Welllllll......slow down lol. A limiting factor here is tuning in my opinion. I have taken off my twin screw just because I was having consistency issues which made it not quite as fun as it should have been. No not selling it just yet.

The engine itself is not rocket science it will respond just like any other supercharged engine. Sadly performance parts just aren’t there. So what you can do is work on intake and exhaust. More boost, better ic circulation and cooling and meth injection in my opinion. And yes that lsd. Certainly if you went internal and ported your heads, maybe am am regrinds...tuning will eventually be an issue .

SC wise I wouldn’t waste money getting the sc ported. I would do a pulley and send out the rotors to get recoated. Not sure where you are but I can send you information. I’d have the inlet reworked and a bored TB if you can still get them done. It’s a shame because a 90mm Tb would be wonderful....but none exist.. You can custom make and air intake setup or buy what’s out there. That certainly helps. Also pro m makes larger MAF that you can use for the jag to reduce restriction.

The upgraded ic pump I used a bosche 010 and a larger heat exchanger helps. A company on eBay sells them much cheaper than eurotoys and I was told the same manufacturer makes all of them. Can’t confirm.

A methanol kit will help avoid detonation with increased boost. Nothing like making less Ho because of timing being pulled.

Exhaust wise just free it up.

600 Hp may be a stretch especially with the stock Heaton.

Good luck though I’m always lurking in the background watching. There are a few here that have maxed out the factory setup. Just search you’ll find them. Or they will find you I think that’s my next route. For now

 

Lightweight wheels reduce drivetrain losses, in other words, a set of lightweight wheels and tyres can boost wheel horsepower by about 10 bhp according to this dynotest comparison.

https://www.civicx.com/forum/threads...-2#post-138103

 

As with lighter wheels, lighter brake rotors can also increase horsepower at the wheel by reducing drivetrain losses.
https://rightfootdown.com/opinions/g...-brake-rotors/

Has anyone installed a set of these to an x350/358?
https://swallows-jag.co.uk/product/w...brake-package/



An extra 20 bhp at the wheels with lightweight rotating parts might be possible. The benefits of quicker acceleration, superior braking and handling make it well worth doing if you want to enhance your driving experience.

 

Those brakes look amazing. Bet they're worth a good amount $$$$

 

With reduced non suspended mass, you don't get more bhp, but you reduce the inertia of the rotating parts, hence a slightly increased acceleration (and livelier steering).
This is also why slightly smaller wheels (e.g. 19" instead of 20") are often used for racing

You can also get lighter, still robust, wheels when they are forged instead of cast (that's the case of the 9"x20" Calisto wheels: less than 10 kg per wheel).
Unfortunately, forged wheels are quite expensive.

 

They dyno measures greater wheel horsepower to be clear, the engine crank horsepower does not increase.

Brakes:



Wheels:







Are you saying that Calisto wheels are forged and weigh less than 10 kg each? There wouldn't be much benefit changing them, even magnesium wheels of that size would only save 2 kg per wheel, I don't think you'll notice that.

I'd be curious to know some actual Jaguar OEM wheel weights (wheels alone and wheels + tyres combined)

 

The OEM wheel size tested is similar to an XJR's with 20 inch wheels.



Results:
1. (Blue curve) Factory wheels: 20”x9.0” with Pirelli 275/40-20 tires weighing 68 lbs combined per rear wheel. – Max hp: 371 hp, Max Torque: 375 ftlbs - (Baseline)
2. (Red curve) Aftermarket wheels: 20”x9.0” with Pirelli 275/40-20 tires weighing 72 lbs combined per rear wheel – Max hp: 369 hp, Max Torque: 373 ftlbs - (A [-] loss of 2 hp and 2 ftlbs)
3. (Green curve) HRE wheels: 20”x11.0” with Nitto 315/35-20 tires weighing 60 lbs combined per rear wheel – Max hp: 380hp, Max Torque: 384 ftlbs - (A [+] gain of 8 hp and 9 ftlbs and that is running a 2” wider wheel/tire combo)

On a Jag X350, if you fit some of the lightest 285/30 ZR 20 rear tyres on 20"x10" forged magnesium wheels you get a much lower combined wheel weight:

28 pounds for a Michelin Pilot Sport Cup 2 tyre and approximately 19.8 pounds for a forged Magnesium rear wheel = 47.8 lbs combined per rear wheel

So if an 8 lb per wheel weight saving produces an 8 wbhp increase, would a 20 lb saving produce an extra 20 wbhp? You'd really notice that kind of improvement.

The car will be 70-80 lbs lighter overall, add those lightweight brakes and it'll be around 100 lbs lighter - that's like removing the weight a slim female passenger.

 

Are you saying if I do these modifications, I can bring a slim female passenger and not feel any decrease in performance?? Sounds like a win win to me

 

YES... and you'll be able to impress her with dragster-like acceleration!


These tyres look so cool:
https://tiresize.com/tires/Toyo/Prox...-255-35R20.htm



but they weigh 6 lbs more than these which also look cool:
https://tiresize.com/tires/Michelin/...-255-35R20.htm - just the tyre weight savings alone are almost comparable with the above dyno test.



Choose wisely or there'll be no slim female wanting to sit in your passenger seat!

 

Looks like I'm out of luck then...



They might be heavy, but the R888r's hook better than any other street tire (as long as its dry, otherwise no traction).

 

Oops!
Weight isn't really a consideration for most people when buying tyres and not many people are aware of the performance benefits. Tyre brands' marketing departments are missing out on something valuable. I'm a keen cyclist and a bit of a "weight weenie" so I can feel what adding lightness provides when riding up hill but the above dynotests were quite surprising to me, small rotational weight savings make a big difference.
I'm sure you'll put those tyres to some good use and they really do look good.

 

Continentals are considered the best overall performing tyres on road bicycles, I'm not surprised to find that they are by far the lightest 285/30ZR20 performance tyres you can buy for cars.

https://tiresize.com/tires/Continent...-285-30R20.htm
Weight: 26.2 lbs

Comparison:
https://tiresize.com/tiresizes/285-30R20.htm

Proxes weigh: 31 lbs (they probably contain more rubber for intense track days)

 

Some weights and prices for Litespeed Racing forged magnesium wheels.

https://www.corvetteforum.com/forums...ceptional.html

The RS5 monoblock wheels are actually lighter than I thought at 16.9 lbs for a 20" x 9.5" wheel (so maybe 17.2 lbs for 20" x 10" ?)

The maximum possible drivetrain power loss reduction from the lightest wheel and tyre combination available on the market = 17.2 + 26.2* lbs = 43.4 lbs combined per rear wheel (approx)

*Continental Extreme Contact Sport summer tyre

 

I was wondering about performance camshafts for the AJV8, does anyone know of any other place to get them? Or is there any other information like dyno tests etc.

https://jagexports.en.ecplaza.net/pr...amshafts_74928

I wonder how different camshaft profiles would change a supercharged engine's performance profile.

 

Here is a thread with some 20" Jaguar XFR-S OEM vs lightweight wheel weights: https://www.jaguarforums.com/forum/x...2/#post2023765

2014-15 XFR-S- Front - 20" x 9" = 32.2 lbs, (Rear - 20" x10" = 36.6 lbs)

Were Pirelli P-Zeros standard fit to the x350/358 XJR?
https://tiresize.com/tires/Pirelli/P-Zero-255-35R20.htm = 25 lbs

So if X350 XJR OEM wheels weigh the same or close:
Combined per wheel weight = 57 lbs
Lightest possible wheel combo = 43.3 lbs

Weight reduction = 13.7 lbs per wheel (or close)

 

The above list of upgrades is based on dynotest data and claims from companies offering their services. The power increases stated are usually measured at the wheels so the above additions don't take into account drivetrain losses making it possible for engine power at the crank to approach or pass beyond 600 BHP

Is there anything mentioned in the above upgrade list that seems unrealistic to you?

 

There isn't much I can agree with, except maybe the start engine hp of 400 ;-)

1st of all ask yourself why after so many years there is no one yet that comes even close to what you hope to get, except for the Brisks and the ported heads, its not so exotic what was listed.

With regards to plugs, are these dyno increases against the known iridium brands?
Ported heads, even ET doesn't have any evidence you can gain the suggested amounts, and I have never seen any dynos on our engines, not much I can say about it else. Another way to get more air into the cylinders is modifying the cams, or even go further in enlarging the valves, especially if you consider such an expensive update as porting.
Never seen any evidence from a ported Eaton on our cars, I doubt you gain really something measurable, other then noise.
Pulleys, indeed, take the 25 number top end as closer to reality
A sports cat will probably help most when thinking about an exhaust, should be easily 15 HP or more. Some exhaust experiences (larger ones) here on the forum noted lower midrange with them, so really hard to say without any detailed specifications on an Exhaust. Anyway I don't have experiences myself (other then the cats), am still using the stock exhaust.
An intake update, so from air entry all the way into the SC would be needed, so a larger TB as well that could give you around 20 hp on a stock car, and allows also more gains when doing multiple upgrades. Its simple the more air you want to get in, the better the intake needs to be to accommodate that.

Haven't followed so much the threads, but iirc getting to 500 is already a challenge with the (h)eaton, doing another 100 extra would give you a god like status, but go for it, the path alone maybe already worth it!

You may want to consider way more, like NOS or so.

 

I think that I have listed all the well known performance upgrades for the XJR, have I missed anything?

 

Thanks for your input Avos! Perhaps there is still potential to get your car up to 800 hp? There are lots of untested claims.

The 4.2L Supercharged cars have reached a price range where they are a good base for performance mods, it's good to know what works and what doesn't.

Silver electrodes in Brisk spark plugs create a more powerful spark apparently, whereas iridium plugs are designed to be longer lasting. I did link some dynotests in post #15. Small HP gains were made which isn't bad for such a cheap upgrade.

Oh and by the way these might be the cats you're looking for - https://www.verociousmotorsports.com...tic-Converters when you build your new exhaust system

 

800 HP is in reach, at least with some efficiency updates, for example switching now to the 3.2L KB unit, would yield already 30 (potentially 60), but at some point something will say boom am afraid, so am not going to push into that direction anymore, 700 is great, believe me.

Didn't see any dyno (checked 2) that compared the Brisk to a known iridium brand, do you have that? Only then you may know if and how much you get there, so far I am not convinced about gains (for info I use the Denso IK01-24)

How much do you want to spend actually?