I have a 03 STR - i'm new to Jag and the STR.
I was putting my "new" car thru its paces today.

In non sport mode , at WOT off the line , the box seems to short shift and change at about 4700 , in sport mode , 1st goes to round 5000.
The car feels fast , but not 400HP fast...I have lesser powered Corvettes that seem a lot faster...but they are far less refined

Traction control was on .. I haven't tried TC off... Do I need to have TC off to reach redline?
I'm pretty sure the accelerator pedal cant go more - no mats/carpet under it ..or maybe I need to use more force?
Should I rather row thru the gears manually in the jgate , which I dont fancy as they are not one push sequential , so its east to skip a gear..
I didnt hold it against the brake and try get the revs up when launching..
What am I doing wrong ? or am I expecting too much?

 

Sounds about right to me, you can try a pulley upgrade for about 35-40 extra hp (at lower revs, no difference towards redline) , hi flow cats, exhaust etc... Or add nos for 100hp more, I belive the gearbox is good for upto 600hp but I'm sure someone more knoladgeable will be along shortly.

 

I'm not really wanting to modify it , I have my vettes for that
I'm just thinking that the 5000 redline in D (S or nonS) is scrubbing off power that is already there...

 

A lot of what you noticed gets reviewed here: 2003 Jaguar S-type R - Road Test - Car Reviews - Car and Driver

 

My 03 STR short shifts first as well. But in sport mode takes 2nd and 3rd all the way to 6100 rpm. There is nothing that I know of atm that you can do about 1st gear, apparently it is in the programming of the zf tranny's pcm. Not sure if it's even referred to as that. But being domestic guy like me you know what I mean. Keep in mind she is a heavy girl.3968 lbs. Mixed with an open diff and highway gears. I believe 2.89. So even with 400 ftlbs she isn't going to react like your vette. From what I have read and found from searching there isn't a lot of aftermarket support for these cars like there should be,imho. I too would like mine to truly be a wolf in sheep's clothing. Personally I like the idea of swapping in a 5.0 out of an xkrs. But have not found any support on the idea. But there is a complete engine on e bay for $5500.00 I wish you luck on your quest.

 

You'd be the first I've heard of who'd contemplate $5500 or anything in that region. People seem to have a budget much closer to zero.

 

I would imagine a nice seat of the pants upgrade would be a diff ratio change...done lots on my vettes , makes even a docile car lot wilder
A 3.55:1 LS diff would be a peach...

 

There are existing threads about pretty much any potential change you can name if you read, including that.

 

Rear end ratio change won't work, it will throw the tcm into a tizzy.

TCM short shifts to save the tranny in first.


Keep it as it is and enjoy it, there is no easy way to get power from these cars.

 

TCM short shifting 1-2 and 2-3 is well documented, the 05+ cars supposedly remedy this...?

There is no known TCM flash or modification that can be performed to bring those shifts to redline. If you manually shift using the J-gate, you will just bounce off the (slightly lowered) rev limiter,

As for the mods to get the most out of your STR, they are limited,

Pulley (boost increase), intake and exhaust mods, that about frees up all the power you can net from the factory eaton m112 blower,

Differential/gear change would be nice, as the 2.87 final drive is pretty long, but for one thing, there is no known way to reprogram the electronics to accept the gear change without going into limp mode,

There is a kenne bell twin screw supercharger upgrade on the horizon, brought to you by our man AVOS in Belgium, which promises 100-200hp power increase, depending on options/spec you set it up to, but price is not for the faint of heart... and it's still in the final stages of development, so not yet available...

 

dont know about 1st ,but my 06 red lines on the rest...

 

Rodney you have to take into consideration power to weight ratio! I'm sure your Vettes don't weight 4,000lbs!

 

LOL I hear ya money doesn't grow on trees. But to me 5500 for more cubes and more go isn't bad compared to just a supercharger upgrade. Just thinking out loud. I wonder how hard it would be to go to a 5r55s? That auto in the form of 5r55n comes in late model jags. It is a Ford tranny out of s197 mustang with the 3valve v8. It too is good to 600hp+ from factory. With much more positive shifts and will hold the gear change to redline.again just thinking out loud.

 

They make the clutch pack that can hold 600hp or 1000+hp, what else would you need? lol

 

How to wring out the last ounce of power?

Based on your title. I was hoping you were building up an engine...

I am tearing apart the engine from the 03 STR I recently purchased. I am making plans for a 4.2 engine build. I am still in the planning stage.. Budget versus power gains and reliability. What to do...