VAP tried to design some long tube headers for the AJ133 but gave up a couple of years ago, they just could not get them to work in the constrained engine bay space of most applicable JLR vehicles such as the F-Type.

 

In my 16 XJR I’m well over 700-750 with the tune and ported supercharger and many many other mods. So whoever said Max of 615hp is dead wrong on that unless I misread that somehow. I’ve been hammering on mine for over 5 years and no issues other than the pvc coolant pipe deteriorating basically. (Knock on wood).

I’ve heard anymore than 800HP and the studs need to be replace and potentially better pistons. I’d like to get into the engine sometime but I’ll probably wait till it’s necessary.

 

Marcofromtrubulya, Have you driven a 3 liter V6 SC XJ? It's no slouch. I was also hunting for a V8 in a specific color, mileage, and interior for a year. I found the pristine CPO car but with a V6, 8 speed tranny, and RWD, (RWD is a little quicker than AWD). I drove it and was pleasantly surprised at how agile and quick it was. I bought it and it does everything I need to do for a daily driver. And I certainly wasn't disappointed with 29.5 mpg either. So, unless you absolutely have to tear the tires off for blocks, there is nothing to sneeze at with the V6 SC and 8 speed trans.

 

The transmission as posted above can take what you throw at it.
How do I know? Easy-where are all the blown up transmissions because of engine mods making more power? We have none on this forum that I can find.

I have posted this before but the Jaguar world is WAY behind the US muscle cars! If we were building big power you would see what happens on the muscle car forums. Broken axles, rear ends and twisted off drive shafts. Yes I have read of maybe one or two broken axles with guys racing XF's. That's not many.

Then look at the aftermarket and see what's out there and that also tells the tale.
Here is one of many upgraded drive shafts for a CTS-V which is a fairly equivalent car to the Jaguar 5.0L SC in stock form.
Note it's rated at 1500HP! They would not be building parts like this unless there was a need and a demand. Plus it's $2500 so not something you would add unless it was absolutely needed!
CF CTS-V Drive Shaft

When the forum becomes filled with broken parts because of mods and racing then you can see where the weak points of the car are. We don't have that and never will.
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I believe Boosted Ricky is in the 10’s in the 1/4 with a stock tranny, rear end, etc.

The cars can make and take power - you’re just limited on options.

 

Yes he is one of the fastest and he does beat on the car which is what has to be done to find all the weak spots.
I thought he had broken an axle? I can't remember?
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I don't know if he did or not but if he did I would assume that's related to very sticky drag tires combined with the power output. I would think that the casual guy that's highly modified running PS4S' wouldn't have that problem because traction will be optional. Hell, even at stock power my XJR running 305 PS4S' still fights for traction.

 

Oh my car too. I read a statement on a car forum that really hit home. He said once you get the car above about 500HP or so on the street it's then all about traction. As posted above power without traction=smoke!
So drag radials are needed for us to hook properly. But man does that load the drive train!
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