Non SC XK horsepower upgrade
#1
#3
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The easiest, cheapest and most responsible way to do what you ask is, and I'm totally serious here, is to sell the XK and buy an XKR. I'm an old hot rodder from way back and it was my job to make more power from everything I owned. I won't do that on an XK, it's not easy nor cheap to do it other than going XKR. Plus then, you can go up from there!
#4
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This question is asked across our model forums with great regularity. Unless you have very deep pockets and specifically want the challenge, that is the answer.
Graham
#6
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Get a 5.0 XKR, there's still some more there to play with. 550 is easy with a tune and X-pipe with resonator delete. Add a pulley, cooler pump and a proper tune and you're around 600.
For me, and ever since I was a kid, there is no such thing as "...which is plenty". More power is ALWAYS better.
#7
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Thing is though, once you're on par with the 4.2 XKR, there's nowhere else to go. Also, that's not a huge upgrade from a 5.0 N/A.
Get a 5.0 XKR, there's still some more there to play with. 550 is easy with a tune and X-pipe with resonator delete. Add a pulley, cooler pump and a proper tune and you're around 600.
For me, and ever since I was a kid, there is no such thing as "...which is plenty". More power is ALWAYS better.
Get a 5.0 XKR, there's still some more there to play with. 550 is easy with a tune and X-pipe with resonator delete. Add a pulley, cooler pump and a proper tune and you're around 600.
For me, and ever since I was a kid, there is no such thing as "...which is plenty". More power is ALWAYS better.
The Turbo 13b is capable of over 1,000 flywheel horse.
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#8
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https://www.caranddriver.com/news/a1...he-difference/
It's not "more or less". It's "more and less." That modded XK engine will have more HP than before, but still less than the XKR.
That will be most noticeable in normal, everyday street driving where torque matters.
I'm not saying that it's not worth doing those mods. What I am saying is don't expect it to drive like an XKR.
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khlee (03-04-2021)
#9
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I found out it is possible to have too much horsepower. I had a '75 Porsche 911 that needed an engine rebuild. The 2.7 magnesium case was 170 flywheel horse from the factory. The max the magnesium case was capable of was 270 flywheel. The '75's were not worth the cost of a rebuild at the time so I installed a Turbo rotary 13b for less than the cost of a stock rebuild. Redline was 10,500 RPM Dynoed at 333 Rear Wheel Horsepower. It was not safe to floor it unless it was pointed straight ahead. Turn the steering wheel and the rear end came around. I will say that it was a LOT of fun.
The Turbo 13b is capable of over 1,000 flywheel horse.
The Turbo 13b is capable of over 1,000 flywheel horse.
My naturally aspirated P/S Mustang II has about 800 hp, 1100 on spray, and yes, the front end comes up on acceleration and if it the steering wheel was turned, the car still goes straight...... until the front comes down. NOT a good scenario.
Regardless, I stick with my original comment.
#10
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Those two statements completely negated each other.
My naturally aspirated P/S Mustang II has about 800 hp, 1100 on spray, and yes, the front end comes up on acceleration and if it the steering wheel was turned, the car still goes straight...... until the front comes down. NOT a good scenario.
Regardless, I stick with my original comment.
My naturally aspirated P/S Mustang II has about 800 hp, 1100 on spray, and yes, the front end comes up on acceleration and if it the steering wheel was turned, the car still goes straight...... until the front comes down. NOT a good scenario.
Regardless, I stick with my original comment.
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Cee Jay (03-01-2021)
#11
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In 1983, a California jury decided that the Porsche 930 Turbo was too dangerous to drive.
https://www.upi.com/Archives/1983/06...4466425793600/
https://www.upi.com/Archives/1983/06...4466425793600/
Last edited by Stuart S; 03-01-2021 at 12:51 PM.
#12
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What is "more or less"? In terms of 1/4 mile times, those mods will make it quicker on the strip but, with all other things being equal, a 300HP 4.2L normally aspirated XK with those mods won't have the low end torque or horsepower of a stock 420HP supercharged XKR. Those mods will be most noticeable at the highest RPMs. "... to make more power an engine needs to generate more torque, operate at higher rpm, or both."
https://www.caranddriver.com/news/a1...he-difference/
It's not "more or less". It's "more and less." That modded XK engine will have more HP than before, but still less than the XKR.
That will be most noticeable in normal, everyday street driving where torque matters.
I'm not saying that it's not worth doing those mods. What I am saying is don't expect it to drive like an XKR.
https://www.caranddriver.com/news/a1...he-difference/
It's not "more or less". It's "more and less." That modded XK engine will have more HP than before, but still less than the XKR.
That will be most noticeable in normal, everyday street driving where torque matters.
I'm not saying that it's not worth doing those mods. What I am saying is don't expect it to drive like an XKR.
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Cee Jay (03-01-2021)
#13
#15
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In light of current prices of used 5.0L models and if power is an important factor, it simply makes more sense to put that $3K towards buying an XKR.
I'm not knocking the XK; it's a great car with plenty of power for most people most of the time. The XK is plenty fast and really doesn't need more power. But if you want more power, forget the XK and get the XKR. It's scary fast!
I'm not knocking the XK; it's a great car with plenty of power for most people most of the time. The XK is plenty fast and really doesn't need more power. But if you want more power, forget the XK and get the XKR. It's scary fast!
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SEAICE (03-04-2021)
#17
#18
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In light of current prices of used 5.0L models and if power is an important factor, it simply makes more sense to put that $3K towards buying an XKR.
I'm not knocking the XK; it's a great car with plenty of power for most people most of the time. The XK is plenty fast and really doesn't need more power. But if you want more power, forget the XK and get the XKR. It's scary fast!
I'm not knocking the XK; it's a great car with plenty of power for most people most of the time. The XK is plenty fast and really doesn't need more power. But if you want more power, forget the XK and get the XKR. It's scary fast!
I never said that the OP should sell his XK and buy an XKR. You did.
I simply presented some food for thought. Does it make more sense to spend $3,000 to modify an XK or put that money towards buying an XKR?
Many 5.0L XK/XKR models are currently for sale in the USA. It's possible to pay $3,000 or less over the price of an XK to buy an XKR. Search this site: https://www.cars.com/
Cheers!
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Stuart
#19
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#20
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My ECU tune is way less than 3k , for a similar gain on NA car . Pm for pricing
__________________
2008 XKR Convertible, (mods: AlphaJagTuning ECU Tune , 1.5lb pulley, (200cel cats( are now melted), xpipe, Bosch 001 pump, 180 Thermostat.
Drag strip : 7.9sec 1/8mi 90 MPH . 1/4 mile 12.55 at 111.98mph
432rwh Dyno on Mustang Dynometer , Approx 511 crank HP.
2013 XJ 5.0 Supercharged, (stock with Alpha Jag ECU tune), estimated power: 600+ hp, 7.7sec 1.8th mi/95mph
![](https://www.jaguarforums.com/forum/signaturepics/sigpic171814_2.gif)
Drag strip : 7.9sec 1/8mi 90 MPH . 1/4 mile 12.55 at 111.98mph
432rwh Dyno on Mustang Dynometer , Approx 511 crank HP.
2013 XJ 5.0 Supercharged, (stock with Alpha Jag ECU tune), estimated power: 600+ hp, 7.7sec 1.8th mi/95mph