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The aluminium construction makes the x350/358 impressively light for a car its size, that is why it attracts me so much. With a kerb weight of 1659 Kg - (3657 lbs) it doesn't weigh much more than some 2 seat supercars like the Porsche Turbo or Corvette
Boosting the engine's power is simple enough but soon gets maxed out unless you can afford a twin screw mod etc. so subtracting weight is the next step to increase performance.
Which elements can be removed or modified to make the X350/358 lighter and how much weight can be saved with each modification?
Last edited by SABARRAS; Feb 22, 2021 at 03:02 AM.
This Swallows Racing X300 race car is in a 1400 kg (3086 lbs) racing category, the manual gearbox production car weighs 1775 Kg / 3913 Lbs - so a weight reduction of 375 kg / 827 lbs assuming they reached the minimum weight for that class.
If you were to reduce the X350's weight by the same 375 kg, that would put it in the same weight category as the Pagani Zonda C12. at 1284 kg / 2830 lbs!!!
If the X350 XJR actually produces 400 bhp at the crank and has a curb weight of 1659 kg, that gives it a power to weight ratio (in the UK form) of 241.11 BHP/Tonne
The power to weight ratio of the stripped out race car spec x350 mentioned above with a standard engine - 400 BHP + 1284 Kg = 311.53 BHP/Tonne
This is similar to a 2012 Lotus Exige S3 V6 which accelerates from 0-60 mph in 4.0 seconds, a whole second quicker than the standard Jag XJR.
To put that into perspective, you would require 517 BHP to achieve the same power to weight ratio with the standard car's weight.
So what if you wanted to create the lightest and most powerful X350 XJR for drag racing, hardcore track days etc. Starting with the above race spec weight of 1284 Kg and say 650 BHP with a Kenne Bell Twin screw supercharger and all the trimmings. You get 506.23 BHP/Tonne
That's not much less than the original Bugatti Veyron - 530 BHP/Tonne
Depending on traction, 0-60 mph time should be somewhere between 2.8 and 3.5 seconds.
To put that into perspective, if you maintained the standard car weight, you would need 840 BHP to achieve the same power to weight ratio.
11.5 kg (25.3 lbs) for a reclining composite sports seat, This could be a big weight reduction if you are willing to reduce the luxury levels of the Jag's interior. I suppose you could make them match the other trim.
"Like the seat, the base is powerful and lightweight. Consider this example. The Sportster GT weighs about 35 lbs., the metal base and slider are about 8 lbs., and the bolts are an additional 2 lbs. For two GT seats, that comes to a grand total of 90 lbs. In contrast, stock OEM seats of a BMW are stuffed full of electronic and mechanical hardware and will typically weigh around 75 lbs. each. This means that you will shave a full 60 lbs. off your vehicle’s weight by switching to Sportster GT."
Last edited by SABARRAS; Feb 21, 2021 at 12:30 PM.
Front Wheel 20" x 9" Litespeed Racing RS5 Forged magnesium= 7.5 Kg (16.7 lbs)
Rear Wheel 20" x 10" Litespeed Racing RS5 Forged magnesium = 7.8 Kg (17.2 lbs)
Front Tyre 255/35ZR20 Continental Extreme Contact Sport = 10.9 Kg (24 lbs)
Rear Tyre 285/30ZR20 Continental Extreme Contact Sport = 11.9 Kg (26.2 lbs)
Total = 76.2 Kg (168 lbs) approx.
Approximate 20" x 9" OEM wheel weight = 14.6 Kg (32.2 lbs)
Pirelli P zero tyres 255/35ZR20 = 11.4 Kg (25 lbs)
Total = 104 Kg (229 lbs)
Total wheel/tyre weight reduction = 27.6 Kg (60.8 lbs) - all 4 wheels.
*You could buy even lighter 19" wheels but if you were going to invest that much money in magnesium wheels you'd want them to look good too.
So Lighter wheels, tyres and front seats can reduce the overall weight by 54.9 Kg, (120.8 lbs) If you do all this your Jag's curb weight will now be down to approximately 1604 Kg
Last edited by SABARRAS; Feb 21, 2021 at 12:28 PM.
Carbon ceramic brakes can save a total of 11- 13 Kg (24-28 lbs) over cast iron brakes according to this article, it doesn't specify if that means 2 piece or monoblock rotors.
Run on empty. A full tank of petrol weighs 60kg ~ 66kg.
Drive barefoot. Typical pair of shoes weighs 0.7kg.
But you just can't compete with teenagers, very old people, or an amputee...
Run on empty. A full tank of petrol weighs 60kg ~ 66kg.
Drive barefoot. Typical pair of shoes weighs 0.7kg.
But you just can't compete with teenagers, very old people, or an amputee...
Brilliant! Competitors will never think of that on the drag strip!
If you upgrade from cast iron mononlock rotors to 2 piece rotors of the same size, there is a 0.6 - 0.7 Kg (1.32 - 1.54 lbs) weight saving per corner. so a small 2.6 Kg (5.72 lbs) weight saving overall
Brembo calipers weigh 4.6 Kg (10lbs - 6 piston) while porsche OEM calipers weigh 5.2 Kg (11.44 lbs.) I suspect that Jaguar pistons will be similar 5 - 6 Kg for the fronts.
Lets estimate that Magnesium calipers are about 2.6 + 2.4 Kg lighter than Jaguar OEMs or Brembos per corner, that is an extra 10 Kg reduction
Rotors = 2.6 kg saving + Calipers = 10 Kg saving = Total saving with lightweight metallic brakes = 12.6Kg
Throw out the spare tire. I've got 2 other cars that don't even have a spare tire. Just a squirty thing.
I didn't have any spare in my Lotus Elise, just the squirty stuff too.
How much of a weight saving is that? Would you be able to weigh those 2 elements (for science ) please?
Last edited by SABARRAS; Feb 22, 2021 at 02:47 AM.
How much weight could you save by removing all that paint? I suspect a substantial amount. The plastic bumpers do need to be painted with some chrome paint to match and a few layers of 2 pack lacquer would protect from oxidation but there is a lot of surface area on the jag and several layers of primer, paint and lacquer are required.
Adding lightness
at 1284 kg / 2830 lbs!!!
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