual exhaust and a modified air box that can use cones or factory filters threw new cold air ducting into the factory box. I wrote an article on it here. A simple Cold Air Intake mod that uses either 4" Cone or OEM filter | Lincoln vs Cadillac Forums I was going to chip the 4.6 but it runs so well now I decided to leave it as is. It runs fine on 87 octane with an occasional 93 tank full on trips as a system cleaner. Ford's PCM corrects pre ignition firing but does recommend premium fuel. Oddly, the car gets the same hand calculated millage on 87 or 93 on the interstate runs. So I dont want to go back wards millage wise over the big Ford's 25 hwy despite the higher cost of fuel since the base XK may not handle 87 octane. It looks like the extra 85hp would be the octane cost adjustment if the 4.2 and 5.0 share the same highway millage. Watched the Brit on YT that likes the 385 hp car best for a DD. Not into the supercharged engines. Being old school, the extra flash engine temps with a water to air intake normally punches up the power with a cost to engine and drive train longevity not to mention all the extra components that can go wrong on top of the fact it will be a used car...... most of which that wont have detailed service records. A used R is not in my picture. As we all have had decent coupes, mine were not as extravagant as an XK, mine being a 71 Cutlass Supreme, 79 RS Camaro and 91 Dodge Stealth. Hopefully, I wont have to travel more than a couple hundred miles for a relatively clean 5.0 base car under 30K. I want this to be my last coupe since I keep them for years and I'm running out of time!

 

Stock for stock (no tune,no mods,,stock) the Mk8 LSC and the 4.2 XK run about the same in the mid 14s,
the 5.0 XK is mid to high 13s,, again stock for stock with average drivers..
Believe it or not your MK8 is just slightly lighter than an XK..
Dont ask me how an aluminum car weighs more than one made of steel but it does.
Hope this helps,, I used to be into hot rod lincolns but mine was a MK7 LSC special edition ..
http://www.hotrodlincoln.org/Gain.jpg

 

Beautiful car. I had a red one just like it (although the wheel spokes were black). The only car I ever bought new. The traction lock really sucked in the winter though.

 

I had a red special edition as well,, in fact I had 3 black SEs and two red SEs but except for the black one above all were stock

 

always had a thing for comfortable fast cars.. another red se

 

Hot Rod Lincoln meet mine is the red se with the black wheels.

 

Stock? I don’t recall mine having that bulging hood.

 

Ahh,yes,,I meant mechanically.

 

I had one of these, super nice to drive. It was also quicker than a lot of other vehicles out there.
Many, many times I'd embarrass a young 'un in a Civic or Scubi off a red light.